Corrosion-resistant ultrafiltration membrane and method for manufacturing the same

Abstract

The application discloses a kind of corrosion-resistant ultrafiltration membrane, three (4-carboxyl phenyl) imidazole as MOF organic ligand, with graphene, metal ion in emulsion interface reaction, MOF plane and graphene plane are realized by metal ion coordination structure, then after calcination, obtain porous carbon material, after crushing, with PVDF compound obtains the ultrafiltration membrane with strong corrosion resistance, strong metal ion adsorption performance and good mechanical property, can be used for waste battery sewage heavy metal ion adsorption.

Description

Technical Field

[0001] This invention relates to the field of ultrafiltration, and more specifically to a corrosion-resistant ultrafiltration membrane and its manufacturing method. Background Technology

[0002] New energy vehicles are currently the hottest technology field, with a large number of lithium battery vehicles entering the market. As the service life of these vehicles increases, the disposal of used lithium batteries will become an increasingly serious problem. In particular, lithium batteries contain a lot of heavy metals such as cobalt, nickel, lead, and mercury, and conventional filtration methods, such as ultrafiltration membranes, cannot filter out heavy metal ions.

[0003] An ultrafiltration membrane is a semi-permeable polymer membrane used in the ultrafiltration process to separate polymeric colloids or suspended particles of a certain size from a solution. It is generally made of polymeric materials such as cellulose acetate, cellulose acetate esters, polyethylene, polysulfone, and polyamide.

[0004] Because polymer materials typically cannot adsorb heavy metal ions, and excessive modification of polymer materials can reduce their corrosion resistance. Inorganic materials, such as activated carbon and graphene, have excellent heavy metal adsorption properties and good corrosion resistance. However, due to the difficulty in controlling the porosity of inorganic materials and their complexity in fabricating ultrafiltration membranes, most current ultrafiltration membranes are prepared by combining graphene with organic materials. For example, CN106215720A discloses a method for preparing an organic solvent-resistant ultrafiltration membrane doped with graphene quantum dots. Graphene quantum dot nanoparticles are added during the preparation of a polyimide ultrafiltration membrane, and the polyimide ultrafiltration membrane doped with graphene quantum dots is crosslinked and modified using ethylenediamine, resulting in an organic solvent-resistant polyimide ultrafiltration membrane doped with graphene quantum dots. However, this ultrafiltration membrane is mainly used for organic solvent resistance, and has relatively few sites for adsorbing heavy metal ions.

[0005] Another typical structure of inorganic and organic composite materials is MOF (metal-organic framework) material. MOF is an extremely versatile ultraporous nanomaterial, ideal for detecting and capturing / adsorbing minute concentrations of substances, purifying water or air. Compared with other porous materials, the crystallinity, porosity, and surface activity of MOF materials can be controlled through experimental design. MOF has also been used to prepare ultrafiltration membranes. CN116036867A discloses an iron-based MOF modified ultrafiltration membrane, which is obtained by crystallizing a mixture of iron salt and 2-aminoterephthalic acid to obtain an iron-based MOF material. An acrylic monomer and a PVDF membrane are then added sequentially to the mixture containing the iron-based MOF material, followed by ultrasonic mixing and irradiation. The ultrafiltration membrane is used to treat radioactive Ce. 3+ However, the structure of the MOF in this ultrafiltration membrane is unstable under acidic or alkaline conditions, and its corrosion resistance is poor.

[0006] If ultrafiltration membranes are to be used for large-scale treatment of heavy metal wastewater, they need to possess a large number of heavy metal ion binding sites, corrosion resistance, and stable mechanical properties to withstand filtration pressure. Current ultrafiltration membranes cannot simultaneously meet these requirements. Therefore, this invention is proposed. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a corrosion-resistant ultrafiltration membrane and its manufacturing method. The ultrafiltration membrane is composed of PVDF and porous carbon materials, and possesses strong corrosion resistance, strong metal ion adsorption performance, and good mechanical properties.

