Geopolymer-metal mesh composite membrane and preparation method and application thereof

Abstract

The application discloses a geopolymer-metal mesh composite membrane, which comprises a metal mesh, a geopolymer, TiO2 nanoparticles with polyethylene imine on the surface and dopamine; wherein the metal mesh is used as a support body, the geopolymer doped with activated carbon is used as a filter layer, and the TiO2 nanoparticles with polyethylene imine on the surface are used as fillers to fill holes in the transition layer. The application of the geopolymer-metal mesh composite membrane in adsorbent materials, especially wastewater adsorbent materials, is disclosed. The geopolymer-metal mesh composite membrane is used as an adsorbent material, has excellent adsorption performance, and can effectively treat oil-water emulsion and dye organic wastewater. The preparation method is simple, low in cost and environmentally friendly.

Description

Technical Field

[0001] This invention relates to a composite membrane, its preparation method, and its application, specifically to a geopolymer-metal mesh composite membrane, its preparation method, and its application. Background Technology

[0002] In today's rapidly developing society, industries such as petrochemicals, textiles, and food processing are generating large amounts of oily wastewater. The discharge of large quantities of oily wastewater, as well as oil spills during offshore crude oil development and transportation, not only wastes energy but also poses a significant threat to aquatic life and human health. Traditional methods for treating oily wastewater, such as flotation, combustion, adsorption, and flocculation, suffer from drawbacks including high cost, high energy consumption, and low efficiency. Furthermore, large-scale application can lead to secondary pollution of water bodies. Therefore, developing low-cost, high-efficiency oil-water separation technologies is a pressing need for society as a whole. Compared to traditional separation technologies, membrane technology is gaining increasing attention due to its low energy consumption, stable permeability, high separation efficiency, and simple operation, making it suitable for various types of oily wastewater.

[0003] While membrane materials for oily wastewater treatment have been developed, they still face challenges such as high raw material costs, high energy consumption, short lifespan, and secondary pollution. Furthermore, real-world wastewater is more complex, often containing multiple pollutants like organic dyes and heavy metal ions. These substances typically carry positive or negative charges, significantly limiting the application of single-function membrane materials. Recent reports have highlighted the use of nanofiltration membranes for removing small molecules, but efficient separation often comes at the cost of reduced permeate flux. In membrane technology, microfiltration membranes offer higher flux and provide ample time for adsorption of small molecules compared to nanofiltration. Therefore, modifying ordinary microfiltration membranes into adsorption-specific microfiltration membranes, while maintaining high permeate flux, holds immense potential for treating complex wastewater. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a geopolymer-metal mesh composite membrane, its preparation method, and its application as an adsorption material. This invention uses a metal mesh with excellent mechanical properties and toughness as a support, a geopolymer doped with activated carbon as a filter layer, and TiO2 nanoparticles to fill the pores of the transition layer. Polyethyleneimine and dopamine are physically adsorbed onto the surfaces of the TiO2 nanoparticles and the geopolymer-metal mesh composite membrane, respectively, resulting in a bifunctional geopolymer-metal mesh composite membrane. This composite membrane exhibits dual functionality, capable of separating oil-water emulsions through retention and removing dyes through adsorption. This further improves the separation efficiency of the composite membrane for oil-water emulsions, enhancing the dispersion and utilization rate of its active components, while simultaneously strengthening the adsorption of dye molecules.

[0005] To achieve the above objectives, the first aspect of the present invention provides a geopolymer-metal mesh composite membrane, comprising a metal mesh, a geopolymer, TiO2 nanoparticles with polyethyleneimine coated on their surface, and dopamine; wherein, the metal mesh serves as a support, the geopolymer doped with activated carbon serves as a filter layer, and the TiO2 nanoparticles with polyethyleneimine coated on their surface serve as fillers to fill the pores of the transition layer; the polyethyleneimine and dopamine have the functions of stabilizing the TiO2 nanoparticle filling structure and enhancing the adsorption of dye molecules.

[0006] Furthermore, the metal mesh is one of copper mesh, nickel mesh, or iron mesh; the dopamine is a dopamine deposition solution, which is obtained by weighing dopamine hydrochloride powder and dissolving it in Tris-HCl buffer solution.

