A method for coupling an anode and a cathode electrocatalytic flow reactor and deep treatment of trace pollutants in water

Abstract

The application provides a coupling cathode and anode electrocatalytic flow reactor and a method for treating trace pollutants in water, which comprises a membrane electrode and a gas diffusion electrode, a liquid chamber module is arranged between the membrane electrode and the gas diffusion electrode, and an anion exchange membrane is arranged between the liquid chamber module and the gas diffusion electrode. Compared with the prior art, the application can couple the cathode and the anode to efficiently degrade trace pollutants in wastewater in a continuous flow state by reasonably arranging the positions of the gas diffusion electrode liquid, the liquid chamber module and the anode membrane electrode. The device couples hydrogen peroxide generated by cathode reduction oxygen and active oxygen species generated by anode membrane electrode oxidation to simultaneously degrade organic pollutants in water. The abundant pores on the membrane electrode can intercept and enrich trace pollutants in water, thereby realizing efficient degradation. Compared with a traditional single-side working electrode reactor, the device greatly reduces energy consumption and improves the pollutant degradation efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of water pollutant degradation, and relates to a coupling anode-cathode electro-catalytic flow reactor and a method for deep treatment of trace pollutants in water. BACKGROUND

[0002] Antibiotics, endocrine disruptors and other micro-pollutants have become a new type of environmental pollutants. Due to the difficulty in detection, enrichment and degradation of these trace micro-pollutants, they have been widely present in water bodies for a long time. Numerous studies have confirmed that long-term exposure to these low-concentration micro-pollutants (ng / L-10 mg / L) can cause harm. Based on this, various treatment technologies have been tried and used for the removal of these trace micro-pollutants.

[0003] Microfiltration (MF) and ultrafiltration (UF) technologies have been widely used in water and wastewater treatment due to their interception and enrichment functions, high water quality, small footprint, and easy automation control. However, due to the limitation of membrane pore size, the removal rates of these two technologies for micro-pollutants are very low. In addition, micro-pollutants can accumulate on the surface or pores of microfiltration and ultrafiltration membranes, eventually leading to membrane fouling and permeability loss.

[0004] In order to overcome these challenges, researchers combined MF or UF with electrochemical advanced oxidation processes (EAOP) and developed a hybrid technology of electro-catalytic membrane (EM). In this technology, pollutants intercepted by the membrane can be removed by EAOP to achieve self-cleaning, and the mass transfer of pollutants from the solution to the reaction surface (i.e. the membrane surface) is also enhanced. Compared with traditional MF and UF processes, the EM process has the advantages of producing high-quality effluent, reducing membrane fouling, and eliminating secondary pollution.

[0005] However, in existing studies on flow-type electro-catalytic degradation of pollutants, only the reaction of a single electrode is studied, such as the degradation of pollutants by anodic oxidation or the degradation of pollutants by a cathodic electro-Fenton system. However, the electro-catalytic process involves the simultaneous action of both anode and cathode. These studies only consider a single electrode, resulting in energy waste. SUMMARY

[0006] The present application aims to provide a coupling anode-cathode electro-catalytic flow reactor and a method for deep treatment of trace pollutants in water. The anode and cathode are coupled by this device, and the anode and cathode are used simultaneously to degrade pollutants, which improves the degradation efficiency while reducing energy consumption. In addition, the anode membrane material is designed to further degrade pollutants and improve the degradation efficiency.

[0007] The specific technical solutions of the present application are as follows:

[0008] The application discloses a coupling anode and cathode electrocatalytic flow reactor, which comprises a membrane electrode and a gas diffusion electrode, a liquid chamber module is arranged between the membrane electrode and the gas diffusion electrode, and an anion exchange film is arranged between the liquid chamber module and the gas diffusion electrode.

[0009] A first gasket is arranged between the membrane electrode and the liquid chamber module to prevent water leakage.

[0010] A second gasket is arranged between the anion exchange film and the gas diffusion electrode to prevent water leakage.

[0011] The anion exchange film can prevent short circuit and effectively react some cathode reaction products with the anode.

[0012] The membrane electrode is connected with a conductive adhesive tape or a conductive wire and serves as an anode working electrode.

[0013] The gas diffusion electrode is connected with a conductive adhesive tape or a conductive wire and serves as a cathode counter electrode.

