JPH08166377A - Water quality monitor and water quality monitoring method - Google Patents

Abstract

(57) [Summary] [Structure] Ion concentration column packed with strongly acidic cation exchange resin and strongly basic anion exchange resin, sample water supply mechanism that supplies a predetermined amount of sample water to the ion concentration column, trapped on the ion concentration column A high temperature water supply mechanism for eluting the generated ions, a switching mechanism for sample water and high temperature water to be supplied to the ion concentration column, and an electrical conductivity meter for measuring the electrical conductivity of the eluent from the ion concentration column. A characteristic water quality monitor and a water quality monitoring method using the monitor. [Effect] According to the water quality monitor and the water quality monitoring method of the present invention, it is possible to measure an extremely low ion concentration in sample water that cannot be confirmed by a conventional resistivity meter such as ultrapure water for electronic industry.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water quality monitor and a water quality monitoring method. More specifically, the present invention relates to a water quality monitor and a water quality monitoring method capable of accurately and rapidly measuring the total ion concentration of water having extremely low impurity concentrations such as ultrapure water for electronic industry.

[0002]

2. Description of the Related Art Ultrapure water for electronic industry has extremely high purity,
The dissolved ion concentration is extremely low, such as several μg / liter to several ng / liter. Regarding the ions present in such ultrapure water, the abundance of all ions has been conventionally evaluated by continuously measuring the electrical conductivity of sample water and using this value as an index. Further, in order to grasp all the dissolved ions in detail, sample water is sampled and concentrated by an ion chromatograph equipped with a concentration column filled with an ion exchange resin,
By separate analysis, the type was identified and individual ion concentration was measured. However, as the purity of ultrapure water for electronic industry rises, the resistivity of ultrapure water approaches the resistivity of theoretical pure water containing no impurities, 18.24 MΩ · cm, as much as possible. When measuring extremely low resistivity like this, the sensitivity and accuracy of the detector currently used in the resistivity meter is insufficient, and it is very difficult to confirm the total amount of ions present. There is. Therefore, there is a demand for a total ion concentration measuring device that has higher sensitivity and accuracy, is compact, and is easy to operate.

[0003]

The present invention provides a water quality monitor for ultrapure water and a water quality monitoring method capable of capturing and concentrating ionic impurities in ultrapure water and easily monitoring the concentration. It was made for the purpose of doing.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that after capturing ionic impurities in ultrapure water with an ion exchange resin, the captured ionic It was found that the amount of ionic impurities in ultrapure water can be easily measured by eluting impurities with high temperature water and measuring the electric conductivity thereof, and the present invention was completed based on this finding. It was That is, the present invention provides (1)
Ion concentration column packed with strongly acidic cation exchange resin and strong basic anion exchange resin, sample supply mechanism that supplies a predetermined amount of sample water to the ion concentration column, high temperature water for eluting the ions trapped in the ion concentration column Supply mechanism,
A water quality monitor characterized by having a switching mechanism for sample water and high-temperature water supplied to the ion concentration column, an electric conductivity meter for measuring the electric conductivity of the eluent from the ion concentration column, and (2) sample water Was passed through an ion concentration column packed with a strongly acidic cation exchange resin and a strongly basic anion exchange resin to capture cations and anions,
Provided is a water quality monitoring method, characterized in that high-temperature water is supplied to an ion concentrating column to elute cations and anions, and the electric conductivity of the eluent is measured to determine the total electrolytic mass in sample water. It is a thing. Furthermore, as a preferred embodiment of the present invention, (3) the volume ratio of the strongly acidic cation exchange resin and the strongly basic anion exchange resin is 4: 6 to.
The water quality monitor according to item (1) or the water quality monitoring method according to item (2), which is 6: 4, and (4) the water quality according to item (2), wherein the temperature of the high-temperature water is 60 to 100 ° C. A monitoring method can be mentioned.