[0007] A second aspect of this invention provides a method for preparing a geopolymer-metal mesh composite membrane, comprising the following steps:

[0008] (1) Metal mesh pretreatment;

[0009] (2) Preparation of geopolymer slurry;

[0010] (3) Take the metal mesh pretreated in step (1) and coat it with the geopolymer slurry obtained in step (2) by coating, then cure it to obtain composite membrane I;

[0011] (4) Take the composite membrane I obtained after curing in step (3), place it in a filter, and use vacuum filtration to draw the TiO2 suspension with polyethyleneimine on the surface into the pores of the composite membrane I. After curing, immerse it in a dopamine deposition solution, and after cleaning and drying, the geopolymer-metal mesh composite membrane is obtained.

[0012] Further, in step (1), the metal mesh pretreatment is to chemically etch the metal mesh for 20-50 minutes with a solution of ammonium persulfate, sodium hydroxide and deionized water, and then clean and dry it to obtain the final product; the mass ratio of ammonium persulfate, sodium hydroxide and deionized water is 0.2-0.4:1:10.

[0013] Further, the preparation of the geopolymer slurry in step (2) involves mixing activated carbon and slag evenly to obtain a mixed powder, then adding sodium hydroxide solution to the mixed powder and mechanically stirring to mix evenly.

[0014] Further, the activated carbon content is 1-9 wt% of the mixed powder; the mass ratio of sodium hydroxide to deionized water in the sodium hydroxide solution is 0.2-1:3; the mass ratio of the sodium hydroxide solution to the mixed powder is 2-5:5; the mechanical stirring speed is 500-3000 r / min, and the time is 0.5-5 min.

[0015] Furthermore, the curing temperature in step (3) is 20–120℃ and the curing time is 24–72h; the curing temperature in step (4) is 20–80℃ and the curing time is 1–5h.

[0016] Further, the drying temperature in step (4) is 20-120°C and the drying time is 10-60 min; the vacuum filtration pressure in step (4) is 0.07-0.1 MPa; and the immersion time in the dopamine deposition solution in step (4) is 12-36 h.

[0017] Further, the TiO2 suspension with polyethyleneimine on the surface mentioned in step (4) is obtained by mixing polyethyleneimine, TiO2 nanoparticles and deionized water in a mass ratio of 1:0.05 to 0.2:99; the volume of the TiO2 suspension with polyethyleneimine on the surface used is 10 to 30 mL.

[0018] Further, the mass concentration of the dopamine deposition solution in step (4) is 0.6 mg / L; the volume of the dopamine deposition solution used is 20 to 100 mL.

[0019] A third aspect of the present invention is to provide an application of the aforementioned geopolymer-metal mesh composite membrane in adsorption materials, particularly wastewater adsorption materials.

[0020] Furthermore, the organic wastewater is an organic wastewater of a binary system composed of oil-water emulsion and dye.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention utilizes the properties of activated carbon-doped geopolymer, rutile TiO2 nanoparticles, polyethyleneimine, and dopamine to prepare a geopolymer-metal mesh composite membrane through controlled synthesis. The dense structure of the activated carbon-doped geopolymer fills the pores of the metal mesh, while the strong adsorption properties of activated carbon facilitate the adsorption and separation of dye molecules. The filling with TiO2 nanoparticles reduces the pore size of the filter layer, significantly improving the retention effect and further enhancing the separation efficiency of oil-water emulsions. The use of polyethyleneimine and dopamine stabilizes the TiO2 nanoparticle filling structure and enhances the adsorption of dye molecules by the geopolymer-metal mesh composite membrane. The preparation method of this invention is simple, low-cost, and environmentally friendly.

[0023] Using the geopolymer-metal mesh composite membrane of this invention as an adsorption material, it exhibits excellent adsorption performance and can effectively treat oil-water emulsions and dye organic wastewater. Attached Figure Description

[0024] Figure 1These are scanning electron microscope images of the composite membranes; among them, (a) and (d) are composite membrane I with 5 wt.% activated carbon content prepared in step (3) of Example 1 of the present invention, (b) and (e) are geopolymer-metal mesh composite membranes with 5 wt.% activated carbon content and 0.1 g TiO2 content prepared in step (4) of Example 1 of the present invention, and (c) and (f) are geopolymer-metal mesh composite membranes with 0.2 g TiO2 nanoparticle content prepared in step (4) of Example 2 of the present invention.

