WO2014171383A1 - Device and method for reducing ion concentration in aqueous liquid held in system, and apparatus equipped with said device - Google Patents

Abstract

Disclosed is a device for reducing the ion concentration in an aqueous liquid (201) held in a system (200). The device is equipped with at least one ion adsorption unit (100). The ion adsorption unit (100) is equipped with a liquid passage and multiple electrode pairs arranged in the liquid passage. The liquid passage is equipped with an inlet port (110a) and an outlet port (110b) both of which are connected to the system (200) so as to form a circulation path that includes the liquid passage and the system (200). Each of the electrode pairs comprises a first electrode and a second electrode. The first electrode contains a first electrically conductive substance containing activated carbon. The second electrode contains a second electrically conductive substance containing activated carbon. Each of the first electrode and the second electrode faces a void in which the aqueous liquid (201) flows.

Description

Apparatus and method for reducing ion concentration of aqueous liquid held in system, and apparatus including the apparatus

The present invention relates to an apparatus and method for reducing the ion concentration of an aqueous liquid held in a system, and an apparatus including the apparatus.

Water used for cooling, such as cooling tower water, accounts for nearly 80% of industrial water. This cooling water is cooled by removing the heat of evaporation. Therefore, it is necessary to replenish the evaporated water. At that time, various ions contained in the makeup water are added to the cooling water. On the other hand, the evaporated water contains almost no ions. Therefore, as the cooling water evaporates, the ion concentration in the cooling water increases and scale is generated. Further, when the chlorine ion concentration in the cooling water is increased, the system is easily corroded. Therefore, in the conventional cooling water system, the cooling water is periodically drained and replaced with makeup water. In this case, a large amount of waste liquid is generated. In this case, a large amount of makeup water is required. Large amounts of waste liquid and make-up water increase system maintenance costs.

In order to reduce the amount of waste liquid, a chemical that suppresses the precipitation of scale is also added to cooling water (for example, JP 2011-224455 A). However, even with the use of chemicals, the amount of waste liquid and makeup water could not be reduced sufficiently. Moreover, when a chemical | medical agent is used, environmental pollution may arise or the process of a waste liquid may be needed.

In order to suppress scaling, a method using a flow-through capacitor has also been proposed (for example, Japanese Patent Application Laid-Open No. 2012-232233). Japanese Patent Application Laid-Open No. 2012-232233 proposes a structure for reducing the distance between electrodes of a liquid-pass capacitor. However, such a liquid passing type capacitor has a problem as described later.

JP 2011-224455 A JP 2012-232233 A

Although the above issues are very important in a country with little water resources, no good methods have been proposed yet.

In such a situation, an object of the present invention is to provide a novel apparatus and method for reducing the ion concentration of an aqueous liquid retained in a system.

In order to achieve the above object, the present invention provides an apparatus for reducing the ion concentration of an aqueous liquid held in a system. The ion concentration reducing device includes at least one ion adsorbing unit, the ion adsorbing unit includes a liquid path and a plurality of electrode pairs arranged in the liquid path, and the liquid path is the liquid path. And an inlet connected to the system so that a circulation path including the system is formed, the electrode pair includes a first electrode and a second electrode, and the first electrode The electrode includes a first conductive substance containing activated carbon, the second electrode includes a second conductive substance containing activated carbon, and each of the first and second electrodes includes the aqueous liquid. Facing the air gap through which.

The present invention also provides another device. The apparatus includes a system for holding an aqueous liquid and the ion concentration reducing apparatus of the present invention for reducing the ion concentration of the aqueous liquid.

The present invention also provides a method for reducing the ion concentration of an aqueous liquid retained in the system using the ion concentration reducing apparatus of the present invention. This method
(I) Between the first electrode and the second electrode so that the first electrode becomes an anode in a state where the aqueous liquid is circulating between the ion adsorbing portion and the system. Adsorbing ions in the aqueous liquid to the first and second conductive materials by applying a voltage to
(Ii) In a state where the flow of the aqueous liquid from the ion adsorbing unit to the system is interrupted, the ions adsorbed by the first and second conductive substances are released to the liquid in the ion adsorbing unit, And discharging the liquid from which the ions have been discharged to the outside of the circulation path.

According to the present invention, the ion concentration of the aqueous liquid retained in the system can be easily reduced.

It is a figure which shows typically the relationship between the electric potential of an activated carbon electrode, the reaction potential of the electrolysis of water, and adsorption | suction of ion. It is a figure which shows typically the state of adsorption | suction and discharge | release of an ion in case the capacity | capacitance of an anode and the capacity | capacitance of a cathode are the same. It is a figure which shows the typical equivalent circuit of an ion adsorption electrode. It is a figure which shows typically the state of ion adsorption when the capacity | capacitance of an anode is made larger than the capacity | capacitance of a cathode. It is an image figure which shows the relationship between voltage application time and an ion adsorption rate. It is a figure which shows typically an example of the ion adsorption part contained in the apparatus of this invention. It is sectional drawing which shows typically an example of the electrode block contained in an ion adsorption part. It is a figure which shows an example of arrangement | positioning of wiring typically. It is a front view which shows typically an example of the spacer used by this invention. FIG. 10 is a cross-sectional view of the spacer shown in FIG. 9. FIG. 10 is another cross-sectional view of the spacer shown in FIG. 9. It is a figure which shows typically an example of the apparatus of this invention. It is a figure which shows typically another example of the apparatus of this invention. It is a figure which shows typically a part of other example of the apparatus of this invention. It is a figure which shows typically another example of the apparatus of this invention. It is a figure showing typically one state of an example of an embodiment of the present invention. It is a figure which shows typically other states of the example shown to FIG. 16A. It is a figure which shows typically an example of the electrode pair of this invention. It is a figure which shows typically another example of the electrode pair of this invention. It is sectional drawing which shows typically another example of the electrode pair used by this invention. It is sectional drawing which shows typically another example of the electrode pair used by this invention. It is a figure which shows typically an example of the water quality adjustment apparatus which can be used by this invention. It is a figure which shows typically an example of the free chlorine concentration adjustment apparatus which can be used by this invention. It is a graph which shows an example of the result of having investigated the relationship between the flow velocity of the aqueous liquid which flows through an ion adsorption part, and the change of the electrical conductivity of aqueous liquid. It is a graph which shows another example of the result of having investigated the relationship between the flow velocity of the aqueous liquid which flows through an ion adsorption part, and the change of the electrical conductivity of aqueous liquid. It is a graph which shows a part of result of the Example which processed 100 L of aqueous liquid. It is a graph which shows a part of result of the Example which processed 100 L of aqueous liquid. It is an image figure which shows the change of the ion concentration of a system | strain by this invention. 10 is a graph showing the results of Example 2. 10 is a graph showing the results of Example 3. It is a figure which shows typically an example of the ion removal by the conventional batch method.

Hereinafter, embodiments of the present invention will be described. In the following description, embodiments of the present invention will be described by way of examples, but the present invention is not limited to the embodiments described below. In the following description, specific numerical values and specific materials may be exemplified, but other numerical values and other materials may be applied as long as the effect of the present invention is obtained.

(Ion concentration reduction device)
The apparatus of the present invention for reducing the ion concentration of the aqueous liquid held in the system will be described below. Hereinafter, the device may be referred to as “device (A)”. In addition, the system in which the aqueous liquid is held may be described as “system (S)” below. In another aspect, the apparatus (A) of the present invention is an apparatus for removing ions in an aqueous liquid in the system (S), and concentrates ions in the aqueous liquid in the system (S) to remove the ions from the system (S). It can also be used as a device for discharging, a device for preventing deterioration of the system (S), a device for increasing the ion concentration by circulating and concentrating the aqueous liquid on the drain side, or a device for reducing the hardness of water.

The apparatus (A) of the present invention includes at least one ion adsorption unit. One ion adsorption portion includes a liquid path and a plurality of electrode pairs arranged in the liquid path. Hereinafter, the liquid path may be referred to as “liquid path (P)”. The liquid path (P) includes an inlet and an outlet connected to the system (S) so that a circulation path including the liquid path (P) and the system (S) is formed. In one aspect, by connecting both ends of the liquid path (P) to the system (S), a circulation path including the liquid path (P) and the system (S) is formed. One electrode pair includes a first electrode and a second electrode. Each of the first and second electrodes is typically a flat electrode. The first electrode includes a first conductive material containing activated carbon. The second electrode includes a second conductive material containing activated carbon. Each of the first and second conductive materials typically has a flat plate shape. Each of the first and second electrodes faces a void through which the aqueous liquid flows. In another aspect, the first and second conductive materials each face a void through which an aqueous liquid flows. The plurality of electrode pairs may be connected in parallel or in series. When a plurality of electrode pairs are connected in parallel, the first electrodes included in the plurality of electrode pairs are connected to each other, and the second electrodes included in the plurality of electrode pairs are connected to each other.

The electrode pair may further include a spacer disposed between the first electrode and the second electrode. And the space | gap through which aqueous liquid flows may be formed of the spacer.

The spacer is disposed between the first electrode and the second electrode in order to prevent a short circuit between the first electrode and the second electrode and to secure a flow path of the aqueous liquid. By arranging the spacers, the distance between the electrodes can be kept at an equal interval. As the spacer, an insulating spacer having a space through which liquid flows can be used. Examples of such a spacer include a resin net (for example, Netron (registered trademark, NETLON)). An example of a preferable spacer is a resin net in which the thickness of the crossed portion is thicker than the other portions. The spacer preferably has a hydrophilic surface. Examples of the spacer having a hydrophilic surface include a spacer made of hydrophilic acrylic resin.

In an example of the ion adsorption unit, a plurality of electrode pairs are connected in series to form one electrode group, and only two electrodes existing at both ends of the electrode group are connected to the power source. In this case, the two electrodes present at both ends of the electrode group are connected to the positive electrode and the negative electrode of the power source. Even in this case, a spacer is usually disposed between the first electrode and the second electrode in one electrode pair.

An example of the apparatus of the present invention may include a plurality of the above electrode groups. And the some electrode group may be connected in parallel. When many electrode pairs are connected in series, the voltage to be applied may be too high. In such a case, the electrode pairs may be divided into a plurality of electrode groups and connected in series within one electrode group, and the plurality of electrode groups may be connected in parallel.

When a voltage is applied between the electrodes in step (i) described later, water may be electrolyzed to generate gas. If the generated gas remains on the surface of the spacer or electrode, the speed of ion adsorption decreases. In order to quickly release the generated gas to the outside, the surface of the spacer is preferably hydrophilic. Moreover, the flow rate of the aqueous liquid flowing through the ion adsorbing portion may be increased to facilitate gas discharge. Further, in the ion adsorbing portion, the gas may be easily discharged by allowing the aqueous liquid to flow upward from below.

The distance between the first electrode and the second electrode can be changed depending on the thickness of the spacer. Usually, the distance between the electrodes of the plurality of electrode pairs in the electrode block is substantially equal. In one electrode pair, the spacing between the first electrode and the second electrode (substantially equal to the spacer thickness) may be in the range of 0.2 to 10 mm, for example 0.3 It may be in the range of ˜10 mm, in the range of 0.3 to 5 mm, in the range of 0.5 to 2 mm, or in the range of 0.5 to 1.5 mm. By narrowing the electrode interval (for example, 10 mm or less or 2 mm or less), the ion movement distance can be shortened, and the potential gradient at the time of voltage application can be abrupt. As a result, the ion adsorption rate can be increased. Further, by setting the electrode interval to 0.2 mm or more (preferably 0.3 mm or more or 0.5 mm or more), the aqueous liquid can easily flow between the electrodes, and as a result, the flow of the aqueous liquid is concentrated in part. The phenomenon (channeling) can be suppressed. By suppressing channeling, variations in the amount of ion adsorption within the surface of the conductive material (activated carbon electrode) can be reduced, the rate of ion adsorption can be increased, and the ion adsorption amount of the electrode can be increased. In addition, because the aqueous liquid can flow quickly by maintaining the space between the electrodes, the variation in the amount of ion adsorption on the activated carbon on the introduction side of the aqueous liquid and the amount of ion adsorption on the activated carbon on the discharge side of the aqueous liquid Can be small.

In the conventional liquid passing type capacitor, two electrodes (anode and cathode) are arranged so as to be alternately stacked with a separator interposed therebetween. In order to increase the capacity per unit volume and reduce the resistance between the electrodes in the liquid-permeable capacitor, it is necessary to shorten the distance between the anode and the cathode as much as possible. For this reason, in a conventional liquid-flowing capacitor (for example, the capacitor described in JP 2012-232233 described above), the distance between the electrodes is shortened by using an extremely thin separator. In that case, the liquid flowing through the capacitor mainly flows through a small path called a channel existing at the interface between the electrode and the separator. As a result, the adsorption of ions increases in the vicinity of the channel and decreases in other portions. In order to adsorb as many ions as possible, it is necessary to perform ion adsorption even at a portion away from the channel. However, it is necessary to apply a voltage for a long time to adsorb ions to such a portion.

In addition, since the conventional liquid-flow type capacitor is designed so that as many ions as possible are adsorbed while the liquid passes through the capacitor once, before the ion adsorption amount near the liquid discharge port is saturated, The amount of ion adsorption near the liquid inlet is saturated. That is, in the conventional liquid flow type capacitor, the bias of ion adsorption in the electrode is large. Therefore, most of the activated carbon does not contribute to the ion adsorption in the conventional liquid-flow type capacitor. For example, compared with the activated carbon utilization rate of a parallel plate type capacitor in which two electrodes are separated in an aqueous liquid, the activated carbon utilization rate of a conventional liquid passing type capacitor was only about 1/100 (Tanahashi). Shoji and Masakazu Tanahashi, “Method of removing ions from aqueous solution by forming an electric double layer using activated carbon,” Chemical Engineering, Vol. 35, No. 4, pp. 364-369, 2009.)

Furthermore, when the voltage applied between the electrodes is high, the electrolysis of water occurs in the portion where the adsorption of ions is saturated, and the electrode may be deteriorated by the generated gas. Moreover, when the electrolysis of water occurs, the utilization efficiency of electricity is reduced.

Conventionally, various proposals have been made to prevent the liquid flow from being biased near the channel. However, in the conventional liquid passing type capacitor, the electrode interval is narrow, and since there was no idea of flowing the liquid to the separator part at high speed, the device for flowing the liquid to the separator part was not sufficiently devised. .

On the other hand, in a preferred example of the present invention, a spacer that keeps the distance between the electrodes constant is arranged between the electrodes so that the aqueous liquid flows smoothly in the spacer. Thereby, the bias of ion adsorption in the electrode can be reduced. In order to further reduce this bias, in a preferred example of the present invention, in the step of adsorbing ions (step (i) described later), the ion concentration of the aqueous liquid before being introduced into the ion adsorbing unit, and the ion adsorbing unit The difference from the ionic concentration of the aqueous liquid after being introduced into is reduced. Details will be described later.