[0014] A reference electrode is arranged in the liquid chamber module, that is, the reference electrode is inserted into a baffle cavity of the liquid chamber module, the baffle cavity provides a water outlet channel and a reference electrode insertion port, the reference electrode is inserted into the insertion port, and the whole system is a three-electrode system.

[0015] The coupling anode and cathode electrocatalytic flow reactor further comprises a first titanium plate and a second titanium plate.

[0016] A water inlet and a first water outlet are arranged on the first titanium plate.

[0017] A second water outlet is arranged on the liquid chamber module.

[0018] An air inlet and an air outlet are arranged on the second titanium plate.

[0019] The first titanium plate is connected with the membrane electrode.

[0020] The second titanium plate is connected with the gas diffusion electrode.

[0021] The distance between the membrane electrode and the gas diffusion electrode is the thickness of the baffle of the liquid chamber module.

[0022] The electrocatalytic film material of the membrane electrode is composed of one or more of inorganic ceramic films, organic polymer films or metal films with good electrical conductivity; or the electrocatalytic film material is composed of a non-conductive film material and carbon paper; the non-conductive film material is selected from ultrafiltration membranes, microfiltration membranes or nanofiltration membranes; or other materials that can be used for electrocatalytic degradation of pollutants can also be operated through the device.

[0023] Preferably, the active component in the electrocatalytic membrane material used by the membrane electrode is one or several of lead oxide clusters or nanoparticles, tin-based oxide clusters or nanoparticles;

[0024] The gas diffusion electrode comprises a hydrophobic carbon paper loaded oxygen reduction catalyst, and the oxygen reduction catalyst is a partially oxidized carbon material; the carbon material is selected from one or a combination of several of activated carbon, conductive carbon black, carbon nanotubes and graphene; or other materials that can be used for electrocatalytic oxygen reduction can also be operated by the device.

[0025] The first gasket and the second gasket used in the application are fluorine rubber gaskets.

[0026] The application provides a method for treating trace pollutants in water in depth, comprising the following steps:

[0027] 1) Start the coupled anode-cathode electrocatalytic flow reactor, and connect the membrane electrode to the positive electrode of an external power supply through a conductive tape or wire, so that the membrane electrode works as an anode working electrode; connect the gas diffusion electrode to the negative electrode of the external power supply through a conductive tape or wire, so that the gas diffusion electrode works as a cathode counter electrode;

[0028] 2) Pump the sewage containing pollutants into the water inlet through a peristaltic pump, close the first water outlet after the air in the pipeline is exhausted, and make the sewage pass through the membrane electrode; the pollutants in the water are preliminarily degraded through direct oxidation or indirect oxidation of the membrane electrode; oxygen enters the gas diffusion electrode through the gas inlet and is discharged through the gas outlet; the gas diffusion electrode in the cathode reduces the oxygen to perhydroxyl ions under the action of an electric field, and the perhydroxyl ions pass through the anion exchange membrane into the liquid chamber module and combine with the protons generated by anode oxidation to produce hydrogen peroxide, which further reacts with the pollutants in the liquid chamber module to degrade the pollutants; the sewage degraded through the double action of the anode and the cathode is discharged through the second water outlet.

[0029] The pollutants are levofloxacin, rhodamine B, refractory organic matter oxytetracycline (OTC), estrone (E1) or atrazine (ATZ);

[0030] The voltage of the coupled anode-cathode electrocatalytic flow reactor is controlled to be 2.0-3V, and the preferred voltage is 2.5V-3V;

[0031] The time for treating the sewage by the coupled anode-cathode electrocatalytic flow reactor is 10-60min.

[0032] In the treatment of the application, the sewage (waste water) containing pollutants flows through the membrane electrode, and the membrane electrode oxidizes the water to generate ·OH and H + , H + on the membrane surface, which flow into the liquid chamber module with the waste water, and the ·OH generated by the membrane electrode preliminarily degrades the pollutants in the waste water. -HO2 enters the liquid chamber module through the anion exchange membrane. - and H + In the liquid chamber module, H2O2 is generated to further degrade pollutants in the wastewater. Because the cathode and anode are relatively close, the anion exchange membrane can both prevent short circuits and allow the H2O2 generated at the cathode to further degrade pollutants. - Entering the liquid chamber module prevents the reverse reaction from occurring.

[0033] In step 2), wastewater generates reactive oxygen species such as hydroxyl radicals and superoxide radicals through the membrane electrode.

[0034] The external power source can be one or more of chemical fuel cells, biofuel cells, and physical energy batteries, or it can be achieved through an external electrochemical workstation.

