Method and system for converting organic pollutants into pure formic acid through electrocatalytic degradation and application

Abstract

The invention belongs to the technical field of electrochemistry, and particularly relates to a method and a system for converting organic pollutants into pure formic acid through electro-catalytic degradation and application of the system, the system comprises a wastewater pool, a peristaltic pump, a double-chamber two-electrode membrane electrode reactor, a constant potential rectifier and a gas-liquid separator, the double-chamber two-electrode membrane electrode reactor is electrically communicated with the constant potential rectifier, and the constant potential rectifier is electrically communicated with the wastewater pool. A water circulating pipe is arranged among the wastewater pool, the peristaltic pump and the double-chamber two-electrode membrane electrode reactor, a guide pipe is arranged between the wastewater pool and the double-chamber two-electrode membrane electrode reactor, selective electrochemical conversion from organic pollutants to formic acid can be achieved through the system, recycling of organic carbon resources is achieved, and the system is suitable for industrial production. The carbon emission of the sewage treatment process is effectively reduced, the high-purity formic acid serving as a cathode product can be obtained by taking bismuth trioxide as a cathode plate, the subsequent product separation is avoided, and the system can continuously operate and is high in stability.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical technology, and in particular relates to a method, system and application of electrocatalytic degradation of organic pollutants into pure formic acid. Background Art

[0002] Rising global energy consumption and carbon emissions have severely disrupted the natural carbon cycle, posing a serious challenge to sustainable social development. At the same time, water pollution caused by human activities and industrial production has become one of the most significant environmental issues, threatening ecological balance and human health. Currently, advanced oxidation technologies, including physical adsorption, membrane separation, strong oxidant oxidation, biochemical treatment, and electrocatalysis, are commonly used to treat the diverse organic pollutants in complex water bodies.

[0003] Advanced oxidation technologies, including electrocatalysis, provide an efficient, controllable, and environmentally friendly green degradation method that does not require the addition of chemical agents and can effectively avoid secondary pollution. It has high degradation efficiency and is suitable for a variety of wastewaters such as high-salt, highly toxic, and antibiotic wastewaters. Controllable reaction conditions can achieve precise regulation of pollutant degradation pathways, and therefore it has been widely used in sewage treatment. However, the final products of the oxidative degradation of organic pollutants are often carbon dioxide and water. Increased carbon emissions will not only aggravate climate change, but also lead to waste of organic carbon resources and fail to achieve resource recycling. Electrocatalysis has also received widespread attention in the selective reduction and conversion of CO2 due to its environmental friendliness and sustainability. In particular, with the help of advanced electrolyzers such as membrane electrode assembly electrolyzers and solid electrolyte reactors, high-rate conversion of CO2 to high-value-added fuels and chemicals can be achieved at industrial-grade current density.

[0004] As an important organic chemical raw material, formic acid has a wide range of application value in the fields of medicine, textiles, agriculture, rubber industry, etc. At the same time, it is also a hydrogen energy carrier with high energy density, which can be used as a potential hydrogen storage material for fuel cells and has a high market value. In industry, formic acid is mainly synthesized by the carbonylation reaction of methanol and CO under high temperature and high pressure conditions. The reaction conditions are harsh and the reaction energy consumption is high. The electrocatalytic reduction of CO2 to formic acid driven by renewable electricity provides a green and sustainable synthesis strategy. Some main group metal-based (such as Bi, Sn, Pb, In, etc.) electrocatalysts have been confirmed by many studies to be able to achieve high-selectivity conversion of CO2 to formic acid, but still require external high-concentration, high-purity CO2. The cost of carbon capture is high, and the recycling of carbon resources cannot be achieved. In addition, the low solubility of CO2 in the aqueous phase leads to a low current density, which is difficult to meet the needs of industrial applications. For this reason, the present invention provides a method, system and application for the electrocatalytic degradation of organic pollutants into pure formic acid. Summary of the Invention

[0005] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows: the system for electrocatalytic degradation of organic pollutants into pure formic acid comprises a wastewater tank, a peristaltic pump, a dual-chamber two-electrode membrane electrode reactor, a potentiostat, and a gas-liquid separator; the dual-chamber two-electrode membrane electrode reactor is electrically connected to the potentiostat, a water circulation pipe is provided between the wastewater tank, the peristaltic pump, and the dual-chamber two-electrode membrane electrode reactor; a conduit is provided between the wastewater tank and the dual-chamber two-electrode membrane electrode reactor, and a conduit is provided between the dual-chamber two-electrode membrane electrode reactor and the gas-liquid separator; the dual-chamber two-electrode membrane electrode reactor comprises an anode plate, a cathode plate, and an ion exchange membrane; a supporting electrolyte is provided in the dual-chamber two-electrode membrane electrode reactor, the anode plate is made of a gas diffusion layer carbon paper with an oxygen evolution potential of 1.8 V vs. SCE or above, the cathode plate is made of a gas diffusion layer carbon paper loaded with a catalyst containing main-group metal elements such as Bi, Sn, In, and Pb, the ion exchange membrane is a proton exchange membrane, and the supporting electrolyte is an aqueous solution containing sulfate.

