A method for deep treatment of wastewater based on adsorbent

Abstract

The present invention relates to the technical field of water pollution control and treatment, and specifically discloses a method for deep treatment of wastewater based on an adsorbent. First, a mixture of carbon dioxide and air is introduced into a fly ash water washing liquid. During the continuous ventilation process, calcium ions in the water washing liquid are removed in the form of calcium carbonate precipitation, thereby avoiding interference of calcium ions with adsorption and electrodialysis processes in subsequent treatment processes. Iron-sulfur loaded magnetic mesoporous biochar is used to activate efficient oxidation of persulfate while accurately adsorbing and removing heavy metals in the water washing liquid. Finally, a self-made bipolar membrane is used to perform electrodialysis treatment on the water washing liquid to remove chlorine in the water, so that the water washing liquid meets the requirements for wastewater discharge.

Description

Technical Field

[0001] The present invention relates to the technical field of water pollution control and treatment, and in particular to a method for deep treatment of wastewater based on an adsorbent. Background Art

[0002] Waste incineration fly ash is a by-product of the waste incineration process. In addition to 20%-30% soluble chloride salts, waste incineration fly ash also contains harmful substances such as heavy metal-based dioxins. Therefore, waste incineration fly ash is identified as hazardous waste. At present, the treatment methods for waste incineration fly ash include solidification landfill, cement kiln co-processing, low-temperature pyrolysis and high-temperature sintering. However, these methods require pretreatment of the waste incineration fly ash to remove chlorine and heavy metals. Common pretreatment methods include acid washing, alkaline washing and water washing. Acid washing can easily dissolve about 90% of the substances in the fly ash, and alkaline washing can solidify the heavy metals in the fly ash and retain almost 100% of the calcium in the fly ash. However, acid washing and alkaline washing treatment methods require the consumption of large amounts of acid and alkaline chemical reagents, while increasing the cost of acid and alkaline waste liquid treatment. In addition, the economic value of waste incineration fly ash is relatively low. Therefore, due to cost considerations, the most commonly used fly ash pretreatment method in the industry is still water washing.

[0003] The washing liquid obtained from the water washing treatment of fly ash from garbage combustion contains a large amount of soluble chloride salts and trace amounts of heavy metals and other harmful components. If discharged directly, the chloride salts in the washing liquid will cause soil alkalinization and lead to the death of farmland plants. The heavy metals in the washing liquid will be enriched in animals and plants, endangering the health of residents. Therefore, the fly ash washing liquid must be treated to remove the chlorine and heavy metals in the washing liquid so that it meets the sewage discharge standards, thereby saving water resources and achieving the harmless treatment needs of the washing liquid. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for deep treatment of wastewater based on adsorbents, which removes heavy metals by adsorbents and separates chlorine in the washing liquid by electrodialysis, thereby solving the problem of high chlorine and heavy metal content in the washing liquid, making the washing liquid meet the standards for sewage discharge, and realizing the needs of saving water resources and harmless treatment of the washing liquid.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for deep treatment of wastewater based on adsorbent, specifically:

[0007] Step 1: introducing a mixture of carbon dioxide and air into the fly ash water washing liquid to perform a decalcification pretreatment on the fly ash water washing liquid to obtain a decalcified water washing liquid;

[0008] Step 2: Add the loaded iron-sulfur magnetic mesoporous biochar and persulfate to the decalcified water wash solution, stir at 150-200 rpm for 90-120 minutes at room temperature, and after the reaction is completed, separate the loaded iron-sulfur magnetic mesoporous biochar by applying an external magnetic field, filter, and obtain a secondary treatment solution;

[0009] Step 3: Use a bipolar membrane to electrodialyze the secondary treatment liquid to obtain deeply treated wastewater.

[0010] As a limitation of the present invention, in step 1, the volume ratio of carbon dioxide to air is 1:(5-10), and the flow rate of the mixed gas is (1-5) mL / min; during the ventilation process, pay attention to the pH of the water washing solution at all times, and stop ventilation when the pH of the water washing solution is neutral.

[0011] As a limitation of the present invention, the preparation method of the loaded iron-sulfur magnetic mesoporous biochar is:

[0012] The straw is dried at 80-90°C, crushed to remove impurities, and ground to obtain straw powder with a particle size of 100-150 μm. The straw powder, potassium bicarbonate, and potassium chloride are mixed and ball-milled for 15-20 minutes to mix them evenly. Under nitrogen as a protective gas, the temperature is increased to 850-900°C at a heating rate of 5°C / min and kept warm for 2-3 hours. After the insulation is completed, the mixture is sealed and cooled to room temperature. The obtained solid is crushed, washed with deionized water, and dried at 80-90°C to obtain mesoporous biochar;

[0013] The mesoporous biochar was added to deionized water and ultrasonically dispersed for 15-20 minutes. Ferric chloride and ferrous sulfate were then added and stirred evenly to fully dissolve. The pH was adjusted to 9-10 with sodium hydroxide to obtain a biochar suspension. The biochar suspension was then heated in a water bath at 80-90°C for 0.5-1h. Nitrogen was continuously introduced into the suspension during the reaction. After the reaction was completed, an external magnetic field was applied to separate the product. The separated product was washed with anhydrous ethanol and deionized water and dried at 80-90°C to obtain magnetic mesoporous biochar.

[0014] Add ferric nitrate to deionized water, stir evenly, slowly add thiourea after fully dissolved, ultrasonically disperse for 10-15 minutes to form a dispersion, then evaporate the dispersion at 80-90°C, mix the solid obtained after evaporation with magnetic mesoporous biochar, and heat it to 850-900°C at a heating rate of 5°C / min under closed conditions and keep it warm for 2-3 hours. After the insulation is completed, cool it to room temperature in a closed manner. After the product is crushed, wash it with 0.1 mol / L hydrochloric acid and deionized water, and dry it at 80-90°C to obtain iron-sulfur loaded magnetic mesoporous biochar.

[0015] As a limitation of the present invention, the mass ratio of straw powder, potassium bicarbonate and potassium chloride is (2-4):(2-4):(8-12); the mass ratio of mesoporous biochar, ferric chloride and ferrous sulfate is (1-3):(1-3):(0.5-1.5); the mass ratio of ferric nitrate, thiourea and magnetic mesoporous biochar is (0.1-0.3):(0.35-0.45):(8-12).