The opening ratio of the spacer may be in the range of 0.3 to 0.9 (for example, in the range of 0.5 to 0.7). By setting the aperture ratio to 0.3 or more, the aqueous liquid can easily flow through the voids in the spacer, and the resistance between the electrodes can be reduced. By setting the aperture ratio to 0.9 or less, a short circuit between the electrodes can be suppressed. The aperture ratio means a value of (aperture area) / (spacer area), and more specifically, a value of (opening projection area) / (spacer projection area). . An example of the spacer is a net-like spacer having an aperture ratio in the range of 0.3 to 0.9. The porosity of the spacer may be in the range of 50% to 95% (for example, in the range of 60% to 85%). The porosity of the spacer can be obtained from the occupied volume of the spacer, the mass of the spacer, and the density of the material constituting the spacer. When determining the occupied volume of the spacer, the distance between the two plates when the spacer is sandwiched between the two plates is used as the thickness of the spacer.

The spacer may be formed with irregularities. In this case, the uneven gap (the distance between the convex portion and the concave portion in the thickness direction) may be in the range of 0.2 mm to 5 mm (for example, 0.5 mm to 3 mm). By forming the unevenness, a space through which the aqueous liquid flows can be secured between the spacer and the electrode surface.

In the electrode pair, even if a plurality of flow paths arranged in stripes are formed by the gaps of the spacers on the surfaces of the first and second electrodes (the surfaces of the first and second conductive materials), respectively. Good. According to this configuration, the aqueous liquid can easily flow through the voids in the spacer.

In a preferred example, it is preferred that the first and second conductive materials have a sheet-like shape and they are arranged parallel to the flow of the aqueous liquid, such an example is shown in FIGS. Indicated.

The capacity (saturated ion adsorption amount) of the first electrode is in a range of 1.5 to 3 times (for example, a range of 1.7 to 2.2 times) the capacity (saturated ion adsorption amount) of the second electrode. It is preferable. That is, the value of (capacity of the first electrode) / (capacity of the second electrode) is preferably in the range of 1.5 to 3 (for example, in the range of 1.7 to 2.2). As will be described later, in step (i) for adsorbing ions, a voltage is applied so that the first electrode serves as an anode and the second electrode serves as a cathode. In this specification, the capacitance C of the electrode is the amount of electricity Q stored in the electrode per unit voltage ΔV, and is expressed as capacitance C = Q / ΔV. The capacity ratio of the electrode can be regarded as being equal to the total charge amount ratio of ions adsorbed on the electrode by applying a minute unit voltage in the vicinity of the rest potential.

In the following description, “saturated ion adsorption amount” means the total charge amount of ions adsorbed by the electrode (substantially a conductive substance including activated carbon) from the rest potential to the gas generation potential. To do. For example, the saturated ion adsorption amount of the anode means the total charge amount of anions adsorbed on the anode from the rest potential to the oxygen gas generation potential. Further, the saturated ion adsorption amount of the cathode means the total charge amount of cations adsorbed on the cathode from the rest potential to the hydrogen gas generation potential.

The relationship between the reaction potential of water electrolysis and the adsorption of ions is shown in FIG. FIG. 1 (a) shows the reaction potential of water on the electrode, and FIG. 1 (b) shows the corresponding state of ion adsorption. As charging to the anode (that is, adsorption of anions) proceeds, the anode potential reaches the oxygen generation potential (approximately 0.6 volts with respect to the silver-silver chloride electrode), and oxygen gas is generated at the anode. On the other hand, as the charging of the cathode proceeds, the cathode potential reaches the hydrogen generation potential (about -0.6 volts with respect to the silver-silver chloride electrode), and hydrogen gas is generated at the cathode.

FIG. 2 schematically shows the state of ion adsorption / release when the anode capacity and the cathode capacity are the same. As shown in FIG. 1A, the rest potential before the start of voltage application is at a position of about 0.1 volts with respect to the silver-silver chloride electrode. When a voltage is applied in this state, as shown in FIG. 2A, the anode first reaches the oxygen gas generation potential, and generation of oxygen gas is started. The amount of electricity consumed to generate oxygen gas is used for charging the cathode (adsorption of cations) as shown in FIG. 2B (arrow B in FIG. 2B). Thereafter, when the electrodes are short-circuited to release ions, the state shown in FIG. 2 (c) is reached, and finally, as shown in FIG. Will be adsorbed. When a voltage is applied from this state to a voltage V1 shown in FIG. 2E, cations are released at the anode, while cations are adsorbed at the cathode. At this time, the ion concentration in the aqueous liquid does not decrease. When a voltage is further applied, as shown in FIG. 2 (f), anions are adsorbed at the anode and cations are adsorbed at the cathode, where the ion concentration in the liquid decreases. That is, the ion concentration does not decrease from 0 volts to V1 volts. Thus, when the capacity of the anode and the capacity of the cathode are the same, the utilization efficiency of activated carbon and the utilization efficiency of electricity are lowered.

The above discussion applies even when only a part of the electrode capacitance is used. FIG. 3 shows a schematic equivalent circuit of the ion adsorption electrode (first and second electrodes). As shown in FIG. 3, the ion adsorption electrode can be considered as a circuit in which a plurality of capacitors (capacitance Cn) having different resistance components (resistance values Rn) are connected in parallel. For example, the resistance component increases at a deep portion of the pores of the activated carbon and decreases at a shallow portion. When such an ion-adsorbing electrode is charged, the portion with the smaller resistance component is charged faster and reaches the gas generation voltage earlier. That is, even if only a part of the capacity of the electrode is used, gas generation occurs in a portion where the resistance component is small. Therefore, when adjusting the capacity of the anode electrode and the capacity of the cathode electrode for the purpose of suppressing gas generation, it is necessary to compare capacities with low resistance components rather than comparing the capacity of the entire electrode. In order to increase the capacity with a low resistance component, it is necessary to increase the amount of activated carbon. Therefore, even when only a part of the capacity of the electrode is used, it is preferable to make the capacity of the anode larger than that of the cathode.

As described above, it is preferable to make the capacity of the anode larger than that of the cathode. Specifically, as shown in FIG. 4, the capacity of the anode is increased, the amount of electricity until the anode reaches the oxygen gas generation potential (saturated ion adsorption amount), and the time until the cathode reaches the hydrogen gas generation potential. It is preferable to adjust so that the amount of electricity (saturated ion adsorption amount) is substantially equal. For this purpose, the capacity of the anode (first electrode) is set to a range of 1.5 to 3 times (for example, a range of 1.7 to 2.2 times) the capacity of the cathode (second electrode). preferable.

Experimentally, the anode capacity is preferably about twice the cathode capacity. However, the optimal capacity ratio varies depending on the difference in the ion species adsorbed and the activated carbon. For example, in FIG. 1 and FIG. 2, the differential capacitance is constant regardless of the potential, but actually there is little potential dependence. Further, the relationship between the resistance component Rn and the capacitance Cn in FIG. 3 varies depending on the activated carbon. Therefore, the resistance value changes depending on the type of activated carbon and the ion type, and the optimum capacity ratio changes slightly. However, by setting the ratio of (anode capacity) :( cathode capacity) to 1.5 to 3: 1, ions can be adsorbed more efficiently than liquid-type capacitors with a capacity ratio of 1: 1. . In addition, when ion emission is stopped when the voltage between the electrodes reaches the voltage V1 in FIG. 2 (e) during ion emission, a decrease in current efficiency can be avoided. (Particularly, the portion where the ion adsorption speed is high) cannot be used. Therefore, it is preferable to adjust the capacity ratio so that the potential when all the ions adsorbed on the anode and the cathode are released is in the vicinity of the rest potential.

The electrode capacitance C is represented by the formula C = Q / ΔV as described above. The capacity ratio of the electrodes can be determined by measuring the differential capacity near the rest potential. The differential capacity of the electrode (substantially equal to the differential capacity of the conductive material including activated carbon in the electrode) can be determined, for example, by the following method. A potentiostat is used as a measuring device. First, an electrode to be measured is connected to the working side, a counter electrode (which may be a counter electrode including activated carbon) is connected to the counter side, and a reference electrode is connected to the reference side. Next, the electrodes are immersed in an aqueous solution in which the salt is dissolved. Next, a constant minute voltage ΔV (for example, 0.1 V) is applied from a potential (rest potential) in a state where ions are not adsorbed, and the current value that flows in that state is integrated to obtain an integrated electric quantity Q. . The differential capacitance C ′ at this time is obtained by the equation C ′ = Q / ΔV. The ratio between the differential capacity of the first electrode and the differential capacity of the second electrode can be regarded as the capacity ratio of those electrodes.

Also, the saturated ion adsorption amount of the anode can be obtained by measuring the total amount of electricity flowing to the anode before the anode reaches the oxygen gas generation potential from the rest potential. Further, the saturated ion adsorption amount of the cathode can be obtained by measuring the total amount of electricity flowing to the cathode before the cathode reaches the oxygen gas generation potential from the rest potential. The saturated ion adsorption amount may be obtained from the integrated electric quantity that flows by applying a voltage so that the potential of the electrode becomes the gas generation potential from the beginning. By measuring the amount of saturated ion adsorption, the amount of electricity required for the anode to reach the oxygen gas generation potential and the amount of electricity required for the cathode to reach the hydrogen gas generation potential are approximately the same. And cathode can be designed.

When measuring the differential capacity, the measurement value varies depending on the ion species, and therefore it is necessary to measure with the ion species fixed. An example of a method for measuring the differential capacity is shown below. In addition, the thing which is not adsorb | sucking ion is used for both the electrode of a measuring object, and a counter electrode.
(1) Prepare a counter electrode in which the mass of the activated carbon is 5 times or more that of the electrode to be measured.
(2) A sodium chloride aqueous solution having a concentration of 1 mol / L is prepared.
(3) With the electrode immersed in the aqueous solution of (2), a voltage is applied for 10 hours so that the potential of the electrode to be measured changes 0.1 volt from the rest potential. At this time, sodium ions are adsorbed using the electrode to be measured as a cathode. And the electric current value which flowed between electrodes is integrated | accumulated, an electric quantity is calculated | required, and the calculated electric quantity is made into the differential capacity | capacitance of the electrode of a measuring object.

The capacity of the electrode (ion adsorption capacity) is substantially the same as the capacity of the conductive substance, and the capacity of the conductive substance can be controlled by the amount of activated carbon. Therefore, from another viewpoint, the ratio of (capacity of the first electrode) / (capacity of the second electrode) is (mass of activated carbon contained in the first electrode) / (activated carbon contained in the second electrode). Mass)) ratio. That is, in the present invention, the mass of the activated carbon contained in the first electrode is in the range of 1.5 to 3 times the mass of the activated carbon contained in the second electrode (for example, a range of 1.7 to 2.2 times). May be. This replacement is particularly appropriate when the same conductive material (activated carbon) is used for the first conductive material and the second conductive material.

A plurality of electrode pairs are usually stacked in the thickness direction of the electrode pair to constitute one electrode block. By exchanging the electrode block, a plurality of electrode pairs can be exchanged simultaneously. Therefore, the maintenance becomes easy by adopting the form of the electrode block. The number of electrode pairs included in one ion adsorbing portion may be in the range of 5 to 300 (for example, in the range of 10 to 150), or may be a number not in these ranges.

The device (A) usually further includes at least one power source (DC power source) for applying a voltage between the first electrode and the second electrode. The power source is not particularly limited, and an AC-DC converter that converts an AC voltage obtained from an outlet into a DC voltage may be used.

In this specification, “aqueous liquid” means a liquid containing water, and is typically an aqueous solution (including tap water). The aqueous liquid may contain an organic solvent (for example, alcohol) other than water, but normally the solvent of the aqueous liquid is only water. The amount of water in the solvent of the aqueous liquid is 50% by mass or more (for example, 80% by mass or more, 90% by mass or more, or 95% by mass or more), and 100% by mass or less.

There is no limitation on the system (S) in which the aqueous liquid is retained. The system (S) may be an open circulation system such as cooling water or washing water including a cooling tower. Further, the system (S) may be a system in which an aqueous liquid is held in a tank or a tank.

Both ends (inlet and outlet) of the liquid path (P) are connected to the system (S). The aqueous liquid flows from the system (S) through the inlet through the liquid path (P) and returns to the system (S) through the outlet. That is, a part of the system (S) and the liquid path (P) constitute a circulation path. The aqueous liquid in the system (S) returns to the system (S) after being treated in the liquid path (P). This adjusts the water quality of the aqueous liquid present in the system (S) and the liquid path (P). As a result, the ion concentration of the aqueous liquid in the system (S) can be reduced. According to the present invention, it is possible to suppress the generation of scale in the system (S).

The liquid path (P) is a path through which an aqueous liquid can flow, and an electrode can be disposed therein. Examples of the liquid path (P) include a tank provided with an inlet and an outlet.

The first and second conductive materials include activated carbon. Therefore, the first and second conductive materials can adsorb ions reversibly. That is, the first and second conductive materials can repeatedly adsorb and release ions. Ions are adsorbed by the surface charge of the conductive material (activated carbon). That is, the ions are adsorbed on the surface of the conductive material (activated carbon) in the form of an electric double layer.

The first and second conductive materials may be sheets formed using granular activated carbon and a binder. In addition, the first and second conductive materials may be sheets formed using granular activated carbon, conductive carbon, and a binder. The conductive substance may be an activated carbon block formed by solidifying activated carbon particles. In addition, the conductive material may be activated carbon fiber cloth, that is, a cloth formed using activated carbon fiber. These sheets have conductivity. As the activated carbon fiber cloth, for example, activated carbon fiber cloth manufactured by Gunei Chemical Industry Co., Ltd. may be used. In a preferred example, the conductive substance has a flat plate shape (sheet shape). The first and second conductive materials may be a laminate of a plurality of flat plate (sheet-like) conductive materials.

The specific surface area of the conductive substance is, for example, 300 m ² / g or more, preferably 900 m ² / g or more. The upper limit of the specific surface area is not particularly limited, but may be, for example, 3000 m ² / g or less or 2500 m ² / g or less. The specific surface area of the conductive material can be measured by, for example, the BET method.

The content of activated carbon in the first and second conductive materials may be 50% by mass or more. According to this configuration, the capacity of the electrode and the saturated ion adsorption amount can be increased. The content of activated carbon in the first and second conductive materials may be in the range of 50 to 100% by mass (for example, in the range of 70% to 100% by mass).

The first and second electrodes may be composed only of the first and second conductive materials, respectively. The first and second electrodes may include a current collector (for example, wiring). The current collector may be disposed so as to contact the surfaces of the first and second conductive materials, or may be disposed inside the first and second conductive materials. As the current collector, it is preferable to use a current collector that does not substantially undergo corrosion or dissolution when a voltage is applied. Examples of such a current collector include a metal coated with platinum (for example, titanium) and a conductive carbon sheet (for example, a graphite sheet).

