Electrochemical membrane reaction device and treatment method for treating acidic wastewater

Abstract

The present invention provides an electrochemical membrane reaction device and method for treating acidic wastewater, belonging to the field of wastewater treatment, particularly the field of acidic wastewater treatment. The membrane reaction device applies an electric field to the cathode and anode membrane electrodes through a power supply, generating hydroxide at the membrane cathode for neutralizing the acidic wastewater in the wastewater neutralization tank. Excess hydroxide can also combine with heavy metal ions to form hydroxide precipitation. At the same time, a water pump is used to extract the supernatant after the reaction to achieve the recycling of the brine. The membrane anode can electrolyze water to produce hydrogen ions, which are extracted by a water pump to obtain an acid solution. H2 and O2 precipitated by side reactions at the membrane cathode and membrane anode can also be collected by a gas collection device to achieve resource recycling. The reaction device can achieve acid recovery and heavy metal ion removal from acidic wastewater without the addition of external chemical reagents, while improving resource recovery and utilization rates. It has the advantages of simple and efficient treatment methods, simple operation, and high economic benefits.

Description

Technical Field

[0001] The present invention relates to the field of water treatment, and in particular to an electrochemical membrane reaction device and a treatment method for treating acidic wastewater. Background Art

[0002] Acidic wastewater primarily originates from industries such as chemical processing, electroplating, metal smelting, and mining. my country discharges an average of nearly one million cubic meters of industrial waste acid annually. This acidic wastewater, with an acid concentration of 1-10% or less, is corrosive, potentially corroding pipes and structures. Furthermore, heavy metal content can exceed permitted levels. The indiscriminate discharge and treatment of acidic wastewater can severely damage the environment, hindering biological growth and impairing its self-purification capacity. Therefore, neutralizing acidic wastewater and removing heavy metals are key goals of acidic wastewater treatment.

[0003] Currently, commonly used methods for treating acidic wastewater include neutralization precipitation, ion exchange, membrane separation, and other processes, or a combination of these. However, these methods are not only costly and therefore cost-effective, but also prone to secondary pollution, which conflicts with current environmental protection concepts. For example, the most widely used neutralization method typically requires the addition of expensive chemical reagents, and different neutralization reagents produce different sludges, which can easily cause secondary pollution.

[0004] In recent years, electrochemical treatment has garnered increasing attention in the field of acidic wastewater treatment. Electrochemical technology requires no additional chemicals, reduces secondary pollution, and offers simple processes, low treatment costs, and excellent treatment results. However, traditional electrochemical treatment methods suffer from numerous bottlenecks, such as low mass transfer efficiency, high energy consumption, and the development of side reactions such as hydrogen evolution and oxygen reduction reactions. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention proposes an electrochemical membrane reaction device and treatment method for treating acidic wastewater. The reaction device can achieve neutralization treatment of acidic wastewater and removal of heavy metal ions without adding external chemical reagents, reducing secondary pollution while realizing the recycling of water bodies and acid recovery of acidic wastewater. It can also collect gases released by side reactions, thereby improving resource utilization and economic benefits and further reducing costs.

[0006] The specific scheme adopted in the present invention is as follows:

[0007] An electrochemical membrane reactor for treating acidic wastewater, comprising: a cathode reaction tank, an anode reaction tank, a brine tank, a wastewater neutralization tank, an acid recovery tank, and a power supply; the brine tank is located between the cathode reaction tank and the anode reaction tank, the brine tank and the cathode reaction tank being connected via a cation exchange membrane, and the brine tank and the anode reaction tank being connected via an anion exchange membrane; a porous membrane cathode is provided in the cathode reaction tank, and the porous membrane cathode is connected to the wastewater neutralization tank; a porous membrane anode is provided in the anode reaction tank, and the porous membrane anode is connected to the acid recovery tank; the porous membrane cathode and the porous membrane anode are connected via a power supply. The wastewater neutralization tank contains acidic wastewater to be treated, the brine tank contains an electrolyte solution, the anode reaction tank contains an electrolyte, and the cathode reaction tank contains an initial electrolyte.