In the water quality monitor of the present invention, the ion-concentrating column packed with the strongly acidic cation exchange resin and the strongly basic anion exchange resin is one packed with a mixture of the strongly acidic cation exchange resin and the strongly basic anion exchange resin. Column, or a column packed with a strongly acidic cation exchange resin and a column packed with a strongly basic anion exchange resin can be connected in series. When the column filled with the strongly acidic cation exchange resin and the column filled with the strongly basic anion exchange resin are connected in series, there is no limitation on the order of connection, and any column can be placed on the upstream side. In the water quality monitor of the present invention, the sample water supply mechanism can be used without particular limitation as long as it can supply a predetermined amount of sample water to the ion concentration column. For example, a metering pump can be used. It can be supplied by using, or can be supplied by combining a pressurizing device and a constant flow device. As the high temperature water supply mechanism, for example, a mechanism that supplies high temperature water from a constant temperature water tank that stores high temperature water with a constant volume pump, or sends normal temperature water with a constant volume pump, and installs a heat exchange device between the constant volume pump and the ion concentration column. It is possible to use a mechanism that is provided to heat water. As a mechanism for switching the supply of sample water and high temperature water to the ion concentration column, it is possible to switch between the sample water and high temperature water by connecting the sample water and high temperature water pipes to the column and providing a cock on each pipe. The sample water and the high-temperature water can be connected to the three-way cock by piping and the other one can be connected to the column, or a switching valve for switching the flow paths of the sample water and the high-temperature water can be provided. In the water quality monitor of the present invention, the eluent from the ion concentration column can be directly led to an electric conductivity meter,
A heat exchanger can be installed between the ion concentration column and the conductivity meter to lower the temperature of the eluent to a certain temperature.
Alternatively, a container may be provided between the ion concentrating column and the electric conductivity meter to store a certain amount of the eluent and mix it uniformly. Since the measured value of electric conductivity varies greatly depending on the temperature, should the electric conductivity meter be installed in a thermostatic chamber?
Those having a temperature compensation function, particularly a dual temperature compensation function, are preferable. In the present invention, an electric conductivity meter can be used instead of the electric conductivity meter. When using an electric conductivity meter, the electric conductivity is calculated by multiplying the measured electric conductivity by the cell constant.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a system diagram of one embodiment of the water quality monitor of the present invention. This figure shows a state where ions in the sample water are captured in the ion concentration column. The sample water is supplied from the sample water channel 1 by the sample water supply pump 2 at a constant speed through the switching valve 3 to the ion concentration column 4 filled with the strongly acidic ion exchange resin and the strongly basic ion exchange resin, and the ion concentration column After the ions are captured by, the ions are discharged via the switching valve 5. The other part of the sample water is guided to the constant temperature water tank 7 through the pipe 6, and is heated to a predetermined temperature by the temperature controller 8 equipped with a temperature-setting type jet stirring device in the constant temperature water tank to obtain high temperature water. Become. The high temperature water is the high temperature water supply pump 9
Is sent at a constant speed and is sent to the electric conductivity meter 10 via the switching valves 5 and 3, and the electric conductivity κ ₀ is measured. When using ultra pure water for electronics industry as sample water,
The value of electrical conductivity κ ₀ is usually very small. FIG. 2 shows FIG.
3 is a system diagram showing an ion elution state of the water quality monitor shown in FIG. The sample water supply pump 2 sends the sample water to the ion concentration column 4 at a predetermined flow rate for a predetermined period of time to capture cations and anions in the sample water in the column, and then the switching valves 3 and 5 are rotated. The state of FIG. 2 is assumed. In this state, the sample water sent by the sample water supply pump 2 is
It is discharged via the switching valves 3 and 5. Constant temperature water tank 7
The high-temperature water in the inside is sent at a constant speed by the high-temperature water supply pump 9, elutes the ions in the ion concentration column 4 via the switching valve 5, and the eluent passes through the switching valve 3 and the electric conductivity meter 10 And the electrical conductivity is measured. The electric conductivity of the eluent can be continuously measured. FIG.
In this state, the high-temperature water obtained by heating the sample water is cooled again and kept being sent to the electric conductivity meter 10, so that a stable base corresponding to the electric conductivity κ ₀ is recorded on the recorder attached to the electric conductivity meter. Draw a line. Then, by switching the switching valve, the ions captured in the ion concentrating column are eluted by the high temperature water and sent to the electric conductivity meter. As the eluted ions are sent to the electric conductivity meter, the electric conductivity rises and a peak is drawn on the recording paper, and the electric conductivity value returns to the baseline again. Can be asked. The amount of ions contained in the sample water can be easily obtained by performing measurement in advance using sample water containing a known amount of ions and creating a calibration curve that shows the relationship between the ion amount and the peak area. You can The electrical conductivity of the eluent eluted from the ion concentrating column with high temperature water can be measured batchwise. When measuring in batch mode,
An eluent storage tank (not shown in FIGS. 1 and 2) is provided between the switching valve 3 and the electric conductivity meter 10 to elute cations and anions with a certain amount of high temperature water, and then the high temperature water. The liquid supply is stopped, the eluents stored in the eluent storage tank are uniformly mixed and sent to the electric conductivity meter 10, and the electric conductivity κ ₁ is measured. The value of κ ₁ −κ ₀ is the electrical conductivity due to the electrolyte present in the sample water.Therefore, from this value and the amount of sample water sent to the ion concentration column, the calibration curve is used to determine the electrolyte The quantity can be calculated.