[0007] Preferably, the gas-liquid separator includes a tower body, the inner wall of the tower body is slidably connected to a cleaning ring made of magnetic material, the outer wall of the tower body is slidably connected to a connecting ring, the inner wall of the connecting ring is fixedly connected to a group of magnetic blocks that are magnetically attracted to the cleaning ring, the outer wall of the tower body is fixedly connected to a first connecting plate and a second connecting plate, a screw rod is rotatably connected between the first connecting plate and the second connecting plate, a connecting assembly connected to the connecting ring is provided on the screw rod, and a motor that drives the screw rod to rotate can be installed on the bottom surface of the second connecting plate.

[0008] Preferably, the connecting assembly includes a connecting block threadedly connected to the screw rod, a sliding groove is provided on the side of the connecting block close to the tower body, a slide is slidably connected to the inner wall of the slide, the top surface of the connecting ring is fixedly connected to the slide, a first spring is fixedly connected between the bottom surface of the slide and the inner wall of the slide, and a push rod for pushing the slide is provided on the side wall of the tower body, and the push rod is made of elastic material.

[0009] Preferably, a pair of positioning plates are fixedly connected to the inner wall of the tower body, and the inner wall of the cleaning ring is arc-shaped, and the arc-shaped side is used to guide the liquid.

[0010] Preferably, an annular hollow groove is provided in the cleaning ring, the inner wall of the hollow groove is sealingly and slidingly connected to an annular push plate, the top surface of the positioning plate is fixedly connected to a push rod, the bottom surface of the cleaning ring is provided with a circular hole corresponding to the push rod, the push rod passes through the circular hole, an annular connecting groove is provided in the cleaning ring, a group of through grooves connected to the connecting groove and the hollow groove are provided in the cleaning ring, and the bottom surface of the cleaning ring is provided with an air outlet groove connected to the connecting groove.

[0011] A method for electrocatalytically degrading organic pollutants into pure formic acid, using the above-mentioned system for electrocatalytically degrading organic pollutants into pure formic acid, comprises the following steps:

[0012] S1: A boron-doped diamond electrode with a high oxygen evolution potential is used as the anode plate, bismuth trioxide is used as the cathode plate material, and a supporting electrolyte of 0.1M Na2SO4 aqueous solution is used in a two-chamber two-electrode membrane electrode reactor;

[0013] S2: The electrolyte solution of organic pollutants is circulated in the anode chamber by a peristaltic pump at a flow rate of 10 mL / min, and nitrogen carrier gas is passed into the closed wastewater tank at a flow rate of 30 mL / min to carry out the carbon dioxide generated by the mineralization of organic pollutants and pass it into the cathode gas chamber;

[0014] S3: The cathode chamber gas outlet is connected to a gas-liquid separator filled with deionized water to collect pure formic acid products. The operating conditions of the entire system are: cell voltage +4.5V, electrode area 4cm 2 , the concentration of organic pollutants is 100 mg / L;

[0015] S4: During gas-liquid separation, the gas and liquid will enter the tower body of the gas-liquid separator, undergo gas-liquid separation to obtain pure formic acid product, and then the pure formic acid product is discharged from the bottom of the tower body;

[0016] S5: After the pure formic acid product is discharged, the motor drives the screw to rotate, causing the screw to drive the connecting ring to move. At this time, due to the magnetic attraction between the cleaning ring and the magnetic block, the cleaning ring will move up and down synchronously, causing the cleaning ring to move back and forth to scrape and discharge the residual liquid on the inner wall of the tower body;

[0017] S6: With the help of a screw-driven cleaning ring to move up and down, the top rod repeatedly pushes the push plate, so that the push plate pushes the gas in the hollow groove out of the gas outlet groove and then blows it to the bottom of the tower body to assist in the discharge of residual liquid at the bottom.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The present invention can achieve selective electrochemical conversion of organic pollutants into formic acid through the system, realize the recycling and utilization of organic carbon resources, and effectively reduce carbon emissions from the sewage treatment process. By using bismuth trioxide as the cathode plate, the cathode product can be obtained as high-purity formic acid, avoiding subsequent product separation. The system can operate continuously and has high stability.

