Integrated electrochemical membrane reactor based on high-salinity wastewater in-situ deep purification and water treatment method thereof

Abstract

The invention discloses an integrated electrochemical membrane reactor based on in-situ deep purification of high-salinity wastewater and a water treatment method of the integrated electrochemical membrane reactor. A ceramic membrane is used as a substrate, an iron-based non-metal coordination porous carbon active layer modified on the surface is used as a cathode, and the integrated electrochemical membrane reactor with catalytic oxidation and filtering functions is jointly formed by the ceramic membrane and an anode. The method is suitable for treating high-salt and degradation-resistant organic wastewater, can efficiently remove more than 90% of typical pollutants such as 5-fluorouracil and stably remove more than 50% of wastewater COD (Chemical Oxygen Demand) in a continuous flow operation mode, has the advantages of high catalytic activity, stable structure, flexible operation mode and the like, and is suitable for industrial production. And an efficient and reliable technical solution is provided for deep purification of the high-salt degradation-resistant wastewater.

Description

Technical Field

[0001] This invention relates to an integrated electrochemical membrane reactor and its water treatment method based on in-situ deep purification of high-salt wastewater, belonging to the field of water pollution control. Background Technology

[0002] In recent years, with the rapid development of industries such as pharmaceuticals, fine chemicals, and printing and dyeing, the discharge of wastewater with high salt, high organic matter concentration, and high toxicity has been increasing year by year, becoming a prominent problem in the field of water environment management. This type of wastewater usually contains recalcitrant organic pollutants (such as residual drugs, pharmaceutical intermediates, dye intermediates, etc.), high concentrations of inorganic salts, and suspended particulate matter, exhibiting characteristics such as high COD, poor biodegradability, and strong toxicity. It seriously inhibits traditional biological treatment processes, and if discharged directly without adequate treatment, it will pose long-term potential risks to the ecological safety of aquatic bodies and human health.

[0003] The coupling of advanced electrochemical oxidation with membrane separation technology is a potentially effective approach to achieve deep purification of such wastewater. The cathode, as the key component of the coupling system, can electrogenerate reactive oxygen species such as hydrogen peroxide through the oxygen reduction reaction to achieve continuous mineralization of pollutants. Existing technologies have explored this direction extensively, but significant shortcomings remain in the regulation mechanism of the cathode oxygen reduction reaction pathway and in membrane filtration and fouling control.

[0004] Firstly, at the cathode oxygen reduction reaction pathway level, existing electrochemical membrane technologies mostly rely on the traditional two-step electro-Fenton reaction pathway (oxygen is first reduced to H2O2, then activated to generate ·OH) or the four-electron oxygen reduction pathway (oxygen is directly reduced to water), lacking the ability to selectively control the three-electron oxygen reduction pathway, making it difficult to achieve the direct generation of hydroxyl radicals at the cathode. For example, the NF / P@Fe-NC cathode disclosed in patent CN119059613B has a four-electron dominant oxygen reduction pathway, with water as the product, and the cathode cannot directly generate hydroxyl radicals. Patent CN116986683A discloses a deep oxidation treatment system for desulfurization wastewater, whose electrochemical catalytic membrane reaction unit uses a nano-titanium oxide tube porous membrane electrode, where the cathode oxygen reduction pathway is mainly two-electron or four-electron, and the generation of hydroxyl radicals depends on the anodic reaction or the addition of H2O2. Patent CN108394960B discloses a cathode electrochemical microfiltration membrane coupled reactor, employing a graphite anode and a flat microfiltration membrane cathode with embedded steel wire mesh. Although it can generate H2O2 in situ at the cathode and react with Fe(II) dissolved from the steel wire mesh to generate ·OH, its essence remains a traditional two-step electro-Fenton pathway, with the H2O2 generation and activation steps separated, and it relies on the dissolution of iron ions, posing a risk of secondary pollution from iron sludge. Patent CN109607746A discloses a carbon membrane-based electro-Fenton device, using a carbon membrane module as the cathode, and enhancing mass transfer through membrane filtration to improve H2O2 yield. However, its reaction mechanism still involves the two-electron pathway to generate H2O2, which then reacts with an added ferrous reagent to generate ·OH, failing to achieve direct oxygen reduction at the cathode to generate hydroxyl radicals. Patent CN106966465A discloses a three-dimensional electrode electrochemical system, which also relies on a chain reaction between ferrous ions and H2O2 to catalyze the generation of ·OH, belonging to the traditional electro-Fenton pathway. Secondly, regarding cathode membrane filtration and membrane fouling control, while existing technologies attempt to integrate membrane separation and electrochemical functions into the cathode, they mostly employ a partitioned design of "electro-oxidation after filtration," or rely on indirect effects such as physical repulsion and metal ion sterilization to alleviate membrane fouling. They lack the ability for continuous, direct, in-situ catalytic oxidation at the membrane interface, and pollutants still easily accumulate on the membrane surface, leading to membrane fouling. For example, patent CN114504952A discloses a double-sided conductive membrane filtration component, in which a metal conductive coating is formed on both surfaces of a porous membrane substrate as the cathode. The function of its cathode membrane interface focuses on electrochemical reduction reactions, without involving in-situ catalytic degradation of pollutants through the generation of hydroxyl radicals via oxygen reduction. Patent CN107459106A discloses an electrochemical-membrane separation water treatment device, in which the membrane module and cathode plate are spatially separated. The electrochemical effect mainly affects membrane fouling indirectly through electro-oxidation and electrocoagulation, and the membrane interface lacks direct catalytic oxidation function.Patent CN101941759A discloses a method for improving the antifouling performance of membranes by using a weak electric field. By applying a weak negative electric field near the membrane surface, pollutants are pushed away from the membrane surface by the principle of like charges repelling each other. Its antifouling mechanism relies on physical repulsion rather than directly generating hydroxyl radicals through the oxygen reduction process to achieve membrane fouling control.