[0008] The technical solution adopted in this invention is as follows:

[0009] A method for preparing a corrosion-resistant ultrafiltration membrane includes the following steps:

[0010] (1) Treat graphene oxide with an acid solution, then disperse it in an aqueous solution, add metal ions and emulsifier to obtain a dispersion;

[0011] (2) The dispersion is added to the oil phase to form a water-in-oil emulsion;

[0012] (3) Dissolve tris(4-carboxyphenyl)imidazole in an organic solvent, then add it to the water-in-oil emulsion and mix well;

[0013] (4) Heat the mixed emulsion for a certain time and add diluent;

[0014] (5) A membrane structure is deposited on the filter plane, filtered and washed to obtain the MOF composite material;

[0015] (6) Calcined MOF composite material, rinsed with water, dried and pulverized to obtain porous carbon material;

[0016] (7) Add porous carbon material to an organic solvent and add an organic pore-forming agent. Ultrasonic vibration is performed, and then polyvinylidene fluoride is added and stirred to obtain a casting solution. Degassing and scraping are performed to obtain a membrane. Finally, the membrane is placed in water to separate into a membrane and then soaked to remove residual organic solvent. The corrosion-resistant ultrafiltration membrane is then obtained.

[0017] In one or more embodiments, in step (1), the acid solution is a mixture of phosphoric acid and sulfuric acid, with a phosphoric acid concentration of 10-30% and a sulfuric acid concentration of 20-40%. Treating graphene oxide with phosphoric acid and sulfuric acid can modify the graphene surface with phosphate and sulfonate ions, which is beneficial for binding metal ions and thus forming a coordination structure with MOF; moreover, phosphate and sulfonate ions are beneficial for the adsorption of heavy metal ions by the final corrosion-resistant ultrafiltration membrane.

[0018] Furthermore, in step (1), the graphene oxide accounts for 5-10% of the mass percentage of the acid solution.

[0019] Furthermore, in step (1), the concentration of graphene oxide in the dispersion is 0.5-5%.

[0020] Further, in step (1), the metal ions are selected from polyvalent light metal ions, preferably from one or more of iron, aluminum, calcium, zinc, magnesium, and titanium. Selecting light metal ions avoids the release of heavy metal ions during filtration. The metal ions are added to the aqueous solution in the form of soluble metal salts, such as nitrates, chlorides, and some metal ions can also be sulfates, such as ferric nitrate, ferric chloride, aluminum nitrate, zinc chloride, magnesium sulfate, and titanium chloride; furthermore, the concentration of the soluble metal salt in the dispersion is 0.5-20%.

[0021] Further, in step (1), the emulsifier is selected from one or more of Span 80, Tween 80, Tween 60, Tween 40, and glyceryl monostearate; the concentration of the emulsifier in the dispersion is 1-3%.

[0022] In one or more embodiments, in step (2), the weight ratio of the dispersion to the oil phase is 1:5-10.

[0023] Furthermore, in step (2), the oil phase is selected from one or more of stearic acid, palmitic acid, oleic acid, linoleic acid, and palmitic acid.

[0024] Since graphene oxide is prone to agglomeration in aqueous solution, in step (2), graphene agglomeration can be avoided by forming a water-in-oil emulsion. In addition, graphene oxide is amphiphilic, so graphene oxide can form a coordination structure with MOF at the water-in-oil interface.

[0025] In one or more embodiments, in step (3), tris(4-carboxyphenyl)imidazole (CAS: 2329408-06-0) is an organic ligand of a metal-organic framework, with the following structural formula: Tris(4-carboxyphenyl)imidazolium contains an imidazolium group, which allows it to form a coordination structure with graphene in a plane perpendicular to the metal-organic framework. Simultaneously, its three carboxyl groups, when forming a MOF, enable the creation of larger pores, which is beneficial for ultrafiltration speed. Therefore, choosing tris(4-carboxyphenyl)imidazolium as an organic ligand is advantageous for improving the filtration efficiency of corrosion-resistant ultrafiltration membranes.

