CN201043148Y - Photocatalytic and electrocatalytic co-processing device for organic wastewater - Google Patents

Abstract

The utility model relates to a photocatalytic and electrocatalytic co-processing device for organic waste water. The sewage flows in from the water inlet at the bottom and flows out from the water outlet at the top, including an ultraviolet light source, a DC power supply and an electrode. The three-dimensional electrocatalytic electrode and the three-dimensional photocatalytic electrode of positive polarity, the three-dimensional electrode and the ultraviolet light source are horizontally oriented, perpendicular to the flow direction of sewage from bottom to top; the three-dimensional electrocatalytic electrode of positive polarity is located Below the catalytic three-dimensional electrode, a porous insulating separator is provided between the positive three-dimensional electrocatalytic electrode and the negative three-dimensional electrocatalytic electrode; the positive three-dimensional photocatalytic electrode is respectively located on the negative three-dimensional electrocatalytic electrode, and A porous insulating separator is arranged between the electrocatalytic electrode and the positive three-dimensional photocatalytic electrode. It has multiple reaction zones with different characteristics, and can treat organic wastewater that cannot be solved by conventional methods, with good effect, energy saving and convenient maintenance.

Description

Photocatalytic and electrocatalytic co-processing device for organic wastewater

technical field

The utility model relates to a device for synergistically treating organic wastewater by photocatalysis and electrocatalysis, which belongs to the technical field of electrochemistry.

Background technique

With the rapid development of modern industry, the amount of wastewater discharge is increasing day by day, and the types of organic pollution in wastewater are also increasing. Among the organic matter with complex components, most of them are substances that are difficult to be degraded by microorganisms, and conventional biotechnology cannot be used for sewage treatment. If the adsorption method or membrane filtration method is used, it is easy to cause secondary pollution of organic matter. Although in recent years, the photocatalytic technology using TiO ₂ semiconductor as photocatalyst has been proved to be able to convert most of the organic matter in the sewage into substances that are easy to biochemically treat, and even be completely mineralized—into CO ₂ and H ₂ O, etc. Inorganic molecules, but there is a problem of low degradation rate of organic matter, which still needs to be further solved.

In order to improve the reaction speed of converting organic matters in sewage into biochemically treatable substances, or into mineral substances (simple inorganic substances such as CO ₂ and H ₂ O), the utility model proposes a new technical solution.

Contents of the invention

The purpose of the utility model is to provide a photocatalytic and electrocatalytic co-processing device for organic waste water, so as to increase the reaction speed of converting organic matter in sewage into biochemically treatable substances or into mineral substances.

The purpose of the utility model is achieved through the following scheme: a device for co-processing organic wastewater by photocatalysis and electrocatalysis, the sewage flows in from the water inlet at the bottom of the device, and flows out from the water outlet at the top, including an ultraviolet light source, a DC power supply and electrodes, and the power supply is positively output connected to the positive electrode, and the negative output terminal connected to the negative electrode, the electrodes include a positive electrocatalytic three-dimensional electrode, a negative electrocatalytic three-dimensional electrode, and a positive three-dimensional photocatalytic electrode, wherein the three-dimensional electrode and the ultraviolet light source It is horizontally oriented and perpendicular to the flow direction of sewage from bottom to top; the positive polarity electrocatalytic three-dimensional electrode is located below the negative polarity electrocatalytic three-dimensional electrode. There are porous insulating separators between the electrocatalytic electrodes; the positive three-dimensional photocatalytic electrodes are respectively located on the negative three-dimensional electrocatalytic electrodes, and there is also a porous insulation barrier between the negative three-dimensional electrocatalytic electrodes and the positive three-dimensional photocatalytic electrodes. Insulating partitions.

On the basis of the above scheme, there are upper and lower positive three-dimensional photocatalytic electrodes, and the ultraviolet light source is located between the upper and lower positive three-dimensional photocatalytic electrodes. That is: the two positive three-dimensional photocatalytic electrodes are respectively located on the negative three-dimensional electrocatalytic electrode and the ultraviolet light source.