The plurality of electrode pairs may include a conductive sheet that supports the first and second conductive sheets. For example, the first and second electrodes may include first and second conductive sheets that support the first and second conductive materials, respectively. Examples of the conductive sheet include a conductive carbon sheet (for example, a graphite sheet), a conductive rubber sheet, and a conductive resin sheet. The conductive sheet may be larger than the first and second conductive materials. For example, the conductive sheet may protrude to the upstream side (in the example, the upstream side and the downstream side) of the aqueous liquid flow from the first and second conductive materials, respectively.

An insulating sheet may be connected to the end of the conductive sheet. The insulating sheet may be larger than the first and second conductive materials. For example, the insulating sheet may protrude to the upstream side (in the example, the upstream side and the downstream side) of the aqueous liquid flow from the first and second conductive materials. There is no particular limitation on the insulating sheet, and a sheet made of an insulating material (for example, insulating resin or rubber) can be used.

Some or all of the steps performed by the apparatus of the present invention may be performed manually. In addition, the apparatus of the present invention may include a controller, and the controller may execute some or all of the steps performed in the apparatus of the present invention. The controller includes an arithmetic processing unit and storage means. Note that the storage means may be integrated with the arithmetic processing unit. Examples of the storage means include an internal memory, an external memory, and a magnetic disk (for example, a hard disk drive) of the arithmetic processing unit. A program for executing each process is recorded in the storage means. An example of the controller includes a large scale integrated circuit (LSI). In addition to various devices (power supply, pump, valve, etc.), the device of the present invention includes various measuring devices (ammeter, voltmeter, pH meter, ion concentration meter, conductivity meter, oxidation-reduction potentiometer, dissolved oxygen meter). , And residual chlorine meter, etc.). The controller may be connected to these devices and measuring instruments. The controller may control processing (for example, voltage application) in each processing unit based on the output of the measuring instrument.

In the apparatus of the present invention, the following steps (i) and (ii) are repeatedly executed in this order. For example, the controller may repeatedly execute the following steps (i) and (ii) in this order. In the step (i), a voltage (DC voltage) is applied between the first electrode and the second electrode so that the first electrode becomes the anode (the second electrode becomes the cathode). . This voltage application is performed in a state where the aqueous liquid is circulating between the ion adsorbing portion and the system (S). By applying this voltage, ions in the aqueous liquid are adsorbed on the first and second conductive substances. Specifically, the anion in the aqueous liquid is adsorbed on the first electrode (anode), and the cation is adsorbed on the second electrode (cathode).

The voltage applied in step (i) is preferably adjusted according to the electrical conductivity of the aqueous liquid to be treated. The applied voltage is usually 2 volts or more in consideration of the voltage drop due to the aqueous liquid. If the applied voltage is too low, the ion adsorption rate is slowed down. On the other hand, if the applied voltage is too high, the electrolysis of water at the first and second electrodes increases. The applied voltage may be in the range of 2-20 volts (eg, in the range of 3-10 volts), preferably in the range of 3-7 volts in one example.

The voltage applied in step (i) may be constant or variable. For example, a voltage may be applied so that a constant current flows between the electrodes. Generally, an inexpensive power source can be used when applying a constant voltage. When applying a constant voltage, if the ion concentration of the aqueous liquid is high, the ion adsorption rate is increased, and if the ion concentration of the aqueous liquid is low, the ion adsorption rate is decreased. Therefore, the method of applying a constant voltage is a simple and convenient method when the ion concentration of the aqueous liquid is kept at a constant low concentration. Also, in open circulation systems such as cooling towers, when the water temperature is high, the volatilization amount increases and the ion concentration of the aqueous liquid tends to increase, but the ion adsorption speed also increases, so a certain degree of control is possible with constant voltage It is.

Next, in step (ii), the ions adsorbed by the first and second conductive substances are turned into the liquid in the ion adsorbing unit in a state where the flow of the aqueous liquid from the ion adsorbing unit to the system (S) is blocked. The liquid from which ions are released is discharged out of the circulation path. That is, the ions in the system (S) are discharged out of the system (S) by the steps (i) and (ii). As a result, corrosion in the system (S) and generation of scale in the system (S) are suppressed.

In the step (ii), an aqueous liquid of the system (S) is usually used as the liquid from which ions are released. However, the ions may be released into an aqueous liquid different from the system (S).

The release of ions may be performed by short-circuiting the first electrode and the second electrode. By short-circuiting these electrodes, the surface charge of the conductive material disappears and ions adsorbed by the surface charge are released. Moreover, you may perform discharge | release of ion by applying a voltage in the reverse direction to process (i). That is, by applying a voltage (DC voltage) between the first electrode and the second electrode so that the first electrode becomes a cathode (second electrode becomes an anode), May be released. In this case, in order to prevent the released ions from being adsorbed again by the conductive material, it is preferable to apply a voltage (for example, in the range of 1 to 2 volts) lower than the voltage applied in step (i). . Note that the first electrode and the second electrode may be short-circuited after applying ions in the opposite direction to the step (i) to release ions. Further, a voltage having the same magnitude as the applied voltage at the time of ion adsorption may be applied in a direction opposite to that at the time of ion adsorption (for example, a time 1/2 to 1/20 of the time at the time of ion adsorption). In this case, the surface of the conductive substance is reversely charged, and a potential difference is generated between the back side (deep part) of the conductive substance and the surface. As a result, ion emission from the high resistance portion is accelerated. In this case, after applying a voltage in the reverse direction for a short time, the voltage application may be stopped and left in an open state, and the electrode may be short-circuited when the voltage at the electrode terminal becomes 0 volts. This makes it possible to release ions quickly.

Further, when a cation is adsorbed on the first electrode (anode) or an anion is adsorbed on the second electrode (cathode), as shown in FIG. It becomes impossible to release ions. As a result, as shown in FIG. 2E, the ion concentration does not decrease even when a voltage is applied up to the voltage V1. Therefore, when the potential of one electrode reaches the potential (the potential at the voltage V1 in FIG. 2E) in a state where ions are not adsorbed (the state in FIG. 2C), The release process may be stopped. Specifically, the ion emission process may be stopped before the absolute value of the voltage between the electrodes becomes 0.2 volts or less (the voltage between the electrodes is in the range of −0.2 volts to 0.2 volts). .

In step (ii), the release of ions and the discharge of the aqueous liquid from which the ions have been released may be performed simultaneously. Further, after the ions are released, the liquid from which the ions are released may be discharged. In that case, the controller executes step (ii-a) and step (ii-b) in this order in a state where the flow of the aqueous liquid from the ion adsorbing portion to the system (S) is blocked in step (ii). . In step (ii-a), ions adsorbed on the first and second conductive substances are released into the liquid in the ion adsorbing portion. In step (ii-b), the liquid from which the ions have been released is discharged to the outside of the circulation path. According to this configuration, it is possible to reduce the amount of discharged waste liquid.

Step (ii-a) may be performed in a state where the flow of the aqueous liquid in the ion adsorption unit is stopped. That is, step (ii-a) may be performed in a state where not only the flow of the aqueous liquid from the ion adsorbing unit to the system (S) but also the flow of the aqueous liquid from the ion adsorbing unit to the drainage path is blocked. . In this way, the amount of waste liquid can be reduced.

In the apparatus of the present invention, step (i) may be stopped and step (ii) may be started before at least one of the following conditions is satisfied in step (i). This process may be performed by a controller.
(A) The total charge amount of ions adsorbed on the first electrode in the step (i) being executed reached 60% of the saturated ion adsorption amount of the first electrode.
(B) The total charge amount of ions adsorbed on the second electrode in the step (i) being executed reached 60% of the saturated ion adsorption amount of the second electrode.

It should be noted that the ratio (60%) in the above (a) and (b) may be a lower value, for example, 50%.

Activated carbon has a large number of pores and can adsorb ions inside the pores. The resistance at the time of adsorbing ions (resistance in the equivalent circuit in FIG. 3) varies depending on the depth from the surface of the pore, and generally the resistance to ion adsorption increases as the distance from the surface of the pore increases. If a portion having a high resistance to ion adsorption is used, it takes time to adsorb and release ions, which slows the processing. On the other hand, when only the portion with low ion adsorption resistance is used, the time required for ion adsorption / release can be shortened, and the processing can be accelerated.

FIG. 5 shows an image showing the relationship between voltage application time (ion adsorption time) and ion adsorption rate. The ion adsorption rate on the vertical axis indicates the ratio of the total charge amount of adsorbed ions to the saturated ion adsorption amount. That is, the ion adsorption rate is expressed by the equation: ion adsorption rate = (total charge amount of adsorbed ions) × 100 / (saturated ion adsorption amount). In the following, the total charge amount of the adsorbed ions with respect to the saturated ion adsorption amount may be referred to as “ion adsorption rate”. Note that FIG. 5 is an image and not an actually measured value. As shown in FIG. 5, the voltage application time and the ion adsorption rate are not in a proportional relationship. This is because initial ion adsorption occurs in the low resistance portion, while subsequent ion adsorption occurs in the high resistance portion. In FIG. 5, it is assumed that the relationship between the voltage application time and the ion adsorption rate is 25% for 10 minutes, 50% for 30 minutes, and 75% for 60 minutes.

Here, it is assumed that the same time as that required for ion adsorption (voltage application) is required to release the adsorbed ions. In that case, by applying 10 minutes of voltage application (ion adsorption) and 10 minutes of ion release four times (that is, by treatment for 80 minutes), ions of 100% of the saturated ion adsorption amount are adsorbed and released. Can do. On the other hand, when voltage application (ion adsorption) for 30 minutes and ion release for 30 minutes are repeated, by repeating adsorption / release twice (that is, by treatment for 120 minutes), 100% of the saturated ion adsorption amount is obtained. Ions can be adsorbed and released. Further, in the case of repeating the voltage application (ion adsorption) for 60 minutes and the ion release for 60 minutes, even if the adsorption / release is performed once (that is, the treatment for 120 minutes is performed), the saturated ion adsorption amount is 75. Only% ions can be adsorbed and released.

The above indicates that the time required for the ion concentration reduction treatment of the system (S) can be shortened by mainly using the low resistance portion of the conductive substance that adsorbs ions. In the conventional treatment, adsorption / release of ions has been performed for the purpose of adsorbing as many ions as possible while the aqueous liquid passes between the electrodes once. In a preferred example of the present invention, processing is performed from a viewpoint completely different from such processing, and a configuration for that is adopted. In addition, instead of shortening the time required for the ion concentration reduction process, the amount of the conductive substance (activated carbon) that adsorbs ions can be reduced.

For the above reasons, it is preferable that the total charge amount of ions adsorbed on the first and second conductive substances (activated carbon) is less than 60% (for example, less than 50%) of the saturated ion adsorption amount. That is, it is preferable to adsorb ions mainly using a low resistance portion of the conductive material. This ratio (ion adsorption rate) may be 2% or more, 5% or more, 10% or more, or 20% or more, and less than 60%, less than 50%, less than 40%, or less than 30%. There may be. For example, this ratio may be 2% or more and less than 50%, 5% or more and less than 30%, or 5% or more and less than 20%.

That is, in the apparatus of the present invention, when at least one of the following conditions is satisfied in step (i), step (i) may be stopped and step (ii) may be started. This process may be performed by a controller.
(A ′) The ratio of the total charge amount of ions adsorbed to the first electrode (first conductive material) in the step (i) being executed to the saturated ion adsorption amount of the first electrode It became a range.
(B ′) The ratio of the total charge amount of ions adsorbed to the second electrode (second conductive material) in the step (i) being executed to the saturated ion adsorption amount of the second electrode It became a range.

However, in the present invention, ion adsorption may be performed using not only a low resistance portion but also a high resistance portion. For example, the total charge amount of ions adsorbed on the first and second conductive materials (activated carbon) in one step (i) may be in the range of 5 to 85% of the saturated ion adsorption amount, and 50 % Or more (for example, 50 to 85%). Such treatment is preferably used when the ion concentration of the system (S) is high. Such treatment is particularly effective when the ion removal rate described later is small (for example, when the ion removal rate is in a range described later). By reducing the ion removal rate, variations in ion adsorption can be reduced. When the ion removal rate is small, the electrolysis of water can be suppressed even if the ion adsorption rate is 50% or more.

When an ion is adsorbed mainly using a low resistance portion of the conductive material, it is preferable to make the electrode (conductive material) thin. In this case, the volume occupied by the first and second electrodes in the electrode pair (or the electrode block constituted by the electrode pair) is 0.4 to 0.4 of the volume occupied by the spacer (including the gap in the spacer). The range may be 10 times (for example, 0.7 to 6 times). The planar shape of the electrode (or the first and second conductive materials) and the planar shape of the spacer are usually the same. Therefore, the magnification can be lowered by reducing the ratio of the electrode thickness to the spacer thickness. In this case, the thickness of the second electrode included in one electrode pair may be in the range of 0.2 to 4.0 mm (for example, in the range of 0.5 to 2.0 mm). In addition, the thickness of the first electrode included in one electrode pair is in a range of 1.5 to 3 times the thickness of the second electrode (for example, 1.7 to 2. The range may be about twice as high.

Further, when the adjacent electrode pairs are arranged apart without using a spacer, the volume occupied by the first and second electrodes in one electrode group is 0.4 to 0.4 of the volume between the adjacent electrode pairs. The range may be 10 times (for example, 0.7 to 6 times).

On the other hand, the magnification can be increased by increasing the ratio of the electrode thickness to the spacer thickness or the ratio of the electrode thickness to the distance between the electrode pairs. By increasing the magnification, the saturated ion adsorption amount per unit volume can be increased. When ion adsorption is performed using not only a low resistance portion but also a high resistance portion, the magnification may be in the range of 3 to 50 times (for example, in the range of 5 to 20 times). In this case, the thickness of the second electrode included in one electrode pair may be in the range of 1.0 to 10 mm (for example, in the range of 1.5 to 5 mm). In addition, the thickness of the first electrode included in one electrode pair is in a range of 1.5 to 3 times the thickness of the second electrode (for example, 1.7 to 2. The range may be about twice as high.

The ion adsorption unit may include a tank in which an electrode pair is disposed. This tank constitutes a part of the liquid path (P). The ratio of the volume of the electrode pair (the volume occupied between the electrodes) to the inner volume of the tank may be in the range of 50% to 98% (for example, in the range of 70 to 95%). By increasing this ratio, the amount of waste liquid can be reduced. In particular, the amount of waste liquid can be reduced by stopping the flow of the aqueous liquid in the ion adsorbing portion during ion release and releasing the ions into as little liquid (aqueous liquid) as possible. For example, in the present invention, the amount of waste liquid is reduced by setting the ion concentration in the liquid (aqueous liquid) discharged in step (ii) to a range of 5 to 100 times the ion concentration of the aqueous liquid present in the system. It can be reduced to about 1/5 to 1/100 of the conventional waste liquid amount. Further, when ions are released into a small amount of liquid, the ion conductivity can be increased by increasing the ion concentration in the liquid, and as a result, the ion release rate can be increased. The ion concentration in the liquid (aqueous liquid) discharged in step (ii) may be in the range of 3 to 200 times (preferably in the range of 5 to 50 times) the ion concentration of the aqueous liquid present in the system.