[0020] 2. The present invention rationally designs the membrane electrode assembly and constructs a coupled electrochemical system for the oxidation and degradation of organic pollutants and the electroreduction of CO2, which is used to achieve the directional conversion of organic matter into high-purity formic acid. The anode electrocatalytic water oxidation is used to produce highly oxidizing hydroxyl radical species to oxidatively degrade organic matter, thereby avoiding secondary pollution caused by the addition of chemical agents. At the same time, the CO2 generated in situ by anode mineralization is circulated to the cathode through nitrogen carrier gas for electrocatalytic reduction, realizing the resource utilization of organic carbon in pollutants. The system can accelerate the oxidation and mineralization removal of pollutants under the continuous flow action of a dual-chamber two-electrode membrane electrode reactor, enhance gas mass transfer through a gas diffusion electrode, and utilize the zero-gap structure of the membrane electrode without cathode electrolyte to achieve the enrichment of pure formic acid product, solving the problem of product separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] Figure 1 is a system diagram of the present invention;

[0023] Figure 2 This is a graph showing the change in removal rate of 100 mg / L of phenol by oxidation degradation of the system according to the present invention versus electrolysis time;

[0024] Figure 3 This is a curve diagram showing the change of total organic carbon removal rate of 100 mg / L phenol oxidatively degraded by the system of the present invention as a function of electrolysis time;

[0025] Figure 4 This is a graph showing the change in the yield of formic acid generated at the cathode as a function of electrolysis time when the system of the present invention oxidizes 100 mg / L of phenol at the anode;

[0026] Figure 5 This is a graph showing the change in the output of formic acid generated at the cathode as a function of electrolysis time when the system of the present invention is oxidizing 100 mg / L of bisphenol A, humic acid, and rhodamine B at the anode;

[0027] Figure 6 It is a structural schematic diagram of the gas-liquid separator in the present invention;

[0028] Figure 7 It is a schematic diagram of the internal structure of the tower body in the present invention;

[0029] Figure 8 yes Figure 7 Schematic diagram of part of the structure;

[0030] Figure 9 yes Figure 8 A magnified view of point A;

[0031] Figure 10 It is a flow chart of the method in the present invention.

[0032] In the figure: 1. Wastewater tank; 2. Peristaltic pump; 3. Anode plate; 4. Cathode plate; 5. Ion exchange membrane; 6. Constant potentiostat; 7. Gas-liquid separator; 8. Tower body; 9. First connecting plate; 10. Second connecting plate; 11. Connecting block; 12. Connecting ring; 13. Cleaning ring; 14. Magnetic block; 15. Screw; 16. Slide; 17. Slide plate; 18. Push rod; 19. Positioning plate; 20. Hollow groove; 21. Push plate; 22. Connecting groove; 23. Air outlet groove; 24. Push rod. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0034] Example 1: Figures 1 to 5 As shown, the system for electrocatalytic degradation of organic pollutants into pure formic acid according to the embodiment of the present invention comprises a wastewater tank 1, a peristaltic pump 2, a dual-chamber two-electrode membrane electrode reactor, a potentiostat 6 and a gas-liquid separator 7; the system is mainly composed of a dual-chamber two-electrode membrane electrode reactor equipped in a closed gas-liquid circulation system, which includes two 2×2 cm 2 The titanium plate, anode plate 3, cathode plate 4, ion exchange membrane 5 and supporting electrolyte of the serpentine flow channel use a boron-doped diamond electrode with a high oxygen evolution potential as the anode plate 3, bismuth trioxide as the cathode plate 4 material, the ion exchange membrane 5 is a proton exchange membrane, and the supporting electrolyte is a 0.1M Na2SO4 aqueous solution. The electrolyte solution containing organic pollutants circulates in the anode chamber at a flow rate of 10mL / min through a peristaltic pump 2, and the nitrogen carrier gas is passed into the closed wastewater pool 1 at a flow rate of 30mL / min to carry out the carbon dioxide produced by the mineralization of organic pollutants and pass it into the cathode gas chamber. The gas outlet of the cathode chamber is connected to a gas-liquid separator 7 filled with deionized water to collect pure formic acid products. The operating conditions of the system are: the cell voltage is +4.5V, the electrode area is 4cm 2 , the concentration of organic pollutants is 100 mg / L.

[0035] The present invention is suitable for wastewater systems containing various organic pollutants such as polycyclic aromatic hydrocarbons, phthalates, bisphenols, organic pesticides, etc., and can be used in the field of water pollution control. In the coupled electrochemical system of the present invention, water molecules are oxidized and activated into strongly oxidizing hydroxyl radicals (standard redox potential 2.38V) on the anode plate 3. The hydroxyl radicals directly oxidize organic matter through hydrogen abstraction reaction, addition reaction or electron transfer to mineralize it into CO2. The CO2 generated in situ is carried into the reaction chamber of the cathode plate 4 with nitrogen rich in air as carrier gas, obtains electrons on the surface of the gas diffusion electrode and is reduced to formic acid. The CO2 tail gas generated by the degradation of pollutants is effectively collected and converted, realizing the in-situ recycling of organic carbon resources. At the same time, the application of zero-gap membrane electrode assembly ensures the high-purity synthesis of cathode liquid products and avoids subsequent separation of products. Compared with existing pollutant degradation technologies and CO2 electroreduction technologies, the present invention creatively utilizes the CO2 electroreduction generated in situ by organic matter mineralization to synthesize high-purity formic acid, reducing carbon emissions in sewage treatment, efficiently recycling and utilizing carbon resources in pollutants, and obtaining high-value-added fuel without the need to introduce high-purity CO2. This organic carbon resource recycling technology has high conversion efficiency, is environmentally friendly, simple to operate, and easy to implement industrial automation.