[0026] Further, in step (3), the organic solvent is one or both of DMSO and DMF. Further, the mass-volume percentage of tris(4-carboxyphenyl)imidazole in the organic solvent is 1-5%; the volume ratio of the organic solvent to the dispersion of tris(4-carboxyphenyl)imidazole is 1:0.5-2.

[0027] In one or more embodiments, in step (4), the heating reaction temperature is 60-80℃, and the reaction time is 12-72h. In step (4), the synthesis of MOF and the coordination reaction between MOF and graphene are carried out simultaneously. In the water-in-oil emulsion, the carboxyl group of tris(4-carboxyphenyl)imidazolium is a hydrophilic group, which easily contacts the water-in-oil metal ions, thereby reacting. At the same time, the metal ions will form a coordination structure with graphene, thereby achieving coordination between the plane of MOF and the plane of graphene. In addition, MOF usually forms a three-dimensional morphology, but when it forms a coordination structure with graphene, graphene can become a substrate template, thereby forming a sheet-like structure.

[0028] Furthermore, in step (4), the diluting solvent is selected from one or more of ethanol, acetone, DMF, and DMSO. The diluting solvent is mainly used to dilute and dissolve the emulsion, separating the oil phase from the reaction product. The amount of diluting solvent can be 2-10 times that of the emulsion.

[0029] In one or more embodiments, in step (5), the filter plane is a filter mesh, filter nonwoven fabric, etc., forming a membrane structure while filtering out the diluted emulsion. Further, the washing refers to rinsing with ethanol followed by rinsing with water.

[0030] In one or more embodiments, the calcination in step (6) refers to calcination at a temperature of 400-800℃ under inert gas protection for 1-6 hours. After calcination, the ultrafiltration membrane retains only the carbon-nitrogen framework, exhibiting stable chemical properties and strong mechanical properties. The drying is freeze-drying or room temperature drying.

[0031] Furthermore, to improve the bonding strength between graphene and MOF, in step (4), after adding the diluent, 5-20% by weight of a silane coupling agent of graphene oxide can be added and heated in a water bath for a certain period of time. Preferably, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-mercaptopropyltriethoxysilane. Preferably, the water bath temperature is 50-80℃, and the water bath heating time is 4-8h.

[0032] Furthermore, in order to improve the binding sites of metal ions, in step (6), after calcination, the material is first impregnated with hydrofluoric acid for a certain period of time; preferably, the concentration of hydrofluoric acid is 30%-40%, and the impregnation time is 0.5-2h. Hydrofluoric acid can remove silicon atoms from the porous carbon material after crosslinking with silane crosslinking agent, increase ion defects in the porous carbon material, and thus improve the adsorption of metal ions.

[0033] Further, in step (7), the pore-forming agent is polyethylene glycol or polyvinylpyrrolidone, and the organic solvent is dimethylacetamide or N-methylpyrrolidone; the mass ratio of the porous carbon material:PVDF:pore-forming agent:organic solvent is 1-3:8-12:0.5-1:30-40.

[0034] The present invention also provides a corrosion-resistant ultrafiltration membrane obtained from any of the above embodiments.

[0035] When appropriate components are selected, the inorganic carbon materials in the corrosion-resistant ultrafiltration membrane structure of the present invention include carbon, carbon nitrogen, sulfur, phosphorus, iron, zinc, etc. Under certain conditions, such as sunlight or ultraviolet radiation, they may also have photocatalytic degradation properties, which is more conducive to wastewater treatment.

[0036] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0037] 1. In this invention, tris(4-carboxyphenyl)imidazolium is used as an organic ligand for MOF, which can form larger pores. Then, through the coordination of metal ions, it forms a layered composite structure with graphene, which is beneficial to improving the ultrafiltration rate.

[0038] 2. In this invention, the synthesis of MOF and the coordination reaction between MOF and graphene are carried out simultaneously at the emulsion interface, which can avoid the aggregation of graphene and make the coordination between MOF and graphene through metal ions more uniform.