[0035] The voltage between the anolyte and the cathode can be flexibly set according to the oxygen evolution potential of different membrane electrodes.

[0036] Currently, traditional mobile phase electrocatalytic degradation of wastewater mostly involves recycled water degradation (returning the water after the first degradation to the wastewater pond for multiple degradation cycles) and uses only a single electrode (using only the anode to generate ·OH or only the cathode to generate hydrogen peroxide, resulting in energy waste). This invention, however, utilizes both the cathode and anode simultaneously (wastewater flows through the membrane electrode, where the membrane electrode oxidizes the water, generating ·OH and H₂ on the membrane surface). + H + As wastewater flows into the liquid chamber module, the ·OH generated by the membrane electrode initially degrades pollutants in the wastewater. The gas diffusion electrode generates HO2 through oxygen reduction. - HO2 enters the liquid chamber module through the anion exchange membrane. - and H + The process combines H2O2 generated in the liquid chamber module to further degrade pollutants in the wastewater, and complete pollutant degradation can be achieved with a single filtration. Simultaneously, the use of a gas diffusion electrode at the cathode increases the contact area between oxygen and the catalyst, improving current density. Furthermore, the wastewater bypasses the cathode, passing directly through the liquid chamber module for discharge, effectively reducing side reactions.

[0037] Compared with existing technologies, the fluidized electrocatalytic membrane reactor provided by this invention is used for the deep treatment of trace organic pollutants in water. The reactor mainly consists of a membrane electrode, a gas diffusion electrode, an anion exchange membrane, and a liquid chamber module. By rationally arranging the positions of the gas diffusion electrode, the liquid chamber module, and the anode membrane electrode, the anode and cathode can be coupled to efficiently degrade trace pollutants in wastewater under continuous flow conditions. This device utilizes HO2 generated from the reduction of oxygen at the cathode. -The application is a kind of coupling cathode and anode electro-catalytic flow reactor, which is coupled with active oxygen species generated by electro-Fenton and anode membrane electrode oxidation to degrade organic pollutants in water. Compared with the traditional through-type reactor of cathode and anode, the application adds anion membrane and liquid chamber module, and the materials after cathode and anode reaction flow out from the middle liquid chamber module, which can effectively inhibit the occurrence of reverse reaction. The cathode adopts gas diffusion electrode, which greatly improves the efficiency of electro-Fenton compared with the traditional liquid electrolytic cell. The abundant pores on the anode ceramic membrane electrode can intercept and enrich trace pollutants in water, thereby realizing efficient degradation. Compared with the traditional single-side working electrode reactor or the through-type reactor of cathode and anode, the device greatly reduces the energy consumption and improves the degradation efficiency of pollutants, which is expected to promote the industrial application process of electro-catalytic degradation of pollutants in water. The application can achieve deep treatment, and the removal rate is as high as 99% or more; when the concentration of pollutants is milligram and microgram level, such as 2mg / L levofloxacin, the removal rate of 99% can also be achieved, and the application can be used for treating trace pollutants. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 Figure 1 is a structural schematic diagram of the coupling cathode and anode electro-catalytic device of the application,

[0039] 1, water inlet, 2, first water outlet, 3, membrane electrode, 41, first gasket, 42, second gasket, 5, second water outlet, 6, liquid chamber module, 7, anion exchange membrane, 8, gas diffusion electrode, 9, gas inlet, 10, gas outlet, 11, first titanium plate, 12, second titanium plate;

[0040] Figure 2 Figure 4 is the removal rate of 2mg / L levofloxacin under different voltages in Example 1;

[0041] Figure 3 Figure 5 is the removal rate of different pollutants in Example 2;

[0042] Figure 4 Figure 6 is the removal rate of rhodamine B in Example 3. DETAILED DESCRIPTION

[0043] The application is further illustrated by the following examples, which can better understand the application, but do not limit the application in any form. It should be pointed out that, without departing from the concept of the application, the device can be deformed and modified, which belongs to the protection scope of the application.

[0044] The application provides a kind of coupling cathode and anode electro-catalytic flow reactor, including membrane electrode 3 and gas diffusion electrode 8, liquid chamber module 6 is arranged between the membrane electrode 3 and gas diffusion electrode 8, anion exchange membrane 7 is arranged between the liquid chamber module 6 and gas diffusion electrode 8.

[0045] The first gasket 41 is arranged between the membrane electrode 3 and the liquid chamber module 6 to prevent water leakage.