[0036] In the electrochemical system of the present invention, the simulated pollutants are added at a concentration of 100mg / L, the concentration of the pollutants is detected by high performance liquid chromatography, the concentration of organic carbon in the water body is measured by a total organic carbon analyzer, and the concentration of the product formic acid is measured by a nuclear magnetic resonance spectrometer. Utilizing this coupled electrochemical system to degrade 100mg / L of phenol, bisphenols, and dyestuff pollutants, its total organic carbon removal efficiency all reached more than 70% within 8 hours, the formic acid output collected by the negative plate 4 was more than 35μmol, and the total carbon utilization rate from organic carbon to formic acid can reach more than 20%. When this electrochemical system is used to degrade and convert industrial wastewater with a total organic carbon (TOC) content of 1000mg / L, the TOC removal rate reached more than 60% within 8 hours, and the formic acid output could reach 20μmol.

[0037] The coupled electrochemical reaction system constructed by the present invention, which uses CO2 reduction reaction as a bridge for the directional conversion of multiple organic pollutants into pure formic acid, not only exhibits a high efficiency in removing pollutants and reduces carbon emissions in the sewage treatment process, but also stably generates pure formic acid products with high energy density, avoids product separation, and realizes the recycling of pollutant organic carbon.

[0038] By rationally designing the membrane electrode assembly and constructing a coupled electrochemical system for the oxidation and degradation of organic pollutants and the electroreduction of CO2, it is used to achieve the directional conversion of organic matter into high-purity formic acid. The anode electrocatalytic water oxidation is used to produce highly oxidizing hydroxyl radical species to oxidatively degrade organic matter, thereby avoiding secondary pollution caused by the addition of chemical agents. At the same time, the CO2 generated in situ by anode mineralization is circulated to the cathode through nitrogen carrier gas for electrocatalytic reduction, realizing the resource utilization of organic carbon in pollutants. The system can accelerate the oxidation and mineralization removal of pollutants under the continuous flow of a dual-chamber two-electrode membrane electrode reactor, enhance gas mass transfer through gas diffusion electrodes, and utilize the zero-gap structure of the membrane electrode without cathode electrolyte to achieve the enrichment of pure formic acid product, solving the problem of product separation.

[0039] Example 2: At room temperature, a boron-doped diamond electrode with a high oxygen evolution potential was used as the anode plate 3, and bismuth trioxide was used as the cathode plate 4. The cathode and anode were separated by a proton exchange membrane. The electrochemical system was operated under the following conditions: a cell voltage of +4.5 V, an electrode area of ​​4 cm 2 The supporting electrolyte is 0.1M Na2SO4 aqueous solution, 100mg / L phenol is added as the pollutant, and the electrolysis time is 8 hours. Figure 2 As shown in the attached manual, the removal rate of phenol reached nearly 100% within 5 hours, achieving efficient removal of pollutants. Figure 3 As shown in the figure, within 8 hours of continuous electrolysis, the total organic carbon removal rate of phenol reached more than 80%, indicating that the pollutants were efficiently mineralized into CO2 and water, which could provide sufficient CO2 for the cathode to be used for formic acid synthesis, as shown in the attached manual. Figure 4 As shown in the figure, as the electrolysis time increases, the output of formic acid collected from the cathode plate gradually increases. After 8 hours of electrolysis, the cumulative formic acid output can reach more than 60 μmol, realizing the efficient conversion of carbon resources from organic pollutants to synthesize formic acid.

[0040] Example 3: At room temperature, a boron-doped diamond electrode with a high oxygen evolution potential was used as the anode plate 3, and bismuth trioxide was used as the cathode plate 4. The cathode and anode were separated by a proton exchange membrane. The electrochemical system was operated under the following conditions: a cell voltage of +4.5 V, an electrode area of ​​4 cm 2 The supporting electrolyte was a 0.1M aqueous Na₂SO₄ solution. Phenol, at a concentration of 100 mg / L, was added as the target pollutant. After 8 hours of electrolysis, the cathode product was collected for quantitative analysis. Phenol was then added again to bring the concentration back to 100 mg / L. After repeating this electrolysis process 10 times, the yield of formic acid synthesized by this electrochemical system decreased by only 7.6%, demonstrating its high stability.