[0016] As a limitation of the present invention, in step 2, the amount of loaded iron-sulfur magnetic mesoporous biochar is 1-2% of the mass fraction of the decalcified water wash; the persulfate is a mixture of one or more of ammonium persulfate, potassium persulfate, and sodium persulfate, and the amount is 0.5-1% of the mass fraction of the decalcified water wash.

[0017] As defined in the present invention, the bipolar membrane comprises a sulfonic acid-zirconium phosphate hybrid cation exchange membrane with a thickness of 0.08-0.12 mm, a quaternized nanocellulose hybrid anion exchange membrane with a thickness of 0.08-0.12 mm, and an iron-loaded catalytic intermediate layer with a thickness of 30-50 nm between the two.

[0018] As a limitation of the present invention, the preparation method of the zirconium phosphate hybrid cation exchange membrane is:

[0019] Zirconium oxychloride and polyvinylidene fluoride are added to a mixed solution of N,N-dimethylacetamide and methanol, and ultrasonically dispersed for 20-30 minutes, followed by standing for degassing for 1-2 hours to obtain a cation exchange membrane casting solution, which is then spin-coated into a film by spin coating, and then heated and cured at 60-70°C for 2-3 hours. After curing, the mixture is cooled to room temperature to obtain a zirconium oxychloride hybrid cation exchange membrane;

[0020] The zirconium oxychloride hybrid cation exchange membrane is immersed in a phosphoric acid solution, heated at 110-120° C. for 1-2 hours, cooled to room temperature after the reaction is completed, washed with hydrochloric acid and deionized water, and dried to obtain a zirconium phosphate hybrid cation exchange membrane;

[0021] The pH of the Tris buffer is adjusted to 7-8 with hydrochloric acid, and sodium polystyrene sulfonate is added and stirred evenly to fully dissolve to obtain a sodium polystyrene sulfonate solution. The zirconium phosphate hybrid exchange membrane is treated with plasma under an argon atmosphere, and the plasma discharge current is controlled to be 4.0-5.0A, and the treatment time is 5-10 minutes. After the treatment, the membrane is quickly immersed in the sodium polystyrene sulfonate solution and immersed for 1.5-2 hours. After the immersion is completed, the membrane is taken out, washed with deionized water, and dried to obtain a sulfonic acid-zirconium phosphate hybrid cation exchange membrane.

[0022] In the cation exchange membrane casting solution, the mass ratio of zirconium oxychloride to polyvinylidene fluoride is (1-3):(8-10); the concentration of polyvinylidene fluoride is (1-2) g / L; the concentration of sodium polystyrene sulfonate solution is (1-2) g / L.

[0023] As a limitation of the present invention, the preparation method of the supported iron catalytic intermediate layer is:

[0024] Ferrous sulfate is added to deionized water and stirred evenly to obtain a ferrous sulfate solution. Tetrabutyl titanate is added to the ferrous sulfate solution, stirred evenly, and ultrasonically dispersed to obtain a tetrabutyl titanate dispersion. Dopamine hydrochloride is added to a Tris buffer solution and stirred evenly to obtain a dopamine hydrochloride solution. The dopamine hydrochloride solution and the tetrabutyl titanate dispersion are sprayed into films at a spraying rate of 400-500 μL / min. After spraying, the films are cured at 40-50°C for 20-30 minutes to obtain a loaded iron catalytic intermediate layer.

[0025] The concentration of the ferrous sulfate solution is (4-6) g / L, the mass fraction of tetrabutyl titanate in the dispersion is 13%-17%, and the concentration of the dopamine hydrochloride solution is (0.8-1.2) g / L.

[0026] As a limitation of the present invention, the preparation method of the quaternized nanocellulose hybrid anion exchange membrane is:

[0027] Add nanocellulose and deionized water to methanol, ultrasonically disperse for 15-20 minutes to obtain a nanocellulose dispersion, add silane coupling agent KH-550 and deionized water to ethanol, stir evenly, adjust the pH to 4-5 with hydrochloric acid, and then stir at room temperature for 2-4 hours. After stirring, add the nanocellulose dispersion, react at 50-70°C for 2-4 hours, cool after the reaction, filter, wash with anhydrous ethanol and deionized water, and dry at 100-110°C. Add the dried product and methyl iodide to N-methylpyrrolidone, react at room temperature for 18-24 hours, centrifuge after the reaction is completed, wash the centrifuged product with ethanol, and freeze-dry to obtain quaternized nanocellulose;

[0028] The method comprises the following steps: adding polyethyleneimine to dimethyl sulfoxide, stirring evenly, adding bromoethane, and fully reacting at 50-70°C for 2-4 hours. After the reaction is completed, cooling is performed to obtain quaternized polyethyleneimine; adding polyvinyl alcohol to dimethyl sulfoxide, stirring evenly, then adding quaternized polyethyleneimine, KH-560 silane coupling agent and quaternized nanocellulose, ultrasonically dispersing for 15-30 minutes, heating at 80-90°C for 2-4 hours, cooling after the reaction is completed to obtain a quaternary ammonium hybrid anion exchange membrane casting solution; spin-coating the quaternary ammonium hybrid anion exchange membrane casting solution into a membrane by spin coating, then heating and curing at 60-70°C for 2-3 hours, and cooling to room temperature after the curing is completed to obtain a quaternary nanocellulose hybrid anion exchange membrane.

[0029] The dosage ratio of nanocellulose to methyl iodide is (3-5) g: (20-30) mL, and the mass ratio of polyvinyl alcohol, quaternized polyimide, and quaternized nanocellulose is (20-30): (10-12): (0.2-0.8).

[0030] As a limitation of the present invention, in step 3, during electrodialysis, the dialysis voltage is 10-12 V, the dialysis electrode liquid is a 0.1-0.15 mol / L sodium sulfate solution, the membrane surface flow rate is 10-12 cm / s, the temperature of the secondary treatment liquid is 25-30°C, and the feed flow rate is 4-6 L / h.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention first performs decalcification pretreatment on the fly ash washing liquid by mixing carbon dioxide with air and passing the mixed gas into the washing liquid, thereby removing calcium ions in the fly ash washing liquid and forming calcium carbonate precipitation from the calcium ions in the washing liquid. This reduces the alkalinity of the washing liquid and can also adsorb some heavy metals in the washing liquid, thereby preventing the calcium ions from affecting the subsequent adsorption and electrodialysis processes.