[0046] The second gasket 42 is arranged between the anion exchange membrane 7 and the gas diffusion electrode 8 to prevent water leakage.

[0047] The anion exchange membrane 7 can prevent short circuit and effectively react some cathode reaction products with the anode.

[0048] The membrane electrode 3 is connected with a conductive tape or wire and works as an anode working electrode.

[0049] The gas diffusion electrode 8 is connected with a conductive tape or wire and works as a cathode counter electrode.

[0050] The reference electrode is inserted into the baffle cavity of the liquid chamber module, the baffle cavity provides a water outlet channel and a reference electrode insertion port, and the reference electrode is inserted into the interface to make the whole system a three-electrode system.

[0051] The coupled anode-cathode electrocatalytic flow reactor further comprises a first titanium plate 11 and a second titanium plate 12.

[0052] The first water inlet 1 and the first water outlet 2 are arranged on the first titanium plate 11.

[0053] The second water outlet 5 is arranged on the liquid chamber module 6.

[0054] The gas inlet 9 and the gas outlet 10 are arranged on the second titanium plate 12.

[0055] The first titanium plate 11 is connected with the membrane electrode 3.

[0056] The second titanium plate 12 is connected with the gas diffusion electrode 8.

[0057] The first titanium plate 11 and the second titanium plate 12 are electrode plates and provide flow channels for material transportation.

[0058] The distance between the membrane electrode 3 and the gas diffusion electrode 8 is the distance of the baffle of the liquid chamber module 6.

[0059] The electrocatalytic membrane material of the membrane electrode 3 is composed of one or more of inorganic ceramic membranes, organic polymer membranes or metal membranes with good electrical conductivity; or, the electrocatalytic membrane material is composed of non-conductive membrane material and carbon paper; the non-conductive membrane material is selected from ultrafiltration membranes, microfiltration membranes or nanofiltration membranes; or, other materials that can be used for electrocatalytic degradation of pollutants can also be operated by the device.

[0060] Preferably, the active components in the electrocatalytic membrane material of the membrane electrode 3 are one or more of lead oxide clusters or nanoparticles, tin-based oxide clusters or nanoparticles.

[0061] The gas diffusion electrode 8 comprises a hydrophobic carbon paper loaded oxygen reduction catalyst, the oxygen reduction catalyst is a partially oxidized carbon material; the carbon material is selected from one or a combination of several of activated carbon, conductive carbon black, carbon nanotube and graphene; or, other materials that can be used for electrocatalytic oxygen reduction can also be operated by the device.

[0062] The first gasket 41 and the first gasket 42 are both fluorine rubber gaskets.

[0063] The method for deep treatment of trace pollutants in water by using the above-mentioned coupling anode and cathode electrocatalytic flow reactor comprises the following steps:

[0064] 1) Start the coupling anode and cathode electrocatalytic flow reactor, the membrane electrode 3 is connected to the positive pole of an external power supply by a conductive tape or wire, and serves as an anode working electrode; the gas diffusion electrode 8 is connected to the negative pole of the external power supply by a conductive tape or wire, and serves as a cathode counter electrode.

[0065] 2) The first titanium plate 11 is provided with a water inlet 1 and a first water outlet 2, and the wastewater containing pollutants enters the whole reaction system through the water inlet 1; the second titanium plate 12 is provided with an air inlet 9 and an air outlet 10, and is responsible for the gas transmission of the cathode and participates in the cathode reaction. Both the titanium plates 11 and 12 can also serve as conductive materials. The sewage containing pollutants is pumped into the water inlet 1 by a peristaltic pump, the first water outlet 2 is closed after the air in the pipeline is exhausted, the sewage passes through the membrane electrode 3, and the pollutants in the water are preliminarily degraded by direct oxidation or indirect oxidation through the membrane electrode 3; oxygen enters through the air inlet 9, passes through the gas diffusion electrode and is discharged through the air outlet 10, the gas diffusion electrode 8 in the cathode reduces the oxygen to hydrogen peroxide ions by oxygen reduction, and the hydrogen peroxide ions enter the liquid chamber module 6 through the anion exchange membrane 7 under the action of an electric field, combine with the protons generated by the anode oxidation to produce hydrogen peroxide, and further oxidize and react with the pollutants in the liquid chamber module to degrade the pollutants; the sewage degraded by the double action of the anode and the cathode is discharged through the second water outlet 5 of the liquid chamber module.