There are porous insulating separators between the positive three-dimensional electrocatalytic electrode and the negative three-dimensional electrocatalytic electrode, and between the negative three-dimensional electrocatalytic electrode and the positive three-dimensional photocatalytic electrode.

Wherein, the positive three-dimensional electrocatalytic electrode and two positive three-dimensional photocatalytic electrodes are connected to the positive output terminal of the direct current power supply, and the negative three-dimensional electrocatalytic electrode is connected to the negative output terminal of the direct current power supply. The working current is provided for the three-dimensional electrocatalytic electrode, and the forward bias voltage is provided for the three-dimensional photocatalytic electrode.

In addition, the distance between the ultraviolet light source and the upper and lower positive three-dimensional photocatalytic electrodes is kept to form a liquid phase region with a thickness of not less than 3 cm.

The ultraviolet light source is a low-pressure mercury lamp or a high-pressure mercury lamp.

The low-pressure mercury lamp or the high-pressure mercury lamp adopts multiple lamp tubes, and the quartz tube is used as the jacket of the lamp tubes.

The positive three-dimensional electrode is composed of a main electrode and a particle material, wherein the main electrode is a porous titanium plate whose surface is coated with a metal oxide catalyst with a high oxygen evolution overpotential, and the particle material is aluminum silicate beads or silica gel One of r-Al ₂ O ₃ particles is used as a matrix, and the surface is modified with a conductive metal oxide.

The negative three-dimensional electrocatalytic electrode is composed of a main electrode and a particle material, wherein the main electrode is a Pb-plated copper mesh or a stainless steel mesh; the particle material is a carbon particle bed treated with waterproofing and activation.

The main electrode of the negative polarity three-dimensional electrocatalytic electrode can be arranged at the center position of the carbon particle bed. In order to facilitate the complete reduction reaction.

The positive three-dimensional photocatalytic electrode is composed of a main electrode and a particle material, wherein the main electrode is a surface-modified InO ₂ -Ta ₂ O ₅ /SnO ₂ (Sb) conductive oxide film and a SnO ₂ /TiO ₂ photocatalytic film Titanium mesh; the particle material is quartz glass beads, granular activated carbon or silica gel as the matrix, and the surface is modified with nano-TiO ₂ semiconductor.

The working principle of the utility model is: when entering the working state, four regions with different reaction characteristics are formed from bottom to top:

1. The positive three-dimensional electrocatalytic electrode is an electrocatalytic oxidation reaction zone. Three oxidation reactions take place in this region:

a. Organic molecules are directly electrochemically oxidized on the electrode surface:

RH→Oxidation product+ne ①

b. Water molecules are electrochemically oxidized on the surface of the catalyst (MO _X ) to generate OH radicals and the reaction of oxygen (O ₂ ):

MO _X +H ₂ O→MO _X [·OH]+H ⁺ +e ②

2MO _X [·OH]→2MO _X +O ₂ +2H ⁺ +2e ③

OH free radical is a highly oxidizing substance, and its oxidation potential is 2.85V, which is much higher than that of ozone (2.07V) and H ₂ O ₂ (1.77V), so it can oxidize most organic substances , trigger carbon chain fission, and eventually degrade into simple inorganic molecules such as CO ₂ and H ₂ O:

RH+MO _X [·OH]→…→MO _X +CO ₂ +H ₂ O ④

Since the catalyst modified on the surface of the main electrode and the particle material is a metal composite oxide with high oxygen evolution overpotential, it is very beneficial to the reactions ① and ②. In other words, it can accelerate the oxidative degradation rate of organic molecules. Reaction ③ is a side reaction.