[0005] This invention proposes an integrated electrochemical membrane reactor and its water treatment method for in-situ deep purification of high-salinity wastewater. Its core innovation lies in integrating iron-based porous carbon with phosphorus (P) and sulfur (S) atoms as the active component with a high-strength ceramic membrane substrate to form a dual-functional membrane cathode capable of both catalytic oxidation and filtration. The highly dispersed iron active centers and the unsaturated coordination structure of P (S) atoms in this active component effectively regulate electron delocalization, achieving high catalytic activity. Simultaneously, leveraging the excellent stability of the ceramic substrate and the enhanced mass transfer effect of membrane filtration, in-situ efficient degradation of pollutants on the membrane surface and within the pores, along with membrane fouling control, are achieved. This invention provides an efficient, stable, and highly engineering-potential technical pathway for the deep purification of high-salinity, recalcitrant wastewater. Summary of the Invention

[0006] 1. This invention relates to an integrated electrochemical membrane reactor and its water treatment method for in-situ deep purification of high-salinity wastewater. The reactor is characterized by using a ceramic membrane as a substrate, with a surface-modified iron-based non-metallic coordinated porous carbon active layer as the cathode. Together with the anode, they form an integrated electrochemical membrane reactor that combines catalytic oxidation and filtration functions. The specific preparation, principle, and application methods are as follows: (1) Preparation of precursor: Dissolve 4-5 mmol of terephthalic acid in 30-50 mL of N,N-dimethylformamide to prepare a solution. Then slowly add 4-5 mmol of ferric chloride hexahydrate to the solution and stir until completely dissolved. Then, under continuous stirring, add 0.8-1.0 mL of sodium hydroxide solution with a concentration of 4-5 mol / L dropwise to the mixed solution. At this time, a dark brown flocculent precipitate gradually forms in the solution. Transfer the above mixed solution to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and crystallize in an oven at 90-110℃ for 10-12 h to obtain a light orange jelly-like product. After the reaction, wash the obtained product three times with ethanol and ultrapure water respectively, and dry it under vacuum at 80-90℃ for 10-12 h to obtain the precursor MIL-88B(Fe). (2) Precursor pyrolysis: Weigh 1.8~2.0 g of MIL-88B (Fe) prepared in step (1), grind it thoroughly, and place it in a tube furnace for high-temperature pyrolysis. The pyrolysis process is carried out under the protection of high-purity argon gas, with the gas flow rate controlled at 280~320 mL / min. The furnace temperature is raised to 730~770℃ at a heating rate of 4~6℃ / min, and calcined at this temperature for 2.5~3.5 h. After calcination, it is naturally cooled to room temperature to obtain black iron oxide powder. (3) Phosphoric acid etching treatment: 0.20~0.30 g of iron oxide powder obtained in step (2) is dispersed in 150~180 mL of phosphoric acid solution with a concentration of 2.0~2.2 mol / L, and stirred for 4~6 h under water bath conditions of 75~85℃. After the reaction, it is washed three times with ultrapure water and dried at 75~85℃ to obtain iron-phosphorus-carbon powder, which is denoted as Fe-PC active component. It exhibits a highly graphitized structure. The intensity ratio of the defect peak to the graphite peak in the Raman spectrum is 0.6~0.7. Iron is anchored in the carbon matrix in an atomically dispersed form. Its iron active site is composed of phosphorus atoms and carbon atoms forming an unsaturated coordination environment. Iron atoms coordinate with three oxygen atoms and one phosphorus atom to form an unsaturated four-coordinate structure. The H2O2 selectivity is 40~45%, and the number of transferred electrons is 3.1~3.2. (4) Sulfuric acid etching treatment: Disperse 0.20~0.30 g of iron oxide powder obtained in step (2) in 150~180 mL of sulfuric acid solution with a concentration of 2.0~2.2 mol / L, stir and react for 4~6 h under water bath conditions of 75~85℃, wash three times with ultrapure water and dry at 75~85℃ to obtain iron-sulfur-carbon powder, which