[0066] The external power supply can be one or several of a chemical fuel cell, a biological fuel cell and a physical energy cell, and can also be realized by an external electrochemical workstation.

[0067] The voltage between the anode working electrode and the cathode counter electrode can be flexibly set according to the oxygen evolution potential of different membrane electrodes.

[0068] The application will be further described below by combining with several specific cases.

[0069] The anion exchange membrane used in the application is model FAA-3-PK-130.

[0070] Example 1

[0071] A coupling anode and cathode electrocatalytic flow reactor, comprising a membrane electrode 3 and a gas diffusion electrode 8, a liquid chamber module 6 is arranged between the membrane electrode 3 and the gas diffusion electrode 8, and an anion exchange membrane 7 is arranged between the liquid chamber module 6 and the gas diffusion electrode 8.

[0072] A first gasket 41 is arranged between the membrane electrode 3 and the liquid chamber module 6 to prevent water leakage.

[0073] A second gasket 42 is arranged between the anion exchange membrane 7 and the gas diffusion electrode 8 to prevent water leakage.

[0074] The anion exchange membrane 7 can prevent short circuiting on one hand and effectively react some cathode reaction products with the anode on the other hand.

[0075] The membrane electrode 3 is connected to a conductive tape or wire as an anode working electrode;

[0076] The gas diffusion electrode 8 is connected to a conductive tape or wire as a cathode counter electrode;

[0077] A reference electrode is inserted into the baffle of the liquid chamber module 6;

[0078] The coupling anode and cathode electrocatalytic flow reactor further comprises a first titanium plate 11 and a second titanium plate 12;

[0079] The first titanium plate 11 is connected to the membrane electrode 3;

[0080] The second titanium plate 12 is connected to the gas diffusion electrode 8;

[0081] A water inlet 1 and a first water outlet 2 are arranged on the first titanium plate 11;

[0082] A second water outlet 5 is arranged on the liquid chamber module 6;

[0083] An air inlet 9 and an air outlet 10 are arranged on the second titanium plate 12;

[0084] The distance between the membrane electrode 3 and the gas diffusion electrode 8 is the distance of the baffle of the liquid chamber module 6;

[0085] The preparation process of the membrane electrode 3 is as follows: 0.025 g of PbTiO3 metal oxygen cluster and commercial Ti4O7 powder are mixed and ball milled at 800 rpm for 3 hours, the PbTiO3 accounts for 5% of the total mass, and the balance is commercial Ti4O7 powder. A certain amount of paraffin oil is added to the above-mentioned powder to make a homogenate according to the amount of 6 drops of paraffin oil per gram of powder, and then the homogenate is cast-molded at 50 MPa in a 1 cm x 1 cm mold, and then calcined at 1000°C for 2 hours under argon protection to form a Ti4O7 ceramic membrane as the membrane electrode. The pore size and porosity of the ceramic membrane electrode are tested by mercury injection method, the average pore size is 495 nm, and the porosity is 36%.

[0086] The gas diffusion electrode 8 is a 1 cm x 1 cm hydrophobic carbon paper loaded with 0.46 mg of oxidized carbon black catalyst;

[0087] The method for deep treatment of trace pollutants in water by using the anode-cathode coupled electrocatalytic flow reactor of Example 1 comprises the following steps:

[0088] 1) Start the anode-cathode coupled electrocatalytic flow reactor, the membrane electrode 3 is connected to the positive electrode of an external power supply as the anode working electrode through conductive tape or wire, and the gas diffusion electrode 8 is connected to the negative electrode of the external power supply as the cathode counter electrode through conductive tape or wire; the external power supply is an electrochemical workstation.