[0025] Figure 2 These are digital photographs of various composite membranes; among them, (a) is a geopolymer-metal mesh composite membrane with 5 wt.% activated carbon and 0.1 g TiO2 added, prepared in step (4) of Example 1 of the present invention, and (b) is a geopolymer-metal mesh composite membrane with 0.2 g TiO2 nanoparticles added, prepared in step (4) of Example 2 of the present invention. Detailed Implementation

[0026] The following is a detailed description of specific embodiments in conjunction with the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise specified, the raw materials and reagents used in the examples are commercially available. The TiO2 nanoparticles are commercially available rutile TiO2 nanoparticles.

[0027] Example 1

[0028] 1. Preparation of geopolymer-metal mesh composite membrane

[0029] (1) Metal mesh pretreatment: Ammonium persulfate, sodium hydroxide and deionized water were mixed in a mass ratio of 0.2:1:10 to prepare a solution. The solution was used to chemically etch several circular copper metal meshes cut to r=0.02m and 2000 mesh for 30 minutes, and then cleaned and dried.

[0030] (2) Preparation of geopolymer slurry: Weigh activated carbon and slag and mix them evenly to obtain a mixed powder. Fix the total mass of the mixed powder and change the content of activated carbon to obtain mixed powders with different activated carbon contents (the activated carbon contents are 1wt%, 3wt%, 5wt%, 7wt%, and 9wt% of the mixed powder, respectively); then add sodium hydroxide solution (the mass ratio of sodium hydroxide to deionized water in the sodium hydroxide solution is 1:3) to the mixed powders with different activated carbon contents. The mass ratio of sodium hydroxide solution to mixed powder is 4:5. Keep the speed at 2000 r / min and mechanically stir for 2 min to mix evenly to obtain geopolymer slurries with different activated carbon contents;

[0031] (3) Take the geopolymer slurry with different activated carbon content obtained in step (2) and coat it on the surface of the metal copper mesh after the pretreatment in step (1). Fix the mass of the coated slurry to 0.6g, and then cure it in an oven at 60℃ for 72h to obtain a series of composite films I; after curing, the geopolymer slurry becomes a geopolymer doped with activated carbon.

[0032] (4) Weigh 1g of polyethyleneimine, add 99g of deionized water, and sonicate until the polyethyleneimine is completely dissolved. Then add 0.1g of rutile TiO2 nanoparticles and mix with magnetic stirring for 1h to obtain a TiO2 suspension with polyethyleneimine on the surface, for later use. Weigh 0.1211g of tris(hydroxymethyl)aminomethane powder and dissolve it in 100mL of deionized water. After stirring, obtain a Tris solution with a concentration of 10mM. Adjust the pH of the Tris solution to 8.5 using a 0.1mol / L hydrochloric acid solution to obtain a Tris-HCl buffer solution. Weigh 0.6g of dopamine hydrochloride powder and dissolve it in 100mL of Tris-HCl buffer solution to obtain a dopamine deposition solution with a concentration of 0.6mg / L, for later use.

[0033] Take the composite membrane I obtained after curing in step (3), place it in a filter, and use a vacuum filtration process at a pressure of 0.08 MPa to draw 20 mL of the prepared TiO2 suspension with polyethyleneimine coating onto its surface into the pores of the composite membrane I. Remove the membrane, place it in an oven at 60°C for 1 hour, and then immerse it in 20 mL of the prepared dopamine deposition solution for 24 hours. After washing with water and drying at 60°C for 30 minutes, a series of geopolymer-metal mesh composite membranes with different activated carbon content are obtained. The TiO2 suspension with polyethyleneimine coating on its surface after curing becomes TiO2 nanoparticles with polyethyleneimine coating.

[0034] 2. Adsorption performance determination

[0035] An application of the aforementioned geopolymer-metal mesh composite membrane in adsorption materials: The geopolymer-metal mesh composite membrane prepared in step (4) of Example 1 with 5 wt.% activated carbon and 0.1 g TiO2 was used to perform filtration experiments on simulated n-hexadecane emulsion and crystal violet dye: The geopolymer-metal mesh composite membrane prepared in step (4) of Example 1 with 5 wt.% activated carbon and 0.1 g TiO2 was placed in a filter and gravity filtered 20 mL of n-hexadecane emulsion (mass ratio of n-hexadecane, deionized water, and sodium dodecyl sulfate = 1:99:0.005) and methylene blue solution (10 mg / L), respectively. The separation efficiencies reached 99.68% and 91.55%, respectively.