[0033] The present invention prepares iron-sulfur loaded magnetic mesoporous biochar. During the straw pyrolysis process, pore-forming agents potassium bicarbonate and potassium chloride are added to obtain mesoporous biochar with suitable pore size, uniform pore distribution and good specific surface area. Then, magnetic ferrite-ferroferric oxide is loaded on the surface and in the pores of the mesoporous biochar through in-situ synthesis, so that the mesoporous biochar can not only selectively adsorb heavy metals in the water washing liquid, but also has good magnetism, which facilitates the separation of the biochar after adsorption. Finally, an iron-sulfur catalyst is loaded on the surface of the magnetic biochar, thereby activating persulfate to enable it to have the ability to efficiently oxidize and degrade heavy metal-organic complexes, so that the complexed heavy metals formed in the fly ash water washing process are released, thereby enhancing the removal of heavy metals in the water washing liquid and reducing the residual heavy metals in the water washing liquid.

[0034] The present invention prepares a sulfonic acid-zirconium phosphate hybrid cation exchange membrane with good chlorine resistance and a quaternized nanocellulose hybrid anion exchange membrane, and combines the two ion exchange membranes with a loaded iron catalytic intermediate layer. Zirconium phosphate with good acid and oxidation resistance is introduced into the polyvinylidene fluoride membrane structure by in-situ synthesis, thereby increasing the ion exchange capacity of the membrane and forming a higher membrane potential. At the same time, the reverse migration performance of the membrane is enhanced to prevent the leakage of chloride ions. Stable and negatively charged sulfonate groups are introduced into the surface of the polyvinylidene fluoride membrane by low-temperature plasma modification, thereby enhancing the attraction of the polyvinylidene fluoride membrane to cations. An iron-based catalyst is fixed in the dopamine intermediate layer by an in-situ growth method. The introduction of the iron-based catalyst provides more active sites for water dissociation, reduces the water reaction dissociation resistance of the bipolar membrane, reduces the bipolar membrane transmembrane voltage, and promotes the progress of electrodialysis. Quaternized polyimide and quaternized cellulose are added to polyvinyl alcohol and cross-linked and modified using a silane coupling agent. The surface of the formed anion exchange membrane contains a large number of hydroxyl groups, which can accelerate the transfer of hydroxide ions and has good alkali stability and thermal stability. The bipolar membrane is formed and applied in the electrodialysis process. An external power supply is used to promote the directional movement of chlorine in the washing liquid, which is concentrated through the ion exchange membrane, thereby achieving the purpose of removing chlorine from the washing liquid, so that the washing liquid meets the sewage discharge standards and can be directly discharged or re-entered into the production cycle as treated water. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] Fly ash washing liquid (liquid-to-solid ratio during washing is 5 mL / g), straw purchased from the market, Tris buffer (1 mol / L, pH=8.5), polyvinylidene fluoride (Mw=400000), polyvinyl alcohol (degree of polymerization: 1700, degree of alcoholysis: 99%), polyethyleneimine (Mw=27000), nanocellulose (diameter: 15-25 nm, length: 200-300 nm).

[0037] Content of each element in fly ash washing liquid (mg / L)

[0038]

[0039] Example 1: A method for deep treatment of wastewater based on adsorbent, specifically:

[0040] Step 1: Mix carbon dioxide and air in a volume ratio of 1:9 to form a mixed gas, then pass the mixed gas into the fly ash water washing liquid and stir continuously, control the flow rate of the mixed gas to 1 mL / min, and monitor the pH of the water washing liquid at all times. When the pH of the water washing liquid drops to neutral, stop ventilation, let it stand for aging, and filter to obtain the decalcified water washing liquid.

[0041] Step 2: Add the iron-sulfur-loaded magnetic mesoporous biochar and sodium persulfate to the decalcified water wash solution. The amount of iron-sulfur-loaded magnetic mesoporous biochar is 2% of the mass fraction of the decalcified water wash solution, and the amount of sodium persulfate is 1% of the mass fraction of the decalcified water wash solution. Stir at 200 rpm at room temperature for 120 minutes. After the reaction is complete, separate the iron-sulfur-loaded magnetic mesoporous biochar using an external magnetic field and filter to obtain a secondary treated solution.

[0042] Step 3: Use a bipolar membrane to perform electrodialysis on the secondary treatment liquid, set the dialysis voltage to 12 V, the dialysis electrode liquid to 0.1 mol / L sodium sulfate solution, the membrane surface flow rate to 10 cm / s, the temperature of the secondary treatment liquid to 25°C, and the feed flow rate to 5 L / h to obtain deeply treated wastewater.

[0043] The preparation method of the loaded iron-sulfur magnetic mesoporous biochar used in step 2 is:

[0044] The straw was dried at 80°C, crushed to remove impurities, and ground to obtain straw powder with a particle size of 100 μm. 3 g of straw powder, 3 g of potassium bicarbonate, and 10 g of potassium chloride were mixed and ball-milled for 15 minutes to mix them evenly. The mixture was then transferred to a tube furnace and heated to 900°C at a heating rate of 5°C / min under nitrogen as a protective gas and kept warm for 2 hours. After the insulation was completed, the mixture was cooled to room temperature in a sealed furnace. The obtained solid was crushed, washed with deionized water, and dried at 80°C to obtain mesoporous biochar.

[0045] 20 g of mesoporous biochar was added to 800 mL of deionized water, and after ultrasonic dispersion for 15 min, 20 g of ferric chloride and 11.1 g of ferrous sulfate were added, stirred evenly, and sodium hydroxide was added to adjust the pH to 10 after sufficient dissolution to obtain a biochar suspension. The biochar suspension was then heated in an 80°C water bath for 1 h. Nitrogen was continuously introduced into the suspension during the reaction. After the reaction was completed, it was separated using an external magnetic field. The separated product was washed with anhydrous ethanol and deionized water, and dried at 80°C to obtain magnetic mesoporous biochar.