[0089] 2) Treat the model pollutant solution containing electrolyte and refractory organic matter levofloxacin, the electrolyte concentration is 0.1 M Na2SO4, and the refractory organic matter is 2 mg / L levofloxacin; the mixed solution is continuously transported into the reactor at a flow rate of 1 mL / min by a peristaltic pump in a continuous mode, the external power supply is turned on, the peristaltic pump pumps the wastewater containing pollutants into the water inlet 1, the first water outlet 2 is closed after the air in the pipeline is exhausted, the wastewater passes through the membrane electrode 3, and the pollutants in the water are preliminarily degraded by direct oxidation or indirect oxidation through the membrane electrode 3 to generate active oxygen species such as hydroxyl radicals and superoxide radicals; oxygen enters the gas diffusion electrode through the gas inlet 9 and is discharged through the gas outlet 10, the oxygen in the cathode is reduced to perhydroxyl ions by the oxygen reduction of the gas diffusion electrode 8, and the perhydroxyl ions enter the liquid chamber module 6 through the anion exchange membrane 7 under the action of the electric field, combine with the protons generated by anode oxidation to produce hydrogen peroxide, and further react with the pollutants to degrade the pollutants; the wastewater degraded by the double action of the anode and the cathode is discharged from the second water outlet 5 of the liquid chamber module. Different voltages are applied, and the concentration of levofloxacin after degradation is measured by high performance liquid chromatography. The removal rate is calculated according to the concentration change, and the test results are as follows: Figure 2The voltage is different, the current is different, the ·OH and H2O2 yield are different, at 2V, the current is small, so the ·OH produced by the oxidation of water and the H2O2 produced by the reduction of oxygen are less, and the degradation effect on pollutants is poor, with the increase of the voltage, the ·OH and H2O2 yield increase, the degradation effect on pollutants increases, and the best voltage is 2.5V-3V, and the removal rate reaches more than 99%.

[0090] Example 2

[0091] A coupling anode and cathode electrocatalytic flow reactor comprises a membrane electrode 3 and a gas diffusion electrode 8, a liquid chamber module 6 is arranged between the membrane electrode 3 and the gas diffusion electrode 8, and an anion exchange membrane 7 is arranged between the liquid chamber module 6 and the gas diffusion electrode 8.

[0092] A first gasket 41 is arranged between the membrane electrode 3 and the liquid chamber module 6 to prevent water leakage.

[0093] A second gasket 42 is arranged between the anion exchange membrane 7 and the gas diffusion electrode 8 to prevent water leakage.

[0094] The anion exchange membrane 7 can prevent short circuit on one hand and effectively react some cathode reaction products with the anode on the other hand.

[0095] The membrane electrode 3 is connected with a conductive tape or wire as an anode working electrode;

[0096] The gas diffusion electrode 8 is connected with a conductive tape or wire as a cathode counter electrode;

[0097] A reference electrode is inserted into the baffle cavity of the liquid chamber module 6, the baffle cavity provides a water outlet channel and a reference electrode insertion port, and the reference electrode is inserted into the interface, so that the whole system is a three-electrode system;

[0098] The coupling anode and cathode electrocatalytic flow reactor further comprises a first titanium plate 11 and a second titanium plate 12;

[0099] The first titanium plate 11 is connected with the membrane electrode;

[0100] The second titanium plate 12 is connected with the gas diffusion electrode 8;

[0101] The first titanium plate 11 is provided with a water inlet 1 and a first water outlet 2;

[0102] The liquid chamber module 6 is provided with a second water outlet 5;

[0103] The second titanium plate 12 is provided with an air inlet 9 and an air outlet 10;

[0104] The distance between the membrane electrode and the gas diffusion electrode 8 is the distance of the baffle of the liquid chamber module 6.

[0105] The membrane electrode 3 was prepared by mixing 0.025 g of titanium tin oxide cluster and commercial Ti4O7 powder, then ball-milling for 3 hours at 800 rpm, with PbTiO3 accounting for 5% of the total mass, and the balance being commercial Ti4O7 powder. A certain amount of paraffin oil was added to the above-mentioned powder to make a uniform slurry, and the amount of paraffin oil used was 6 drops per gram of powder. The slurry was cast into a mold with dimensions of 1 cm x 1 cm and then pressure-molded at 50 MPa. Then, the slurry was calcined at 1000°C for two hours under argon protection to form a Ti4O7 ceramic membrane.

[0106] The gas diffusion electrode 8 was a 1 cm x 1 cm hydrophobic carbon paper loaded with 0.46 mg of oxidized carbon black catalyst.

[0107] The method for deep treatment of trace pollutants in water using the anode-cathode coupled electrocatalytic flow reactor of Example 2 comprises the following steps:

[0108] 1) Start the anode-cathode coupled electrocatalytic flow reactor, and connect the membrane electrode 3 to the positive electrode of an external power source as the anode working electrode through a conductive tape or wire, and connect the gas diffusion electrode 8 to the negative electrode of the external power source as the cathode counter electrode through a conductive tape or wire; the external power source is an electrochemical workstation.