[0036] Example 2

[0037] 1. Preparation of geopolymer-metal mesh composite membrane

[0038] (1) Metal mesh pretreatment: Ammonium persulfate, sodium hydroxide and deionized water were mixed in a mass ratio of 0.2:1:10 to prepare a solution. The solution was used to chemically etch several circular copper metal meshes cut to r=0.02m and 2000 mesh for 30 minutes, and then cleaned and dried.

[0039] (2) Preparation of geopolymer slurry: Weigh activated carbon and slag and mix them evenly to obtain a mixed powder, wherein the content of activated carbon is 5 wt% of the mixed powder; then add sodium hydroxide solution (the mass ratio of sodium hydroxide to deionized water in the sodium hydroxide solution is 0.75:3) to the mixed powder, the mass ratio of sodium hydroxide solution to mixed powder is 4:5, and keep the speed at 1500 r / min and mechanically stir for 3 min to mix evenly to obtain a geopolymer slurry with an activated carbon content of 5 wt%;

[0040] (3) The geopolymer slurry obtained in step (2) is coated on the surface of the pretreated copper mesh in step (1). The mass of the coated slurry is fixed at 0.6g. Then it is cured in an oven at 60℃ for 48h to obtain composite membrane I. After curing, the geopolymer slurry becomes a geopolymer doped with activated carbon.

[0041] (4) Weigh 1g of polyethyleneimine, add 99g of deionized water, and sonicate until the polyethyleneimine is completely dissolved. Then add different masses of rutile TiO2 nanoparticles (0.05g, 0.1g, 0.15g, and 0.2g of rutile TiO2 nanoparticles, respectively). Mix with magnetic stirring for 1.5h to obtain a series of TiO2 suspensions with polyethyleneimine on the surface, and set aside. Weigh 0.1211g of tris(hydroxymethyl)aminomethane powder and dissolve it in 100mL of deionized water. After stirring, obtain a Tris solution with a concentration of 10mM. Adjust the pH of the Tris solution to 8.5 using a 0.1mol / L hydrochloric acid solution to obtain a Tris-HCl buffer solution. Weigh 0.6g of dopamine hydrochloride powder and dissolve it in 100mL of Tris-HCl buffer solution to obtain a dopamine deposition solution with a concentration of 0.6mg / L, and set aside.

[0042] Take the composite membrane I obtained after curing in step (3), place it in a filter, and use a vacuum filtration method at a pressure of 0.08 MPa to draw 30 mL of the above-prepared TiO2 suspensions with polyethyleneimine on the surface into the pores of the composite membrane I. Take it out, place it in an oven at 60°C for 2 hours, and then let it stand in 40 mL of the above-prepared dopamine deposition solution for 36 hours. After washing with water and drying at 60°C for 20 minutes, a series of geopolymer-metal mesh composite membranes with different amounts of rutile TiO2 nanoparticles are obtained. The TiO2 suspensions with polyethyleneimine on the surface after curing become TiO2 nanoparticles with polyethyleneimine on the surface.

[0043] 2. Adsorption performance determination

[0044] An application of the aforementioned geopolymer-metal mesh composite membrane in adsorption materials: Using the geopolymer-metal mesh composite membrane with 0.2g of TiO2 nanoparticles prepared in step (4) of Example 2 above, filtration experiments were conducted on simulated n-hexadecane emulsion and crystal violet dye respectively: The geopolymer-metal mesh composite membrane with 0.2g of TiO2 nanoparticles prepared in step (4) of Example 2 was placed in a filter and gravity filtered 40mL of n-hexadecane emulsion (mass ratio of n-hexadecane, deionized water, and sodium dodecyl sulfate = 1:99:0.01) and crystal violet solution (10mg / L), respectively, and the separation efficiencies reached 99.75% and 98.63% respectively.

[0045] Example 3

[0046] 1. Preparation of geopolymer-metal mesh composite membrane

[0047] (1) Metal mesh pretreatment: Ammonium persulfate, sodium hydroxide and deionized water were mixed in a mass ratio of 0.3:1:10 to prepare a solution. The solution was used to chemically etch several circular iron meshes cut to r=0.02m and 2000 mesh for 50 minutes, and then cleaned and dried.