[0046] 0.2 g of ferric nitrate was added to 20 mL of deionized water, stirred evenly and fully dissolved to obtain a ferric nitrate solution. Subsequently, 0.38 g of thiourea was slowly added to the ferric nitrate solution, stirred evenly, and ultrasonically dispersed for 10 minutes to form a dispersion. The dispersion was then evaporated to dryness at 80°C. The solid obtained after evaporation was mixed with 10 g of magnetic mesoporous biochar, and then transferred together to a tubular furnace. Under closed conditions, the temperature was increased to 900°C at a heating rate of 5°C / min and kept warm for 2 hours. After the insulation was completed, the mixture was cooled to room temperature in a sealed furnace. The product was crushed and washed with 0.1 mol / L hydrochloric acid and deionized water, and dried at 80°C to obtain iron-sulfur loaded magnetic mesoporous biochar.

[0047] The preparation method of the bipolar membrane used in step 3 is:

[0048] 2 g of zirconium oxychloride and 9 g of polyvinylidene fluoride were added to a mixture of 54 mL of N,N-dimethylacetamide and 2 mL of methanol, and ultrasonically dispersed for 30 min, followed by standing for degassing for 2 h to obtain an exchange membrane casting solution. The exchange membrane casting solution was spin-coated on a metal plate using a coating machine, heated and cured at 60°C for 3 h, and then cooled to room temperature to obtain a zirconium oxychloride hybrid cation exchange membrane.

[0049] The zirconium oxychloride hybrid cation exchange membrane was immersed in a 10% by mass phosphoric acid solution, heated at 110°C for 2 hours, cooled to room temperature after the reaction was completed, washed with hydrochloric acid and deionized water, and dried to obtain a zirconium phosphate hybrid cation exchange membrane;

[0050] The pH of the Tris buffer was adjusted to 8 with hydrochloric acid, and sodium polystyrene sulfonate was added, stirred evenly, and fully dissolved to obtain a 1.5 g / L sodium polystyrene sulfonate solution. Under an argon atmosphere, the zirconium phosphate hybrid exchange membrane was placed in a plasma treatment instrument for plasma treatment, the discharge current was controlled to be 4.0 A, and the treatment time was 10 min. After the treatment was completed, it was quickly immersed in the sodium polystyrene sulfonate solution and soaked for 2 h. After the soaking was completed, it was taken out, washed with deionized water, and dried to obtain a sulfonic acid-zirconium phosphate hybrid cation exchange membrane with a thickness of 0.1 mm;

[0051] Ferrous sulfate was added to deionized water and stirred evenly to obtain a ferrous sulfate solution with a concentration of 5 g / L. Tetrabutyl titanate was added to the ferrous sulfate solution, stirred evenly, and ultrasonically dispersed to obtain a dispersion with a mass fraction of tetrabutyl titanate of 15%. Dopamine hydrochloride was added to Tris buffer and stirred evenly to obtain a dopamine hydrochloride solution with a concentration of 1 g / L. An ultrasonic sprayer was used to spray the dopamine hydrochloride solution on the surface of the sulfonic acid-zirconium phosphate hybrid cation exchange membrane, followed by the tetrabutyl titanate dispersion. The volume area ratio of the dopamine solution to the sulfonic acid-zirconium phosphate hybrid cation exchange membrane was 40 μL / cm 2The volume area ratio of tetrabutyl titanate dispersion to sulfonic acid-zirconium phosphate hybrid cation exchange membrane is 60 μL / cm 2 The spraying rate was 400 μL / min, the membrane surface temperature was 40°C, and after the spraying was completed, the membrane was cured at 40°C for 20 minutes to form a 50 nm thick iron-loaded catalytic intermediate layer on the surface of the sulfonic acid-zirconium phosphate hybrid cation exchange membrane.

[0052] 4 g of nanocellulose and 50 mL of deionized water were added to 200 mL of methanol and ultrasonically dispersed for 15 minutes to obtain a nanocellulose dispersion. 6 g of silane coupling agent KH-550 and 30 mL of deionized water were added to 570 mL of ethanol and stirred evenly. After stirring evenly, the pH was adjusted to 4 with hydrochloric acid, and then stirred at room temperature for 2 hours. After stirring, the nanocellulose dispersion was added and reacted at 70°C for 2 hours. After the reaction was completed, the mixture was cooled, filtered, washed with anhydrous ethanol and deionized water, and dried at 110°C. The dried product and 24 mL of iodomethane were added to 50 mL of N-methylpyrrolidone and reacted at room temperature for 24 hours. After the reaction was completed, the mixture was centrifuged, and the centrifuged product was washed with ethanol and freeze-dried to obtain quaternized nanocellulose.

[0053] 10 g of polyethyleneimine was added to 40 g of dimethyl sulfoxide, stirred evenly, and then 3.2 mL of ethyl bromide was added. The mixture was fully reacted at 60 ° C for 2 h. After the reaction was completed, it was cooled to obtain quaternized polyethyleneimine. 25 g of polyvinyl alcohol was added to 100 g of dimethyl sulfoxide and stirred evenly. Subsequently, 11 g of quaternized polyethyleneimine, 0.5 g of KH-560 silane coupling agent and 0.5 g of quaternized nanocellulose were added. After ultrasonic dispersion for 15 min, the mixture was heated at 90 ° C for 4 h. After the reaction was completed, it was cooled to obtain a quaternary ammonium hybrid anion exchange membrane casting solution. The exchange membrane casting solution was spin-coated on the loaded iron catalytic intermediate layer using a coating machine, heated and cured at 60 ° C for 3 h, and then cooled to room temperature to obtain a bipolar membrane (thickness: 0.1 mm + 50 nm + 0.1 mm).

[0054] Example 2: A method for deep treatment of wastewater based on adsorbent, specifically:

[0055] Step 1: Mix carbon dioxide and air in a volume ratio of 1:9 to form a mixed gas, then pass the mixed gas into the fly ash water washing liquid and stir continuously, control the flow rate of the mixed gas to 1 mL / min, and monitor the pH of the water washing liquid at all times. When the pH of the water washing liquid drops to neutral, stop ventilation, let it stand for aging, and filter to obtain the decalcified water washing liquid.

[0056] Step 2: Add the iron-sulfur-loaded magnetic mesoporous biochar and sodium persulfate to the decalcified water wash solution. The iron-sulfur-loaded magnetic mesoporous biochar is added in an amount of 1% by weight of the decalcified water wash solution, and the sodium persulfate is added in an amount of 1% by weight of the decalcified water wash solution. Stir at 200 rpm for 120 minutes at room temperature. After the reaction is complete, separate the iron-sulfur-loaded magnetic mesoporous biochar using an external magnetic field and filter to obtain a secondary treated solution.