[0041] Example 4: At room temperature, a boron-doped diamond electrode with a high oxygen evolution potential was used as the anode plate 3, and bismuth trioxide was used as the cathode plate 4. The cathode and anode were separated by a proton exchange membrane. The electrochemical system was operated under the following conditions: a cell voltage of +4.5 V, an electrode area of ​​4 cm 2 The supporting electrolyte was 0.1M Na2SO4 aqueous solution, 100 mg / L bisphenol A was added as the pollutant, and the electrolysis time was 8 hours. After 8 hours of continuous electrolysis, the total organic carbon removal rate of bisphenol A reached more than 70%, and the cumulative formic acid production at the cathode could reach more than 50 μmol.

[0042] Example 5: At room temperature, a boron-doped diamond electrode with a high oxygen evolution potential was used as the anode plate 3, and bismuth trioxide was used as the cathode plate 4. The cathode and anode were separated by a proton exchange membrane. The electrochemical system was operated under the following conditions: a cell voltage of +4.5 V, an electrode area of ​​4 cm 2 The supporting electrolyte was 0.1M Na2SO4 aqueous solution, 100mg / L humic acid was added as the pollutant, and the electrolysis time was 8 hours. After 8 hours of continuous electrolysis, the total organic carbon removal rate of humic acid reached more than 75%, and the cumulative formic acid production at the cathode could reach more than 40μmol.

[0043] Example 6: At room temperature, a boron-doped diamond electrode with a high oxygen evolution potential was used as the anode plate 3, and bismuth trioxide was used as the cathode plate 4. The cathode and anode were separated by a proton exchange membrane. The electrochemical system was operated under the following conditions: a cell voltage of +4.5 V, an electrode area of ​​4 cm 2 The supporting electrolyte was 0.1 M Na2SO4 aqueous solution, 100 mg / L Rhodamine B was added as the pollutant, and the electrolysis time was 8 hours. After 8 hours of continuous electrolysis, the total organic carbon removal rate of Rhodamine B reached more than 70%, and the cumulative formic acid production at the cathode could reach nearly 40 μmol.

[0044] Example 7: Under room temperature conditions, a boron-doped diamond electrode with a high oxygen evolution potential is used as the anode plate 3, bismuth trioxide is used as the cathode plate 4, the cathode and anode are separated by a proton exchange membrane, and the supporting electrolyte is a 0.1M Na2SO4 aqueous solution. This electrochemical system is used to degrade and convert industrial wastewater with a total organic carbon (TOC) of 1000 mg / L. The TOC removal rate reaches more than 60% within 8 hours, and the formic acid production can reach nearly 20 μmol.

[0045] It can be seen from Examples 4-7 that the coupled electrochemical system constructed by the present invention can achieve efficient degradation of various organic pollutants at the anode, while the CO2 produced by in situ mineralization can be selectively reduced to formic acid at the cathode. This strategy can achieve selective conversion of different organic matter under the same electrode and electrochemical system operating conditions. The conversion efficiency depends on the molecular structure of the organic matter and the number of carbon atoms it contains, and can be extended to the actual value-added conversion of wastewater.

[0046] Example 8: Figures 6 to 9 As shown, comparative example seven, wherein another embodiment of the present invention is: the gas-liquid separator 7 includes a tower body 8, the inner wall of the tower body 8 is slidably connected to a cleaning ring 13 made of magnetic material, the outer wall of the tower body 8 is slidably connected to a connecting ring 12, the inner wall of the connecting ring 12 is fixedly connected to a group of magnetic blocks 14 that are magnetically attracted to the cleaning ring 13, the outer wall of the tower body 8 is fixedly connected to a first connecting plate 9 and a second connecting plate 10, a screw rod 15 is rotatably connected between the first connecting plate 9 and the second connecting plate 10, the screw rod 15 is provided with a connecting assembly connected to the connecting ring 12, and the bottom surface of the second connecting plate 10 can be installed with a motor that drives the screw rod 15 to rotate;

[0047] The pure formic acid product in the present application needs to be obtained in the tower body 8, and formic acid needs to be obtained by gas-liquid separation. During the drainage process of the tower body 8, due to the effects of liquid adhesion and surface tension, part of the formic acid solution will inevitably remain on the inner wall of the tower body 8 and the surface of the internal components, forming a residual liquid film that is difficult to completely drain. These residual liquids not only cause direct waste of raw materials, but may also cause concentration deviation in subsequent processes, increase production costs and waste liquid treatment burdens. Through the above structure, after drainage, the motor can be used to drive the screw rod 15 to rotate, so that the screw rod 15 drives the connecting assembly to move. At this time, the connecting assembly will drive the connecting ring 12 to move. Because of the magnetic attraction between the cleaning ring 13 and the magnetic block 14, the cleaning ring 13 will move synchronously with the connecting ring 12. The screw rod 15 can control the connecting ring 12 to move up and down, so that the cleaning ring 13 can scrape and discharge the liquid remaining on the inner wall of the tower body 8 back and forth, thereby avoiding unnecessary waste.