is denoted as Fe-SC active component. It exhibits a highly graphitized structure. The intensity ratio of the defect peak to the graphite peak in the Raman spectrum is 0.7~0.8. Iron is anchored in the carbon matrix in an atomically dispersed form. Its iron active site is composed of sulfur atoms and carbon atoms forming an unsaturated coordination environment. Iron atoms coordinate with three oxygen atoms and one sulfur atom to form an unsaturated four-coordinate structure. The H2O2 selectivity is 45~50%, and the number of transferred electrons is 2.9~3.0. (5) Cleaning of ceramic membrane substrate: Using alumina ceramic membrane as substrate, soak it in pure water for 1.5~2.5 h and then dry it at 75-85℃ for later use; (6) Preparation of electrochemical membrane: Fe-PC (Fe-SC) was used as the active ingredient (loading amount of 10~20 mg) to prepare a slurry. Pure water, isopropanol and 5% perfluorosulfonic acid solution were mixed in a volume ratio of 20:5:1. Then Fe-PC (Fe-SC) was added and fully dispersed. The slurry was uniformly loaded onto a clean ceramic membrane substrate by vacuum filtration and dried at 75~85℃ for 4~6 h. Under argon protection, the temperature was programmed to rise to 350~370℃ at a rate of 4~6℃ / min and calcined at this temperature for 25~35 min. Copper powder conductive adhesive was used to firmly bond the copper mesh on the surface coating of the membrane. (7) Characteristics of the electrochemical membrane: The area of ​​the electrochemical membrane is 10.0~12.0 cm². 2 The electrochemical membrane pore size is 60.0–65.0 nm, the active layer thickness is 20.0–23.0 μm, and the electroactive area is 6.0–8.0 cm². 2 The pure water flux reaches 250.0–300.0 L / m³. 2 ·h; (8) The integrated electrochemical membrane device adopts an integrated design, with the upper layer being the anode chamber, the middle layer being the membrane reaction chamber, and the lower layer being the cathode water collection chamber. The side wall of the anode chamber is equipped with porous anodes (porous ruthenium-iridium-titanium electrodes, platinum-based electrodes, and other highly active and stable anodes). The ceramic-based electrochemical membrane is placed horizontally in the membrane reaction chamber with its active surface facing the anode above. The cathode water collection chamber is used to collect water that has passed through the membrane. When the device is running, the raw water flows in from the anode chamber and undergoes an electrochemical oxidation reaction with the membrane surface under the action of the electric field. The effluent passes through the membrane and enters the water collection chamber below for discharge. (9) The principle of integrated electrochemical membrane reactor: It can regulate the electron delocalization of active ingredients, and use the iron-based unsaturated coordination structure to drive oxygen to be reduced in situ to generate hydroxyl radicals at the membrane interface. Combined with the mass transfer enhancement effect of membrane filtration, it can simultaneously remove recalcitrant organic matter and suspended matter, and significantly alleviate membrane fouling. (10) Operating conditions of integrated electrochemical membrane reactor: control the electrode spacing at 1~3 cm, and apply 4~6 mA / cm 2 By adjusting the current density and the influent flow rate to 60~100 mL / min, it can stably treat and purify water containing [specific pollutants]. Wastewater with a total dissolved solids concentration of 7000~12000 mg / L; (11) Integrated electrochemical membrane reactor operation mode: Two operation modes are adopted: one is the through-filtration mode, which simultaneously couples electro-oxidation and membrane separation; the other is the multi-stage array mode, which forms a series treatment system. (12) Effect of integrated electrochemical membrane reactor on high-salt wastewater treatment: The device performs significantly in treating high-salt wastewater with high COD and containing recalcitrant fluorine-containing organic pollutants, ensuring that the COD of chemical pharmaceutical wastewater and bio-fermentation pharmaceutical wastewater tailwater is deeply purified by more than 50%, and removing more than 90% of 5-fluorouracil-containing organic pollutants. Attached Figure Description

