Electrochemical membrane reactor and its use in acidic wastewater

Abstract

This invention provides an electrochemical membrane reactor and its application in acidic wastewater treatment, belonging to the field of wastewater treatment, and particularly relating to the treatment of acidic wastewater. The device mainly includes membrane electrodes (including anodes and cathodes, with the number of cathodes and anodes being the same), an electrolytic cell, an acidic wastewater neutralization tank, a product water tank, and a DC power supply. The membrane reactor applies an electric field to the cathode and anode membrane electrodes via the power supply, generating hydroxide ions on the cathode surface to neutralize the acidic wastewater in the neutralization tank. Excess hydroxide ions can combine with heavy metal ions to form hydroxide precipitates. Simultaneously, a water pump extracts the clarified liquid containing organic pollutants after the reaction, and the organic pollutants in the water are degraded through electrochemical oxidation at the anode. This reactor can achieve the neutralization of acidic wastewater and the removal of heavy metal ions without the addition of external chemical reagents, while simultaneously electrochemically oxidizing and degrading organic pollutants in the water.

Description

Technical Field

[0001] This invention relates to the field of water treatment, and more particularly to an electrochemical membrane reactor and its application in acidic wastewater. Background Technology

[0002] With industrialization, the manufacturing sector has grown, leading to a gradual increase in industrial wastewater generated during production processes in metallurgical, electroplating, petrochemical, and metal processing enterprises. This wastewater is typically either acidic or alkaline, with acidic wastewater being produced in larger quantities. This acidic wastewater usually contains 1-10% acid, is corrosive, and can damage pipes and structures. Furthermore, it often contains excessive levels of heavy metals. The indiscriminate discharge and treatment of acidic wastewater can severely damage the environment, affecting biological growth and impairing the environment's self-purification capacity. Therefore, neutralizing acidic wastewater and removing heavy metals is a crucial objective of acidic wastewater treatment.

[0003] For low-concentration acidic wastewater (containing less than 4% acid), neutralization can be performed (through methods such as neutralization of acidic wastewater, use of alkaline residue, flue gas, or additives, filtration, etc.), and further biological treatment may be necessary. However, some acidic wastewaters have high salinity (mainly chloride), high color, high toxicity, and low pH, making direct biological treatment impossible. While coagulation and sedimentation can transfer pollutants from the water to the precipitate, they do not achieve true degradation. Electrolysis is far more effective than traditional methods for treating this type of wastewater.

[0004] Electrolysis generally offers several advantages for treating this type of wastewater: it requires minimal chemical inputs; post-treatment is relatively simple, producing less sludge and is easy to operate and manage; it is energy-efficient and environmentally friendly, with no secondary pollution. However, the complex composition of the wastewater leads to lower electrolysis efficiency, thus limiting its practical application. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes an electrochemical membrane reactor and applies it to the field of acidic wastewater treatment. This reactor eliminates the need for cation and anion exchange membranes, achieving high mass transfer efficiency through dynamic treatment via membrane electrodes. Furthermore, the reactor can neutralize acidic wastewater and remove heavy metal ions without the addition of external chemical reagents, while also degrading organic pollutants in the water through electrocatalytic oxidation.

[0006] The specific solution adopted in this invention is as follows:

[0007] An electrochemical membrane reactor mainly comprises: an electrolytic cell, an acidic wastewater neutralization tank, a product water tank, a hydrogen evolution membrane cathode, an electrocatalytic membrane anode, and a DC power supply; wherein the hydrogen evolution membrane cathode and the electrocatalytic membrane anode are both located in the electrolytic cell, the DC power supply is connected to the hydrogen evolution membrane cathode and the electrocatalytic membrane anode respectively, the acidic wastewater neutralization tank is connected to the hydrogen evolution membrane cathode, and the product water tank is connected to the electrocatalytic membrane anode; the acidic wastewater neutralization tank is equipped with a filter element, and the filter element is connected to the electrolytic cell.