[0048] The connecting assembly includes a connecting block 11 threadedly connected to the screw rod 15, and a slide groove 16 is provided on the side of the connecting block 11 close to the tower body 8. The inner wall of the slide groove 16 is slidably connected to a slide plate 17. The top surface of the connecting ring 12 is fixedly connected to the slide plate 17, and a first spring is fixedly connected between the bottom surface of the slide plate 17 and the inner wall of the slide groove 16. The side wall of the tower body 8 is provided with a push rod 18 for pushing the slide plate 17, and the push rod 18 is made of elastic material; when the screw rod 15 in the present application rotates, it will drive the connecting block 11 to move up and down, and at this time the connecting block 11 will drive The connecting ring 12 moves, thereby driving the cleaning ring 13 to move. When the slide 17 reaches the push rod 18, the slide 17 will be pushed by the push rod 18. As the connecting block 11 rises, the slide 17 will push the push rod 18 to deform, thereby allowing the push rod 18 to move away from above the slide 17. At this time, the first spring will push the slide 17 to reset, and will drive the slide 17 to shake, thereby causing the connecting ring 12 to shake. At this time, the cleaning ring 13 will also shake synchronously, and then shake off the residual liquid scraped off the cleaning ring 13 to improve the effect of cleaning and recovering the liquid.

[0049] A pair of positioning plates 19 are fixedly connected to the inner wall of the tower body 8, and the inner wall of the cleaning ring 13 is arc-shaped, and the arc-shaped side is used to guide the liquid; by setting the inner wall of the cleaning ring 13 to be arc-shaped, the scraped liquid can be guided when the cleaning ring 13 moves upward to scrape the liquid, so as to reduce the liquid residue on the cleaning ring 13. Since the cleaning ring 13 will shake during the movement, in order to prevent the magnetic block 14 from separating from the cleaning ring 13, the cleaning ring 13 can be brought into contact with the positioning plate 19 when the cleaning ring 13 descends, and then when the connecting ring 12 descends synchronously, the position of the magnetic block 14 and the cleaning ring 13 can be repositioned and magnetically attracted.

[0050] The cleaning ring 13 is provided with an annular hollow groove 20, the inner wall of the hollow groove 20 is sealed and slidably connected with an annular push plate 21, the top surface of the positioning plate 19 is fixedly connected with a push rod 24, the bottom surface of the cleaning ring 13 is provided with a circular hole corresponding to the push rod 24, the push rod 24 passes through the circular hole, the cleaning ring 13 is provided with an annular connecting groove 22, the cleaning ring 13 is provided with a group of through grooves communicating with the connecting groove 22 and the hollow groove 20, the bottom surface of the cleaning ring 13 is provided with a The air outlet groove 23 is connected to the connecting groove 22; since the bottom of the tower body 8 is set to be conical in order to facilitate the discharge of liquid, the cleaning ring 13 can be driven by the screw 15 to move up and down. The moving stroke is to allow the push rod 24 to repeatedly push the push plate 21. When the push plate 21 moves upward, the push plate 21 will push the gas in the hollow groove 20 from the through groove into the connecting groove 22, and finally blow it from the air outlet groove 23 to the bottom of the tower body 8 to assist in the discharge of residual liquid at the bottom and improve the effect of liquid discharge.

[0051] like Figure 10 As shown, a method for electrocatalytically degrading organic pollutants into pure formic acid adopts the above-mentioned system for electrocatalytically degrading organic pollutants into pure formic acid, and the method comprises the following steps:

[0052] S1: A boron-doped diamond electrode with a high oxygen evolution potential is used as the anode plate 3, bismuth trioxide is used as the cathode plate 4 material, and a supporting electrolyte is used in a double-chamber two-electrode membrane electrode reactor, and the supporting electrolyte is a 0.1M Na2SO4 aqueous solution;

[0053] S2: The electrolyte solution of organic pollutants is circulated in the anode chamber at a flow rate of 10 mL / min by peristaltic pump 2, and nitrogen carrier gas is passed into the closed wastewater tank 1 at a flow rate of 30 mL / min to carry out the carbon dioxide generated by the mineralization of organic pollutants and pass it into the cathode gas chamber;

[0054] S3: The cathode chamber gas outlet is connected to a gas-liquid separator 7 filled with deionized water to collect pure formic acid products. The operating conditions of the entire system are: cell voltage +4.5V, electrode area 4cm 2 , the concentration of organic pollutants is 100 mg / L;