[0008] Preferably, the membrane electrode (porous membrane cathode, porous membrane anode) material can be a homogeneous membrane or a composite membrane.

[0009] As a further preference, the main material of the porous membrane cathode is graphite, coke, metallic platinum or metallic silver, and the main material of the porous membrane anode is a carbon-based material, or a metal or its metal oxide, such as graphite, coke, metallic titanium, metallic zinc or metallic lead. The pore size of the membrane electrode (porous membrane cathode, porous membrane anode) is between 0.05 and 10 μm, and the porosity is between 20% and 70%. The configuration of the membrane electrode (porous membrane cathode, porous membrane anode) includes plate type, tubular type and hollow plate type.

[0010] Preferably, the cathode reaction tank is provided with an H2 collection port, and the anode reaction tank is provided with an O2 collection port.

[0011] Preferably, a filter membrane is provided in the wastewater neutralization tank, and the filter membrane is connected to the brine tank.

[0012] Preferably, a water pump I is provided between the porous membrane cathode and the wastewater neutralization tank, a water pump II is provided between the porous membrane anode and the acid recovery tank, and a water pump III is provided between the filter membrane and the brine tank.

[0013] Preferably, in the electrochemical membrane reaction device, the power supply is a direct current power supply.

[0014] Preferably, the electrolyte in the brine tank is a mixture of one or more alkali metal chlorides, nitrates and sulfates, such as a mixture of one or more sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium sulfate and potassium sulfate, with a concentration of 0.01M to saturation concentration, preferably 1M to saturation.

[0015] Preferably, the initial electrolyte in the anode reaction tank is a dilute acid solution, such as a mixture of one or more of hydrochloric acid, nitric acid, sulfuric acid, etc., with a concentration of 0.01mM to 5M, preferably 0.01 to 50mM.

[0016] Preferably, the initial electrolyte in the cathode reaction tank is a dilute alkaline solution, such as a mixture of one or more of sodium hydroxide, potassium hydroxide, etc., with a concentration of 0.01mM to 5M, preferably 0.01 to 100mM.

[0017] Preferably, the acidic wastewater is a mixture of one or more of acidic mineral washing wastewater, electroplating wastewater, metallurgical wastewater, petrochemical wastewater, chemical fiber wastewater, acidic heavy metal (such as copper, lead, zinc, cobalt, nickel, vanadium, manganese, cadmium, mercury, tungsten) wastewater, etc.

[0018] The method for treating acidic wastewater using the electrochemical membrane reaction device comprises the following steps:

[0019] Voltage is applied to the membrane electrodes (porous membrane cathode and porous membrane anode) through a power supply to form an electric field and cause an electrochemical reaction. Hydroxide and hydrogen are generated on the porous membrane cathode, and the hydrogen is collected through the H2 collection port. The hydroxide solution is transported to the wastewater neutralization tank through water pump I to react with the acidic wastewater. At the same time, excess hydroxide can also combine with heavy metal ions to form heavy metal hydroxide precipitation. Water is electrolyzed on the porous membrane anode to generate acid and oxygen. The oxygen is collected through the O2 collection port, and the acid solution is extracted by water pump II and transported to the acid recovery tank to achieve acid recovery. After running for a period of time, the supernatant after the reaction in the wastewater neutralization tank is filtered through a filter membrane by water pump III and transported to the brine tank, so that the treated wastewater can be recycled.

[0020] Preferably, the voltage intensity applied during the operation is 1 to 50V, preferably 2 to 15V.

[0021] The main purpose of the present invention is to achieve neutralization treatment of acidic wastewater and removal of heavy metal ions, while improving resource recovery rate and utilization rate.

[0022] The reaction equation occurring on the membrane electrode is:

[0023] Cathode: 2H2O+2e - →H2↑+2OH -

[0024] Anode: 2H2O-4e - →O2↑+4H +

[0025] Beneficial effects:

[0026] In the electrochemical membrane reaction device described in the present invention, the membrane cathode can generate hydroxide on the surface for neutralizing the acidic wastewater in the wastewater neutralization tank. The excess hydroxide can also combine with heavy metal ions to form hydroxide precipitation. At the same time, a water pump is used to extract the supernatant after the reaction to achieve the recycling of the water body; the membrane anode can electrolyze water in the anode tank to generate hydrogen ions, which are extracted by a water pump to obtain an acid solution; the gas precipitated by the reaction between the membrane cathode and the membrane anode can also be collected by a gas collection device to achieve resource recycling.