2. The negative three-dimensional electrocatalytic electrode is an electrochemical reduction reaction zone. There are mainly two reduction reactions in this area:

a. Organic molecules with reducing groups are electrochemically reduced, triggering chain scission and degradation.

b. The by-product O ₂ of the positive electrode below obtains electrons from the surface of the negative three-dimensional electrode and is reduced to generate H ₂ O ₂ :

O ₂ +2H ₂ O+2e→H ₂ O ₂ ⑤

Since the reduction potential of _O2 is higher than that of H ⁺ , and carbonaceous materials are good catalysts for the reaction ⑤, this region is also the site for the in-situ electrochemical synthesis _{of H2O2} .

3. The positive polarity three-dimensional photocatalytic electrode is the area for photocatalytic oxidation of organic matter. The TiO ₂ semiconductor photocatalyst on the electrode surface is excited by the ultraviolet photon hγ to generate a large number of electron (e ^- ) hole (h ⁺ ) pairs:

TiO ₂ +hγ→(h ⁺ +e ^- )/TiO ₂ ⑥

Under the action of forward bias, the photogenerated electrons move to the negative three-dimensional electrocatalytic electrode through the external circuit, and participate in the electrochemical reduction reaction of organic molecules and _O2 molecules; Holes (h ⁺ ) can initiate two oxidation reactions:

a. Photogenerated holes (h ⁺ ) directly oxidize organic molecules to degrade them;

b. Photogenerated holes (h ⁺ ) oxidize OH ^- ions, generate OH radicals, and then oxidize organic molecules (RH)

RH+·OH→…→CO ₂ +H ₂ O ⑦4. The liquid phase region near the ultraviolet light source is the region for photochemical oxidation of organic matter. After the H ₂ O ₂ generated by formula ④ is delivered to this region, under the action of ultraviolet light, H ₂ O ₂ undergoes chain scission to generate OH free radicals:

H ₂ O ₂ →2·OH ⑧

And then oxidize organic molecules (see ⑦ formula).

It can be seen from the above that the organic sewage flowing from bottom to top has to go through 4 reaction zones and various reaction pathways, and except for the liquid-phase photochemical oxidation zone, the other three-dimensional electrolytic reactors with a large surface-to-body ratio and a high porosity are used. Catalytic and photocatalytic reaction bed structure, which increases the contact area between sewage and catalyst and the absorption area of ultraviolet light in the photocatalytic bed, reduces the migration distance of reactants, and increases the probability of organic molecules effectively colliding with electrocatalysts and photocatalysts. It is beneficial to accelerate the oxidative degradation rate of organic matter. In addition, the reasonable relative spatial position and configuration between positive and negative electrocatalytic electrodes and between electrocatalytic and photocatalytic electrodes in the device makes a benign synergy between electrocatalysis and photocatalysis—electrocatalysis The by-product O ₂ precipitated at the positive electrode becomes the raw material for the on-site synthesis of H ₂ O ₂ at the negative electrode, and the H ₂ O ₂ synthesized by the electrocatalytic negative electrode becomes an indispensable substance for the photochemical generation of OH radicals. Constitute a coupling electrode, so that the photocatalytic electrode can obtain a forward bias voltage; reduce the recombination of photogenerated electrons and holes, and improve the efficiency of photocatalytic oxidation of organic matter; organic matter that is easier to oxidize is first decomposed by electrocatalysis, and the remaining difficult to decompose Organic matter is processed by photocatalysis, which has the strongest oxidizing power but relatively high energy consumption, which is conducive to improving the purification speed of pollutants and saving energy. Such various coordination functions make an important contribution to increasing the water treatment effect of the device and reducing energy consumption and treatment costs. Therefore, this device is a new type of electrochemical water treatment device that can quickly convert organic matter in sewage into substances that are easy to biochemically treat or into inorganic substances, such as CO ₂ and H ₂ O.