In order to further increase the ion concentration of the waste liquid, the waste liquid may be stored in a tank, and the waste liquid may be treated with the method and apparatus of the present invention. Thereby, the ion concentration of the waste liquid can be further increased, and the amount of the waste liquid can be reduced. This method / device can also be used as a method / device for concentrating and extracting ions in an aqueous liquid.

The total charge amount of ions adsorbed to the electrode (conductive substance) by the voltage application in step (i) may be calculated from the current value flowing between the electrodes in the voltage application in step (i). For example, the integrated value of the current values that flow between the electrodes in the voltage application in step (i) may be regarded as the total charge amount of ions adsorbed on the electrode (conductive material) by the voltage application in step (i). .

When the aqueous liquid of the system (S) is released as a waste liquid or decreases due to evaporation, the aqueous liquid may be replenished to the system (S). At this time, the ions in the aqueous liquid replenished to the system (S) can be removed using the above-described ion adsorption unit. Thereby, it is possible to suppress an increase in ion concentration in the system (S).

The apparatus of the present invention may include a plurality of ion adsorption units. In that case, a plurality of ion adsorption portions are divided into a first group and a second group, and discharge (ion release) and charge (ion adsorption) are alternately repeated in the first group and the second group. Also good. Specifically, when the first group is discharged, the power may be used for charging the second group, and when the second group is discharged, the power may be used for charging the first group.

(Apparatus equipped with ion concentration reduction device)
The apparatus of the present invention provided with the ion concentration reducing apparatus of the present invention will be described. This apparatus includes a system for holding an aqueous liquid and the ion concentration reducing apparatus of the present invention. In this apparatus, the ion concentration of the system is reduced by the ion concentration reducing apparatus of the present invention. The system may be a system including a cooling tower. Moreover, you may reduce the hardness of an aqueous liquid using an ion concentration reduction apparatus.

An example of the apparatus of the present invention provided with the ion concentration reducing apparatus of the present invention will be described below. In this example, the system (S) includes a water tank. The ion concentration reducing device is connected to the water storage tank. The water storage tank is formed with an aqueous liquid inlet and outlet. While the aqueous liquid flows through the water storage tank through the inlet and the outlet, the ion concentration of the aqueous liquid is reduced by the ion concentration reducing device. In this apparatus, the ion concentration of the aqueous liquid can be reduced while the aqueous liquid flows through the water tank once.

(Water quality adjustment device)
The device of the present invention (ion concentration reducing device or a device including the device) may further include a water quality adjusting device installed in a part of the circulation path. The water quality adjusting device is a device for adjusting at least one water quality selected from the pH and free chlorine concentration of an aqueous liquid. The water quality adjusting device includes a tank in which an aqueous liquid flows and two electrodes (electrode pairs) arranged in the tank. The two electrodes (electrode pairs) include an electrode for performing electrolysis and an ion adsorption electrode for adsorbing ions. The tank of the water quality adjusting device may be connected to a part of the circulation path. Moreover, the tank of the water quality adjusting device may constitute a part of the circulation path (including the system (S), the liquid path (P), and the tank of the ion adsorption unit). Moreover, two flow paths may be connected to the tank of the water quality adjusting device, and another circulating path including the water quality adjusting device may be formed by connecting the two flow paths to the circulating path. The water quality adjusting device may further include a DC power source for applying a voltage to the electrode pair, or a power source of an ion concentration reducing device. As the ion adsorption electrode, the same electrode as the first and second electrodes described above can be used. As an electrode for performing electrolysis, an electrode that easily undergoes electrolysis can be used. For example, a metal electrode can be used. A preferred example of an electrode for performing electrolysis is an electrode having platinum on the surface (for example, a metal electrode coated with platinum).

As will be described later, this water quality adjusting device can be used as a pH adjusting device for changing the pH of an aqueous liquid. Moreover, as will be described later, this water quality adjusting device can be used as a sterilizing device for generating free chlorine and sterilizing. The water quality adjusting device may process the aqueous liquid in a batch manner. That is, the aqueous liquid may be processed by stopping the flow of the aqueous liquid in the tank of the water quality adjusting device. Further, the water quality adjusting device may process the aqueous liquid by a liquid passing method. That is, the aqueous liquid may be processed in a state where the aqueous liquid is flowing in the tank of the water quality adjusting device.

An example of an apparatus for adjusting the pH of the aqueous liquid in the system includes an electrode pair including a metal electrode and an ion adsorption electrode, and a power source for applying a DC voltage thereto. As the ion adsorption electrode, the electrode described in the first and second electrodes of the present invention can be used. For example, a metal electrode having platinum on the surface can be used as the metal electrode. By applying a voltage between the two so that water is electrolyzed at the metal electrode and ions are adsorbed or released at the ion adsorption electrode, the pH of the aqueous liquid can be changed. By adjusting the pH of the aqueous liquid in the system, it becomes possible to prevent corrosion of the system and sterilize the aqueous liquid. Further, as will be described later, it becomes possible to remove unnecessary precipitates (for example, scale) in the circulation path.

Note that a silicon component (for example, silicic acid (H ₂ SiO ₃ )) in the aqueous solution may also contribute to scaling. Silicic acid is considered to be ionizable when the aqueous liquid is made alkaline (for example, the pH is about 10 to 11). Therefore, the pH of the aqueous liquid may be made alkaline and the ionized silicic acid may be adsorbed and removed by a conductive substance. Is possible. In that case, the pH of the aqueous liquid introduced into the ion adsorbing unit may be increased to be alkaline, and the pH of the aqueous liquid may be returned to the original pH level after being treated in the ion adsorbing unit.

(Free chlorine concentration adjustment device)
The device of the present invention (ion concentration reducing device or a device having the same) adjusts the free chlorine concentration of the aqueous liquid flowing in the flow path instead of the water quality adjusting device or in addition to the water quality adjusting device. An apparatus may further be provided. The free chlorine concentration adjusting device includes a container (tank) in which an aqueous liquid is disposed, a separator that partitions the container into a first tank and a second tank, and a third electrode disposed in the first tank. And a fourth electrode disposed in the second tank. The free chlorine concentration adjusting device may further include a direct current power source for applying a voltage between the electrodes, or a power source of an ion concentration reducing device. The second tank is formed with an inlet and an outlet that are connected to the flow path so that the second tank forms a part of the flow path. The space in the first tank is connected to the flow path via a separator. This flow path is connected to a part of the circulation path of the apparatus of the present invention.

As the third and fourth electrodes of the free chlorine concentration adjusting device, electrodes for causing electrolysis are used, and for example, the metal electrodes described above can be used. In the free chlorine concentration adjusting device, a direct current voltage is applied between the third electrode and the fourth electrode in a state where the aqueous liquid is flowing through the second tank to cause electrolysis. Specifically, a voltage is applied so that the third electrode serves as a cathode and the fourth electrode serves as an anode, and chlorine ions are oxidized at the fourth electrode (anode) to form chlorine molecules. This produces free chlorine.

(Ion concentration reduction method)
The method of the present invention for reducing the ion concentration of the aqueous liquid retained in the system (system (S)) will be described below. This method uses the ion concentration reducing apparatus of the present invention. Therefore, the matters described for the apparatus of the present invention can be applied to the method of the present invention. Further, the matters described for the method of the present invention can be applied to the apparatus of the present invention.

The method of the present invention includes a step of repeating the steps (i) and (ii) described above in this order. In the method of the present invention, step (i) may be stopped and step (ii) may be started before at least one of the above-described conditions (a) and (b) is satisfied in step (i).

In the apparatus and method of the present invention, the electrical conductivity of the aqueous liquid present in the system (S) is monitored, and the cycle of steps (i) and (ii) is performed when the electrical conductivity of the system becomes a predetermined value or less. May be stopped.

In the apparatus and method of the present invention, when the aqueous liquid in the system (S) has a temperature distribution, the aqueous liquid on the high temperature side may be taken into the ion removing unit and processed. Since the higher the temperature, the higher the moving speed of the ions, the processing speed can be increased.

In step (i), the electrical conductivity σx (S / m) of the aqueous liquid introduced into the ion adsorbing part and the electrical conductivity σy (S / m) of the aqueous liquid after being processed in the ion adsorbing part , 0.0002 <(σx−σy) /σx≦0.2 may be satisfied. Hereinafter, the value of (σx−σy) / σx may be referred to as “ion removal rate”. The ion removal rate can be controlled by a voltage applied between the electrodes. For example, when the applied voltage is increased, σy is decreased and the ion removal rate is increased. Further, when the flow rate of the aqueous liquid flowing between the electrodes is increased, σy increases and the ion removal rate decreases. Step (i) may be performed so as to satisfy 0.01 ≦ (σx−σy) /σx≦0.1. At least one selected from the flow rate and the voltage of the aqueous liquid in the ion adsorption unit may be controlled so that σx and σy satisfy any of the above relationships. When the apparatus of the present invention includes a controller, the controller may control at least one selected from the flow rate and voltage of the aqueous liquid in the ion adsorption unit so that σx and σy satisfy any of the above relationships.

Here, the ion concentration is 0 in the ion adsorbing portion (the amount of liquid disposed in the ion adsorbing portion is 1 L, for example) that can adsorb 0.1 mol of monovalent ions per minute (9650 coulombs at 0.1 mol). Assume that 1 mol / L of aqueous liquid is flowing. Further, it is assumed that the ions contained in the aqueous liquid are only monovalent ions. At this time, if an aqueous liquid is allowed to flow through the ion adsorbing portion for 1 minute at a treatment speed of 10 L / min, ions removed from 10 L of the aqueous liquid (aqueous liquid containing 1 mol of ions at 10 L) flowing through the ion adsorbing portion. The amount is theoretically 0.1 mol. On the other hand, when an aqueous liquid is passed through the ion adsorbing portion for 1 minute at a processing speed of 100 L / min, the amount of ions removed from 100 L of the aqueous liquid (an aqueous liquid containing 10 mol of ions at 100 L) flowing through the ion adsorbing portion. Is theoretically 0.1 mol. In this case, the value of (σx−σy) / σx is smaller when the aqueous liquid is flowed at a processing speed of 100 L / min. Thus, the ion removal rate can be reduced by increasing the flow rate of the aqueous liquid flowing between the electrodes.

Although depending on the ion adsorption speed, when the flow rate of the aqueous liquid flowing between the electrodes is low, the variation in the amount of ions adsorbed in the electrodes becomes large, and gas is likely to be generated near the inlet. As a result, the utilization efficiency of electricity and the adsorption efficiency of ions may decrease.

The flow rate of the aqueous liquid flowing between the electrodes can be controlled by a pump or a flow rate adjusting valve. Unlike a conventional liquid-flow capacitor, in a preferred example of the present invention, an aqueous liquid flows between electrodes at a high flow rate. The flow rate of the aqueous liquid flowing between the electrodes depends on the value of the current flowing between the electrodes, but may be in the range of 1 to 100 mm / second (for example, in the range of 5 to 50 mm / second). By increasing the flow rate of the aqueous liquid flowing between the electrodes, the value of (σx−σy) / σx (ion removal rate) can be within the above range. In addition, the bias of ions adsorbed on the electrode can be reduced.

When 0.0002 <(σx−σy) /σx≦0.2 is satisfied, ions can be adsorbed to the conductive substance almost evenly. Thereby, it is possible to prevent the ion adsorption of a part of the conductive material of the electrode (for example, the conductive material near the inlet of the aqueous liquid) from being saturated first. If ion adsorption of a part of the conductive material is saturated first, gas generation may occur in that part, which is not preferable.

In general industrial water and tap water, the electrical conductivity has a correlation with the ion concentration, and in a typical example, the two are almost proportional. Therefore, the above relationship regarding σx and σy can be replaced with the relationship of ion concentration. Specifically, in step (i), the ion concentration Cs (mol / L) of the aqueous liquid introduced into the ion adsorbing part and the ion concentration Ct (mol / L) of the aqueous liquid after being processed in the ion adsorbing part. ) May satisfy step (i) so that 0.0002 <(Cs−Ct) /Cs≦0.2. In addition, step (i) may be performed so as to satisfy 0.01 ≦ (Cs−Ct) /Cs≦0.1.

Ions are adsorbed so that the ion concentration of the aqueous liquid treated in the ion adsorbing unit is sufficiently lower than the target ion concentration of the system, and mixed with the aqueous liquid of the system to mix the aqueous liquid of the system. It is also possible to lower the ion concentration. However, if many ions are adsorbed and the electric conductivity of the aqueous liquid in the ion adsorbing portion is lowered, the ion adsorption speed is lowered. Therefore, it is preferable that the ion concentration of the aqueous liquid processed by the ion adsorption part is higher than or comparable to the target ion concentration of the system. For example, the step (i) is performed such that the electrical conductivity σy (or ion concentration Ct) of the aqueous liquid processed in the ion adsorbing unit is higher than the target ion concentration in the initial stage of the processing, As the process proceeds (as steps (i) and (ii) are repeated), step (i) may be performed such that the electrical conductivity σy (or ion concentration Ct) decreases.

As a method for removing ions uniformly from the aqueous liquid in the tank, there is a batch process using electric double layer adsorption. However, in that case, normally, the electrode is uniformly placed in the entire tank to adsorb ions. In this case, if the distance between the electrodes is increased in order to treat a large amount of water, the ion adsorption rate is reduced, and the amount of waste liquid is increased. On the other hand, in order to shorten the distance between electrodes, a large number of electrodes are required, and the cost of the electrodes increases.

When the present invention is applied to an apparatus such as a cooling tower, the amount of water used can be greatly reduced, and the maintenance cost of the apparatus can be reduced. In addition, since the amount of the chemical used for scale prevention can be zero or small, environmental pollution due to waste liquid can also be reduced. Moreover, when reducing the hardness of water using this invention, while being able to reduce the quantity of a waste liquid, an ion adsorption part (electrode pair) can be reduced in size.

In order to prevent corrosion of the system (S) holding an aqueous liquid such as tap water or industrial water, it is preferable to maintain the electrical conductivity of the aqueous liquid in the system (S) at 100 μS / cm or less. Further, in order to suppress an increase in the ion concentration of the aqueous liquid held in the system (S), an amount of ions equal to or greater than the amount of ions contained in the aqueous liquid supplied to the system (S) is adsorbed. Is preferably discharged. These conditions can be achieved by adjusting the size and number of ion adsorbing portions (electrode pairs).