[0039] 3. The corrosion-resistant ultrafiltration membrane of the present invention has PVDF as its organic component and porous carbon material as its inorganic material, which has strong corrosion resistance, stable mechanical properties and metal ion adsorption performance.

[0040] 4. In some technical solutions, the binding between MOF and graphene is improved by using silane coupling agents, followed by treatment with hydrofluoric acid, thereby increasing the ion defects in the inorganic carbon material and thus improving the adsorption of metal ions.

[0041] 5. By selecting appropriate components, the ultrafiltration membrane of the present invention may also have photocatalytic degradation properties. Detailed Implementation

[0042] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Examples of the embodiments are shown below. It should be understood that the specific embodiments described in the following embodiments of the invention are merely illustrative examples of specific implementations of the invention and are intended to explain the invention, but do not constitute a limitation thereof.

[0043] The endpoints of the ranges and any values ​​disclosed herein are not limited to the exact ranges or values, which should be understood to include those close to them.

[0044] Example 1

[0045] A method for preparing a corrosion-resistant ultrafiltration membrane includes the following steps:

[0046] (1) Weigh 1g of graphene oxide, disperse it in 20g of a mixed acid containing 20% ​​phosphoric acid and 30% sulfuric acid, soak it for 1h and then filter it, and then rinse it with water; disperse the treated graphene oxide in 100ml of aqueous solution, add 1g of ferric nitrate, 1g of calcium nitrate and 2g of Tween 80, stir evenly to obtain a dispersion.

[0047] (2) Add the dispersion to 500 ml of oleic acid and stir to form a water-in-oil emulsion;

[0048] (3) Dissolve 1g of tris(4-carboxyphenyl)imidazolium in 100ml of DMSO, and then slowly add it to the water-in-oil emulsion and mix well;

[0049] (4) Seal the mixed emulsion and then heat it in a water bath at 60°C for 24 hours. Add 1.5L of ethanol to dilute the emulsion.

[0050] (5) Pour the diluted emulsion evenly onto the nonwoven fabric, filter and deposit to form a membrane structure, rinse slowly with 500ml of ethanol, rinse with 500ml of water, and dry to obtain MOF composite material.

[0051] (6) The MOF composite material was calcined at 600℃ and under nitrogen protection for 2 hours, rinsed with water, freeze-dried, and pulverized to obtain 1.93 g of porous carbon material;

[0052] (7) Add 1g of porous carbon material to 30g of dimethylacetamide and 0.5g of polyethylene glycol, sonicate, then add 8g of polyvinylidene fluoride and stir to obtain a casting solution, degas, scrape the membrane to obtain a membrane sheet, finally put the membrane sheet into water to separate it into a membrane, and continue to soak to remove residual organic solvents, and take it out to obtain a corrosion-resistant ultrafiltration membrane sheet.

[0053] Example 2

[0054] A method for preparing a corrosion-resistant ultrafiltration membrane includes the following steps:

[0055] (1) Weigh 1g of graphene oxide, disperse it in 15g of a mixed acid containing 15% phosphoric acid and 40% sulfuric acid, soak it for 1 hour and then filter it, and then rinse it with water; disperse the treated graphene oxide in 50ml of aqueous solution, add 2g of aluminum nitrate, 0.5g of zinc chloride and 1g of Tween 60, stir evenly to obtain a dispersion.

[0056] (2) Add the dispersion to 400 ml palmitic acid and stir to form a water-in-oil emulsion;

[0057] (3) Dissolve 2g of tris(4-carboxyphenyl)imidazolium in 80ml of DMSO, and then slowly add it to the water-in-oil emulsion and mix well;

[0058] (4) Seal the mixed emulsion and then heat it in a water bath at 70°C for 36 hours. Add 1.4L of ethanol to dilute the emulsion.

[0059] (5) Pour the diluted emulsion evenly onto the nonwoven fabric, filter and deposit to form a membrane structure, rinse slowly with 500ml of ethanol, rinse with 500ml of water, and dry to obtain MOF composite material.