[0007] Figure 1 Electron micrograph of the active component of Fe-PC (Fe-SC) prepared in this invention; Figure 2 The Raman spectrum of Fe-PC (Fe-SC) prepared in this invention; Figure 3 X-ray absorption near-edge structure diagram of Fe-PC (Fe-SC) prepared in this invention; Figure 4 The selectivity and number of transferred electrons of H2O2, the active component of Fe-PC (Fe-SC) prepared in this invention; Figure 5 The integrated electrochemical membrane reactor constructed for this invention; Figure Labels 1-Valve, 2-Water collection tank, 3-Power supply, 4-Water pump, 5-Inlet, 6-Outlet, 7-Electrochemical membrane loaded with Fe-PC (Fe-SC) active ingredient, 8-Integrated electrochemical membrane reactor, 9-Porous anode, 10-Flow meter, 11-Pressure gauge, 12-Anode chamber, 13-Membrane reaction chamber, 14-Cathode water collection chamber Figure 6 The diagram shows the degradation effect of the integrated electrochemical membrane reactor constructed in this invention on 5-fluorouracil. Figure 7 The integrated electrochemical membrane reactor constructed in this invention is shown in the figure for COD degradation of chemical pharmaceutical wastewater and bio-fermentation pharmaceutical wastewater. Detailed Implementation The present invention will be described in further detail with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0008] Example 1: Preparation method of Fe-PC (Fe-SC) active ingredient.

[0009] (1) Preparation of precursor: 4-5 mmol of terephthalic acid was dissolved in 30-50 mL of N,N-dimethylformamide to prepare a solution; then 4-5 mmol of ferric chloride hexahydrate was slowly added to the solution and stirred until completely dissolved; then, under continuous stirring, 0.8-1.0 mL of sodium hydroxide solution with a concentration of 4-5 mol / L was added dropwise to the mixed solution, at which point a dark brown flocculent precipitate was gradually formed in the solution; the above mixed solution was transferred to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and crystallized in an oven at 90-110℃ for 10-12 h to obtain a light orange jelly-like product; after the reaction was completed, the obtained product was washed three times with ethanol and ultrapure water respectively, and dried at 80-90℃ under vacuum for 10-12 h to obtain the precursor MIL-88B(Fe). (2) Precursor pyrolysis: Weigh 1.8~2.0 g of MIL-88B (Fe) prepared in step (1), grind it thoroughly, and place it in a tube furnace for high-temperature pyrolysis; the pyrolysis process is carried out under the protection of high-purity argon gas, and the gas flow rate is controlled at 280~320 mL / min; the furnace temperature is raised to 730~770℃ at a heating rate of 4~6℃ / min, and calcined at this temperature for 2.5~3.5 h; after calcination, it is naturally cooled to room temperature to obtain black iron oxide powder; (3) Phosphoric acid etching treatment: 0.20~0.30 g of iron oxide powder obtained in step (2) is dispersed in 150~180 mL of phosphoric acid solution with a concentration of 2.0~2.2 mol / L, and stirred for 4~6 h in a water bath at 75~85℃. After the reaction, it is washed three times with ultrapure water and dried at 75~85℃ to obtain iron-phosphorus-carbon powder, which is denoted as Fe-PC active ingredient; (4) Sulfuric acid etching treatment: Disperse 0.20~0.30 g of the iron oxide powder obtained in step (2) in 150~180 mL of sulfuric acid solution with a concentration of 2.0~2.2 mol / L, stir and react for 4~6 h in a water bath at 75~85℃, wash three times with ultrapure water and dry at 75~85℃ to obtain iron-sulfur-carbon powder, which is denoted as Fe-SC active ingredient; Example 2: Preparation method of electrochemical membrane.