Description of drawings

Fig. 1 structural representation of the utility model

Explanation of symbols in the figure:

1--Positive three-dimensional electrocatalytic electrode 11--Main electrode 12--Particle material

2--Negative three-dimensional electrocatalytic electrode 21 Main electrode 22--Particle material

3. 3'-Positive three-dimensional photocatalytic electrode

31, 31'--Main electrode 32, 32'--Particle material

4-Ultraviolet light source 41--Lamp 42-Quartz tube

5--Water distribution board 6--Water inlet

7--Water outlet 8--DC power supply

10--hole insulation partition 101, 102--upper and lower porous insulation partition

9--Shell 91--Bracket

Detailed ways

As shown in the structure diagram of the utility model in Fig. 1, the utility model water treatment device consists of a positive three-dimensional electrocatalytic electrode 1, a negative three-dimensional electrocatalytic electrode 2, a positive three-dimensional photocatalytic electrode 3, 3 ', an ultraviolet light source 4, Porous insulating partition 10, water distribution plate 5, water inlet 6, water outlet 7, DC working power supply 8, shell 9, support 91 is formed.

As shown in Figure 1, the ultraviolet light source 4 adopts a low-pressure mercury lamp or a high-pressure mercury lamp, and the lamp tube 5 is placed in a quartz tube 42 to form a light source. The power of the mercury lamp depends on the size of the device, and the general range is 100w-1kw.

Among them, the three-dimensional electrodes and the light source are installed in the horizontal direction, and the sewage flows into the water distribution plate 5 from the lower end of the water inlet 6, and then passes through the positive three-dimensional electrocatalytic electrode 1, the negative three-dimensional electrocatalytic electrode 2, and the positive electrode from bottom to top. The positive three-dimensional photocatalytic electrode 3, the light source 4 and the positive three-dimensional photocatalytic electrode 3' finally flow out from the water outlet 7 at the upper end. There is a certain distance between the light source 4 and the positive three-dimensional photocatalytic electrodes 3, 3' to ensure a liquid phase region with a certain thickness.

Between the positive and negative three-dimensional electrocatalytic electrodes 1 and 2, between the positive three-dimensional photocatalytic electrode 3 and the negative three-dimensional electrocatalytic electrode 2, upper and lower porous insulating separators 101 and 102 are respectively installed to prevent current short circuit .

The positive three-dimensional electrocatalytic electrode 1 of the present utility model is composed of a main electrode 11 and a particle material 12. The substrate of the main electrode is a microporous titanium plate, and the surface of the main electrode is modified by a thermal decomposition method of InO ₂ -Ta ₂ O ₅ /SnO ₂ (Sb )-PbO ₂ composite metal oxide film, the particle material is made of silica gel, r-Al ₂ O ₃ or aluminum silicate beads or a combination thereof, and the impregnation-pyrolysis method is used to support MnO ₂ -SnO ₂ (Sb)-PbO ₂ composite metal oxide catalyst.

The main electrode 21 of the negative three-dimensional electrocatalytic electrode 2 is a copper mesh or a stainless steel mesh plated with Pb on the surface, and the particle material 22 is a carbon particle bed treated with waterproofing and activation, such as particles blended, shaped and sintered with graphite powder, activated carbon and PTFE .

The main electrodes 31, 31' of the positive three-dimensional photocatalytic electrodes 3, 3' are made by modifying the InO ₂ -Ta ₂ O ₅ /SnO ₂ (Sb) conductive film on the surface of titanium mesh by pyrolysis method, and the particle materials 32, 32' uses granular activated carbon or silica gel as a carrier, and adopts sol-gel method to support anatase nano-TiO ₂ semiconductor photocatalyst on its surface.

As shown in Figure 1, the lead wires of the positive polarity three-dimensional electrocatalytic electrode 1 and the positive polarity three-dimensional photocatalytic electrode 3, 3' are connected together and connected to the output terminal (+) of the DC power supply 19; the negative polarity three-dimensional electrocatalytic electrode 2 The lead wire is connected to the output terminal (-) of the DC power supply 19; the output voltage of the DC power supply is adjusted during operation, which requires that the positive polarity three-dimensional photocatalytic electrode obtain >3V forward bias voltage, and make the electrocatalytic electrode have a certain intensity of work Current (the current density range is 10-50mA/cm ² , and the current is calculated according to the area of the negative three-dimensional electrode main board).