[0060] (6) The MOF composite material was calcined at 500℃ and under nitrogen protection for 4h, rinsed with water, freeze-dried, and pulverized to obtain 2.55g of porous carbon material;

[0061] (7) Add 2g of porous carbon material to 35g of N-methylpyrrolidone and 0.5g of polyvinylpyrrolidone, sonicate, then add 10g of polyvinylidene fluoride and stir to obtain a casting solution, degas, scrape the membrane to obtain a membrane sheet, and finally put the membrane sheet into water to separate it into a membrane, and continue to soak it to remove residual organic solvents. The corrosion-resistant ultrafiltration membrane sheet is then obtained.

[0062] Example 3

[0063] A method for preparing a corrosion-resistant ultrafiltration membrane includes the following steps:

[0064] (1) Weigh 1g of graphene oxide, disperse it in 20g of a mixed acid containing 20% ​​phosphoric acid and 30% sulfuric acid, soak it for 1h and then filter it, and then rinse it with water; disperse the treated graphene oxide in 100ml of aqueous solution, add 1g of ferric nitrate, 1g of calcium nitrate and 2g of Tween 80, stir evenly to obtain a dispersion.

[0065] (2) Add the dispersion to 500 ml of oleic acid and stir to form a water-in-oil emulsion;

[0066] (3) Dissolve 1g of tris(4-carboxyphenyl)imidazolium in 100ml of DMSO, and then slowly add it to the water-in-oil emulsion and mix well;

[0067] (4) Seal the mixed emulsion, then heat it in a water bath at 60°C for 24 hours, add 1.5L of ethanol to dilute the emulsion, add 100mg of γ-aminopropyltriethoxysilane, and heat it in a water bath at 60°C for 4 hours.

[0068] (5) Pour the reacted emulsion evenly onto the nonwoven fabric, filter and deposit to form a membrane structure, rinse slowly with 500ml of ethanol, rinse with 500ml of water, and dry to obtain MOF composite material.

[0069] (6) The MOF composite material was calcined at 600℃ and under nitrogen protection for 2h. After calcination, it was impregnated with 50ml of 30% hydrofluoric acid for 1h, rinsed with water, freeze-dried, and pulverized to obtain 2.05g of porous carbon material.

[0070] (7) Add 1g of porous carbon material to 30g of dimethylacetamide and 0.5g of polyethylene glycol, sonicate, then add 8g of polyvinylidene fluoride and stir to obtain a casting solution, degas, scrape the membrane to obtain a membrane sheet, finally put the membrane sheet into water to separate it into a membrane, and continue to soak to remove residual organic solvents, and take it out to obtain a corrosion-resistant ultrafiltration membrane sheet.

[0071] Example 4

[0072] A method for preparing a corrosion-resistant ultrafiltration membrane includes the following steps:

[0073] (1) Weigh 1g of graphene oxide, disperse it in 10g of a mixed acid containing 30% phosphoric acid and 20% sulfuric acid, soak it for 1h and then filter it, and then rinse it with water; disperse the treated graphene oxide in 30ml of aqueous solution, add 1g of calcium nitrate, 0.5g of magnesium sulfate and 0.9g of Span 60, stir evenly to obtain a dispersion.

[0074] (2) Add the dispersion to 300 ml palmitic acid and stir to form a water-in-oil emulsion;

[0075] (3) Dissolve 0.5g of tris(4-carboxyphenyl)imidazolium in 50ml of DMF, and then slowly add it to the water-in-oil emulsion and mix well;

[0076] (4) Seal the mixed emulsion, then heat it in a water bath at 80°C for 12 hours, add 1 LDMF to dilute the emulsion, add 200 mg γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and heat it in a water bath at 80°C for 4 hours.

[0077] (5) Pour the diluted emulsion evenly onto the nonwoven fabric, filter and deposit to form a membrane structure, rinse slowly with 500ml of ethanol, rinse with 500ml of water, and dry to obtain MOF composite material.