[0057] Step 3: Use a bipolar membrane to perform electrodialysis on the secondary treatment liquid, set the dialysis voltage to 11 V, the dialysis electrode liquid to 0.1 mol / L sodium sulfate solution, the membrane surface flow rate to 11 cm / s, the temperature of the secondary treatment liquid to 25°C, and the feed flow rate to 5 L / h to obtain deeply treated wastewater.

[0058] The preparation method of the loaded iron-sulfur magnetic mesoporous biochar used in step 2 is the same as the preparation method in Example 1.

[0059] The preparation method of the bipolar membrane used in step 3 is the same as that in Example 1.

[0060] Example 3: A method for deep treatment of wastewater based on adsorbent, specifically:

[0061] Step 1: Mix carbon dioxide and air in a volume ratio of 1:9 to form a mixed gas, then pass the mixed gas into the fly ash water washing liquid and stir continuously, control the flow rate of the mixed gas to 1 mL / min, and monitor the pH of the water washing liquid at all times. When the pH of the water washing liquid drops to neutral, stop ventilation, let it stand for aging, and filter to obtain the decalcified water washing liquid.

[0062] Step 2: Add the iron-sulfur-loaded magnetic mesoporous biochar and sodium persulfate to the decalcified water wash. The amount of iron-sulfur-loaded magnetic mesoporous biochar is 2% of the mass fraction of the decalcified water wash, and the amount of sodium persulfate is 0.5% of the mass fraction of the decalcified water wash. Stir at 200 rpm at room temperature for 120 minutes. After the reaction is complete, separate the iron-sulfur-loaded magnetic mesoporous biochar using an external magnetic field and filter to obtain a secondary treated solution.

[0063] Step 3: Use a bipolar membrane to perform electrodialysis on the secondary treatment liquid, set the dialysis voltage to 10 V, the dialysis electrode liquid to 0.1 mol / L sodium sulfate solution, the membrane surface flow rate to 12 cm / s, the temperature of the secondary treatment liquid to 25°C, and the feed flow rate to 5 L / h to obtain deeply treated wastewater.

[0064] The preparation method of the loaded iron-sulfur magnetic mesoporous biochar used in step 2 is the same as the preparation method in Example 1.

[0065] The preparation method of the bipolar membrane used in step 3 is the same as that in Example 1.

[0066] Based on Example 1, control experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0067] Comparative Example 1: This comparative example relates to a method for deep treatment of wastewater based on an adsorbent. The difference from Example 1 is that in step 2, magnetic mesoporous biochar is used to adsorb heavy metals, specifically:

[0068] Step 1: Mix carbon dioxide and air in a volume ratio of 1:9 to form a mixed gas, then pass the mixed gas into the fly ash water washing liquid and stir continuously, control the flow rate of the mixed gas to 1 mL / min, and monitor the pH of the water washing liquid at all times. When the pH of the water washing liquid drops to neutral, stop ventilation, let it stand for aging, and filter to obtain the decalcified water washing liquid.

[0069] Step 2: Add magnetic mesoporous biochar and sodium persulfate to the decalcified water wash. The amount of iron-sulfur-loaded magnetic mesoporous biochar is 2% of the mass fraction of the decalcified water wash, and the amount of sodium persulfate is 1% of the mass fraction of the decalcified water wash. Stir at 200 rpm at room temperature for 120 minutes. After the reaction is complete, separate the iron-sulfur-loaded magnetic mesoporous biochar using an external magnetic field and filter to obtain a secondary treated solution.

[0070] Step 3: Use a bipolar membrane to perform electrodialysis on the secondary treatment liquid, set the dialysis voltage to 12 V, the dialysis electrode liquid to 0.1 mol / L sodium sulfate solution, the membrane surface flow rate to 10 cm / s, the temperature of the secondary treatment liquid to 25°C, and the feed flow rate to 5 L / h to obtain deeply treated wastewater.

[0071] The preparation method of the magnetic mesoporous biochar used in step 2 is:

[0072] The straw was dried at 80°C, crushed to remove impurities, and ground to obtain straw powder with a particle size of 100 μm. 3 g of straw powder, 3 g of potassium bicarbonate, and 10 g of potassium chloride were mixed and ball-milled for 15 minutes to mix them evenly. The mixture was then transferred to a tube furnace and heated to 900°C at a heating rate of 5°C / min under nitrogen as a protective gas and kept warm for 2 hours. After the insulation was completed, the mixture was cooled to room temperature in a sealed furnace. The obtained solid was crushed, washed with deionized water, and dried at 80°C to obtain mesoporous biochar.

[0073] 20 g of mesoporous biochar was added to 800 mL of deionized water, and after ultrasonic dispersion for 15 minutes, 20 g of ferric chloride and 11.1 g of ferrous sulfate were added, stirred evenly, and sodium hydroxide was added to adjust the pH to 10 after full dissolution to obtain a biochar suspension. The biochar suspension was then heated in an 80°C water bath for 1 hour. Nitrogen was continuously introduced into the suspension during the reaction. After the reaction was completed, it was separated using an external magnetic field. The separated product was washed with anhydrous ethanol and deionized water, and dried at 80°C to obtain magnetic mesoporous biochar.

[0074] The preparation method of the bipolar membrane used in step 3 is the same as that in Example 1.

[0075] Comparative Example 2: This comparative example relates to a method for deep treatment of wastewater based on an adsorbent. The difference from Example 1 is that in step 2, mesoporous biochar is used to adsorb heavy metals, specifically:

[0076] Step 1: Mix carbon dioxide and air in a volume ratio of 1:9 to form a mixed gas, then pass the mixed gas into the fly ash water washing liquid and stir continuously, control the flow rate of the mixed gas to 1 mL / min, and monitor the pH of the water washing liquid at all times. When the pH of the water washing liquid drops to neutral, stop ventilation, let it stand for aging, and filter to obtain the decalcified water washing liquid.

[0077] Step 2: Add the iron-sulfur-loaded magnetic mesoporous biochar and sodium persulfate to the decalcified water wash solution. The amount of iron-sulfur-loaded magnetic mesoporous biochar is 2% of the mass fraction of the decalcified water wash solution, and the amount of sodium persulfate is 1% of the mass fraction of the decalcified water wash solution. Stir at 200 rpm at room temperature for 120 minutes. After the reaction is complete, separate the iron-sulfur-loaded magnetic mesoporous biochar using an external magnetic field and filter to obtain a secondary treated solution.