[0027] This reaction device can neutralize acidic wastewater and remove heavy metal ions without the addition of external chemical reagents, reducing secondary pollution while achieving water recycling and acid recovery from acidic wastewater. It can also collect oxygen and hydrogen released during the water electrolysis reaction, improving resource utilization and economic benefits, and further reducing costs. Compared with traditional electrochemical treatment processes, this device can effectively improve the system's mass transfer efficiency, thereby improving overall reaction efficiency. It has the advantages of simple treatment methods, easy operation, and high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the electrochemical membrane reaction device for treating acidic wastewater.

[0029] In the figure: 1. porous membrane cathode, 2. porous membrane anode, 3. cation exchange membrane, 4. anion exchange membrane, 5. cathode reaction tank, 6. anode reaction tank, 7. brine tank, 8. wastewater neutralization tank, 9. acid recovery tank, 10. filter membrane, 11. DC power supply, 12. water pump I, 13. water pump II, 14. water pump III. DETAILED DESCRIPTION

[0030] The present invention is further described below with reference to the following examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples, where specific conditions are not specified, are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes or substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed by the present invention.

[0031] Example 1

[0032] like Figure 1As shown, an electrochemical membrane reactor for treating acidic wastewater comprises: a cathode reaction tank 5, an anode reaction tank 6, a brine tank 7, a wastewater neutralization tank 8, an acid recovery tank 9, and a DC power supply 11. The brine tank 7 is located between the cathode reaction tank 5 and the anode reaction tank 6, and is connected to the cathode reaction tank 5 via a cation exchange membrane 3. The brine tank 7 is connected to the anode reaction tank 6 via an anion exchange membrane 4. A porous membrane cathode 1 is provided in the cathode reaction tank 5, and is connected to the wastewater neutralization tank 8. A porous membrane anode 2 is provided in the anode reaction tank 6, and is connected to the acid recovery tank 9. The positive and negative electrodes of the DC power supply 11 are connected to the porous anode membrane 2 and the porous cathode membrane 1, respectively. The cathode reaction tank 5 is provided with an H2 collection port 15, which is located above the cathode reaction tank 5. The anode reaction tank 6 is provided with an O2 collection port 16, which is located above the anode reaction tank 6. A filter membrane 10 is provided in the wastewater neutralization tank 8, and is connected to the brine tank 7. A water pump I 12 is provided between the porous membrane cathode 1 and the wastewater neutralization tank 8, a water pump II 12 is provided between the porous membrane anode 2 and the acid recovery tank 9, and a water pump III 13 is provided between the filter membrane 10 and the brine tank 7. The porous membrane cathode 1 and the porous membrane anode 2 are homogeneous membranes or composite membranes; the porous membrane cathode 1 is made of graphite, coke, platinum, or silver, and the porous membrane anode 2 is made of a carbon-based material or a metal or its metal oxide, such as graphite, coke, titanium, zinc, or lead; the pore size of the porous membrane cathode 1 and the porous membrane anode 2 ranges from 0.05 to 10 μm, and the porosity is 20% to 70%. The porous membrane cathode 1 and the porous membrane anode 2 can be configured as plates, tubes, or hollow plates. The electrolyte in the brine tank 7 is a mixture of one or more alkali metal chlorides, nitrates and sulfates, with a concentration of 0.01M to saturation concentration; the initial electrolyte in the anode reaction tank 6 is a dilute acid solution, such as a mixture of one or more hydrochloric acid, nitric acid and sulfuric acid, with a concentration of 0.01mM to 5M; the initial electrolyte in the cathode reaction tank 5 is a dilute alkaline solution, such as a mixture of one or more sodium hydroxide and potassium hydroxide, with a concentration of 0.01mM to 5M.