[0010] (1) Using alumina ceramic film as a substrate, soak it in pure water for 1.5~2.5 h and then dry it at 75-85℃ for later use; (2) Preparation of electrochemical membrane: Fe-PC (Fe-SC) was used as the active ingredient (loading amount of 10~20 mg) to prepare slurry; pure water, isopropanol and 5% perfluorosulfonic acid solution were mixed in a volume ratio of 20:5:1, and then Fe-PC (Fe-SC) active ingredient was added and fully dispersed; (3) The slurry is uniformly loaded onto a clean ceramic membrane substrate by vacuum filtration and dried at 75~85℃ for 4~6 h. Under argon protection, the temperature is increased to 350~370℃ at a rate of 4~6℃ / min and calcined at this temperature for 25~35 min. Copper powder conductive adhesive is used on the surface coating of the membrane to firmly bond the copper mesh. (4) Apply copper powder conductive adhesive to the surface coating of the membrane to firmly bond the copper mesh; (5) Figure 1 Aberration-corrected electron microscopy images show that iron atoms were successfully loaded onto the surface of the electrochemical film, and elemental surface scanning results confirm that the P (S) element is uniformly distributed. (6) Figure 2 Raman spectroscopy shows that the Fe-PC (Fe-SC) active component exhibits a highly graphitized structure. The intensity ratio of the defect peak to the graphite peak in the Fe-PC active component is 0.6~0.7, while that in the Fe-SC active component is 0.7~0.8. (7) Figure 3 After X-ray absorption and fitting of the near-edge structure, the iron atom coordinates with three oxygen atoms and one P(S) atom to form an unsaturated four-coordinate structure. (8) Figure 4 The selectivity of H2O2, the active ingredient in Fe-PC, is 40-45%, and the number of transferred electrons is 3.1-3.2; the selectivity of H2O2, the active ingredient in Fe-SC, is 45-50%, and the number of transferred electrons is 2.9-3.0.

[0011] Example 3: Integrated electrochemical membrane reactor for deep purification of high-salt wastewater.

[0012] (1) such as Figure 5 As shown, the integrated electrochemical membrane reactor mainly includes an anode chamber 12, a membrane reaction chamber 13, and a cathode water collection chamber 14. The membrane reaction chamber is located between the anode chamber and the cathode water collection chamber. A porous anode 9 is installed outside the anode chamber, and an electrochemical membrane loaded with Fe-PC (Fe-SC) active ingredients is installed inside the cathode water collection chamber. The electrochemical membrane is positioned opposite the porous anode. The porous anode and the electrochemical membrane are connected to an external power supply 3 via copper wires. (2) The integrated electrochemical membrane reactor operates in continuous flow mode: water is pumped from the water collection tank 2 into the anode chamber 12 through the water inlet pipe and the water pump 4. After flowing through the membrane reaction chamber 13, it is collected by the cathode water collection chamber 14 and discharged through the outlet 6, and finally flows back to the water collection tank 2. When starting, water is introduced first, and then the DC power supply is turned on, and the reaction can continue. (3) Operating conditions of integrated electrochemical membrane reactor: control the electrode spacing at 1~3 cm and apply 4~6 mA / cm 2The current density is maintained at 7000~12000 mg / L total dissolved solids, and the influent flow rate is adjusted to 60~100 mL / min; (4) such as Figure 6 As shown, an electrochemical membrane supported on Fe-PC active components was used as the cathode, and a porous ruthenium-iridium-titanium mesh was used as the anode. The distance between the two electrodes was 1–3 cm, and the applied current density was 4–6 mA / cm². 2 The total dissolved solids concentration was 7000~12000 mg / L, and the 5-fluorouracil concentration was 5~8 μM. The integrated electrochemical membrane reactor could operate stably for 20 cycles (1 hour per cycle), and the 5-fluorouracil removal rate exceeded 90%. (5) such as Figure 7 As shown, an electrochemical membrane supported on Fe-PC active components was used as the cathode, and a porous ruthenium-iridium-titanium mesh was used as the anode. The distance between the two electrodes was 1–3 cm, and the applied current density was 4–6 mA / cm². 2 The integrated electrochemical membrane reactor is designed for high-salinity wastewater from chemical pharmaceutical manufacturing (COD ~200 mg / L) and bio-fermentation pharmaceutical manufacturing (COD ~100 mg / L). Results from 10 consecutive cycles of operation show that the reactor achieves a COD removal rate exceeding 50% for the aforementioned high-salinity wastewater.