[0008] Preferably, the main material of the hydrogen evolution membrane cathode is graphite, coke, or metallic silver, or it is a composite electrocatalytic membrane with an electrocatalyst supported on a graphite, coke, or metallic silver substrate. The pore size of the hydrogen evolution membrane cathode is between 0.05 and 10 μm, and the porosity is between 20% and 60%. The electrocatalyst is platinum, ruthenium, iridium, Co3O4, NiCo2O4, or CoNiP, and the catalyst loading is between 0.01 wt% and 10 wt%. The loading methods include impregnation sintering, electrochemical deposition, chemical vapor deposition, and hydrothermal synthesis.

[0009] Preferably, the main material of the electrocatalytic membrane anode is titanium-based, titanium suboxide-based, or carbon-based, or it is a composite electrocatalytic membrane with an electrocatalyst supported on a titanium-based, titanium suboxide-based, or carbon-based material substrate. The pore size of the electrocatalytic membrane anode is between 0.05 and 10 μm, and the porosity is between 20% and 60%. The electrocatalyst includes lead oxide, antimony-doped tin oxide (tin to antimony molar ratio between 8:1 and 50:1), iridium oxide, or ruthenium oxide, with a catalyst loading between 0.01 wt% and 10 wt%. The loading methods include impregnation sintering, electrochemical deposition, chemical vapor deposition, and hydrothermal synthesis.

[0010] Preferably, the number of hydrogen evolution membrane cathodes and electrocatalytic membrane anodes is the same. The hydrogen evolution membrane cathodes and electrocatalytic membrane anodes form an electrode pair, and the number of said electrode pairs is greater than or equal to one. Multiple hydrogen evolution membrane cathodes and electrocatalytic membrane anodes are arranged alternately.

[0011] Preferably, the positive and negative terminals of the DC power supply are connected to the cathodes of each hydrogen evolution membrane and the anodes of each electrocatalytic membrane, respectively.

[0012] Preferably, the distance between adjacent hydrogen evolution membrane cathodes and electrocatalytic membrane anodes should be greater than or equal to 2 cm.

[0013] Preferably, the initial electrolyte in the electrolytic cell is a salt solution of alkali metal chloride, nitrate or sulfate, such as sodium chloride, potassium nitrate, sodium sulfate, etc., with a concentration of 0.01M to 10M; or the initial electrolyte in the electrolytic cell is a natural saline body, such as seawater, salt lake water, etc.

[0014] Preferably, a water pump I is provided between the acidic wastewater neutralization tank and the hydrogen evolution membrane cathode, a water pump II is provided between the product water tank and the electrocatalytic membrane anode, and a water pump III is provided between the filter element and the electrolytic cell.

[0015] This invention also relates to the application of the above-mentioned electrochemical membrane reactor in acidic wastewater, wherein the acidic wastewater is one or more of acidic ore washing wastewater, electroplating wastewater, metallurgical wastewater, petrochemical wastewater, chemical fiber wastewater, acidic heavy metal wastewater, etc., with a hydrogen ion concentration between 0.01 and 5 M, a heavy metal ion content between 1 and 500 ppm, and an organic pollutant content between 1 and 1000 ppm.

[0016] Preferably, the process of treating acidic wastewater using the electrochemical membrane reactor includes the following steps:

[0017] A voltage is applied to the cathode of the hydrogen evolution membrane and the anode of the electrocatalytic membrane by a DC power supply to form an electric field and induce an electrochemical reaction. Hydrogen is evolved at the cathode of the hydrogen evolution membrane, producing hydroxide ions, which are then pumped by water pump I into an acidic wastewater neutralization tank to neutralize the acidic wastewater and simultaneously precipitate heavy metals. The clarified liquid is then pumped by water pump III through a filter element and pumped into an electrolytic cell, enabling the recycling of the treated wastewater. An electrochemical oxidation reaction occurs at the anode of the electrocatalytic membrane, degrading pollutants in the water. The solution is then pumped by water pump II into a product water tank to obtain a treated water sample.

[0018] Preferably, the processing voltage is 2 to 10V.