[0078] (6) The MOF composite material was calcined at 700℃ and under nitrogen protection for 12h. After calcination, it was impregnated with 50ml of 40% hydrofluoric acid for 0.5h, rinsed with water, freeze-dried, and pulverized to obtain 1.78g of porous carbon material.

[0079] (7) Add 1.5g of porous carbon material to 40g of N-methylpyrrolidone and 1g of polyethylene glycol, sonicate, then add 12g of polyvinylidene fluoride and stir to obtain a casting solution, degas, scrape the membrane to obtain a membrane sheet, and finally put the membrane sheet into water to separate it into a membrane, and continue to soak it to remove residual organic solvents. The corrosion-resistant ultrafiltration membrane sheet is then obtained.

[0080] Example 5

[0081] Performance tests of corrosion-resistant ultrafiltration membranes in Examples 1 and 3.

[0082] Stability in water: The corrosion-resistant ultrafiltration membranes of Examples 1 and 3 showed no significant swelling after being soaked in water at pH=1 and pH=13 for 72 hours, thus demonstrating stability in water.

[0083] Adsorption of heavy metal ions under static conditions: The corrosion-resistant ultrafiltration membranes of Examples 1 and 3 were placed in 50 mL of aqueous solutions containing 0.1 mg / mL cobalt, nickel, lead, mercury, and chromium ions for 1 h, respectively, and then rinsed with water. The amount of metal ions adsorbed by the corrosion-resistant ultrafiltration membranes was analyzed by an elemental analyzer. The results are as follows:

[0084] Example 1 (mg / g) Example 3 Adsorption capacity (mg / g) cobalt ions 17.5 22.3 Nickel ions 19.3 20.6 lead ions 20.9 23.5 Mercury ions 21.1 22.6 Chromium ions 19.4 21.7

[0085] Therefore, under static conditions, the corrosion-resistant ultrafiltration membranes of Examples 1 and 3 have good adsorption performance for heavy metal ions, with adsorption rates of all metal ions reaching over 65%, and the adsorption performance of the ultrafiltration membrane of Example 3 is better than that of Example 1.

[0086] Adsorption of heavy metal ions under dynamic conditions: Under conditions of 0.1 MPa, 0.2 MPa, and 0.5 MPa, aqueous solutions of 0.1 mg / mL cobalt ions, nickel ions, lead ions, mercury ions, and chromium ions were passed through three layers of corrosion-resistant ultrafiltration membranes from Examples 1 and 3. The adsorption rates of metal ions after passing through the ultrafiltration membranes are shown in the table below:

[0087]

[0088]

[0089] Therefore, it can be seen that under dynamic conditions, the adsorption rate of the corrosion-resistant ultrafiltration membrane is significantly improved compared to the static condition. Thus, the corrosion-resistant ultrafiltration membrane of this invention has a significant effect on ultrafiltration adsorption of metal ions. Furthermore, as the pressure increases, the metal ion adsorption in Example 1 first increases and then decreases, presumably because the corrosion-resistant mechanical properties of Example 1 are relatively poor, which may have caused structural damage under high pressure. Therefore, the corrosion-resistant ultrafiltration membrane of Example 1 is suitable for low-pressure ultrafiltration. In contrast, the metal ion adsorption rate of Example 3 increases with increasing pressure and exhibits a high metal ion adsorption rate, which can greatly reduce the heavy metal content in wastewater and can withstand higher pressures, making it suitable for industrial wastewater treatment.

[0090] Regeneration performance of the filter membrane: The corrosion-resistant ultrafiltration membranes of Examples 1 and 3, which adsorbed heavy metal ions, were heated at 80°C for 0.5 h with 1 mol / L hydrochloric acid, and the changes in adsorbed heavy metal ions were detected after treatment. After treatment in Examples 1 and 3, the heavy metal residues were 3.84% and 2.66%, respectively, and the structure remained unchanged. Therefore, the corrosion-resistant ultrafiltration membrane of the present invention can be used multiple times and has stable performance.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and do not constitute a limitation on the content of the present invention. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention and all fall within the protection scope of the present invention.