[0033] The method for treating acidic wastewater using the electrochemical membrane reaction device comprises the following steps:

[0034] A voltage is applied to the porous membrane cathode 1 and the porous membrane anode 2 through a DC power supply 11 to form an electric field and cause an electrochemical reaction. Hydroxide and hydrogen are generated on the porous membrane cathode 1, and the hydrogen is collected through the H2 collection port 15. The hydroxide solution is transported to the wastewater neutralization tank 8 through the pump I 12, and reacts with the acidic wastewater to form a heavy metal hydroxide precipitate. Water is electrolyzed on the porous membrane anode 2 to generate acid and oxygen, and the oxygen is collected through the O2 collection port 16. The acid solution is extracted by the pump II 13 and transported to the acid recovery tank 9 to achieve acid recovery. After running for a period of time, the supernatant after the reaction in the wastewater neutralization tank 8 is filtered by the filter membrane 10 through the water pump III 14 and transported to the brine tank 7, so that the treated wastewater can be recycled.

[0035] Example 2

[0036] The electrochemical membrane reactor described in Example 1 was used, with a plate-type porous graphite membrane (20 cm long, 0.4 cm thick, 6 cm wide, and 40% porosity) with an average pore size of 0.5 μm as the cathode 1, and a plate-type porous titanium membrane (20 cm long, 0.4 cm thick, 6 cm wide, and 35% porosity) with an average pore size of 2.5 μm as the anode 2. The electrolyte in the brine tank 7 was 5M potassium sulfate, the initial electrolyte in the cathode reaction tank 5 was 0.01 mM potassium hydroxide solution, the initial electrolyte in the anode reaction tank 6 was 0.01 mM sulfuric acid solution, and the wastewater neutralization tank 8 contained acidic ore washing wastewater to be treated (hydrogen ion concentration of 0.01 M and heavy metal (including copper, arsenic, aluminum, zinc, etc.) ion content of 15 ppm). The operating voltage was 5V. After running for 4 hours, the supernatant after the reaction in the wastewater neutralization tank 8 is filtered through the filter membrane 10 by the water pump III 14 and then pumped out and transported to the brine tank 7, so as to realize the recycling of the treated wastewater.

[0037] Experimental results: After 10 hours of treatment, the pH value of the treated acidic mineral washing wastewater sample in the wastewater neutralization tank 8 reached about 7, and heavy metal ions formed obvious precipitation; the porous membrane anode 2 extracted a high-concentration mixed acid solution with a pH of about 2, and the porous membrane cathode 1 and the porous membrane anode 2 reacted to precipitate a certain amount of H2 and O2, which were collected by the corresponding gas collection port to realize resource recycling.

[0038] Example 3

[0039] The electrochemical membrane reactor described in Example 1 was used, with a tubular porous coke membrane (15 cm long, 1 cm outer diameter, 0.6 cm inner diameter, 50% porosity) having an average pore size of 1.0 μm as the cathode 1, and a tubular porous zinc membrane (15 cm long, 1 cm outer diameter, 0.6 cm inner diameter, 37% porosity) having an average pore size of 1.0 μm as the anode 2. The electrolyte in the brine tank 7 was 5 M potassium chloride, the initial electrolyte in the cathode reaction tank 5 was 0.05 mM potassium hydroxide solution, the initial electrolyte in the anode reaction tank 6 was 0.05 mM hydrochloric acid solution, and the wastewater neutralization tank 8 contained acidic electroplating wastewater to be treated (with a hydrogen ion concentration of 0.05 M and a heavy metal ion content (including chromium, copper, arsenic, nickel, zinc, etc.) of 50 ppm). The operating voltage was 10 V. After running for 5 hours, the supernatant after the reaction in the wastewater neutralization tank 8 is filtered through the filter membrane 10 by the water pump III 14 and then pumped out and transported to the brine tank 7, so as to realize the recycling of the treated wastewater.

[0040] Experimental results: After 12 hours of treatment, the pH value of the treated acidic mineral washing wastewater sample in the wastewater neutralization tank reached about 7, and heavy metal ions formed obvious precipitation; the porous membrane anode 2 extracted a high-concentration mixed acid solution with a pH of about 1.9, and the porous membrane cathode 1 and the porous membrane anode 2 reacted to precipitate a certain amount of H2 and O2 (Cl2), which were collected by the corresponding gas collection port to achieve resource recycling.