[0019] The reaction equation occurring on the membrane electrode is as follows:

[0020] Cathode: 2H₂O + 2e⁻ - →H2+2OH -

[0021] Anode: H2O2-e - →·OH+1 / 2O2+H + R + ·OH → H₂O + CO₂, Re - →H₂O + CO₂, 2H₂O - 4e⁻ - →O2+4H +

[0022] The purpose of this invention is to achieve the neutralization treatment of acidic wastewater and the removal of heavy metal ions, while simultaneously degrading organic pollutants in the water through electrochemical oxidation.

[0023] Beneficial effects

[0024] In the membrane reactor described in this invention, the membrane cathode can generate hydroxide ions on its surface to neutralize the acidic wastewater in the neutralization tank. Excess hydroxide ions can also combine with heavy metal ions to form hydroxide precipitates. At the same time, a water pump is used to extract the clarified liquid containing organic pollutants after the reaction. This not only enables the recycling of water but also degrades organic pollutants in the water through electrochemical oxidation of the membrane anode.

[0025] This reactor does not require cation and anion exchange membranes. It achieves high mass transfer efficiency through dynamic treatment via membrane electrodes. Furthermore, the reactor can neutralize acidic wastewater and remove heavy metal ions without the addition of external chemical reagents. It can also simultaneously electrochemically oxidize and degrade organic pollutants in water, improving resource utilization and economic benefits. It has the advantages of simple treatment method, easy operation, and high economic benefits. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the electrochemical membrane reactor of the present invention.

[0027] In the diagram: 1. Electrolytic cell, 2. Acidic wastewater neutralization tank, 3. Product water tank, 4. Hydrogen evolution membrane cathode, 5. Electrocatalytic membrane anode, 6. DC power supply, 7. Water pump, 8. Filter element, 9. Acid recovery tank, 10. Filter membrane, 11. DC power supply, 71. Water pump I, 72. Water pump II, 73. Water pump III. Detailed Implementation

[0028] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes or substitutions made by those skilled in the art based on the invention are within the scope of protection claimed by the present invention.

[0029] Example 1

[0030] like Figure 1As shown, an electrochemical membrane reactor includes: an electrolytic cell 1, an acidic wastewater neutralization tank 2, a product water tank 3, a hydrogen evolution membrane cathode 4, an electrocatalytic membrane anode 5, and a DC power supply 6. The electrolytic cell 1 is located between the acidic wastewater neutralization tank 2 and the product water tank 3. The hydrogen evolution membrane cathode 4 and the electrocatalytic membrane anode 5 are both located in the electrolytic cell 1, and the number of hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5 is the same. The positive and negative terminals of the DC power supply 6 are connected to the hydrogen evolution membrane cathode 4 and the electrocatalytic membrane anode 5, respectively. The acidic wastewater neutralization tank 2 is connected to the hydrogen evolution membrane cathode 4, and the product water tank 3 is connected to the electrocatalytic membrane anode 5. The acidic wastewater neutralization tank 2 is equipped with a filter element 8, which is connected to the electrolytic cell 1. The hydrogen evolution membrane cathode 4 is made of graphite, coke, or metallic silver, or is a composite electrocatalytic membrane with an electrocatalyst supported on a graphite, coke, or metallic silver substrate. The electrocatalyst is platinum, ruthenium, iridium, Co3O4, NiCo2O4, or CoNiP, with a catalyst loading ranging from 0.01 wt% to 10 wt%. Loading methods include impregnation sintering, electrochemical deposition, chemical vapor deposition, and hydrothermal synthesis. The electrocatalytic membrane anode 5 is made of titanium-based, sub-titanium oxide-based, or carbon-based material, or is a composite electrocatalytic membrane with an electrocatalyst supported on a titanium-based, sub-titanium oxide-based, or carbon-based substrate. The electrocatalyst is lead oxide, antimony-doped tin oxide (tin to antimony molar ratio of 8:1 to 50:1), iridium oxide, or ruthenium oxide, with a catalyst loading ranging from 0.01 wt% to 10 wt%. Loading methods include impregnation sintering, electrochemical deposition, chemical vapor deposition, and hydrothermal synthesis. The distance between adjacent hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5 is 5 cm. The initial electrolyte in the electrolytic cell 1 is a salt solution of alkali metal chloride, nitrate, or sulfate, with a concentration of 0.01M to 10M; or the initial electrolyte in the electrolytic cell 1 is a natural saline body, such as seawater or salt lake water. A water pump I 71 is installed between the acidic wastewater neutralization tank 2 and the hydrogen evolution membrane cathode 4; a water pump II 72 is installed between the product water tank 3 and the electrocatalytic membrane anode 5; and a water pump III 73 is installed between the filter element 8 and the electrolytic cell 1.