In FIG. 1 and FIG. 2, the sample water and the high temperature water are in a countercurrent system in which they flow in opposite directions in the ion concentrating column. According to the countercurrent method, the ions trapped in each column can be eluted and discharged in a short time. However, if necessary, a parallel flow method in which the sample water and the high temperature water flow in the same direction in the ion concentration column can be adopted. In the water quality monitor of the present invention, the ratio of the strongly acidic cation exchange resin and the strongly basic anion exchange resin used is preferably 3: 7 to 7: 3 by volume ratio,
It is more preferably 4: 6 to 6: 4, and particularly preferably 5: 5. The strongly acidic cation exchange resin and the strongly basic anion exchange resin can be mixed and packed in one column for use, or the strongly acidic cation exchange resin and the strongly basic anion exchange resin can be used in separate columns. It can be packed and used by connecting two columns in series. In the water quality monitoring method of the present invention, the temperature of the high temperature water is preferably 60 to 100 ° C.,
More preferably, the temperature is 90 ° C. When the temperature of the high-temperature water is lower than 60 ° C., the elution rate of the ions captured by the ion concentrating column is slow, the amount of the eluent increases, and the ion concentration of the eluent becomes low. If the temperature of the hot water exceeds 100 ° C., pressure and pressure must be applied to suppress boiling, which complicates the apparatus and operation. In the water quality monitor of the present invention, a control device can be provided, and for example, a control panel is used to set the sample water supply time, flow rate setting, measurement start instruction, operation of the switching valve, recording of detection data, and measurement of peak area. It is possible to control calculation, comparison with a standard sample (calibration curve), recording of results, and start / stop of the pump. In the water quality monitoring method of the present invention, the ions in the sample water are captured by passing the sample water through the ion concentration column, and then the switching valve is switched to pass the high temperature water through the ion concentration column to elute the ions. To do. The eluted ions are
The ion concentration is determined by measuring the electric conductivity with an electric conductivity meter. When the ion concentration of sample water is extremely low, the amount of water flow is increased, that is, by increasing the concentration of ions, the concentration is increased to several tens to several hundreds of times, and all ions of extremely low concentration in the sample water are collected. Can be measured. One aspect of the water quality monitor of the present invention is a sample water supply pump, a concentration column filled with a mixture of a strongly acidic ion exchange resin and a strongly basic ion exchange resin, a switching valve, a constant temperature water tank, a high temperature water feed pump, and an electric conductivity. It consists of a total. By concentrating all the ions by pumping sample water through the concentrating column, then sending hot water to the concentrating column to elute the concentrated ions and measuring them with an electric conductivity meter. The amount of electrolyte at a lower concentration level, which cannot be measured by the electric conductivity meter described above, can be measured as the total ion concentration. Moreover, since the structure of this device is simple and the analysis operation is very simplified, it can be applied as a monitoring device. When the total ion concentration of sample water is extremely low, it is possible to perform accurate measurement by increasing the water passage time and increasing the concentration amount.