According to the present invention, the ion concentration of the aqueous liquid existing in the system (S) can be reduced. Therefore, it is possible to prevent the ion concentration from increasing by applying the present invention to the system (S) in which the ion concentration increases if no treatment is performed. Examples of the system (S) to which the present invention is applied include a cooling system including a cooling tower through which cooling water flows, a cleaning system through which cleaning water for cleaning articles such as molds, and the temperature of articles such as molds are adjusted. A system through which water flows is included. Further, the system (S) may be a system including a tank for holding an aqueous liquid. Examples of such a system (S) include a water dispenser having a tank for holding drinking water, a washing toilet seat having a tank for holding washing water, a washing machine or a dishwasher having a tank for holding washing water. Machine is included. By removing magnesium ions and calcium ions from the aqueous liquid using the present invention, it is possible to reduce the hardness of the aqueous liquid. Therefore, according to the present invention, it is possible to turn hard water that is not suitable for beverages or washing into soft water, and to prevent the occurrence of scale in the system. Moreover, corrosion of the system can be prevented by reducing the chlorine concentration of the aqueous liquid. Further, by reducing the concentration of calcium, magnesium and chlorine, water with little damage to the hair during shampooing can be obtained.

Hereinafter, the present invention will be described with examples, but the present invention is not limited to the following examples.

(Embodiment 1)
In Embodiment 1, an example of the apparatus and method of the present invention will be described. FIG. 6 schematically shows the configuration of the ion adsorption unit 100 included in the ion concentration reduction apparatus of the first embodiment. The ion adsorption unit 100 includes a tank 110 and an electrode block 120 disposed in the tank 110. The tank 110 includes an aqueous liquid inlet 110a and an outlet 110b. A sensor (not shown) for measuring the electrical conductivity σx of the aqueous liquid immediately before being introduced into the ion adsorbing unit 100 is disposed in the inflow port 110a. In addition, a sensor (not shown) for measuring the electrical conductivity σy of the aqueous liquid immediately after being processed by the ion adsorbing unit 100 is disposed at the outlet 110b.

The configuration of an example of the electrode block 120 is schematically shown in FIG. The electrode block 120 includes a plurality of first electrodes 121, a plurality of second electrodes 122, and a spacer 123 disposed therebetween. The electrodes 121 and 122 in the example include a laminate of a plurality of sheets containing activated carbon (hereinafter sometimes referred to as “activated carbon sheet”) and wirings arranged so as to be in contact with the sheets. For the wiring, for example, platinum-coated titanium wiring or the like can be used. An example of the arrangement of the wiring 125 with respect to the activated carbon sheet 124 is schematically shown in FIG.

The mass of the activated carbon contained in the first electrode 121 is in the range of 1.5 to 3 times the mass of the activated carbon contained in the second electrode 122. When the same activated carbon sheet 124 is used, the number of activated carbon sheets included in the first electrode 121 may be in the range of 1.5 to 3 times the number of activated carbon sheets included in the second electrode 122. In FIG. 7, the first electrodes 121 at both ends include three activated carbon sheets 124 (first conductive material), and the other first electrodes 121 include six activated carbon sheets 124. An example in which the electrode 122 includes three activated carbon sheets 124 (second conductive substances) is shown. In this example, one spacer 123, and a first electrode 121 (three activated carbon sheets 124) and a second electrode 122 (1.5 activated carbon sheets 124) facing each other so as to sandwich the spacer 123 are provided. One electrode pair 126 is configured. In a preferred example, the first conductive material of the first electrode 121, the second conductive material of the second electrode 122, and the spacer 123 have the same planar shape (for example, a rectangular shape) and are overlapped. Thus, one electrode block is formed. The plurality of electrode pairs 126 are connected in parallel. Specifically, the first electrodes 121 are connected to each other, and the second electrodes 122 are connected to each other.

An example of the shape of the spacer 123 is shown in FIGS. FIG. 9 is a front view of the spacer 123. 10 and 11 are cross-sectional views taken along lines XX and XI-XI in FIG. 9, respectively. 10 and 11 also schematically show the arrangement of the electrodes 121 and 122. FIG.

The spacer 123 shown in FIG. 9 includes a plurality of fine resin wires 123a arranged in a stripe shape and a plurality of fine resin wires 123b arranged in a stripe shape so as to cross the fine resin wires 123a. The resin fine wire 123a and the resin fine wire 123b are joined at their intersection. A plurality of flow paths 123c extending linearly are formed between the resin thin wires 123a, and a plurality of flow paths 123d extending linearly are formed between the resin thin wires 123b. That is, a plurality of currents arranged in stripes on the surface of the first electrode 121 (the surface of the first conductive material) and the surface of the second electrode 122 (the surface of the second conductive material), respectively. A path is formed by the gap of the spacer 123. An aqueous liquid can be quickly flowed through this flow path. As a result, unlike conventional liquid-flow capacitors, it is possible to reduce variations in ion adsorption on the conductive material of the electrodes.

In order to prevent a short circuit due to electrode expansion or the like, the distance between two adjacent resin fine wires (L in FIG. 9) is preferably 10 times or less the distance between the electrodes.

An example of the ion concentration reduction apparatus of the present invention using the ion adsorption unit 100 is schematically shown in FIG. 12 includes an ion adsorption unit 100, a power source 140, a pump 141, a flow rate adjustment valve 150, valves 151 to 153, and filters 161 to 162. The power source 140 includes an integrating ammeter. The apparatus of the present invention may further include various sensors (electrical conductivity meter and pH meter), other pumps, other valves, other pipes, other power sources, etc., not shown. The apparatus of the present invention may include a controller for monitoring outputs from various sensors and controlling various devices.

The inflow port 110 a of the tank 110 of the ion adsorbing unit 100 is connected to the system 200 by a flow path 171. The outlet 110 b of the tank 110 is connected to the system 200 by a flow path 172. The system 200 is not particularly limited, and may be a water storage tank or a part of the system (S). The tank 110 of the ion adsorbing unit 100 functions as a liquid path (P). By connecting both ends of the tank 110 (the inlet 110a and the outlet 110b) to the system 200, a circulation path including the ion adsorbing unit 100 and the system 200 is formed. A drainage path 173 is connected to the flow path 172 connected to the outflow port 110b. In addition, the drainage path 173 may be connected to the tank 110 or other piping connected to the tank 110.

An example of an ion concentration reduction method using the apparatus 10 will be described below. First, in step (i), ions in the aqueous liquid 201 in the system 200 are adsorbed. Specifically, the pump 161 is driven with the valve 153 closed and the valves 150 to 152 opened, and the aqueous liquid 201 is circulated between the ion adsorbing unit 100 and the system 200. In this state, a DC voltage is applied between the electrodes so that the first electrode 121 serves as an anode and the second electrode 122 serves as a cathode. By applying this voltage, the anions in the aqueous liquid 201 are adsorbed on the activated carbon sheet in the first electrode 121, and the cations in the aqueous liquid 201 are adsorbed on the activated carbon sheet in the second electrode 122. As a result, the ion concentration in the aqueous liquid 201 decreases.

The voltage application in the example of the step (i) is stopped when at least one of the following conditions is satisfied.
(X) The ratio of the total charge amount of ions adsorbed on the first electrode in the step (i) being executed to the saturated ion adsorption amount of the first electrode reached a predetermined value.
(Y) The ratio of the total charge amount of ions adsorbed on the second electrode in the step (i) being executed to the saturated ion adsorption amount of the second electrode reached a predetermined value.

The predetermined values in the above (x) and (y) can be values in the range exemplified for the ion adsorption rate, for example. The saturated ion adsorption amounts of the first and second electrodes are calculated in advance by the method described above. Further, the total charge amount of ions adsorbed on the first and second electrodes can be calculated, for example, assuming that all current values flowing between the electrodes are used for ion adsorption. That is, the total charge amount of the adsorbed ions can be calculated using an integrating ammeter. Therefore, if a predetermined value of (x) and (y) (for example, a value smaller than the ratio of (a) and (b) above) is determined, the value of the integrated ammeter when the ratio is reached is obtained. . Therefore, whether or not to stop the step (i) and start the step (ii) can be determined by whether or not the value of the integrating ammeter has reached a predetermined value.

When at least one of the above (x) and (y) is satisfied, the voltage application in the step (i) is stopped and the step (ii) is started. Specifically, the valves 151 to 153 are closed, and the flow of the aqueous liquid 201 in the ion adsorbing unit 100 is stopped. That is, the flow of the aqueous liquid 201 between the ion adsorbing unit 100 and the system 200 is blocked. In this state, the ions adsorbed by the first and second electrodes 121 and 122 are released into the aqueous liquid 201 in the tank 110. For example, ions can be released into the aqueous liquid 201 by short-circuiting the first electrode 121 and the second electrode 122. In this way, step (ii-a) is performed.

Next, step (ii-b) is performed. First, with the valve 152 closed and the valves 150, 151 and 153 opened, the pump 141 is driven to drain the aqueous liquid 201 (the aqueous liquid 201 from which ions have been released) in the ion adsorbing unit 100. 173 to the outside. In this way, step (ii-b) is performed.

By performing steps (i) and (ii), ions in the aqueous liquid 201 in the system 200 can be discharged to the outside of the system 200. In the present invention, steps (i) and (ii) are defined as one cycle, and this cycle is repeated a plurality of times. In a preferred example of the present invention, in the step (i), the ion can be adsorbed by using a portion where the ion adsorbing speed is high, thereby speeding up the treatment. Further, the amount of waste liquid can be reduced by reducing the amount of the aqueous liquid 201 existing between the valve 151 and the valve 152.

(Embodiment 2)
The ion concentration reducing apparatus of the present invention may include a plurality of ion adsorption units. An example of such a device is shown in FIG. The apparatus 10b of FIG. 13 is basically the same as the apparatus 10 except that the apparatus 10b includes a plurality of ion adsorbing units 100 and pumps and valves provided for each of the ion adsorbing units 100. . In FIG. 13, the illustration is simplified, and the illustration of the power supply is omitted.

13 can adjust the removal rate of the ion concentration by adjusting the number of the ion adsorbing units 100. In addition, in the apparatus 10b, you may provide the drainage path 173 for every ion adsorption part 100. FIG. According to such a configuration, steps (i) and (ii) in each ion adsorption unit 100 can be shifted. In other words, the process (i) can always be performed by any one of the ion adsorption units 100, and the ion concentration in the system 200 can be stabilized.

(Embodiment 3)
The apparatus of the present invention may include a waste liquid tank connected to the drain path 173. And the apparatus (for example, apparatus 10 and apparatus 10b) of this invention may be further connected to the waste liquid tank. One such example is shown in FIG. However, FIG. 14 shows only the portion on the downstream side of the drainage path 173.

As shown in FIG. 14, the drainage path 173 is connected to the waste liquid tank 210. The apparatus 10 is connected to the waste liquid tank 210. The waste liquid 211 in the waste liquid tank 210 is processed by the apparatus 10. As a result, a waste liquid having an ion concentration higher than that of the waste liquid 211 is discharged from the drain path 173a of the apparatus 10 in FIG. According to this configuration, the amount of waste liquid can be particularly reduced.

(Embodiment 4)
Embodiment 4 demonstrates an example of an apparatus provided with the ion concentration reduction apparatus connected to the water tank. FIG. 15 schematically shows the configuration of the apparatus according to the fourth embodiment. The apparatus 250 of FIG. 15 includes a water tank 251 and an ion concentration reducing device 10 connected to the water tank 251. An inlet 251 a and an outlet 251 b are formed in the water storage tank 251, and they are connected to the flow path 252. The aqueous liquid 201 is introduced into the water storage tank 251 from the inflow port 251a and discharged from the outflow port 251b. In addition, since the ion concentration reduction apparatus 10 was demonstrated in Embodiment 1, the overlapping description is abbreviate | omitted.

In the apparatus 250, ions of the aqueous liquid 201 in the water storage tank 251 are removed by the ion concentration reducing apparatus 10 of the present invention. Therefore, ions in the aqueous liquid 201 can be efficiently removed. The water storage tank 251, the flow path 171, the tank 110, and the flow path 172 constitute a circulation path. In a preferred example of the present invention, the flow rate of the aqueous liquid 201 flowing through the circulation path is increased in order to uniformly cause ion adsorption at the electrode. On the other hand, the flow rate of the aqueous liquid 201 flowing through the flow path 252 can be set separately from the flow rate of the aqueous liquid 201 flowing through the circulation path. Therefore, in the apparatus 250, the ion concentration can be greatly reduced while the aqueous liquid 201 flows through the flow path 252 once while the flow rate of the aqueous liquid 201 flowing through the flow path 252 is slow.

When removing ions of the aqueous liquid flowing through the flow path 252 with a conventional liquid-flowing capacitor, a liquid-flowing capacitor is disposed instead of the water storage tank 251 to remove the ions. However, when a large amount of ions is removed using a conventional liquid-flowing capacitor while the aqueous liquid flows through the flow path 252 once, various problems occur as described separately. However, in the apparatus 250 of FIG. 15, it is possible to efficiently remove ions while flowing through the flow path 252 once, and it is possible to avoid a problem caused by a liquid-pass capacitor.

(Embodiment 5)
Embodiment 5 demonstrates an example of the form which reduces power consumption using a some ion adsorption part. The apparatus of Embodiment 5 includes two ion adsorption units 100a and 100b. The relationship between the ion adsorption units 100a and 100b and the power source 140 will be described with reference to FIG. 16A. In FIG. 16A, only the portions necessary for the description are shown, and the other portions are not shown. In FIG. 16A, illustration of a switch for switching the wiring is omitted.

First, ions are adsorbed by the ion adsorption unit 100a. Thereby, ions are adsorbed to the electrodes (the first electrode 121a and the second electrode 122a) of the ion adsorption unit 100a. Here, as an example, a case where cations are adsorbed on the first electrode 121a and anions are adsorbed on the second electrode 122a will be described. The ions adsorbed on the electrode are released in the ion release step (step (ii), step (ii-a)), but the state where the ion is adsorbed on the electrode is the same as the state where the capacitor is charged with electricity. This electricity can be used for the ion adsorption step (step (i)) of the other ion adsorption unit 100b. For that purpose, the electrodes (first electrode 121a and second electrode 122a) of the ion adsorbing unit 100a, the electrodes (first electrode 121b and second electrode 122b) of the ion adsorbing unit 100b, and the power source 140 are, for example, Connections are made as shown in FIG. 16A. Then, a DC voltage is applied so that ions adsorbed on the ion adsorbing unit 100a are released. In FIG. 16A, regardless of the valence of the ion, the cation and the anion are schematically shown as “L ⁺ ” and “L ⁻ ”, respectively. In the ion release process, the second electrode 122a of the ion adsorption unit 100a is connected to the negative electrode of the power supply 140, the first electrode 121b of the ion adsorption unit 100b is connected to the positive electrode of the power supply 140, and the ion adsorption unit 100a You may connect the 1st electrode 121a and the 2nd electrode 122b of the ion adsorption part 100b.