[0013] Example 4: Engineering application of integrated electrochemical membrane reactor in the deep treatment of high-salinity wastewater.

[0014] (1) Process flow for deep treatment of high-salt wastewater: (grit → grit chamber → primary sedimentation tank → biological tank → secondary sedimentation tank) high-salt tailwater → integrated electrochemical membrane reactor → disinfection → effluent; (2) The integrated electrochemical membrane reactor supports two operating modes to adapt to different water quality requirements: "through filtration" mode, such as Figure 5 As shown, the electrochemical oxidation and membrane separation processes are coupled in the same reaction unit to achieve simultaneous degradation and retention of pollutants, which is suitable for the deep purification of organic matter; the "multi-stage array mode" increases the number of electrochemical membrane cathodes and porous anodes in series to form a treatment system, and gradually increases the oxidation intensity to achieve deep degradation and removal of recalcitrant pollutants, which is suitable for high-salt wastewater with complex composition and high toxicity. (3) After the large and small suspended solids in the high-salt wastewater are intercepted by the bar screen, grit chamber and primary sedimentation tank, the high-salt wastewater flows into the integrated electrochemical membrane reactor after being treated by the biological tank and secondary sedimentation tank. The operation mode of the integrated electrochemical membrane reactor is adjusted according to the water quality to effectively degrade the difficult-to-degrade organic matter in the high-salt wastewater. The separated effluent is disinfected and discharged in compliance with standards.

[0015] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that several modifications and improvements can be made without departing from the principle of the present invention, and these all fall within the protection scope of this application.

Claims

1. An integrated electrochemical membrane reactor and its water treatment method based on in-situ deep purification of high-salinity wastewater, characterized in that, Using a ceramic membrane as the substrate and an iron-based nonmetallic coordinated porous carbon active layer as the cathode, together with the anode, they form an integrated electrochemical membrane reactor that combines catalytic oxidation and filtration functions. The specific preparation, principle, and application methods are as follows: (1) Preparation of precursor: Dissolve 4-5 mmol of terephthalic acid in 30-50 mL of N,N-dimethylformamide to prepare a solution. Then slowly add 4-5 mmol of ferric chloride hexahydrate to the solution and stir until completely dissolved. Then, under continuous stirring, add 0.8-1.0 mL of sodium hydroxide solution with a concentration of 4-5 mol / L dropwise to the mixed solution. At this time, a dark brown flocculent precipitate gradually forms in the solution. Transfer the above mixed solution to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and crystallize in an oven at 90-110℃ for 10-12 h to obtain a light orange jelly-like product. After the reaction, wash the obtained product three times with ethanol and ultrapure water respectively, and dry it under vacuum at 80-90℃ for 10-12 h to obtain the precursor MIL-88B(Fe). (2) Precursor pyrolysis: Weigh 1.8~2.0 g of MIL-88B (Fe) prepared in step (1), grind it thoroughly, and place it in a tube furnace for high-temperature pyrolysis. The pyrolysis process is carried out under the protection of high-purity argon gas, with the gas flow rate controlled at 280~320 mL / min. The furnace temperature is raised to 730~770℃ at a heating rate of 4~6℃ / min, and calcined at this temperature for 2.5~3.5 h. After calcination, it is naturally cooled to room temperature to obtain black iron oxide powder. (3) Phosphoric acid etching treatment: 0.20~0.30 g of iron oxide powder obtained in step (2) is dispersed in 150~180 mL of phosphoric acid solution with a concentration of 2.0~2.2 mol / L, and stirred for 4~6 h under water bath conditions of 75~85℃. After the reaction, it is washed three times with ultrapure water and dried at 75~85℃ to obtain iron-phosphorus-carbon powder, which is denoted as Fe-PC active component. It exhibits a highly graphitized structure. The intensity ratio of the defect peak to the graphite peak in the Raman spectrum is 0.6~0.

7. Iron is anchored in the carbon matrix in an atomically dispersed form. Its iron active site is composed of phosphorus atoms and carbon atoms forming an unsaturated coordination environment. Iron atoms coordinate with three oxygen atoms and one phosphorus atom to form an unsaturated four-coordinate structure. The H2O2 selectivity is 40~45%, and the number of transferred electrons is 3.1~3.