[0109] 2) Treat a model pollutant solution containing electrolyte and refractory organic matter oxytetracycline (OTC), estrone (E1) or atrazine (ATZ), wherein the electrolyte concentration is 0.1 M Na2SO4, and the refractory organic matter is 2 mg / L, and continuously pump the mixed solution into the reactor at a flow rate of 1 mL / min by a peristaltic pump in continuous mode, turn on the external power source, and apply a voltage of 3 V. The peristaltic pump pumps the wastewater containing the pollutants into the inlet 1, and after the air in the pipeline is exhausted, the first outlet 2 is closed, the wastewater passes through the membrane electrode 3, and the pollutants in the water are preliminarily degraded by direct or indirect oxidation through the membrane electrode 3, generating active oxygen species such as hydroxyl radicals and superoxide radicals; oxygen enters the gas diffusion electrode through the gas inlet 9 and is discharged through the gas outlet 10, and the oxygen is reduced to hydrogen peroxide ions by oxygen reduction in the cathode gas diffusion electrode 8, which enters the liquid chamber module under the action of the electric field, combines with the protons generated by anodic oxidation to produce hydrogen peroxide, and further reacts with the pollutants to degrade the pollutants; the wastewater degraded by the double action of the anode and the cathode is discharged from the second outlet 5 of the liquid chamber module. The concentration of the refractory organic matter after degradation is measured by high performance liquid chromatography. The removal rate is calculated according to the change in concentration, and the test results are shown in Table 1. Figure 3 The molecular structures of different pollutants are different, and the degradation difficulty is also different, so the removal rates of different pollutants are also different. In this system, the removal rates of the three pollutants can all reach more than 95%.

[0110] Embodiment 3

[0111] A coupled anode-cathode electrocatalytic flow reactor comprises a membrane electrode 3 and a gas diffusion electrode 8, a liquid chamber module 6 is arranged between the membrane electrode 3 and the gas diffusion electrode 8, and an anion exchange membrane 7 is arranged between the liquid chamber module 6 and the gas diffusion electrode 8.

[0112] A first gasket 41 is arranged between the membrane electrode 3 and the liquid chamber module 6 to prevent water leakage.

[0113] A second gasket 42 is arranged between the anion exchange membrane 7 and the gas diffusion electrode 8 to prevent water leakage.

[0114] The anion exchange membrane 7 can prevent short circuiting on one hand and effectively react some cathode reaction products with the anode on the other hand.

[0115] The membrane electrode 3 is connected to a conductive tape or wire as an anode working electrode;

[0116] The gas diffusion electrode 8 is connected to a conductive tape or wire as a cathode counter electrode;

[0117] A reference electrode is inserted into the baffle cavity of the liquid chamber module 6, the baffle cavity provides a water outlet channel and a reference electrode insertion port, and the reference electrode is inserted into the interface, so that the entire system is a three-electrode system.

[0118] The coupled anode-cathode electrocatalytic flow reactor further comprises a first titanium plate 11 and a second titanium plate 12;

[0119] The first titanium plate 11 is connected to the membrane electrode;

[0120] The second titanium plate 12 is connected to the gas diffusion electrode 8;

[0121] The first titanium plate 11 is provided with a water inlet 1 and a first water outlet 2;

[0122] The liquid chamber module 6 is provided with a second water outlet 5;

[0123] The second titanium plate 12 is provided with an air inlet 9 and an air outlet 10;

[0124] The distance between the membrane electrode and the gas diffusion electrode 8 is the distance of the baffle of the liquid chamber module 6;

[0125] The membrane electrode 3 is a 1cm×1cm PVDF ultrafiltration membrane with a pore size of 40nm and a hydrophilic carbon paper loaded with 0.46mg iridium oxide;

[0126] The gas diffusion electrode 8 is a 1cm×1cm hydrophobic carbon paper loaded with 0.46mg carbon black catalyst.

[0127] The method for treating trace pollutants in water by using the coupled anode and cathode electrocatalytic flow reactor of Example 3 comprises the following steps:

[0128] 1) Start the coupled anode and cathode electrocatalytic flow reactor, connect the membrane electrode 3 to the positive pole of the external power supply as the anode working electrode through the conductive tape or wire, and connect the gas diffusion electrode 8 to the negative pole of the external power supply as the cathode counter electrode through the conductive tape or wire; the external power supply is an electrochemical workstation.