In the ion adsorbing part 100a that adsorbs ions, the battery is charged until the voltage between the electrodes reaches a certain voltage (for example, about 1 volt). Therefore, by performing wiring as shown in FIG. 16A, a voltage higher than the voltage supplied from the power supply 140 can be applied to the ion adsorption unit 100b. Alternatively, wiring may be performed as shown in FIG. 16A so that the voltage during charging is a constant voltage. In the wiring in FIG. 16A, control may be performed so that a constant current flows between the electrodes.

As the ion adsorption in the ion adsorption unit 100b and the ion release in the ion adsorption unit 100a proceed, the charging voltage in the ion adsorption unit 100a reaches zero volts. If voltage application is continued without changing the state of the wiring, the ions released in the ion adsorbing unit 100a are adsorbed again in the ion adsorbing unit 100a. Therefore, when the charging voltage in the ion adsorption unit 100a reaches around zero volts, it is preferable to disconnect the ion adsorption unit 100a from the power source and short-circuit the two electrodes as shown in FIG. 16B. Thereby, it is possible to prevent ions from being adsorbed in the ion adsorbing portion 100a in the ion releasing step. In order to shorten the time of the ion release process, voltage application is performed with the wiring of FIG. 16A until the charging voltage in the ion adsorbing unit 100a exceeds zero volts and becomes negative, and then the wiring is switched as shown in FIG. 16B. Also good.

16B, the ion adsorbing unit 100b is in a charged state. In the ion release process of the ion adsorption unit 100b, the power accumulated in the ion adsorption unit 100b can be used for the ion adsorption of the ion adsorption unit 100a in the same manner as described above. That is, when the ion adsorption unit 100a is discharged (ion release), the power can be used for charging the ion adsorption unit 100b, and when the ion adsorption unit 100b is discharged, the power can be used for charging the ion adsorption unit 100a. . In this way, a plurality of ion adsorbing units may be used and the electric power generated in the process (ii) of one ion adsorbing unit may be used as the electric power required for the process (i) of another ion adsorbing unit.

In addition, in the ion adsorption part of the apparatus of the present invention, the plurality of electrode pairs may not be connected in parallel. An example of the structure of the electrode pair in such an ion adsorption part is typically shown in FIG. In the configuration of FIG. 17, a plurality of electrode pairs 126 a are arranged in parallel, and adjacent electrode pairs 126 a are connected in series by a conductive sheet 128. In this way, the plurality of electrode pairs 126a constitute one electrode group (electrode block) 129.

Each electrode pair 126a includes a first electrode 121 and a second electrode 122. A spacer 123 is usually arranged between the first electrode 121 (activated carbon sheet 124) and the second electrode 122 (activated carbon sheet 124) in the same manner as the electrode pair 126 in FIG. Is omitted. A conductive sheet 128 is disposed between the first electrode 121 and the second electrode 122 of the two adjacent electrode pairs 126a. That is, the electrode group 129 (a plurality of electrode pairs) in FIG. 17 includes a conductive sheet 128 that supports the first and second conductive materials (the activated carbon sheet 124). As the electrodes 121 and 122, the electrodes 121 and 122 described in Embodiment 1 can be used. As the conductive sheet 128, a conductive rubber sheet or a graphite sheet can be used. Current collectors 127 a and 127 b are connected to the two electrodes located at both ends of the electrode group 129. Current collectors 127a and 127b are connected to a positive electrode and a negative electrode of a power source. When the current collector 127a is connected to the positive electrode of the DC power source and the current collector 127b is connected to the negative electrode of the power source, the first electrode 121 of each electrode pair 126a becomes the anode and the second electrode 122 becomes the cathode.

In a preferred example, the conductive sheet 128 is a sheet that does not have liquid permeability and is larger in size than the conductive materials of the electrodes 121 and 122. According to such a configuration, there is a case where a leak current flowing between adjacent electrode pairs 126a by ionic conduction can be reduced.

The conductive sheet 128 may be fixed to the tank by an insulating sheet (not shown). In addition, when there is one inflow port and one outflow port of the aqueous liquid formed in the tank, it is necessary to allow the aqueous liquid to flow to each electrode pair 126a. In that case, an insulating sheet (for example, a net-like insulating sheet) through which the liquid can flow may be used. In addition, you may suppress the electrical conduction between electroconductive sheets with the spacer arrange | positioned between an anode and a cathode.

In each electrode pair 126 a of the electrode group 129, the aqueous liquid flows through the gap between the first electrode 121 and the second electrode 122. Therefore, the same effect as the configuration of FIG. 7 can be obtained. Further, the configuration using the electrode group 129 in FIG. 17 has an advantage that the number of current collectors can be reduced and an electric current required for removing ions can be reduced.

Alternatively, a plurality of electrode groups 129 may be used and connected in parallel. Such an example is schematically shown in FIG. The configuration of FIG. 18 includes three electrode groups 129a to 129c. Each of electrode groups 129a-129c includes four electrode pairs 126a connected in series. The first electrode 121 at one end of the electrode group 129a is connected to the current collector 127a. The second electrode 122 at the other end of the electrode group 129a is connected to the second electrode 122 at one end of the electrode group 129b by a current collector 127b. The first electrode 121 at the other end of the electrode group 129b is connected to the first electrode 121 at one end of the electrode group 129c by a current collector 127c. The second electrode 122 at the other end of the electrode group 129c is connected to the current collector 127d. The current collector 127 a and the current collector 127 c are connected to one terminal of the power source 140, and the current collector 127 b and the current collector 127 d are connected to the other terminal of the power source 140. By connecting in this way, the three electrode groups 129 are connected in parallel. As shown in FIG. 18, the electrode groups can be connected in parallel with a small number of current collectors by reversing the arrangement of the electrodes in the adjacent electrode groups and connecting the adjacent electrodes of the adjacent electrode pairs with the current collectors. .

FIG. 19 schematically shows a sectional view of another example of the electrode block. In FIG. 19, the flow of the aqueous liquid is indicated by arrows. The electrode pair of the electrode block shown in FIG. 19 includes a conductive sheet 128 that supports the activated carbon sheet 124 (first and second conductive materials). The conductive sheet 128 protrudes further upstream and downstream of the flow of the aqueous liquid than the activated carbon sheet 124.

FIG. 20 schematically shows a cross-sectional view of another example of the electrode block. In FIG. 20, the flow of the aqueous liquid is indicated by arrows. The electrode pair of the electrode block shown in FIG. 20 includes a conductive sheet 128 that supports the activated carbon sheet 124 (first and second conductive materials). An insulating sheet 131 is connected to the end of the conductive sheet 128. The insulating sheet 131 protrudes further upstream and downstream of the flow of the aqueous liquid than the activated carbon sheet 124. In addition, the electroconductive sheet 128 shown in FIG. 19 and 20 is a sheet | seat which does not have liquid permeability.

In the present invention, a voltage is applied between the activated carbon sheet 124 of the first electrode 121 and the activated carbon sheet 124 of the second electrode 122. At this time, water may be electrolyzed at the end of the activated carbon sheet 124. When such electrolysis occurs, the gas generated thereby impedes the flow of the aqueous liquid, and the utilization efficiency of electricity decreases. Therefore, it is preferable to suppress such electrolysis.

When the conductive sheet 128 having a relatively high resistivity and no liquid permeability is used, the water at the end of the activated carbon sheet 124 is increased by making the conductive sheet 128 larger than the activated carbon sheet 124 as shown in FIG. Electrolysis can be suppressed. In the example shown in FIG. 19, the conductive sheet 128 protrudes from the activated carbon sheet 124 by a length L1 upstream of the flow of the aqueous liquid. In addition, the conductive sheet 128 protrudes from the activated carbon sheet 124 by a length L2 on the downstream side of the aqueous liquid flow. At this time, it is preferable that the electrical resistance of the conductive sheet 128 in the length L1 (and the length L2) is higher than the electrical resistance of the aqueous liquid existing between two adjacent conductive sheets 128. . Examples of the conductive sheet 128 that can be used in the configuration of FIG. 19 include a conductive rubber sheet that does not have liquid permeability and a conductive resin sheet that does not have liquid permeability. Their volume resistivity may be in the range of 10 ³ to 10 ⁷ Ω · cm, for example.

When a conductive sheet having a relatively low resistivity or a conductive sheet having liquid permeability is used, an insulating sheet 131 having no liquid permeability is connected to the conductive sheet 128 as shown in FIG. May be. The insulating sheet 131 is disposed outside the activated carbon sheet 124. In the example shown in FIG. 20, the insulating sheet 131 protrudes from the activated carbon sheet 124 by a length L1 upstream of the flow of the aqueous liquid. Further, the insulating sheet 131 protrudes from the activated carbon sheet 124 by a length L2 downstream of the flow of the aqueous liquid. The conductive sheet 128 is approximately the same size as the activated carbon sheet 124. By using the insulating sheet 131, water electrolysis at the end of the activated carbon sheet 124 can be suppressed. Examples of the conductive sheet that can be used in the configuration of FIG. 20 include a graphite sheet that does not have liquid permeability.

When water is electrolyzed on the upstream side of the conductive sheet 128 and gas is generated, bubbles may remain in the electrode group and obstruct the flow of the aqueous liquid. Therefore, it is necessary to particularly suppress water electrolysis on the upstream side of the conductive sheet 128. Further, when the lengths L1 and L2 are increased, there is a problem that the dead space in the electrode block increases. Considering these points, in FIGS. 19 and 20, it is preferable that the length L1 is longer than the length L2. In the configuration of FIG. 20, the electrical resistance of the aqueous liquid in the flow direction may be increased by increasing the thickness of the insulating sheet 131 so as to be in contact with the spacer 123. According to such a configuration, the lengths L1 and L2 can be shortened.

The spacer protruding from the activated carbon sheet 124 may have a smaller porosity than the spacer existing between the activated carbon sheet 124 of the first electrode 121 and the activated carbon sheet 124 of the second electrode 122. Good. For example, the porosity of the spacer existing between the two activated carbon sheets 124 may be in the range of 50% to 95%, and the porosity of the spacer protruding from the activated carbon sheet 124 may be 5% or more and less than 50%. According to this configuration, the dead space can be reduced and the electrical resistance of the aqueous liquid in the dead space can be increased.

19 and 20, the quantity of electricity that flows between the electrodes as a leakage current without being used for ion adsorption is 1/100 or less (for example, 1/1000 or less) of the quantity of electricity used for ion adsorption. It is preferable that

(Water quality adjustment device)
An example of a water quality adjusting device that can be used in the present invention is shown in FIG. The apparatus 300 in FIG. 21 includes a bath 310, a platinum electrode 311, and an ion adsorption electrode 312. The platinum electrode 311 is, for example, an electrode in which platinum-coated metal wirings are arranged in a stripe shape. The ion adsorption electrode 312 is, for example, a flat electrode including activated carbon (activated carbon powder or activated carbon fiber cloth). The platinum electrode 311 and the ion adsorption electrode 312 are disposed in the tank 310 so as to face each other. The platinum electrode 311 and the ion adsorption electrode 312 are connected to a DC power source (not shown). As the DC power source, a power source dedicated to the water quality adjusting device may be used, or a power source of an ion concentration reducing device may be used. The apparatus 300 can be used to change the pH of the aqueous liquid and produce free chlorine.

Note that an insulating separator (spacer) may be disposed between the electrodes in order to prevent short-circuiting of the electrodes. As the separator, a separator that allows permeation of ions freely can be used. Examples of the separator include a net, a nonwoven fabric, and a woven fabric formed of a resin.

When lowering the pH of the aqueous liquid in the tank 310, voltage is applied to both electrodes so that the platinum electrode 311 serves as an anode and the ion adsorption electrode 312 serves as a cathode and water electrolysis occurs in the platinum electrode 311. Apply. By applying this voltage, oxygen gas and hydrogen ions are generated at the platinum electrode 311. Also, by applying this voltage, cations are adsorbed on the ion adsorption electrode 312 (in the case where anions are adsorbed on the ion adsorption electrode 312 before voltage application, the anions are released). As a result, hydrogen ions in the aqueous liquid increase and the pH decreases. On the other hand, when raising the pH of the aqueous liquid in the tank 310, the platinum electrode 311 serves as a cathode and the ion adsorption electrode 312 serves as an anode, and electrolysis of water occurs in the platinum electrode 311. DC voltage is applied to By applying this voltage, hydrogen gas and hydroxide ions are generated at the platinum electrode 311. Also, by applying this voltage, anions are adsorbed on the ion adsorption electrode 312 (in the case where cations are adsorbed on the ion adsorption electrode 312 before voltage application, the cations are released). As a result, hydrogen ions in the aqueous liquid are reduced and the pH is increased. In one example of changing the pH, a voltage in the range of 3 to 20 volts is applied between both electrodes.

As described above, it is possible to adjust the pH of the aqueous liquid by using the water quality adjusting device. That is, the aqueous liquid can be made acidic or alkaline. There is no particular limitation on the location where the water quality adjusting device is installed. The water quality adjusting device may be installed in the circulation path, and may be installed in any one of the flow path 171, the flow path 172, the system 200, and the tank 110, for example. Moreover, you may install a water quality adjustment apparatus in the drainage path through which the waste liquid with high salt concentration flows. Then, an acidic and / or alkaline aqueous liquid may be prepared using a waste liquid having a high salt concentration, and the aqueous liquid may be returned to the circulation path including the system.

By making the aqueous liquid acidic, it is possible to remove scale (calcium hydroxide, magnesium hydroxide, etc.) generated on the system, tank, flow path, and electrode surface, and corrosive substances. On the other hand, by making the aqueous liquid alkaline, silicon ions that are difficult to be adsorbed as ions can be adsorbed as ions. Moreover, it is possible to remove the deposited silicon component. Further, by adjusting the pH of the aqueous liquid, it is possible to decompose or dissolve organic substances adsorbed on the ion adsorption electrode and remove them. By removing these, it is possible to prevent a decrease in electrode performance and an increase in piping resistance. However, if the acidic state or alkaline state is maintained for a long time, the system may be corroded. Therefore, it is preferable to adjust the pH in consideration thereof. The pH may be adjusted with reference to the output of a pH meter installed in the circulation path.

In an example of making the pH of the aqueous liquid acidic, the pH of the aqueous liquid is changed until the pH is in the range of 4-6. When the treatment for lowering the pH is stopped in this state, the pH is increased by the amount of dissolution of the scale (metal hydroxide), and the aqueous liquid can be made almost neutral. Therefore, by adjusting the pH to the above range, corrosion of the system can be suppressed and scale can be removed. However, even in this case, if the treatment for making the pH acidic in a state where the pH does not return to the neutral range is continued, corrosion may occur. Further, when the pH is lowered below the above range, corrosion due to acid tends to occur.