[0048] (2) Preparation of geopolymer slurry: Weigh activated carbon and slag and mix them evenly to obtain a mixed powder, wherein the content of activated carbon is 7wt% of the mixed powder; then add sodium hydroxide solution (the mass ratio of sodium hydroxide to deionized water in the sodium hydroxide solution is 0.8:3) to the mixed powder, the mass ratio of sodium hydroxide solution to mixed powder is 3:5, and keep the speed at 2000 r / min and mechanically stir for 3 min to mix evenly to obtain a geopolymer slurry with an activated carbon content of 7wt%;

[0049] (3) The geopolymer slurry obtained in step (2) is coated on the surface of the metal iron mesh after the pretreatment in step (1). The mass of the coated slurry is fixed at 0.6g. Then it is cured in an oven at 60℃ for 72h to obtain composite film I. After curing, the geopolymer slurry becomes a geopolymer doped with activated carbon.

[0050] (4) Weigh 1g of polyethyleneimine, add 99g of deionized water, and sonicate until the polyethyleneimine is completely dissolved. Then add 0.1g of rutile TiO2 nanoparticles and mix with magnetic stirring for 1h to obtain a TiO2 suspension with polyethyleneimine on the surface, for later use. Weigh 0.1211g of tris(hydroxymethyl)aminomethane powder and dissolve it in 100mL of deionized water. After stirring, obtain a Tris solution with a concentration of 10mM. Adjust the pH of the Tris solution to 8.5 using a 0.1mol / L hydrochloric acid solution to obtain a Tris-HCl buffer solution. Weigh 0.6g of dopamine hydrochloride powder and dissolve it in 100mL of Tris-HCl buffer solution to obtain a dopamine deposition solution with a concentration of 0.6mg / L, for later use.

[0051] Take the composite membrane I obtained after curing in step (3), place it in a filter, and use a vacuum filtration process at a pressure of 0.08 MPa to draw 30 mL of the prepared TiO2 suspension with polyethyleneimine on its surface into the pores of the composite membrane I. Remove the membrane, place it in an oven at 80°C for 1 hour, and then let it stand in 50 mL of the prepared dopamine deposition solution for 36 hours. After washing with water and drying at 60°C for 20 minutes, the geopolymer-metal mesh composite membrane is obtained. The TiO2 suspension with polyethyleneimine on its surface after curing becomes TiO2 nanoparticles with polyethyleneimine on their surface.

[0052] 2. Adsorption performance determination

[0053] An application of the aforementioned geopolymer-metal mesh composite membrane in adsorption materials: The geopolymer-metal mesh composite membrane obtained above was used in filtration experiments on simulated kerosene emulsion and Congo red dye, respectively: The geopolymer-metal mesh composite membrane prepared in Example 3 was placed in a filter and gravity filtered 20 mL of kerosene emulsion (mass ratio of kerosene, deionized water, and sodium dodecyl sulfate = 1:99:0.01) and Congo red solution (10 mg / L), respectively, and the separation efficiencies reached 99.15% and 92.31%, respectively.

[0054] The geopolymer-metal mesh composite membrane of this invention, after being doped with activated carbon and filled with TiO2 nanoparticles, exhibits high separation efficiency in treating oily wastewater. The TiO2 nanoparticle filling reduces the pore size of the filter layer, further improving the separation efficiency of oil-water emulsions. Furthermore, the modification of the composite membrane with polyethyleneimine and dopamine results in a large number of positively and negatively charged functional groups on the membrane surface (polyethyleneimine carries a positive charge, and dopamine carries a negative charge), which electrostatically adsorbs charged dye molecules, achieving effective removal. The geopolymer-metal mesh composite membrane has advantages such as simple preparation process, low cost, and no need for external pressure.

[0055] This invention uses a flexible, high-mechanical-strength metal mesh as a support and an activated carbon-doped geopolymer as a filter layer. Rutile TiO2 nanoparticles are used to fill the pores of the transition layer to prepare a dual-functional TiO2-filled slag-based geopolymer-metal mesh composite membrane. The dense structure of the activated carbon-doped geopolymer can fill the pores of the metal mesh, while the strong adsorption properties of activated carbon can adsorb and separate dye molecules. The filling of TiO2 nanoparticles can reduce the pore size of the filter layer, further improving the separation efficiency of oil-water emulsions.