[0041] Example 4

[0042] The electrochemical membrane reactor described in Example 1 was used, with a hollow plate-type porous platinum membrane (20 cm long, 5 cm wide, 1 cm thick, 3 pore channels, 0.2 cm thickness, and 40% porosity) having an average pore size of 2.5 μm as the cathode 1, and a hollow plate-type porous graphite membrane (20 cm long, 5 cm wide, 1 cm thick, 3 pore channels, 0.2 cm thickness, and 45% porosity) having an average pore size of 3.0 μm as the anode 2. The electrolyte in the brine tank 7 was saturated sodium nitrate, the initial electrolyte in the cathode reaction tank 5 was a 0.25 mM sodium hydroxide solution, the initial electrolyte in the anode reaction tank 6 was a 0.25 mM nitric acid solution, and the wastewater neutralization tank 8 contained the acidic metallurgical wastewater to be treated (with a hydrogen ion concentration of 0.25 M and a heavy metal ion content (including chromium, copper, arsenic, nickel, zinc, etc.) of 150 ppm). The operating voltage was 12 V. After running for 4 hours, the supernatant after the reaction in the wastewater neutralization tank 8 is filtered through the filter membrane 10 by the water pump III 14 and then pumped out and transported to the brine tank 7, so as to realize the recycling of the treated wastewater.

[0043] Experimental results: After 15 hours of treatment, the pH value of the treated acidic mineral washing wastewater sample in the wastewater neutralization tank 8 reached about 7.2, and heavy metal ions formed obvious precipitation; the porous membrane anode 2 extracted a high-concentration mixed acid solution with a pH of about 1.7, and the porous membrane cathode 1 and the porous membrane anode 2 reacted to precipitate a certain amount of H2 and O2, which were collected by the corresponding gas collection port to realize resource recycling.

[0044] Example 5

[0045] The electrochemical membrane reactor described in Example 1 was used, with a tubular porous silver membrane (20 cm long, 1.5 cm outer diameter, 0.9 cm inner diameter, 33% porosity) with an average pore size of 3.5 μm as the cathode, and a tubular porous coke membrane (20 cm long, 1.5 cm outer diameter, 0.9 cm inner diameter, 55% porosity) with an average pore size of 1.5 μm as the anode 2. The electrolyte in the brine tank consisted of 5 M sodium chloride and 5 M sodium sulfate. The initial electrolyte in the cathode reaction tank 5 was a 0.5 mM sodium hydroxide solution. The initial electrolyte in the anode reaction tank 6 was a mixed solution of 0.5 mM hydrochloric acid and 0.5 mM sulfuric acid. The wastewater neutralization tank 8 contained mixed acidic wastewater from ore washing, electroplating, and metallurgy to be treated (with a hydrogen ion concentration of 0.5 M and a heavy metal ion content of 200 ppm (including chromium, copper, arsenic, nickel, zinc, etc.). The operating voltage was 10 V. After running for 6 hours, the supernatant after the reaction in the wastewater neutralization tank 8 is filtered through the filter membrane 10 by the water pump III 14 and then pumped out and transported to the brine tank 7, so as to realize the recycling of the treated wastewater.

[0046] Experimental results: After 24 hours of treatment, the pH value of the treated acidic mineral washing wastewater sample in the wastewater neutralization tank 8 reached about 7.5, and the porous heavy metal ions formed obvious precipitation; the porous membrane anode 2 extracted a high-concentration mixed acid solution with a pH of about 1.3, and the porous membrane cathode 1 and the porous membrane anode 2 reacted to precipitate a certain amount of H2 and O2, which were collected by the corresponding gas collection port to realize resource recycling.