2. (4) Sulfuric acid etching treatment: Disperse 0.20~0.30 g of iron oxide powder obtained in step (2) in 150~180 mL of sulfuric acid solution with a concentration of 2.0~2.2 mol / L, stir and react for 4~6 h under water bath conditions of 75~85℃, wash three times with ultrapure water and dry at 75~85℃ to obtain iron-sulfur-carbon powder, which is denoted as Fe-SC active component. It exhibits a highly graphitized structure. The intensity ratio of the defect peak to the graphite peak in the Raman spectrum is 0.7~0.

8. Iron is anchored in the carbon matrix in an atomically dispersed form. Its iron active site is composed of sulfur atoms and carbon atoms forming an unsaturated coordination environment. Iron atoms coordinate with three oxygen atoms and one sulfur atom to form an unsaturated four-coordinate structure. The H2O2 selectivity is 45~50%, and the number of transferred electrons is 2.9~3.

0. (5) Cleaning of ceramic membrane substrate: Using alumina ceramic membrane as substrate, soak it in pure water for 1.5~2.5 h and then dry it at 75-85℃ for later use; (6) Preparation of electrochemical membrane: Fe-PC (Fe-SC) was used as the active ingredient (loading amount of 10~20 mg) to prepare slurry. Pure water, isopropanol and 5% perfluorosulfonic acid solution were mixed in a volume ratio of 20:5:

1. Then Fe-PC (Fe-SC) was added and fully dispersed. The slurry was uniformly loaded onto a clean ceramic membrane substrate by vacuum filtration and dried at 75~85℃ for 4~6h. Under argon protection, the temperature was programmed to rise to 350~370℃ at a rate of 4~6℃ / min and calcined at this temperature for 25~35min. Copper powder conductive adhesive was used to firmly bond the copper mesh on the surface coating of the membrane. (7) Characteristics of the electrochemical membrane: The area of ​​the electrochemical membrane is 10.0~12.0 cm². 2 The electrochemical membrane has a pore size of 60.0–65.0 nm, an active layer thickness of 20.0–23.0 μm, and an electroactive surface area of ​​6.0–8.0 cm². 2 The pure water flux reaches 250.0–300.0 L / m³. 2 ·h; (8) The integrated electrochemical membrane device adopts an integrated design, with the upper layer being the anode chamber, the middle layer being the membrane reaction chamber, and the lower layer being the cathode water collection chamber. The side wall of the anode chamber is equipped with porous anodes (porous ruthenium-iridium-titanium electrodes, platinum-based electrodes, and other highly active and stable anodes). The ceramic-based electrochemical membrane is placed horizontally in the membrane reaction chamber with its active surface facing the anode above. The cathode water collection chamber is used to collect water that has passed through the membrane. When the device is running, the raw water flows in from the anode chamber and undergoes an electrochemical oxidation reaction with the membrane surface under the action of the electric field. The effluent passes through the membrane and enters the water collection chamber below for discharge. (9) The principle of integrated electrochemical membrane reactor: It can regulate the electron delocalization of active ingredients, and use the iron-based unsaturated coordination structure to drive oxygen to be reduced in situ to generate hydroxyl radicals at the membrane interface. Combined with the mass transfer enhancement effect of membrane filtration, it can simultaneously remove recalcitrant organic matter and suspended matter, and significantly alleviate membrane fouling. (10) Operating conditions of integrated electrochemical membrane reactor: control the electrode spacing at 1~3 cm, and apply 4~6 mA / cm 2 By adjusting the current density and the influent flow rate to 60~100 mL / min, it can stably treat and purify water containing [specific pollutants]. Wastewater with a total dissolved solids concentration of 7000~12000 mg / L; (11) Integrated electrochemical membrane reactor operation mode: Two operation modes are adopted: one is the through-filtration mode, which simultaneously couples electro-oxidation and membrane separation; the other is the multi-stage array mode, which forms a series treatment system. (12) Effect of integrated electrochemical membrane reactor on high-salt wastewater treatment: The device performs well in treating high-salt wastewater with high COD and containing recalcitrant fluorine-containing organic pollutants, ensuring that the COD of chemical pharmaceutical wastewater and bio-fermentation pharmaceutical wastewater tailwater is deeply purified by more than 50%, and removing more than 90% of 5-fluorouracil fluorine-containing organic pollutants.

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