[0078] Step 3: Use a bipolar membrane to perform electrodialysis on the secondary treatment liquid, set the dialysis voltage to 12 V, the dialysis electrode liquid to 0.1 mol / L sodium sulfate solution, the membrane surface flow rate to 10 cm / s, the temperature of the secondary treatment liquid to 25°C, and the feed flow rate to 5 L / h to obtain deeply treated wastewater.

[0079] The preparation method of the magnetic mesoporous biochar used in step 2 is:

[0080] The straw was dried at 80°C, crushed to remove impurities, and ground to obtain straw powder with a particle size of 100 μm. 3 g of straw powder, 3 g of potassium bicarbonate, and 10 g of potassium chloride were mixed and ball-milled for 15 minutes to mix them evenly. They were then transferred together to a tubular furnace. Under nitrogen as a protective gas, the temperature was increased to 900°C at a heating rate of 5°C / min and kept warm for 2 hours. After the insulation was completed, the mixture was cooled to room temperature in a sealed furnace. The obtained solid was crushed, washed with deionized water, and dried at 80°C to obtain mesoporous biochar.

[0081] The preparation method of the bipolar membrane used in step 3 is the same as that in Example 1.

[0082] Comparative Example 3: This comparative example relates to a method for deep treatment of wastewater based on an adsorbent. The difference from Example 1 is that in step 3, the cation exchange membrane of the bipolar membrane used is a polyvinylidene fluoride membrane, specifically:

[0083] Step 1: Mix carbon dioxide and air in a volume ratio of 1:9 to form a mixed gas, then pass the mixed gas into the fly ash water washing liquid and stir continuously, control the flow rate of the mixed gas to 1 mL / min, and monitor the pH of the water washing liquid at all times. When the pH of the water washing liquid drops to neutral, stop ventilation, let it stand for aging, and filter to obtain the decalcified water washing liquid.

[0084] Step 2: Add the iron-sulfur-loaded magnetic mesoporous biochar and sodium persulfate to the decalcified water wash solution. The amount of iron-sulfur-loaded magnetic mesoporous biochar is 2% of the mass fraction of the decalcified water wash solution, and the amount of sodium persulfate is 1% of the mass fraction of the decalcified water wash solution. Stir at 200 rpm at room temperature for 120 minutes. After the reaction is complete, separate the iron-sulfur-loaded magnetic mesoporous biochar using an external magnetic field and filter to obtain a secondary treated solution.

[0085] Step 3: Use a bipolar membrane to perform electrodialysis on the secondary treatment liquid, set the dialysis voltage to 12 V, the dialysis electrode liquid to 0.1 mol / L sodium sulfate solution, the membrane surface flow rate to 10 cm / s, the temperature of the secondary treatment liquid to 25°C, and the feed flow rate to 5 L / h to obtain deeply treated wastewater.

[0086] The preparation method of the loaded iron-sulfur magnetic mesoporous biochar used in step 2 is the same as the preparation method in Example 1.

[0087] The preparation method of the bipolar membrane used in step 3 is:

[0088] 9 g of polyvinylidene fluoride was added to 54 mL of N,N-dimethylacetamide and ultrasonically dispersed for 30 min to obtain a polyvinylidene fluoride dispersion, which was then allowed to stand for 2 h to degas to obtain a cation exchange membrane casting solution. The exchange membrane casting solution was spin-coated on a metal plate using a coating machine, heated and cured at 60°C for 3 h, and then cooled to room temperature to obtain a 0.1 mm thick polyvinylidene fluoride cation exchange membrane;

[0089] Ferrous sulfate was added to deionized water and stirred evenly to obtain a ferrous sulfate solution with a concentration of 5 g / L. Tetrabutyl titanate was added to the ferrous sulfate solution, stirred evenly, and ultrasonically dispersed to obtain a dispersion with a mass fraction of tetrabutyl titanate of 15%. Dopamine hydrochloride was added to Tris buffer and stirred evenly to obtain a dopamine hydrochloride solution with a concentration of 1 g / L. An ultrasonic sprayer was used to spray the dopamine hydrochloride solution on the surface of the sulfonic acid-zirconium phosphate hybrid cation exchange membrane, followed by the tetrabutyl titanate dispersion. The volume area ratio of the dopamine solution to the sulfonic acid-zirconium phosphate hybrid cation exchange membrane was 40 μL / cm 2 The volume area ratio of tetrabutyl titanate dispersion to sulfonic acid-zirconium phosphate hybrid cation exchange membrane is 60 μL / cm 2 The spraying rate was 400 μL / min, the membrane surface temperature was 40°C, and after spraying, the membrane was cured at 40°C for 20 min to form a 50 nm thick iron-loaded catalytic intermediate layer on the surface of the polyvinylidene fluoride cation exchange membrane.

[0090] 4 g of nanocellulose and 50 mL of deionized water were added to 200 mL of methanol and ultrasonically dispersed for 15 minutes to obtain a nanocellulose dispersion. 6 g of silane coupling agent KH-550 and 30 mL of deionized water were added to 570 mL of ethanol and stirred evenly. After stirring evenly, the pH was adjusted to 4 with hydrochloric acid, and then stirred at room temperature for 2 hours. After stirring, the nanocellulose dispersion was added and reacted at 70°C for 2 hours. After the reaction was completed, the mixture was cooled, filtered, washed with anhydrous ethanol and deionized water, and dried at 110°C. The dried product and 24 mL of iodomethane were added to 50 mL of N-methylpyrrolidone and reacted at room temperature for 24 hours. After the reaction was completed, the mixture was centrifuged, and the centrifuged product was washed with ethanol and freeze-dried to obtain quaternized nanocellulose.