[0031] The above-mentioned electrochemical membrane reactor method for treating acidic wastewater includes the following steps:

[0032] A voltage is applied to the hydrogen evolution membrane cathode 4 and the electrocatalytic membrane anode 5 by a DC power supply 6 to form an electric field and cause an electrochemical reaction. Hydrogen is evolved on the hydrogen evolution membrane cathode 4, producing hydroxide ions, which are pumped out by a water pump 71 into the acidic wastewater neutralization tank 2 to neutralize the acidic wastewater and simultaneously precipitate heavy metals in the wastewater. The clarified liquid is then pumped out through a filter element (8) by a water pump 73 and transported to the electrolytic cell 1, realizing the recycling of the treated wastewater. An electrochemical oxidation reaction occurs at the electrocatalytic membrane anode 5, degrading pollutants in the water. The solution is pumped out by a water pump 72 into the product water tank 3 to obtain a treated water sample. The acidic wastewater is one or more of the following: acidic ore washing wastewater, electroplating wastewater, metallurgical wastewater, petrochemical wastewater, chemical fiber wastewater, and acidic heavy metal wastewater. The treatment voltage is 2–10V.

[0033] Example 2

[0034] The electrochemical membrane reactor described in Example 1 was used to treat acidic wastewater. In the reactor, a platinum-loaded porous graphite membrane was used as the cathode 4. The porous graphite membrane was a hollow plate with a length of 200 mm, a width of 120 mm, a thickness of 15 mm, a wall thickness of 4 mm, an average equivalent pore diameter of 2 μm, and a porosity of 45%. The platinum loading on the membrane was 0.2 wt%. The loading process was chemical vapor deposition: first, the graphite membrane was pretreated (washed with 0.2 M HCl, then washed with deionized water until the wash solution was neutral, and dried at 105 °C for 2 h) to remove adsorbed moisture or impurities from its surface or pores. The graphite membrane was placed in a quartz boat, which was then placed in a tubular resistance furnace for calcination. The furnace was heated from room temperature to 500 °C at a rate of 10 °C / min and held at that temperature for 120 min. The entire calcination process was carried out in a mixed atmosphere of oxygen and argon (oxygen to argon volume ratio 1:9). Then, according to a graphite film to precursor mass ratio of 10:1, 0.2 wt% of the precursor [Pt(C5H9)2] aqueous solution was weighed. The graphite film and the precursor [Pt(C5H9)2] aqueous solution were placed at both ends of the Y-tube of the chemical vapor deposition apparatus and sublimated for 12 hours under reduced pressure (alternating dynamic and static pressure) at room temperature. After the precursor sublimation was completed, hydrogen gas was passed through for reduction for 30 minutes, and the deposited sample turned black. Then, a vacuum was applied for 20 minutes to remove small molecule organic matter generated during the reduction process. A porous titanium membrane loaded with lead oxide was used as anode 5, with the same shape and size as the cathode. The average equivalent diameter of the membrane pores was 1.8 μm, the porosity was 30.5%, and the lead oxide loading on the membrane was 1.5 wt%. The loading process was electrochemical deposition: the porous titanium membrane was used as the anode, and a stainless steel sheet (0.5 mm × 120 mm × 200 mm) was used as the cathode. The electrolyte temperature was 50 °C, and the electrolyte was a mixed solution of Pb(NO)₂ and NaF, with deionized water as the solvent. The concentration of Pb(NO)₂ was 0.6 mol / L, and the concentration of NaF was 0.01 mol / L. The pH of the solution was adjusted to 3 with HNO₃. The NaF aqueous solution was prepared first, followed by the slow addition of Pb(NO)₂ to prevent hydrolysis, and then the pH was adjusted. To shorten the direct contact time between the porous titanium membrane and the acidic electrolyte and prevent the re-formation of an oxide film on the substrate, the electrolyte was first applied at 80 mA / cm². 2 Plating was performed at the current density for 10 seconds, at which point the substrate was covered with an extremely thin lead oxide film. The current density was then reduced to 20 mA / cm². 2After plating for 1 hour, the sample is removed, rinsed with deionized water, and dried. There are three pairs of hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5, with multiple hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5 staggered. The distance between adjacent hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5 is 2.5 cm. The electrolyte in electrolytic cell 1 is 5M sodium chloride. The acidic wastewater neutralization tank 2 contains the acidic ore washing wastewater to be treated (hydrogen ion concentration of 0.01M, heavy metal ion content (such as lead, cadmium, copper, manganese, etc.) of 15ppm, COD concentration of 150ppm), and the operating voltage is 2V. After running for a period of time, the clarified liquid containing organic pollutants from the acidic wastewater neutralization tank 2 is filtered through filter element 8 and pumped to electrolytic cell 1 via water pump Ⅲ73. An electrochemical oxidation reaction occurs at membrane anode 5, degrading pollutants in the water. The reacted solution is pumped into product water tank 3 via water pump Ⅱ72 to obtain the treated water sample.