When a part or all of the circulation path is washed (and sterilized) by changing the pH of the aqueous liquid, the following steps (m) and (n) may be performed sequentially or alternately. May be. Further, after one of the steps is repeated a plurality of times, the other step may be repeated a plurality of times. Any of the following steps (m) and (n) may be performed first.
(M) The aqueous liquid is acidified and washed with the aqueous liquid.
(N) The aqueous liquid is made alkaline, and washing is performed using the aqueous liquid.

Note that, when the aqueous liquid is acidified, calcium ions and magnesium ions are dissolved in the aqueous liquid. Therefore, it is preferable to perform the step (n) after removing ions as much as possible using the ion concentration reducing apparatus of the present invention. Moreover, it is preferable to remove ions using those ion concentration reducing devices of the present invention after these steps. In addition, after washing by changing the pH of the aqueous liquid, a treatment for returning the pH of the aqueous liquid to neutral may be performed.

The above process is particularly effective for cleaning the ion adsorption part. Therefore, in a preferred example, a pH adjusting device is connected to the tank of the ion adsorption unit. In an example of such a case, the washing step (acid / alkaline washing water) prepared by the pH adjuster is placed in the tank of the ion adsorbing portion in a state where the flow of the aqueous liquid and the voltage application are stopped, thereby performing the above washing step. I do. After washing, the aqueous liquid used for washing may be discarded after washing the inside of the tank of the ion adsorbing unit with the aqueous liquid present in the system.

When the aqueous liquid contains chlorine ions, the water quality adjusting device is used as a sterilizer for generating free chlorine (dissolved chlorine, hypochlorous acid, and hypochlorite ions) from the chlorine ions in the aqueous liquid. It is also possible. The sterilizer can be disposed at any place in the circulation path, similar to the pH adjuster. For example, in FIG. 12 and FIG. 13, a sterilizer may be installed in any of the flow path 171, the flow path 172, the system 200, and the tank 110. Moreover, you may install a sterilizer in the drainage path through which the waste liquid with high salt concentration flows. The ion concentration reducing device of the present invention may include one or more pH adjusters and sterilizers. One water quality adjusting device may be used as the pH adjusting device and the sterilizing device.

An example in which the apparatus 300 shown in FIG. 21 is used as a sterilizer will be described. In this case, a DC voltage is applied between the electrodes so that the platinum electrode 311 serves as an anode and the ion adsorption electrode 312 serves as a cathode. At this time, a voltage is applied so that chlorine ions are oxidized at the anode and become chlorine molecules. In one example, a voltage in the range of 2 volts to 40 volts is applied between both electrodes. By this voltage application, chlorine ions are oxidized at the platinum electrode 311 (anode) to generate chlorine molecules. On the other hand, cations are adsorbed on the ion adsorption electrode 312 (cathode).

Chlorine molecules generated at the anode react with water to produce hypochlorous acid and hypochlorite ions. That is, the concentration of free chlorine in the aqueous liquid is increased by the voltage application. Since free chlorine has a high sterilizing ability, it can be used for sterilizing aqueous liquids present in the system. In addition, the platinum electrode 311 can lower the pH of the aqueous liquid by causing electrolysis of water (generation of oxygen gas and hydrogen ions) together with oxidation of chlorine ions. That is, removal of scales and the like by making the aqueous liquid acidic and sterilization of the aqueous liquid can be performed simultaneously. The sterilizing power can be enhanced by setting the pH to slightly acidic to neutral (for example, the pH is in the range of 3 to 6). By using the apparatus 300, it is possible to sterilize bacteria (eg, Legionella) in an aqueous liquid.

After applying a DC voltage between both electrodes so that the platinum electrode 311 becomes a cathode and the ion adsorption electrode 312 becomes an anode, a DC voltage is applied between both electrodes so that the platinum electrode 311 becomes an anode and the ion adsorption electrode 312 becomes a cathode. You may apply. In this case, negative ions are adsorbed to the ion adsorption electrode 312 by the former voltage application. In the latter voltage application, anion release and cation adsorption occur at the ion adsorption electrode 312. In the latter voltage application, chlorine ions are oxidized at the platinum electrode 311 to generate free chlorine. By applying a voltage in this way, it is possible to generate free chlorine without greatly changing the pH.

(Free chlorine concentration adjustment device)
An example of a free chlorine concentration adjusting device that can be used in the present invention is shown in FIG. The apparatus 400 of FIG. 22 includes a container (tank) 410, a separator 413, a third electrode 421, a fourth electrode 422, and a power source 423. The device 400 may comprise a controller.

The container 410 is partitioned into a first tank 411 and a second tank 412 by a separator 413. A channel 414 a and a channel 414 b are connected to the second tank 412. The channel 414a, the channel 414b, and the second tank 412 form one channel 414. The space in the first tank 411 is connected to the flow path 414 through the separator 413. The flow path 414a and the flow path 414b can be connected to a part of the circulation path of the water quality adjusting device of the present invention. The second tank 412 has an inlet 412c and an outlet 412d. The inflow port 412c and the outflow port 412d are connected to the flow paths 414a and 414b in a state where the connection can be released by the connection component 412e. In the apparatus of the present invention, the inflow port 412c and the outflow port 412d may be directly connected to the flow path without using connection parts.

In one example, the flow path 414a is connected below the second tank 412, the flow path 414b is connected above the second tank, an aqueous liquid is introduced from the flow path 414a, and the liquid is processed in the second tank 412. The discharged aqueous liquid is discharged from the flow path 414b. In this case, the aqueous liquid flows into the second tank 412 through the inflow port 412c, and the aqueous liquid flows out into the flow path 414b through the outflow port 412d. A pump and / or a valve is installed in the channel 414a and / or the channel 414b as necessary. In addition, the second tank 412 and / or the flow path 414 (usually the flow path downstream of the second tank 12) has a measuring instrument (ORP meter, pH meter, ion concentration meter, conductivity meter, dissolved meter). An oxygen meter, a dissolved hydrogen meter, etc.) may be installed. The first tank 411 is open to the atmosphere through an opening 411a. On the other hand, the second tank 412 is cut off from the atmosphere. An aqueous liquid is disposed in the tanks 411 and 412. Means for preventing the aqueous liquid from leaking outside from the opening 411a may be provided in the opening 411a. For example, a gas-liquid separation membrane may be disposed in the opening 411a. A well-known thing can be used for a gas-liquid separation membrane.

As shown in FIG. 22, drainage paths 415 and 416 may be connected to the tank 411 and the tank 412 respectively. A valve 415a and a valve 416a are provided in each of the drain paths 415 and 416. The aqueous liquid in the tank 411 can be discharged by opening the valve 415a. By opening the valve 416a, the aqueous liquid in the tank 412 can be discharged. By discharging the aqueous liquid in the tank 411 or the aqueous liquid in the tank 12, the pH of the aqueous liquid can be adjusted.

When the aqueous liquid contains chlorine ions, the device 400 can adjust the free chlorine concentration in the aqueous liquid. The operation of apparatus 400 will be described below. Electrodes 421 and 422 are immersed in an aqueous liquid. The electrolysis process is performed in a state where the aqueous liquid is continuously supplied from the flow path 414a and the aqueous liquid is continuously discharged from the flow path 414b. That is, in the electrolysis step, the aqueous liquid in the second tank 412 is in a liquid-permeable state, while the aqueous liquid in the first tank 411 is not in a liquid-permeable state. However, the aqueous liquids in the tanks 411 and 412 and the ions (cations and anions) contained therein can pass through the separator 413.

In order to increase the free chlorine concentration in the aqueous liquid by the treatment in the second tank 412, a direct current voltage is applied between the third electrode 421 and the fourth electrode 422 so that the third electrode 421 becomes a cathode. Apply. By this voltage application, hydrogen gas and hydroxide ions are generated on the surface of the third electrode 421 (cathode). On the other hand, on the surface of the fourth electrode 422 (anode), chlorine ions are oxidized to generate chlorine molecules. Some of the generated chlorine molecules react with water to produce hypochlorous acid and hypochlorite ions. That is, the concentration of free chlorine (dissolved chlorine, hypochlorous acid, and hypochlorite ions) is increased by the voltage application. In this way, according to the apparatus 400, the concentration of free chlorine in the aqueous liquid can be increased.

By applying the voltage, the water in the tank 411 becomes alkaline, but ions in the aqueous liquid in the tank 411 and the tank 412 diffuse to the other tank via the separator 413, so that a significant change in pH is suppressed. The Further, the pH change can be adjusted by discharging the aqueous liquid in the tank 411.

As described above, the free chlorine concentration can be increased by using the free chlorine concentration adjusting device. Moreover, according to said apparatus, a free chlorine concentration can be raised, without changing pH largely. By increasing the free chlorine concentration, it is possible to sterilize the aqueous liquid present in the system.

The present invention will be described in further detail with reference to examples.

(Relationship between flow velocity and ion adsorption rate)
Here, an example in which the relationship between the flow rate of the aqueous liquid flowing through the ion adsorbing portion and the ion adsorption speed is tested will be described. In this experiment, ions in 0.8 L of tap water of Osaka City placed in the tank were removed with the same apparatus as that shown in FIG. In the ion adsorbing portion, an electrode block composed of six electrode pairs stacked was arranged. Each electrode pair was formed by laminating a first electrode, a spacer, and a second electrode.

For the first electrode (anode), an electrode composed of two activated carbon fiber cloths and a current collector was used. As the second electrode (cathode), an electrode composed of one activated carbon fiber cloth and a current collector was used. As the activated carbon fiber cloth, Kynol ACC-5092-10 (manufactured by Nippon Kynol Co., Ltd.) was used. The size of the activated carbon fiber cloth was 9 cm × 7 cm. The current collector was a platinum-coated titanium wire.

The electric conductivity of the aqueous liquid was measured by changing the flow rate of the aqueous liquid flowing through the ion adsorbing portion with the current value flowing between the electrodes being 0.1A. The measurement results are shown in FIG. As shown in FIG. 23, when the flow rate was 4.0 L / min, the ion adsorption rate was high, and the slower the flow rate, the slower the ion adsorption rate.

The electrical conductivity of the aqueous liquid was measured by changing the flow rate of the aqueous liquid flowing through the ion adsorbing portion under the same conditions as above except that the current value flowing between the electrodes was 0.04 A. The measurement results are shown in FIG. As shown in FIG. 24, the ion adsorption rate was fast when the flow rate was 4.0 L / min and when the flow rate was 1.14 L / min.

Although it is not clear at present, the above results can be interpreted as follows. That is, when the current value is 0.1 A, it is considered that when the flow rate is 1.14 L / min, the flow rate with respect to the current value is insufficient and the ion adsorption bias is increased, and the ion adsorption rate is reduced. On the other hand, when the current value is 0.04 A, it is considered that even when the flow rate is 1.14 L / min, there is little bias in ion adsorption, and the ion adsorption rate is high. That is, when the flow rate of the aqueous liquid is low, it is possible to suppress a decrease in the ion adsorption rate by reducing the value of the current flowing between the electrodes. Further, in order not to decrease the efficiency of ion adsorption when the value of the current flowing between the electrodes is increased, it is preferable to increase the flow rate of the aqueous liquid.

(Example 1)
In Example 1, ions contained in 100 L of tap water (electrical conductivity: 180 to 190 μS / cm) placed in the tank were removed by an apparatus similar to the apparatus shown in FIG. In the ion adsorbing portion, an electrode block composed of 24 electrode pairs stacked was disposed. Each electrode pair was formed by laminating a first electrode, a spacer, and a second electrode.

The size of the electrode (the size of the first and second conductive materials) was 23.5 cm × 23.5 cm. The surface density of the activated carbon contained in the first electrode (anode) was 340 g / m ^2, and the surface density of the activated carbon contained in the second electrode (cathode) was 170 g / m ² . As the spacer, a spacer having a thickness of 1.6 mm was used. Therefore, in one electrode pair, the distance between the first electrode and the second electrode was about 1.6 mm. The ion adsorbing portion was treated by flowing the tap water at a flow rate of 6 L / min. At this time, the flow rate of tap water flowing between the electrodes was 15 mm / second. The volume of the portion (dead space) not occupied by the electrode block in the ion adsorbing portion was 3.1 L, and the liquid disposed in the electrode block was 1.7 L.

The ion adsorption was performed by applying a constant voltage (4.6 volts) between the electrodes for 30 minutes. The maximum current that flowed at this time was 20 A, and the current when stable was about 7 A. Ion release was performed by shorting the electrodes for 30 minutes. The waste liquid from which ions were released was released to the outside of the system. One-time ion adsorption was performed, and changes in the electrical conductivity of tap water were measured. In addition, ion release was performed after ion adsorption, and the change in electrical conductivity of the waste liquid was measured. Next, the same experiment was conducted using the same tap water. This experiment was performed a total of 5 times. The experimental results are shown in FIG.

The graph of FIG. 25 shows the change in the electrical conductivity of tap water during ion adsorption. As shown in the figure, the electrical conductivity of 100 L of tap water could be greatly reduced in 30 minutes. FIG. 26 shows the electrical conductivity of the waste liquid. As shown in the figure, the electrical conductivity of the waste liquid could be about 5 times that of tap water. From this, it is considered that the ionic concentration of the waste liquid was made about 5 times the original tap water. This experimental result shows that according to the present invention, the amount of waste liquid can be reduced to 1/5 compared with the case where the aqueous liquid of the system is discharged as waste liquid as it is. In this experiment, the dead space was as large as 3.1 L. However, it is considered that the ion concentration of the waste liquid can be increased to about 10 times the original tap water by reducing the dead space.

In FIG. 25, the electrical conductivity has a small change from the start of the process until 5 minutes have passed, and thereafter decreases at a constant rate. This is probably because the balance between the ionic adsorption amount of the anode and the ionic adsorption amount of the cathode is poor at the initial stage, and therefore, the phenomenon described in FIG. 2 appears a little. This phenomenon can be reduced by adjusting the capacity ratio of the anode and the cathode. Further, a voltage may be applied when the electrodes are short-circuited to such an extent that this phenomenon does not occur.

FIG. 27 shows an image of a process in which system ions are removed by the apparatus and method of the present invention. It should be noted that the change in ion concentration shown in FIG. 27 is an image and is different from the actual change in ion concentration. In FIG. 27, the adsorption and release of ions are repeated a plurality of times. The ion concentration of the system gradually decreases with each ion adsorption. On the other hand, the ion concentration of the waste liquid is significantly higher than the ion concentration of the system, and the amount of the waste liquid can be reduced.

(Experiment on the production of free chlorine)
Below, the result of having experimented about the production | generation of the free chlorine using a water quality adjusting device is demonstrated. In this experiment, 100 mL of 0.01 mass% KCl aqueous solution (pH is 7.4) was put in an electrolytic cell, and a voltage was applied between the platinum electrode and the ion adsorption electrode. The platinum electrode was constructed by arranging platinum-coated titanium wires in a stripe shape. The ion-adsorbing electrode was configured by stacking three activated carbon fiber cloths (size: 7 cm × 9 cm). These electrodes were placed in an electrolytic cell to apply a voltage.