Claims

1. An electrochemical membrane reaction device for treating acidic wastewater, characterized in that: The electrochemical membrane reaction device comprises: a cathode reaction tank (5), an anode reaction tank (6), a brine tank (7), a wastewater neutralization tank (8), an acid recovery tank (9) and a power supply (11); the brine tank (7) is located between the cathode reaction tank (5) and the anode reaction tank (6), the brine tank (7) and the cathode reaction tank (5) are connected via a cation exchange membrane (3), and the brine tank (7) and the anode reaction tank (6) are connected via an anion exchange membrane (4); a porous membrane cathode (1) is provided in the cathode reaction tank (5), and the porous membrane cathode (1) is connected to the wastewater neutralization tank (8); a porous membrane anode (2) is provided in the anode reaction tank (6), and the porous membrane anode (2) is connected to the acid recovery tank (9); the porous membrane cathode (1) and the porous membrane anode (2) are connected via a power supply (11); The cathode reaction tank (5) is provided with an H2 collection port (15), and the anode reaction tank (6) is provided with an O2 collection port (16); A filter membrane (10) is provided in the wastewater neutralization tank (8), and the filter membrane (10) is connected to the brine tank (7).

2. The electrochemical membrane reaction device according to claim 1, characterized in that: The porous film cathode (1) and the porous film anode (2) are homogeneous films or composite films; The material of the porous membrane cathode (1) is graphite, coke, metal platinum or metal silver, and the material of the porous membrane anode (2) is carbon-based material or metal or metal oxide; The pore size of the porous membrane cathode (1) and the porous membrane anode (2) is between 0.05 and 10 μm, and the porosity is between 20% and 70%; The configurations of the porous membrane cathode (1) and the porous membrane anode (2) include plate type and tube type.

3. The electrochemical membrane reaction device according to claim 1, characterized in that: The porous film anode (2) is made of graphite, coke, metallic titanium, metallic zinc or metallic lead; The configurations of the porous membrane cathode (1) and the porous membrane anode (2) include hollow plate types.

4. The electrochemical membrane reaction device according to claim 1, characterized in that: A water pump I (12) is provided between the porous membrane cathode (1) and the wastewater neutralization tank (8), a water pump II (13) is provided between the porous membrane anode (2) and the acid recovery tank (9), and a water pump III (14) is provided between the filter membrane (10) and the brine tank (7); The power supply (11) is a direct current power supply (11).

5. The electrochemical membrane reaction device according to claim 1, wherein: The electrolyte in the brine tank (7) is a mixture of one or more of alkali metal chlorides, nitrates and sulfates, and its concentration is 0.01 M to saturation concentration.

6. The electrochemical membrane reaction device according to claim 1, wherein: The initial electrolyte in the anode reaction tank (6) is a dilute acid solution with a concentration of 0.01 mM to 5 M.

7. The electrochemical membrane reaction device according to claim 6, characterized in that: The acid solution is a mixture of one or more of hydrochloric acid, nitric acid and sulfuric acid.

8. The electrochemical membrane reaction device according to claim 1, wherein: The initial electrolyte in the cathode reaction tank (5) is a dilute alkaline solution with a concentration of 0.01 mM to 5 M.

9. The electrochemical membrane reaction device according to claim 8, characterized in that: The alkali in the alkaline solution is a mixture of one or more of sodium hydroxide and potassium hydroxide.

10. The method for treating acidic wastewater using an electrochemical membrane reaction device according to any one of claims 1 to 9, characterized in that: The steps include: A voltage is applied to the porous membrane cathode (1) and the porous membrane anode (2) through a power supply (11) to form an electric field and cause an electrochemical reaction; wherein, hydroxide and hydrogen are generated on the porous membrane cathode (1), the hydrogen is collected through the H2 collecting port (15), and the hydroxide solution is transported to the wastewater neutralization tank (8) through the water pump I (12), and reacts with the acidic wastewater to form a heavy metal hydroxide precipitate; water is electrolyzed on the porous membrane anode (2) to generate acid and oxygen, the oxygen is collected through the O2 collecting port (16), and the acid solution is extracted by the water pump II (13) and transported to the acid recovery tank (9) to achieve acid recovery; after running for a period of time, the supernatant after the reaction in the wastewater neutralization tank (8) is filtered by the water pump III (14) through the filter membrane (10) and then transported to the brine tank (7), so that the treated wastewater can be recycled.

11. The method according to claim 10, wherein: The voltage applied during the operation is 1-50 V.

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