[0035] Experimental results: After 10 hours of treatment, the pH value of the acidic ore washing wastewater sample in neutralization tank 2 reached about 7, heavy metal ions formed obvious precipitates, and the COD removal rate in the water reached 65%.

[0036] Example 3

[0037] The electrochemical membrane reactor described in Example 1 was used to treat acidic wastewater. In the reactor, a porous coke membrane loaded with Co3O4 was used as the cathode 4. The porous coke membrane was a hollow plate with a length of 300 mm, a width of 150 mm, a thickness of 20 mm, a wall thickness of 5 mm, an average equivalent pore diameter of 1.5 μm, and a porosity of 50%. The Co3O4 loading on the membrane was 0.32 wt%. The loading process was electrochemical deposition: a three-electrode system was used, with Pt as the counter electrode, the porous coke membrane as the working electrode, and a saturated calomel electrode as the reference electrode. The working voltage was set to -0.9 V, and the process was carried out at room temperature. The concentration of the precursor solution (Co(NO3)2 aqueous solution) was 0.05 mol / L, and the electrodeposition reaction time was 30 min. Finally, the electrodeposited hydroxide-loaded coke membrane was placed in a muffle furnace and calcined at 400 °C for 60 min at a heating rate of 5 °C / min. After calcination, the membrane was washed with deionized water and dried in an oven at 60°C. The porous titanium suboxide membrane loaded with iridium oxide served as anode 5, with the same shape and size as the cathode. The average equivalent diameter of the membrane pores was 1.6 μm, the porosity was 35.2%, and the iridium oxide loading on the membrane was 0.35 wt%. The loading process was impregnation and calcination: the porous titanium suboxide membrane was successively blasted with 80-mesh and 120-mesh brown corundum sand and degreased in a weakly alkaline aqueous solution (5 mM NaOH aqueous solution). It was then rinsed with anhydrous ethanol and water, dried with an air duct, and acid-washed in boiling 15% oxalic acid solution for 60 min. The pretreated titanium suboxide membrane was then impregnated in a chloroiridium acid aqueous solution for 10 min each time. The number of impregnations was adjusted until the total iridium coating amount reached 0.35 wt%. After each impregnation, the coating is dried at 120℃ for 30 minutes, followed by sintering at 450℃ for 30 minutes. After the final coating, it is sintered at 500℃ for 75 minutes. There are two pairs of hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5, which are staggered, with a distance of 3.5 cm between adjacent cathodes 4 and anodes 5. The electrolyte in electrolytic cell 1 is 5M sodium sulfate. Acidic wastewater is neutralized in cell 2, which contains acidic electroplating wastewater to be treated (hydrogen ion concentration of 0.05M, heavy metal ion content (such as lead, manganese, zinc, nickel, etc.) of 50ppm, and COD concentration of 100ppm). The operating voltage is 5V. After running for a period of time, the clarified liquid containing organic pollutants in the neutralization tank 2, after being reacted by the acidic wastewater, is filtered through the filter element 8 and then pumped to the electrolytic cell 1. An electrochemical oxidation reaction occurs at the membrane anode 5 to degrade the pollutants in the water. The solution after the reaction is pumped out by the pump II 72 into the product water tank 3 to obtain the treated water sample.