[0056] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A geopolymer-metal mesh composite membrane, characterized in that: The material comprises a metal mesh, a geopolymer, TiO2 nanoparticles coated with polyethyleneimine, and dopamine. The metal mesh serves as the support, the geopolymer doped with activated carbon acts as the filter layer, and TiO2 nanoparticles coated with polyethyleneimine fill the transition layer to create pores. Polyethyleneimine and dopamine stabilize the TiO2 nanoparticle filling structure and enhance the adsorption of dye molecules. The preparation method of the geopolymer-metal mesh composite membrane includes the following steps: (1) Metal mesh pretreatment; (2) Preparation of geopolymer slurry; (3) Take the metal mesh pretreated in step (1) and coat it with the geopolymer slurry obtained in step (2) and cure it to obtain composite membrane I; (4) Take the composite membrane I obtained after curing in step (3), and use vacuum filtration to draw the TiO2 suspension with polyethyleneimine on the surface into the pores of the composite membrane I. After curing, immerse it in dopamine deposition solution, and after cleaning and drying, the geopolymer-metal mesh composite membrane is obtained.

2. The geopolymer-metal mesh composite membrane according to claim 1, characterized in that: The metal mesh is one of copper mesh, nickel mesh or iron mesh; the dopamine is a dopamine deposition solution, which is obtained by weighing dopamine hydrochloride and dissolving it in Tris-HCl buffer solution.

3. A method for preparing a geopolymer-metal mesh composite membrane as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Metal mesh pretreatment; (2) Preparation of geopolymer slurry; (3) Take the metal mesh pretreated in step (1) and coat it with the geopolymer slurry obtained in step (2) and cure it to obtain composite membrane I; (4) Take the composite membrane I obtained after curing in step (3), and use vacuum filtration to draw the TiO2 suspension with polyethyleneimine on the surface into the pores of the composite membrane I. After curing, immerse it in dopamine deposition solution, and after cleaning and drying, the geopolymer-metal mesh composite membrane is obtained.

4. The method for preparing the geopolymer-metal mesh composite membrane according to claim 3, characterized in that: In step (1), the metal mesh pretreatment is performed by chemically etching the metal mesh for 20-50 minutes with a solution of ammonium persulfate, sodium hydroxide and water, followed by cleaning and drying. The mass ratio of ammonium persulfate, sodium hydroxide and water is 0.2-0.4:1:

10.

5. The method for preparing the geopolymer-metal mesh composite membrane according to claim 3, characterized in that: The preparation of the geopolymer slurry in step (2) involves mixing activated carbon and slag evenly to obtain a mixed powder, then adding sodium hydroxide solution to the mixed powder and stirring to mix evenly. The curing temperature in step (3) is 20~120 ℃ and the curing time is 24~72 h; the curing temperature in step (4) is 20~80 ℃ and the curing time is 1~5 h.

6. The method for preparing the geopolymer-metal mesh composite membrane according to claim 5, characterized in that: The activated carbon content is 1-9 wt% of the mixed powder; the mass ratio of sodium hydroxide to water in the sodium hydroxide solution is 0.2-1:3; the mass ratio of the sodium hydroxide solution to the mixed powder is 2-5:5; the stirring speed is 500-3000 r / min, and the stirring time is 0.5-5 min.

7. The method for preparing the geopolymer-metal mesh composite membrane according to claim 3, characterized in that: The drying temperature in step (4) is 20~120 ℃ and the drying time is 10~60 min; the vacuum filtration pressure in step (4) is 0.07~0.1 MPa; the immersion time in the dopamine deposition solution in step (4) is 12~36 h.

8. The method for preparing the geopolymer-metal mesh composite membrane according to claim 3, characterized in that: The TiO2 suspension with polyethyleneimine on its surface mentioned in step (4) is obtained by mixing polyethyleneimine, TiO2 nanoparticles and water in a mass ratio of 1:0.05~0.2:99; the volume of the TiO2 suspension with polyethyleneimine on its surface used is 10~30 mL; the mass concentration of the dopamine deposition solution mentioned in step (4) is 0.6 mg / L; the volume of the dopamine deposition solution used is 20~100 mL.

9. The application of a geopolymer-metal mesh composite membrane as described in any one of claims 1-8 in wastewater adsorption materials.

10. The application according to claim 9, characterized in that: The wastewater is an organic wastewater consisting of a binary system of oil-water emulsion and dye.

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