Claims

1. A method for preparing a corrosion-resistant ultrafiltration membrane, characterized in that, Includes the following steps: (1) Treat graphene oxide with an acid solution, then disperse it in an aqueous solution, add metal ions and emulsifier to obtain a dispersion; (2) The dispersion is added to the oil phase to form a water-in-oil emulsion; (3) Dissolve tris(4-carboxyphenyl)imidazole in an organic solvent, then add it to the water-in-oil emulsion and mix well; (4) Heat the mixed emulsion for a certain time and add diluent; (5) A membrane structure is deposited on the filter plane, filtered and washed to obtain the MOF composite material; (6) Calcine the MOF composite material, rinse with water, dry, and pulverize to obtain porous carbon material; (7) Add porous carbon material to organic solvent and organic pore-forming agent, ultrasonically vibrate, then add polyvinylidene fluoride and stir to obtain casting solution, degas, scrape membrane to obtain membrane sheet, finally put the membrane sheet into water to separate into membrane, and continue to soak to remove residual organic solvent, and take it out to obtain corrosion resistant ultrafiltration membrane sheet.

2. The preparation method according to claim 1, characterized in that, In step (1), the acid solution is a mixture of phosphoric acid and sulfuric acid, with a phosphoric acid concentration of 10-30% and a sulfuric acid concentration of 20-40%; the graphene oxide accounts for 5-10% of the mass percentage of the acid solution; the concentration of graphene oxide in the dispersion is 0.5-5%; the metal ions are selected from polyvalent light metal ions; the emulsifier is selected from one or more of Span 80, Tween 80, Tween 60, Tween 40, and glyceryl monostearate; and the concentration of the emulsifier in the dispersion is 1-3%.

3. The preparation method according to claim 1, characterized in that, In step (2), the weight ratio of the dispersion to the oil phase is 1:5-10, and the oil phase is selected from one or more of stearic acid, palmitic acid, oleic acid, linoleic acid, and palmitic acid.

4. The preparation method according to claim 1, characterized in that, In step (3), the organic solvent is one or both of DMSO and DMF; the mass-volume percentage of tris(4-carboxyphenyl)imidazole in the organic solvent is 1-5%; and the volume ratio of the organic solvent to the dispersion of tris(4-carboxyphenyl)imidazole is 1:0.5-2.

5. The preparation method according to claim 1, characterized in that, In step (4), the heating reaction temperature is 60-80℃ and the reaction time is 12-72h; the diluent is selected from one or more of ethanol, acetone, DMF, and DMSO.

6. The preparation method according to claim 1, characterized in that, In step (5), the filter plane is a filter mesh or a filter non-woven fabric; the washing refers to rinsing with ethanol and then rinsing with water.

7. The preparation method according to claim 1, characterized in that, The calcination in step (6) refers to calcination at a temperature of 400-800℃ and under the protection of an inert gas for 1-6 hours; the drying is freeze drying or room temperature drying.

8. The preparation method according to claim 1, characterized in that, In step (7), the organic porogen is polyethylene glycol or polyvinylpyrrolidone, and the organic solvent is dimethylacetamide or N-methylpyrrolidone; the mass ratio of the porous carbon material:PVDF:organic porogen:organic solvent is 1-3:8-12:0.5-1:30-40.

9. The preparation method according to any one of claims 1-8, characterized in that, In step (4), after adding the diluent, 5-20% of the weight of graphene oxide silane coupling agent is added, and the mixture is heated in a water bath at 50-80°C for 4-8 hours. And / or, in step (6), after calcination, the sample is first impregnated with hydrofluoric acid, the concentration of which is 30%-40% and the impregnation time is 0.5-2h.

10. A corrosion-resistant ultrafiltration membrane prepared by the preparation method according to any one of claims 1-9.

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