[0038] Experimental results: After 12 hours of treatment, the pH value of the acidic ore washing wastewater sample in neutralization tank 2 reached about 7.2, heavy metal ions formed obvious precipitates, and the COD removal rate in the water reached 78%.

[0039] Example 4

[0040] The electrochemical membrane reactor described in Example 1 was used to treat acidic wastewater. In the reactor, a CoNiP-loaded porous carbon membrane was used as the cathode 4. The porous carbon membrane was a hollow plate with a length of 500 mm, a width of 250 mm, a thickness of 22 mm, a wall thickness of 6 mm, an average equivalent pore diameter of 1.8 μm, a porosity of 49.3%, and a CoNiP loading of 0.48 wt%. The loading process was hydrothermal synthesis: 3 mM cobalt nitrate, 3 mM nickel nitrate, 2 mM ammonium fluoride, and 2 mM urea were added to 1000 mL of deionized water and stirred until homogeneous. The porous carbon membrane was then immersed in this solution. After standing for 2 hours, the membrane and solution were transferred to a hydrothermal reactor and hydrothermally heated at 170°C for 12 hours to obtain a CoNiP / porous carbon membrane precursor. The precursor was then placed in a tube furnace and carbonized at 900°C for 2 hours under pH 3 protection, followed by cooling and removal. The porous carbon membrane loaded with antimony-doped tin oxide (tin to antimony molar ratio of 30:1) serves as anode 5, with the same shape and size as the cathode. The average equivalent diameter of the membrane pores is 2.8 μm, and the porosity is 58.8%. The antimony-doped tin oxide loading on the membrane is 0.5 wt%. The loading process is impregnation and calcination: a mixed aqueous solution of SnCl4·5H2O (0.4 mol / L concentration) and SbCl3 (tin to antimony molar ratio of 30:1) was prepared. Hydrochloric acid was added to inhibit hydrolysis, and the pH of the solution was adjusted to 4 with NaOH. The porous carbon membrane was then immersed in the solution and allowed to stand for 3 hours. After removal, it was calcined in a muffle furnace at 700℃ for 2 hours at a rate of 5℃ / min. There are four pairs of hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5, which are staggered. The distance between adjacent hydrogen evolution membrane cathodes 4 and electrocatalytic membrane anodes 5 is 4 cm. The electrolyte in electrolytic cell 1 is 5M potassium chloride. The acidic wastewater neutralization tank 2 contains the acidic metallurgical wastewater to be treated (hydrogen ion concentration of 0.25M, heavy metal ion content (such as cadmium, zinc, lead, etc.) of 100ppm, and COD concentration of 150ppm). The operating voltage is 3.5V. After a period of operation, the clarified liquid containing organic pollutants from the acidic wastewater neutralization tank is filtered through filter element 8 and pumped to electrolytic cell 1 via water pump Ⅲ73. An electrochemical oxidation reaction occurs at membrane anode 5, degrading the pollutants in the water. The resulting solution is pumped into product water tank 3 via water pump Ⅱ72, yielding the treated water sample.

[0041] Experimental results: After 18 hours of treatment, the pH value of the acidic ore washing wastewater sample in neutralization tank 2 reached about 7.2, heavy metal ions formed obvious precipitates, and the COD removal rate in the water reached 75%.