First, a DC voltage was applied between both electrodes so that the platinum electrode became a cathode and the ion adsorption electrode became an anode. At this time, a voltage was applied for 1 minute so that a constant current of 0.2 A would flow between both electrodes. By applying this voltage, anions were adsorbed on the ion adsorption electrode. Next, a direct current voltage was applied between the electrodes so that the platinum electrode became an anode and the ion adsorption electrode became a cathode. At this time, a voltage was applied for 2.5 minutes so that a constant current of 0.2 A would flow between both electrodes. The concentration of free chlorine in the aqueous solution after this voltage application was 110 mg / L, and the pH was 6.3. In this way, free chlorine could be generated using the water quality adjusting device. Moreover, by applying a voltage as described above, free chlorine could be generated without greatly changing the pH.

(Example 2)
In Example 2, the same apparatus as FIG. 12 was used, and the cycle consisting of the step (i) and the step (ii) was repeated. Specifically, first, an aqueous liquid having an electric conductivity of 225 μS / cm was placed in a water storage tank (system 200) having a capacity of 200L. And the process (i) was performed by applying the voltage of 4.5 volts to the electrode pair of the ion adsorption part 100 for 30 minutes, and the ion of the aqueous liquid was adsorbed. Next, the electrode pair was short-circuited for 30 minutes to perform step (ii), and ions were released to the aqueous liquid in the ion adsorption unit 100. However, in Example 2, the aqueous liquid (waste liquid) from which ions were released in step (ii) was returned to the water tank before step (i) of the next cycle. Specifically, before returning the waste liquid to the water storage tank, it was put in a small tank and the electrical conductivity was measured, and then the waste liquid was returned to the water storage tank. In addition, the electrical conductivity of the aqueous liquid in the water tank was monitored.

FIG. 28 shows the change in electrical conductivity of the aqueous liquid in the water tank and the electrical conductivity of the waste liquid. In the graph of FIG. 28, the decrease in the electrical conductivity of the aqueous liquid in the water tank is due to the removal of ions by ion adsorption. The increase in electrical conductivity is due to the return of the aqueous liquid from which ions have been released to the water storage tank.

Initially, the change in electrical conductivity of the aqueous liquid in the water tank is large. This change becomes smaller as the cycle consisting of step (i) and step (ii) is repeated. Moreover, the electrical conductivity of the aqueous liquid in the water storage tank before the start of the step (i) decreases as the cycle is repeated, and eventually becomes substantially constant. These results indicate that ions adsorbed on a portion having a high resistance (electrical resistance in the equivalent circuit of FIG. 3) are not released under the above conditions. The total charge amount of ions adsorbed on the first and second electrodes in one step (i) after 12 hours of the result of FIG. 28 is 50% or less of the first and second saturated ion adsorption amounts, respectively. It is estimated that there is. Therefore, in order to realize fast processing, it is preferable to stop the step (i) before the ratio reaches 60% (for example, before reaching 50%).

(Example 3)
In Example 3, an experiment was conducted on the relationship between the ion removal rate (value of (σx−σy) / σx) and the change in electrical conductivity of the aqueous liquid. The same experimental apparatus as in Example 1 was used. Also in Example 3, adsorption of ions by applying a voltage for 30 minutes and release of ions by short-circuiting the electrodes for 30 minutes were performed. However, in Example 3, the ion removal rates were 0.01 and 0.25. The ion removal rate was changed by changing the flow rate of the aqueous liquid flowing through the electrode pair. Specifically, the flow rate of the aqueous liquid when the ion removal rate was 0.01 was made faster than the flow rate of the aqueous liquid when the ion removal rate was 0.25.

Results are shown in FIG. As shown in FIG. 29, the rate of decrease in electrical conductivity was faster when the ion removal rate was 0.01 than when the ion removal rate was 0.25. This result supports that 0.0002 <(σx−σy) /σx≦0.2 (for example, 0.01 ≦ (σx−σy) /σx≦0.1) is preferably satisfied. .

In conventional ion adsorption by the batch method, as shown in FIG. 30, two ion adsorption electrodes 1 are immersed in an aqueous liquid 2 having no flow, and ions are adsorbed by applying a DC voltage between these electrodes. In this case, ions are adsorbed almost uniformly on the entire ion adsorption electrode. Therefore, even if ion adsorption progresses, the voltage applied between the two electrodes is substantially equal across the electrodes, and activated carbon can be used efficiently. On the other hand, ion adsorption by a conventional liquid flow method, for example, in a conventional liquid flow capacitor, there is no idea of reducing the ion concentration difference before and after the inflow of the ion adsorbing portion, and the aqueous liquid passes once. It has been considered good to remove as many ions as possible. However, by doing so, the variation in the amount of adsorbed ions increases. Specifically, the adsorption amount of ions increases on the inflow side of the aqueous liquid, and the adsorption amount of ions decreases on the outflow side of the aqueous liquid. When such a variation occurs, the activated carbon on the inflow side of the aqueous liquid reaches the gas generation potential at the stage where the ions are not sufficiently adsorbed on the outflow side of the aqueous liquid, and as a result, the gas is generated on the inflow side of the aqueous liquid. Will occur. Such gas generation results in obstruction of the aqueous liquid flow, deterioration of the activated carbon, and reduction in current efficiency. On the other hand, if the voltage application is stopped before the gas generation occurs, the ion adsorption amount of the activated carbon on the outflow side of the aqueous liquid decreases. As described above, according to the conventional concept of a liquid-permeable capacitor, the activated carbon of the ion adsorption electrode cannot be used efficiently.

On the other hand, in order to process a large amount of aqueous liquid in the batch method, it is necessary to increase the amount of the aqueous liquid existing between the electrodes by widening the electrode interval. However, there is a problem that the voltage to be applied increases when the electrode interval is widened. Moreover, when the electrode interval is widened, there is a problem that the amount of waste liquid from which ions are released increases.

As a result of studying these problems, the present inventors have newly found a method for realizing the advantages of the batch method in a liquid method. In the method, the electrodes shown in FIG. 30 are placed in a small tank with the electrode interval narrowed, and ions are removed by applying the same current as in the batch method. However, the aqueous liquid is circulated at a high speed in order to reduce the ion concentration almost uniformly as in the batch method. That is, as described above, this method is a method of reducing the ion removal rate in the circulation type and liquid passing type processing. According to this method, variations in ion adsorption can be reduced. In this method, the amount of ions removed while the aqueous liquid passes through the ion adsorbing portion once is small. Therefore, this method seems to be contrary to the purpose of efficiently removing ions. However, when the aqueous liquid is circulated and processed under conditions where ion adsorption occurs as uniformly as possible, activated carbon can be used efficiently as in the batch method, and as a result, a high ion removal rate can be realized. These facts are supported by the results of Example 3. Further, since this method is a liquid passing method, a large amount of aqueous liquid can be treated even if the electrode interval is narrowed. By narrowing the electrode interval, the applied voltage can be lowered and the amount of waste liquid can be reduced.

The present invention can be applied to other embodiments without departing from the intent and essential features thereof. The embodiments disclosed in this specification are illustrative in all respects and are not limited thereto. The scope of the present invention is indicated by the claims, and all modifications that are equivalent in meaning and scope to the claims are included therein.

The present invention can be used for an apparatus and a method for reducing the ion concentration of an aqueous liquid held in a system.

Claims (25)

An apparatus for reducing the ionic concentration of an aqueous liquid held in a system,
Including at least one ion adsorbing portion;
The ion adsorption part includes a liquid path and a plurality of electrode pairs arranged in the liquid path,
The liquid path includes an inlet and an outlet connected to the system so that a circulation path including the liquid path and the system is formed;
The electrode pair includes a first electrode and a second electrode;
The first electrode includes a first conductive material containing activated carbon,
The second electrode includes a second conductive material containing activated carbon,
The ion concentration reducing device, wherein each of the first and second electrodes faces a void through which the aqueous liquid flows. A controller further comprising:
(I) Between the first electrode and the second electrode so that the first electrode becomes an anode in a state where the aqueous liquid is circulating between the ion adsorbing portion and the system. Adsorbing ions in the aqueous liquid to the first and second conductive materials by applying a voltage to
(Ii) In a state where the flow of the aqueous liquid from the ion adsorbing unit to the system is interrupted, the ions adsorbed by the first and second conductive substances are released to the liquid in the ion adsorbing unit, The ion concentration reducing device according to claim 1, wherein the step of discharging the liquid from which the ions have been discharged to the outside of the circulation path is repeatedly executed in this order. The controller is
In the step (i), the electrical conductivity σx (S / m) of the aqueous liquid introduced into the ion adsorbing portion and the electric conductivity σy ( S / m) is controlled so as to satisfy 0.0002 <(σx−σy) /σx≦0.2, and at least one selected from the flow rate of the aqueous liquid and the voltage in the ion adsorbing portion. The ion concentration reduction device according to claim 2. In the step (ii), the controller shuts off the flow of the aqueous liquid from the ion adsorption unit to the system,
(Ii-a) releasing the ions adsorbed on the first and second conductive substances into the liquid in the ion adsorption unit;
The ion concentration reducing device according to claim 2 or 3, wherein (ii-b) the step of discharging the liquid from which the ions have been discharged to the outside of the circulation path is executed in this order. 5. The ion concentration reducing apparatus according to claim 4, wherein the controller executes the step (ii-a) in a state where the flow of the aqueous liquid in the ion adsorption unit is stopped. The controller is
In the step (i), the following conditions:
(A) The total charge amount of ions adsorbed on the first electrode in the step (i) during execution has reached 60% of the saturated ion adsorption amount of the first electrode.
(B) The total charge amount of ions adsorbed on the second electrode in the step (i) during execution has reached 60% of the saturated ion adsorption amount of the second electrode.
The ion concentration reduction apparatus according to any one of claims 2 to 5, wherein the process of (i) is stopped and the process of (ii) is started before at least one of the conditions is satisfied. The electrode pair further includes a spacer disposed between the first electrode and the second electrode;
7. The ion concentration reducing device according to claim 1, wherein the gap is formed by the spacer. The ion concentration reducing apparatus according to claim 7, wherein, in the electrode pair, an interval between the first electrode and the second electrode is in a range of 0.3 to 10 mm. The ion concentration reducing device according to claim 7 or 8, wherein the spacer is a net-like spacer having an aperture ratio in a range of 0.3 to 0.9. In the electrode pair, a plurality of flow paths arranged in stripes are respectively formed on the surface of the first electrode and the surface of the second electrode by gaps of the spacers. The ion concentration reduction apparatus of any one of these. The ion concentration reducing apparatus according to any one of claims 1 to 10, wherein the plurality of electrode pairs include a conductive sheet that supports the first and second conductive substances. An insulating sheet is connected to an end of the conductive sheet;
The ion concentration reducing device according to claim 11, wherein the insulating sheet protrudes upstream of the flow of the aqueous liquid from the first and second conductive substances. One electrode group is configured by connecting the plurality of electrode pairs in series,
The ion concentration reducing device according to any one of claims 1 to 12, wherein only two electrodes existing at both ends of the electrode group are connected to a power source. The mass of the activated carbon contained in the first conductive material is in a range of 1.5 to 3 times the mass of the activated carbon contained in the second conductive material. The ion concentration reducing device according to 1. An apparatus comprising: a system that holds an aqueous liquid; and the ion concentration reducing device according to any one of claims 1 to 14 that reduces an ion concentration of the aqueous liquid. The apparatus of claim 15, wherein the system includes a cooling tower. The apparatus according to claim 15, wherein the hardness of the aqueous liquid is lowered by the ion concentration reducing apparatus. The system includes a reservoir,
The ion concentration reducing device is connected to the water tank;
An inlet and an outlet of the aqueous liquid are formed in the water reservoir,
The apparatus according to claim 15, wherein the ion concentration of the aqueous liquid is reduced by the ion concentration reducing device while the aqueous liquid flows through the water storage tank via the inlet and the outlet. A water quality adjusting device for adjusting at least one water quality selected from the pH and free chlorine concentration of the aqueous liquid;
The water quality adjusting device includes a tank through which the aqueous liquid flows, and two electrodes disposed in the tank,
The apparatus according to any one of claims 15 to 18, wherein the two electrodes include an electrode for performing electrolysis and an ion adsorption electrode for adsorbing ions. A free chlorine concentration adjusting device for adjusting the free chlorine concentration of the aqueous liquid flowing in the flow path;
The free chlorine concentration adjusting device is:
A container in which the aqueous liquid is disposed;
A separator that partitions the container into a first tank and a second tank;
A third electrode disposed in the first tank;
A fourth electrode disposed in the second tank,
The second tank is formed with an inlet and an outlet connected to the flow path so that the second tank forms part of the flow path,
The apparatus according to any one of claims 15 to 19, wherein a space in the first tank is connected to the flow path via the separator. A method for reducing the ion concentration of an aqueous liquid held in a system using the ion concentration reducing device according to claim 1,
(I) Between the first electrode and the second electrode so that the first electrode becomes an anode in a state where the aqueous liquid is circulating between the ion adsorbing portion and the system. Adsorbing ions in the aqueous liquid to the first and second conductive materials by applying a voltage to
(Ii) In a state where the flow of the aqueous liquid from the ion adsorbing unit to the system is interrupted, the ions adsorbed by the first and second conductive substances are released to the liquid in the ion adsorbing unit, And a step of repeating the step of discharging the liquid from which the ions have been released to the outside of the circulation path in this order. In the step (i), the electrical conductivity σx (S / m) of the aqueous liquid introduced into the ion adsorbing portion and the electric conductivity σy ( S / m) is controlled so that 0.0002 <(σx−σy) /σx≦0.2, at least one selected from the flow rate of the aqueous liquid and the voltage in the ion adsorbing portion, The ion concentration reduction method according to claim 21. In the step (ii), the flow of the aqueous liquid from the ion adsorption unit to the system is blocked.
(Ii-a) releasing the ions adsorbed on the first and second conductive substances into the liquid in the ion adsorption unit;
The ion concentration reduction method according to claim 21 or 22, further comprising: (ii-b) discharging the liquid from which the ions have been discharged to the outside of the circulation path in this order. The ion concentration reduction method according to claim 23, wherein the step (ii-a) is performed in a state where the flow of the aqueous liquid in the ion adsorption unit is stopped. In the step (i), the following conditions:
(A) The total charge amount of ions adsorbed on the first electrode in the step (i) during execution has reached 60% of the saturated ion adsorption amount of the first electrode.
(B) The total charge amount of ions adsorbed on the second electrode in the step (i) during execution has reached 60% of the saturated ion adsorption amount of the second electrode.
The ion concentration reduction method according to any one of claims 21 to 24, wherein the step (i) is stopped and the step (ii) is started before at least one of the following is satisfied.

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