[0008]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 Using the apparatus shown in FIG. 1, the water quality of water obtained by adding sodium chloride to ultrapure water for electronic industry was measured to prepare a calibration curve. The cation concentration column 4 has an inner diameter of 4 mm and a length of 3
Strongly acidic cation exchange resin 0.14 m in a 5 mm glass column
and 0.14 ml of a strongly basic anion exchange resin. The sample water supply pump 2 is a plunger type metering pump having a water supply rate of 4 ml / min. The temperature of the constant temperature water tank is set by a temperature controller equipped with a temperature setting type jet stirring device. The high temperature water supply pump 9 is a plunger type metering pump having a water supply rate of 4 ml / min. Electrical conductivity meter 10
Is a DX-100 type manufactured by Dionex Co., Ltd., which has a temperature compensation function. With the switching valves 3 and 5 in the state shown in FIG. 1, the sample water supply pump 2 was used to add 3 parts of water added to ultrapure water so that sodium chloride was adjusted to 10 ng / liter.
Water was fed to the ion concentration column 4 through the switching valve 3 for 0 minutes until the amount of water fed reached 120 ml to trap sodium ions and chlorine ions, and then discharged through the switching valve 5. During this time, high temperature water is sent by the high temperature water supply pump 9, and the electric conductivity meter 10 is passed through the switching valves 5 and 3.
The electrical conductivity was measured by. The display of the recorder attached to the electric conductivity meter became stable 5 minutes after the start of water supply, and the baseline became linear. The amount of water sent to the ion concentration column is 1
When it reaches 20 ml, rotate the two switching valves and
Then, elution of sodium ion and chlorine ion with high temperature water was started. The temperature of the high-temperature water is set to 70 ° C, the piping from the constant temperature water tank, the high-temperature water supply pump, the switching valve 5 and the ion concentration column are kept warm, and the temperature of the ion concentration column is 70 ± 1 ° C And chlorine ions were eluted. Eluent is switching valve 3
It sent to the electric conductivity meter via. Soon after, an increase in the electric conductivity was observed in the recorder of the electric conductivity meter, and after the peak was recorded on the recording paper, the electric conductivity value returned to the baseline value again. The peak area obtained by the recorder is
It was 451 nS · cm ⁻¹ · sec. When exactly the same test was repeated using water having sodium chloride concentrations of 50 ng / liter and 100 ng / liter, the peak areas were 523 nS · cm ⁻¹ · sec and 612 nS · cm ⁻¹ · sec, respectively.
Met. When these data were plotted by plotting the concentration of sodium chloride on the horizontal axis and the peak area on the vertical axis, a substantially straight line was obtained as shown in FIG. That is, FIG. 3 is a graph showing the relationship between the peak area and the sodium chloride concentration corresponding to a water flow rate of 120 ml, and a calibration curve was created based on this graph, and the amount of electrolyte in sample water was changed to sodium chloride. It can be calculated and calculated. Example 2 The amount of electrolyte in ultrapure water for electronic industry was measured. The sample water supply pump 2 is connected to the ultrapure water channel, the switching valves 3 and 5 are set to the state shown in FIG. 1, and the sample water supply pump 2 is used to supply ultrapure water for 30 minutes and the amount of water supplied is 120 ml. Water was sent to 4. During this time, high temperature water was sent by a high temperature water supply pump, and the electric conductivity was measured by an electric conductivity meter via two switching valves. The display of the recorder attached to the conductivity meter was stable from beginning to end, and the baseline was linear. When the amount of water supplied to the ion concentrating column reached 120 ml, the two switching valves were rotated to the state shown in FIG. 2, and elution of cations and anions with high temperature water was started in the same manner as in Example 1. Soon after, an increase in the electric conductivity was observed in the recorder of the electric conductivity meter, and after the peak was recorded on the recording paper, the electric conductivity value returned to the baseline value again. The peak area obtained by the recorder is 432
It was nS · cm ⁻¹ · sec. From this result, 240 ng of ultrapure water for electronic industry is converted into sodium chloride.
It was found to contain an electrolyte corresponding to 1 liter / liter.

[0009]

According to the water quality monitor and the water quality monitoring method of the present invention, it is possible to measure an extremely low ion concentration in sample water that cannot be confirmed by a conventional resistivity meter such as ultrapure water for electronic industry. it can.

[Brief description of drawings]

FIG. 1 is a system diagram of one embodiment of a water quality monitor of the present invention.

FIG. 2 is a system diagram showing an ion elution state of the water quality monitor shown in FIG.

FIG. 3 is a graph showing the relationship between peak area and sodium chloride concentration.

[Explanation of symbols]

 1 Sample Water Channel 2 Sample Water Supply Pump 3 Switching Valve 4 Ion Concentration Column 5 Switching Valve 6 Piping 7 Constant Temperature Water Tank 8 Temperature Controller 9 High Temperature Water Supply Pump 10 Electrical Conductivity Meter

Claims (2)

[Claims] 1. An ion concentration column filled with a strongly acidic cation exchange resin and a strongly basic anion exchange resin, a sample water supply mechanism for supplying a predetermined amount of sample water to the ion concentration column, and an ion trapped in the ion concentration column. Water quality characterized by having a high-temperature water supply mechanism for elution, a switching mechanism for sample water and high-temperature water supplied to the ion concentration column, and an electric conductivity meter for measuring the electric conductivity of the eluent from the ion concentration column monitor. 2. Sample water is passed through an ion concentration column packed with a strongly acidic cation exchange resin and a strongly basic anion exchange resin to capture cations and anions, and then high temperature water is supplied to the ion concentration column. A method for monitoring water quality, characterized in that the total electrolytic mass in sample water is obtained by eluting positive and negative ions and measuring the electric conductivity of the eluent.