[0042] Example 5

[0043] The electrochemical membrane reactor described in Example 1 was used to treat acidic wastewater. In the reactor, a porous graphite membrane loaded with NiCo2O4 was used as the cathode 4. The porous graphite membrane was a hollow plate with a length of 800 mm, a width of 350 mm, a thickness of 25 mm, and a wall thickness of 7 mm. The average equivalent diameter of the membrane pores was 3.1 μm, and the porosity was 54.6%. The NiCo2O4 loading on the membrane was 0.74 wt%. The loading process was impregnation and calcination: the solution used was a mixed aqueous solution of 1 mol / L Ni(NO3)2·6H2O and 2 mol / L Co(NO3)2·6H2O to ensure the Ni... 2+ and Co 2+ The ion ratio was 1:2. The porous graphite membrane was immersed in the mixed aqueous solution and sonicated for 30 min, then allowed to stand for 12 h at -0.1 MPa, followed by heating in a 50℃ water bath for 6 h. After removal, it was placed in a 60℃ forced-air drying oven for 12 h. The above-mentioned porous graphite membrane impregnated with Co and Ni nitrates was calcined in air for 1 h at a heating rate of 2℃ / min and a holding temperature of 300℃. During the reaction, Ni(NO3)2 and Co(NO3)2 decomposed at 300℃ to form NiCo2O4. A porous titanium film loaded with antimony-doped tin oxide (tin to antimony molar ratio of 9:1) served as anode 5, with the same shape and size as the cathode. The average equivalent diameter of the film pores was 3.5 μm, and the porosity was 37.2%. The antimony-doped tin oxide loading on the film was 0.82 wt%. The loading process was electrochemical deposition: SbCl3 and SnCl2·2H2O (tin to antimony molar ratio of 9:1) were dissolved in 63 mL of deionized water, and 37 mL of 12M hydrochloric acid was added while stirring. The mixture was then sonicated for 30 min to obtain the electrolyte solution. A bipolar electrochemical cell was used, with the porous titanium film as the cathode and a titanium plate (800 mm × 350 mm) as the anode. The voltage was 2.5 V, and the duration was 1 h. The electrolyte contained positively charged metal cations Sn. 2+ and Sb 3+The adsorbed material is deposited on a porous titanium membrane at the cathode. The membrane is then heated in a deionized water bath at 80°C for 1 hour, followed by drying in an oven at 100°C for 2 hours. Two pairs of hydrogen evolution membrane cathodes (4) and electrocatalytic membrane anodes (5) are used, staggered between each other, with a 5cm spacing between adjacent cathodes. The electrolyte in electrolytic cell 1 is 5M potassium sulfate. Acidic wastewater neutralization tank 2 contains mixed acidic wastewater from ore washing, electroplating, and metallurgical processes (hydrogen ion concentration 0.5M, heavy metal ion content (e.g., cadmium, lead, manganese, zinc, copper, etc.) 150ppm, COD concentration 200ppm), and the operating voltage is 4V. After running for a period of time, the clarified liquid containing organic pollutants in the neutralization tank 2, after being reacted by the acidic wastewater, is filtered through the filter element 8 and then pumped to the electrolytic cell 1. An electrochemical oxidation reaction occurs at the membrane anode 5 to degrade the pollutants in the water. The solution after the reaction is pumped out by the pump II 72 into the product water tank 3 to obtain the treated water sample.

[0044] Experimental results: After 24 hours of treatment, the pH value of the acidic ore washing wastewater sample in neutralization tank 2 reached about 7.4, heavy metal ions formed obvious precipitation, and the COD removal rate in the water reached 68%.

Claims

1. An electrochemical membrane reactor, characterized in that: The electrochemical membrane reactor includes: an electrolytic cell (1), an acidic wastewater neutralization tank (2), a product water tank (3), a hydrogen evolution membrane cathode (4), an electrocatalytic membrane anode (5), and a DC power supply (6); wherein, the electrolytic cell (1) is located between the acidic wastewater neutralization tank (2) and the product water tank (3), the hydrogen evolution membrane cathode (4) and the electrocatalytic membrane anode (5) are both located in the electrolytic cell (1), the DC power supply (6) is connected to the hydrogen evolution membrane cathode (4) and the electrocatalytic membrane anode (5) respectively, the acidic wastewater neutralization tank (2) is connected to the hydrogen evolution membrane cathode (4), and the product water tank (3) is connected to the electrocatalytic membrane anode (5); the acidic wastewater neutralization tank (2) is equipped with a filter element (8), and the filter element (8) is connected to the electrolytic cell (1); The anode (5) of the electrocatalytic membrane is a composite electrocatalytic membrane with a titanium-based, sub-titanium oxide-based, or carbon-based substrate supporting an electrocatalyst. The electrocatalyst is lead oxide, antimony-doped tin oxide, iridium oxide, or ruthenium oxide.