[0091] 10 g of polyethyleneimine was added to 40 g of dimethyl sulfoxide, stirred evenly, and then 3.2 mL of ethyl bromide was added. The mixture was fully reacted at 60 ° C for 2 h. After the reaction was completed, it was cooled to obtain quaternized polyethyleneimine. 25 g of polyvinyl alcohol was added to 100 g of dimethyl sulfoxide and stirred evenly. Subsequently, 11 g of quaternized polyethyleneimine, 0.5 g of KH-560 silane coupling agent and 0.5 g of quaternized nanocellulose were added. After ultrasonic dispersion for 15 min, the mixture was heated at 90 ° C for 4 h. After the reaction was completed, it was cooled to obtain a quaternary ammonium hybrid anion exchange membrane casting solution. The exchange membrane casting solution was spin-coated on the loaded iron catalytic intermediate layer using a coating machine, heated and cured at 60 ° C for 3 h, and then cooled to room temperature to obtain a bipolar membrane (thickness: 0.1 mm + 50 nm + 0.1 mm).

[0092] Detection experiment:

[0093] The same batch of fly ash washing liquid was treated according to the treatment methods in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively, to obtain treated pre-drainage water, and the residual chlorine and heavy metal contents in the treated pre-drainage water were detected.

[0094] Residual chlorine content test: According to the "Water Quality - Determination of Free Chlorine and Total Chlorine - N,N-Diethyl-1,4-phenylenediamine Spectrophotometric Method" (HJ 586-2010), the residual chlorine content was tested using an ultraviolet spectrophotometer. 2.0 mL of 98% concentrated sulfuric acid and 0.2 g of solid disodium EDTA were added to 250 mL of deionized water to prepare a mixed solution. 1.1 g of anhydrous DPD sulfate was added to the mixed solution, mixed, and the volume was adjusted to 1000 mL to obtain a DPD solution. 24.0 g of anhydrous disodium hydrogen phosphate and 46.0 g of potassium dihydrogen phosphate were dissolved in deionized water in sequence. 0.8 g of solid disodium EDTA was added, mixed, and the volume was adjusted to 1000 mL with deionized water to obtain a phosphate buffer solution.

[0095] The residual chlorine standard solution with a chlorine mass concentration of 1.0 mg / L was diluted into standard test solutions with chlorine mass concentrations of 0 / 0.02 / 0.04 / 0.08 / 0.12 / 0.16 / 0.2 mg / L, respectively. 15.0 mL of phosphate buffer, 5.0 mL of DPD solution, 100 mL of standard test solution and 1.0 g of potassium iodide were placed in a conical flask in sequence. After mixing, the absorbance at different chlorine concentrations was measured, and a residual chlorine concentration-absorbance standard curve was drawn with absorbance as the ordinate and residual chlorine concentration as the abscissa. 15.0 mL of phosphate buffer, 5.0 mL of DPD solution, 100 mL of treated pre-drained water and 1.0 g of potassium iodide were placed in a conical flask in sequence and mixed to obtain the test solution. The absorbance of the test solution was then measured. Deionized water was used instead of treated pre-drained water in the blank sample. Other conditions were the same. The residual chlorine concentration in the test solution was calculated using the absorbance value according to the residual chlorine concentration-absorbance standard curve.

[0096] Heavy metal content test: According to the "Determination of 65 Elements in Water Quality by Inductively Coupled Plasma Mass Spectrometry" (HJ700-2014), the heavy metal content test was carried out using an inductively coupled plasma mass spectrometer. First, the treated pre-water was filtered through a 0.45μm filter membrane. After the filtration was completed, an appropriate amount of nitric acid was added to adjust the pH to <2 to obtain a mixed solution. 2.0mL of nitric acid and 1.0mL of hydrochloric acid were added to 100mL of the mixed solution. The solution was then placed on a hot plate and evaporated at a temperature not exceeding 85°C until 20mL of the mixed solution remained. The solution was cooled and diluted to 50mL with deionized water to obtain a test solution. The test solution was tested using an inductively coupled plasma mass spectrometer to detect the heavy metal content in the test solution.

[0097]

[0098] Conclusion: It can be seen from the test results that after the fly ash water washing liquid is treated with the method for deep treatment of wastewater based on adsorbent proposed in the present invention, the chlorine and heavy metals in the water washing liquid are efficiently removed, and the contents of residual chlorine and heavy metals in the treated water washing liquid meet the comprehensive sewage discharge standards. The method for deep treatment of wastewater based on adsorbent proposed in the present invention can efficiently remove chlorine and heavy metals in the fly ash water washing liquid, and the treated fly ash water washing liquid meets the discharge requirements.