[0055] S4: During gas-liquid separation, the gas and liquid enter the tower body 8 of the gas-liquid separator 7, undergo gas-liquid separation to obtain pure formic acid product, and then the pure formic acid product is discharged from the bottom of the tower body 8;

[0056] S5: After the pure formic acid product is discharged, the motor drives the screw 15 to rotate, so that the screw 15 drives the connecting ring 12 to move. At this time, due to the magnetic attraction between the cleaning ring 13 and the magnetic block 14, the cleaning ring 13 will move up and down synchronously, so that the cleaning ring 13 moves back and forth to scrape and discharge the residual liquid on the inner wall of the tower body 8;

[0057] S6: With the help of the screw 15, the cleaning ring 13 is driven to move up and down, so that the push rod 24 repeatedly pushes the push plate 21, so that the push plate 21 pushes the gas in the hollow groove 20 to be discharged from the gas outlet groove 23, and then blown to the bottom of the tower body 8 to assist in the discharge of residual liquid at the bottom.

[0058] Working principle: The motor drives the screw rod 15 to rotate, so that the screw rod 15 drives the connecting assembly to move, and the connecting assembly will drive the connecting ring 12 to move. Because of the magnetic attraction between the cleaning ring 13 and the magnetic block 14, the cleaning ring 13 will move synchronously with the connecting ring 12, and the screw rod 15 can control the connecting ring 12 to move up and down, so that the cleaning ring 13 can scrape and discharge the liquid remaining on the inner wall of the tower body 8 back and forth, thereby avoiding unnecessary waste; when the screw rod 15 in this application rotates, it will drive the connecting block 11 to move up and down, and at this time the connecting block 11 will drive the connecting ring The ring 12 moves, thereby driving the cleaning ring 13 to move. When the slide 17 reaches the push rod 18, the slide 17 is pushed by the push rod 18. As the connecting block 11 rises, the slide 17 pushes the push rod 18 to deform, thereby allowing the push rod 18 to move away from the slide 17. At this time, the first spring pushes the slide 17 to reset and drives the slide 17 to shake, thereby causing the connecting ring 12 to shake. At this time, the cleaning ring 13 will also shake synchronously, thereby shaking off the residual liquid scraped off the cleaning ring 13, thereby improving the effect of cleaning and recycling the liquid;

[0059] The cleaning ring 13 is provided with an arc shape, and the scraped liquid is diverted when the cleaning ring 13 moves upward to scrape the liquid, so as to reduce the residual liquid on the cleaning ring 13. Since the cleaning ring 13 will shake during the movement, in order to prevent the magnetic block 14 from separating from the cleaning ring 13, the cleaning ring 13 can be made to contact the positioning plate 19 when the cleaning ring 13 is lowered, and then the connecting ring 12 is synchronously lowered, so that the position of the magnetic block 14 and the cleaning ring 13 is repositioned and magnetically attracted; since the tower body 8 is provided with a tapered bottom for convenient liquid discharge, the screw rod 15 can be used to drive the cleaning ring 13 to move up and down, and the moving stroke is to allow the push rod 24 to repeatedly push the push plate 21. When the push plate 21 moves upward, the push plate 21 will push the gas in the hollow groove 20 from the through groove into the connecting groove 22, and finally blown to the bottom of the tower body 8 from the air outlet groove 23 to assist in the discharge of the residual liquid at the bottom, thereby improving the effect of liquid discharge.

[0060] The above-mentioned front, back, left, right, up and down are all based on the Figure 1 As a benchmark, according to the person's observation perspective, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0061] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0062] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for electrocatalytically degrading organic pollutants into pure formic acid, comprising a wastewater tank (1), a peristaltic pump (2), a dual-chamber two-electrode membrane electrode reactor, a potentiostat (6), and a gas-liquid separator (7); Its characteristics are: The dual-chamber two-electrode membrane electrode reactor is electrically connected to a potentiostat (6), and a water circulation pipe is provided between the wastewater tank (1), the peristaltic pump (2) and the dual-chamber two-electrode membrane electrode reactor; A conduit is provided between the wastewater tank (1) and the dual-chamber two-electrode membrane electrode reactor, and a conduit is provided between the dual-chamber two-electrode membrane electrode reactor and the gas-liquid separator (7); The dual-chamber two-electrode membrane electrode reactor comprises an anode plate (3), a cathode plate (4) and an ion exchange membrane (5), and a supporting electrolyte is provided in the dual-chamber two-electrode membrane electrode reactor.