[0129] 2) Treat the model pollutant solution containing electrolyte and 10 mg / L, 20 mg / L, 30 mg / L different concentrations of rhodamine B, wherein the electrolyte concentration is 0.5 M H2SO4, and the mixed solution is transported into the reactor at a flow rate of 1 ml / min in a continuous mode by using a peristaltic pump, the external power supply is turned on, a voltage of 2 V is applied, and the absorbance of rhodamine B after degradation is measured by using an ultraviolet-visible spectrophotometer. The removal rate is calculated according to the change in absorbance. The test results are shown in Table 1. Figure 4 The same voltage is used in this system for degradation, so the yields of H2O2 and ·OH are basically the same, but as the concentration of pollutants increases, there is no excess H2O2 and ·OH to participate in the degradation reaction, resulting in poor degradation effect.

[0130] It should be noted that the above description and preferred embodiments cannot be interpreted as limiting the design idea of the present application. Those skilled in the art can modify and change the technical idea of the present application in various forms, and such modifications and changes should be understood as belonging to the protection scope of the present application.

Claims

1. A method for advanced treatment of trace pollutants in water, characterized in that, The method for advanced treatment of trace pollutants in water employs a coupled anode-cathode electrocatalytic flow reactor; the method for advanced treatment of trace pollutants in water includes the following steps: 1) Start the coupled anode-cathode electrocatalytic flow reactor. The membrane electrode is connected to the positive terminal of the external power supply via conductive tape or wire, serving as the working anode electrode. The gas diffusion electrode is connected to the negative terminal of the external power supply via conductive tape or wire, serving as the cathode electrode. 2) The peristaltic pump pumps the wastewater containing pollutants into the inlet. After the air in the pipeline is purged, the first outlet is closed. The wastewater passes through the membrane electrode, where it undergoes direct or indirect oxidation to initially degrade the pollutants in the water. Oxygen enters through the air inlet, passes through the gas diffusion electrode, and exits through the air outlet. The gas diffusion electrode in the cathode reduces oxygen to hydrogen peroxide ions through oxygen reduction. Under the action of the electric field, the hydrogen peroxide ions pass through the anion exchange membrane and enter the liquid chamber module. They combine with the protons generated by the anodic oxidation to produce hydrogen peroxide, which further reacts with the pollutants in the liquid chamber module to degrade them. The wastewater, after being degraded by the dual action of the anode and cathode, is discharged through the second outlet. The coupled anode-cathode electrocatalytic flow reactor includes a membrane electrode and a gas diffusion electrode, with a liquid chamber module disposed between the membrane electrode and the gas diffusion electrode, and an anion exchange membrane disposed between the liquid chamber module and the gas diffusion electrode.

2. The method for advanced treatment of trace pollutants in water according to claim 1, characterized in that, A first gasket is provided between the membrane electrode and the liquid chamber module to prevent water leakage; a second gasket is provided between the anion exchange membrane and the gas diffusion electrode to prevent water leakage.

3. The method for advanced treatment of trace pollutants in water according to claim 1, characterized in that, The coupled anode-cathode electrocatalytic flow reactor further includes a first titanium plate and a second titanium plate, wherein the first titanium plate is connected to the membrane electrode and the second titanium plate is connected to the gas diffusion electrode.

4. The method for deep treatment of trace pollutants in water according to claim 3, characterized in that, The first titanium plate is provided with a water inlet and a first water outlet; the liquid chamber module is provided with a second water outlet; the second titanium plate is provided with an air inlet and an air outlet.

5. The method for advanced treatment of trace pollutants in water according to claim 1, characterized in that, The electrocatalytic membrane material used in the membrane electrode is composed of one or more of the following: inorganic ceramic membrane, organic polymer membrane, and metal membrane with good electrical conductivity; or, the electrocatalytic membrane material is composed of a combination of non-conductive membrane material and carbon paper.

6. The method for advanced treatment of trace pollutants in water according to claim 1 or 5, characterized in that, The active component in the electrocatalytic membrane material used in the membrane electrode is one or more of lead-oxygen clusters or nanoparticles, tin-oxygen clusters or nanoparticles.

7. The method for advanced treatment of trace pollutants in water according to claim 1, characterized in that, The gas diffusion electrode includes an oxygen reduction catalyst supported on hydrophobic carbon paper, wherein the oxygen reduction catalyst is a partially oxidized carbon material.

8. The method for advanced treatment of trace pollutants in water according to claim 1, characterized in that, The pollutants are levofloxacin, rhodamine B, the recalcitrant organic compound oxytetracycline, estrone, or atrazine.

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