2. The electrochemical membrane reactor according to claim 1, characterized in that: The hydrogen evolution membrane cathode (4) is made of graphite, coke or metallic silver, or is a composite electrocatalytic membrane with graphite, coke or metallic silver as the substrate and an electrocatalyst supported thereon. The electrocatalyst is platinum, ruthenium, iridium, Co3O4, NiCo2O4 or CoNiP. The loading method includes impregnation sintering, electrochemical deposition, chemical vapor deposition or hydrothermal synthesis. The pore size of the hydrogen evolution membrane cathode (4) is 0.05 ~ 10 µm and the porosity is 20% ~ 60%.

3. The electrochemical membrane reactor according to claim 1, characterized in that: The antimony-doped tin oxide of the electrocatalytic membrane anode (5) has a tin to antimony molar ratio of 8:1 to 50:1, and the loading method includes impregnation sintering, electrochemical deposition, chemical vapor deposition or hydrothermal synthesis; the pore size of the electrocatalytic membrane anode is 0.05 to 10 µm and the porosity is 20% to 60%.

4. The electrochemical membrane reactor according to claim 1, characterized in that: The number of hydrogen evolution membrane cathodes (4) and electrocatalytic membrane anodes (5) is the same; The positive and negative terminals of the DC power supply (6) are connected to the hydrogen evolution membrane cathode (4) and the electrocatalytic membrane anode (5), respectively.

5. The electrochemical membrane reactor according to claim 1, characterized in that: The hydrogen evolution membrane cathode (4) and the electrocatalytic membrane anode (5) are used as an electrode pair, and the number of the electrode pairs is greater than or equal to 1; the hydrogen evolution membrane cathode (4) and the electrocatalytic membrane anode (5) are arranged alternately.

6. The electrochemical membrane reactor according to claim 1, characterized in that: The distance between the hydrogen evolution membrane cathode (4) and the electrocatalytic membrane anode (5) is greater than or equal to 2 cm; The initial electrolyte in the electrolytic cell (1) is a salt solution of alkali metal chloride, nitrate or sulfate, with a concentration of 0.01 M to 10 M; or the initial electrolyte in the electrolytic cell (1) is a natural saline body.

7. The electrochemical membrane reactor according to claim 1, characterized in that: Pump I (71) is provided between the acidic wastewater neutralization tank (2) and the hydrogen evolution membrane cathode (4), pump II (72) is provided between the product water tank (3) and the electrocatalytic membrane anode (5), and pump III (73) is provided between the filter element (8) and the electrolytic cell (1).

8. The application of the electrochemical membrane reactor according to any one of claims 1 to 7 in acidic wastewater, characterized in that: The acidic wastewater is one or more of the following: acidic ore washing wastewater, electroplating wastewater, metallurgical wastewater, petrochemical wastewater, chemical fiber wastewater, and acidic heavy metal wastewater.

9. The application according to claim 8, characterized in that: Includes the following steps: A voltage is applied to the hydrogen evolution membrane cathode (4) and the electrocatalytic membrane anode (5) by a DC power supply (6) to form an electric field and an electrochemical reaction occurs. Hydrogen is evolved on the hydrogen evolution membrane cathode (4) to generate hydroxide ions, which are pumped out by pump I (71) into the acidic wastewater neutralization tank (2) to neutralize the acidic wastewater and precipitate heavy metals in the wastewater. Then the clarified liquid is pumped out by pump III (73) through the filter element (8) and transported to the electrolytic cell (1) to realize the recycling of the treated wastewater. An electrochemical oxidation reaction occurs at the electrocatalytic membrane anode (5) to degrade pollutants in the water. The solution is pumped out by pump II (72) into the product water tank (3) to obtain the treated water sample.

10. The application according to claim 9, characterized in that: The voltage is 2~10V.

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