Before the sewage enters the device in advance, the pH of the solution should be adjusted to 2.5-3 with acid or alkali, and the suspended solids in the sewage should be filtered out.

The device has the advantages of fast oxidation and degradation of organic matter and energy saving, and is very convenient to assemble, maintain and use.

Claims (10)

1. A device for co-processing organic wastewater by photocatalysis and electrocatalysis. The sewage flows in from the water inlet at the bottom of the device and flows out from the water outlet at the top, including ultraviolet light source, DC power supply and electrodes. connected to the negative electrode at the end, and it is characterized in that: the electrode has a positive polarity electrocatalytic three-dimensional electrode, a negative polarity electrocatalytic three-dimensional electrode, and a positive polarity three-dimensional photocatalytic electrode, wherein the three-dimensional electrode and the ultraviolet light source are horizontally oriented, It is perpendicular to the flow direction of sewage from bottom to top; the positive three-dimensional electrocatalytic electrode is located below the negative three-dimensional electrocatalytic electrode, and a porous insulation is provided between the positive three-dimensional electrocatalytic electrode and the negative three-dimensional electrocatalytic electrode. Separator; the positive three-dimensional photocatalytic electrodes are respectively located on the negative three-dimensional electrocatalytic electrodes, and a porous insulating separator is arranged between the negative three-dimensional electrocatalytic electrodes and the positive three-dimensional photocatalytic electrodes. 2. The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 1, characterized in that: there are two positive three-dimensional photocatalytic electrodes on the upper and lower sides, and the ultraviolet light source is in the upper and lower positive three-dimensional photocatalytic electrodes. between the electrodes. 3. The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 2, characterized in that: the positive three-dimensional electrocatalytic electrode and two positive three-dimensional photocatalytic electrodes are connected to the positive output terminal of the DC power supply, and the negative electrode The three-dimensional electrocatalytic electrode is connected to the negative output terminal of the DC power supply. 4. The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 3, characterized in that: said ultraviolet light source keeps a distance from the upper and lower positive three-dimensional photocatalytic electrodes to form a thickness of no less than 3cm the liquid phase region. 5 . The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 4 , wherein the ultraviolet light source is a low-pressure mercury lamp or a high-pressure mercury lamp. 6. The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 5, characterized in that: the low-pressure mercury lamp or the high-pressure mercury lamp adopts multiple lamp tubes, and the quartz tube is used as the jacket of the lamp tubes. 7. The device for co-processing organic wastewater by photocatalysis and electrocatalysis according to claim 3, characterized in that: the positive three-dimensional electrode is composed of a main electrode and a particle material, and the main electrode is coated with oxygen on the surface Porous titanium plate of InO ₂ -Ta ₂ O ₅ /SnO ₂ (Sb)-PbO ₂ metal oxide catalyst with high overpotential, the particle material is one of aluminum silicate beads or silica gel, r-Al ₂ O ₃ particles The metal oxide MnO ₂ -SnO ₂ (Sb)-PbO ₂ is used as the substrate and the surface is modified to conduct electricity. 8. The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 3, characterized in that: the negative three-dimensional electrocatalytic electrode is composed of a main electrode and a particle material, wherein the main electrode is a surface plated with Pb Copper mesh or stainless steel mesh; the particle material is a carbon bed treated with waterproof activation. 9 . The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 8 , wherein the main electrode is located in the center of the carbon particle bed. 10. The photocatalytic and electrocatalytic co-processing device for organic wastewater according to claim 3, characterized in that: the positive three-dimensional photocatalytic electrode is composed of a main electrode and a particle material, wherein the main electrode is a surface-modified Titanium mesh of InO ₂ -Ta ₂ O ₅ /SnO ₂ (Sb) conductive oxide film and/or SnO ₂ /TiO ₂ photocatalytic film; particle material is quartz glass beads, granular activated carbon or silica gel as carrier, surface modified anatase type of nano-TiO ₂ semiconductor photocatalyst.

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