[0099] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for deep treatment of wastewater based on adsorbent, characterized by: Specifically: Step 1: A mixture of carbon dioxide and air is introduced into the fly ash water washing liquid, with the volume ratio of carbon dioxide to air controlled to be 1:(5-10) and the flow rate of the mixture being (1-5) mL / min, and the fly ash water washing liquid is subjected to decalcification pretreatment. After the pH of the water washing liquid reaches neutral, the aeration is stopped to obtain a decalcified water washing liquid; Step 2: Add the loaded iron-sulfur magnetic mesoporous biochar and persulfate to the decalcified water wash solution, stir at 150-200 rpm for 90-120 minutes at room temperature, and after the reaction is completed, separate the loaded iron-sulfur magnetic mesoporous biochar by applying an external magnetic field, filter, and obtain a secondary treatment solution; Step 3: After forming a bipolar membrane with a 0.08-0.12 mm sulfonic acid-zirconium phosphate hybrid cation exchange membrane, a 0.08-0.12 mm thick quaternized nanocellulose hybrid anion exchange membrane, and a 30-50 nm thick iron catalytic intermediate layer between the two, the secondary treatment liquid is subjected to electrodialysis treatment to obtain deeply treated wastewater; In step 2, the preparation method of the iron-sulfur loaded magnetic mesoporous biochar is: The straw is dried at 80-90°C, crushed to remove impurities, and ground to obtain straw powder with a particle size of 100-150 μm. The straw powder, potassium bicarbonate, and potassium chloride are mixed and ball-milled for 15-20 minutes to mix them evenly. Under nitrogen as a protective gas, the temperature is increased to 850-900°C at a heating rate of 5°C / min and kept warm for 2-3 hours. After the insulation is completed, the mixture is sealed and cooled to room temperature. The obtained solid is crushed, washed with deionized water, and dried at 80-90°C to obtain mesoporous biochar; The mesoporous biochar was added to deionized water and ultrasonically dispersed for 15-20 minutes. Ferric chloride and ferrous sulfate were then added and stirred evenly to fully dissolve. The pH was adjusted to 9-10 with sodium hydroxide to obtain a biochar suspension. The biochar suspension was then heated in a water bath at 80-90°C for 0.5-1h. Nitrogen was continuously introduced into the suspension during the reaction. After the reaction was completed, an external magnetic field was applied to separate the product. The separated product was washed with anhydrous ethanol and deionized water and dried at 80-90°C to obtain magnetic mesoporous biochar. Add ferric nitrate to deionized water, stir evenly, slowly add thiourea after fully dissolving, and ultrasonically disperse for 10-15 minutes to form a dispersion. Then evaporate the dispersion to dryness at 80-90°C, mix the solid obtained after evaporation with magnetic mesoporous biochar, and heat it to 850-900°C at a heating rate of 5°C / min under closed conditions and keep it warm for 2-3 hours. After the insulation is completed, cool it to room temperature in a closed manner. After the product is crushed, wash it with 0.1 mol / L hydrochloric acid and deionized water, and dry it at 80-90°C to obtain iron-sulfur loaded magnetic mesoporous biochar; In step 3, the preparation method of the zirconium phosphate hybrid cation exchange membrane is: Zirconium oxychloride and polyvinylidene fluoride are added to a mixed solution of N,N-dimethylacetamide and methanol, and ultrasonically dispersed for 20-30 minutes, followed by standing for degassing for 1-2 hours to obtain a cation exchange membrane casting solution, which is then spin-coated into a film by spin coating, and then heated and cured at 60-70°C for 2-3 hours. After curing, the mixture is cooled to room temperature to obtain a zirconium oxychloride hybrid cation exchange membrane; The zirconium oxychloride hybrid cation exchange membrane is immersed in a phosphoric acid solution, heated at 110-120° C. for 1-2 hours, cooled to room temperature after the reaction is completed, washed with hydrochloric acid and deionized water, and dried to obtain a zirconium phosphate hybrid cation exchange membrane; The pH of the Tris buffer is adjusted to 7-8 with hydrochloric acid, and sodium polystyrene sulfonate is added and stirred evenly to fully dissolve to obtain a sodium polystyrene sulfonate solution. The zirconium phosphate hybrid exchange membrane is treated with plasma under an argon atmosphere, and the plasma discharge current is controlled to be 4.0-5.0A, and the treatment time is 5-10 minutes. After the treatment, the membrane is quickly immersed in the sodium polystyrene sulfonate solution and immersed for 1.5-2 hours. After the immersion is completed, the membrane is taken out, washed with deionized water, and dried to obtain a sulfonic acid-zirconium phosphate hybrid cation exchange membrane.

2. The method for deep treatment of wastewater based on adsorbent according to claim 1, characterized in that: The mass ratio of straw powder, potassium bicarbonate and potassium chloride is (2-4):(2-4):(8-12); the mass ratio of mesoporous biochar, ferric chloride and ferrous sulfate is (1-3):(1-3):(0.5-1.5); the mass ratio of ferric nitrate, thiourea and magnetic mesoporous biochar is (0.1-0.3):(0.35-0.45):(8-12).

3. The method for deep treatment of wastewater based on adsorbent according to claim 1, characterized in that: In step 2, the amount of loaded iron-sulfur magnetic mesoporous biochar is 1-2% of the mass fraction of the decalcified water wash; the persulfate is a mixture of one or more of ammonium persulfate, potassium persulfate, and sodium persulfate, and the amount is 0.5-1% of the mass fraction of the decalcified water wash.

4. The method for deep treatment of wastewater based on adsorbent according to claim 1, characterized in that: The preparation method of the loaded iron catalytic intermediate layer is as follows: Ferrous sulfate is added to deionized water and stirred evenly to obtain a ferrous sulfate solution. Tetrabutyl titanate is added to the ferrous sulfate solution, stirred evenly, and ultrasonically dispersed to obtain a tetrabutyl titanate dispersion. Dopamine hydrochloride is added to a Tris buffer solution and stirred evenly to obtain a dopamine hydrochloride solution. The dopamine hydrochloride solution and the tetrabutyl titanate dispersion are sprayed into films at a spraying rate of 400-500 μL / min. After spraying, the films are cured at 40-50°C for 20-30 minutes to obtain a loaded iron catalytic intermediate layer.

5. The method for deep treatment of wastewater based on adsorbent according to claim 1, characterized in that: The preparation method of quaternized nanocellulose hybrid anion exchange membrane is as follows: Add nanocellulose and deionized water to methanol, ultrasonically disperse for 15-20 minutes to obtain a nanocellulose dispersion, add silane coupling agent KH-550 and deionized water to ethanol, stir evenly, adjust the pH to 4-5 with hydrochloric acid, and then stir at room temperature for 2-4 hours. After stirring, add the nanocellulose dispersion, react at 50-70°C for 2-4 hours, cool after the reaction, filter, wash with anhydrous ethanol and deionized water, and dry at 100-110°C. Add the dried product and methyl iodide to N-methylpyrrolidone, react at room temperature for 18-24 hours, centrifuge after the reaction is completed, wash the centrifuged product with ethanol, and freeze-dry to obtain quaternized nanocellulose; The method comprises the following steps: adding polyethyleneimine to dimethyl sulfoxide, stirring evenly, adding bromoethane, and fully reacting at 50-70°C for 2-4 hours. After the reaction is completed, cooling is performed to obtain quaternized polyethyleneimine; adding polyvinyl alcohol to dimethyl sulfoxide, stirring evenly, then adding quaternized polyethyleneimine, KH-560 silane coupling agent and quaternized nanocellulose, ultrasonically dispersing for 15-30 minutes, heating at 80-90°C for 2-4 hours, cooling after the reaction is completed to obtain a quaternary ammonium hybrid anion exchange membrane casting solution; spin-coating the quaternary ammonium hybrid anion exchange membrane casting solution into a membrane by spin coating, then heating and curing at 60-70°C for 2-3 hours, and cooling to room temperature after the curing is completed to obtain a quaternary nanocellulose hybrid anion exchange membrane.

6. The method for deep treatment of wastewater based on adsorbent according to claim 1, characterized in that: In step 3, during electrodialysis, the dialysis voltage is 10-12 V, the dialysis electrode liquid is a 0.1-0.15 mol / L sodium sulfate solution, the membrane surface flow rate is 10-12 cm / s, the temperature of the secondary treatment liquid is 25-30° C., and the feed flow rate is 4-6 L / h.

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