2. The system for electrocatalytic degradation of organic pollutants into pure formic acid according to claim 1, characterized in that: The gas-liquid separator (7) comprises a tower body (8), the inner wall of the tower body (8) is slidably connected to a cleaning ring (13) made of magnetic material, the outer wall of the tower body (8) is slidably connected to a connecting ring (12), the inner wall of the connecting ring (12) is fixedly connected to a group of magnetic blocks (14) that are magnetically attracted to the cleaning ring (13), the outer wall of the tower body (8) is fixedly connected to a first connecting plate (9) and a second connecting plate (10), a screw rod (15) is rotatably connected between the first connecting plate (9) and the second connecting plate (10), a connecting assembly connected to the connecting ring (12) is provided on the screw rod (15), and a motor that drives the screw rod (15) to rotate can be installed on the bottom surface of the second connecting plate (10).

3. The system for electrocatalytic degradation of organic pollutants into pure formic acid according to claim 2, characterized in that: The connecting assembly comprises a connecting block (11) threadedly connected to a screw rod (15); a sliding groove (16) is provided on a side of the connecting block (11) close to the tower body (8); a slide plate (17) is slidably connected to the inner wall of the sliding groove (16); the top surface of the connecting ring (12) is fixedly connected to the slide plate (17); a first spring is fixedly connected between the bottom surface of the slide plate (17) and the inner wall of the sliding groove (16); a push rod (18) for pushing the slide plate (17) is provided on the side wall of the tower body (8); and the push rod (18) is made of elastic material.

4. The system for electrocatalytic degradation of organic pollutants into pure formic acid according to claim 3, characterized in that: A pair of positioning plates (19) are fixedly connected to the inner wall of the tower body (8); the inner wall of the cleaning ring (13) is arc-shaped, and the arc-shaped side is used to guide the liquid.

5. The system for electrocatalytic degradation of organic pollutants into pure formic acid according to claim 4, characterized in that: An annular hollow groove (20) is provided in the cleaning ring (13), and an annular push plate (21) is sealingly and slidingly connected to the inner wall of the hollow groove (20), and a top surface of the positioning plate (19) is fixedly connected to a push rod (24), and a circular hole corresponding to the push rod (24) is provided on the bottom surface of the cleaning ring (13), and the push rod (24) passes through the circular hole. An annular connecting groove (22) is provided in the cleaning ring (13), and a group of through grooves communicating with the connecting groove (22) and the hollow groove (20) are provided in the cleaning ring (13), and an air outlet groove (23) communicating with the connecting groove (22) is provided on the bottom surface of the cleaning ring (13).

6. A method for electrocatalytically degrading organic pollutants into pure formic acid, the method using the system for electrocatalytically degrading organic pollutants into pure formic acid as claimed in claim 5, characterized in that: The method comprises the following steps: S1: A boron-doped diamond electrode with a high oxygen evolution potential is used as the anode plate (3), bismuth trioxide is used as the cathode plate (4), and a supporting electrolyte is used in a double-chamber two-electrode membrane electrode reactor, wherein the supporting electrolyte is a 0.1M Na2SO4 aqueous solution; S2: The electrolyte solution of organic pollutants is circulated in the anode chamber at a flow rate of 10 mL / min through a peristaltic pump (2), and nitrogen carrier gas is passed into the closed wastewater tank (1) at a flow rate of 30 mL / min to carry out the carbon dioxide generated by the mineralization of organic pollutants and pass it into the cathode gas chamber; S3: The cathode chamber gas outlet is connected to a gas-liquid separator (7) filled with deionized water to collect pure formic acid products. The operating conditions of the entire system are: cell voltage +4.5V, electrode area 4cm 2 , the concentration of organic pollutants is 100 mg / L.

7. The method for electrocatalytic degradation of organic pollutants into pure formic acid according to claim 6, characterized in that: The method further comprises the steps of: S4: During gas-liquid separation, the gas and liquid enter the tower body (8) of the gas-liquid separator (7), undergo gas-liquid separation to obtain pure formic acid product, and then the pure formic acid product is discharged from the bottom of the tower body (8); S5: After the pure formic acid product is discharged, the motor drives the screw (15) to rotate, so that the screw (15) drives the connecting ring (12) to move. At this time, due to the magnetic attraction between the cleaning ring (13) and the magnetic block (14), the cleaning ring (13) will move up and down synchronously, so that the cleaning ring (13) moves back and forth to scrape and discharge the liquid remaining on the inner wall of the tower body (8); S6: The cleaning ring (13) is driven to move up and down by means of the screw rod (15), so that the push rod (24) repeatedly pushes the push plate (21), thereby allowing the push plate (21) to push the gas in the hollow groove (20) out of the gas outlet groove (23) and then blow it to the bottom of the tower body (8) to assist in the discharge of the residual liquid at the bottom.

8. Application of the electrocatalytic degradation system for converting organic pollutants into pure formic acid according to claim 7, characterized in that: The application of the electrocatalytic degradation of organic pollutants into pure formic acid system is applied to the value-added treatment of wastewater into formic acid.

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