A graphene separation membrane having a pleated structure and a method of manufacturing the same

Abstract

The application discloses a graphene separation membrane with a wrinkle structure and a preparation method thereof, and belongs to the technical field of membrane separation. The graphene separation membrane is prepared by the following steps: depositing a nanofiber layer on a porous membrane substrate, depositing a graphene layer on the nanofiber layer, turning over the obtained material and tightly attaching the graphene layer on a pre-stretched elastic tape, tearing off the porous membrane substrate, and releasing the elastic tape to shrink the nanofiber layer and the graphene layer, then coating an organic polymer casting solution on the shrunk nanofiber layer, immersing the nanofiber layer in anhydrous ethanol to perform phase conversion, and finally peeling the prepared membrane from the elastic tape. The preparation method is simple and reliable, and does not need expensive medicines and equipment. The prepared graphene separation membrane with the wrinkle structure has high porosity, large water flux, and good light-heat conversion capacity, and can heat water on the membrane surface under the irradiation of sunlight, so that the water flux is further improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of membrane separation technology, and particularly relates to a graphene separation membrane with a pleated structure and a preparation method thereof. BACKGROUND

[0002] Water pollution is a serious environmental challenge facing the world today, resulting from various industrial emissions, agricultural activities, domestic sewage, and improper waste disposal methods, leading to excessive levels of harmful substances in water bodies, seriously threatening the balance of the ecosystem and the sustainable use of water resources, and even human health. Membrane separation water treatment technology is an efficient and advanced wastewater treatment technology that uses membranes of different pore sizes to selectively separate and concentrate suspended solids, organic matter, heavy metal ions, and other substances in water. This technology has the advantages of high separation efficiency, low energy consumption, and simple operation, and has been widely used in water treatment. Through membrane separation technology, pollutants in water can be effectively removed, water quality can be improved, and water resources can be reused. At the same time, this technology also has the characteristics of small footprint and simple equipment maintenance, bringing revolutionary changes to the water treatment industry.

[0003] Traditional separation membranes often have a contradiction between permeability and selectivity, i.e. increasing the permeability of the membrane often reduces the selectivity of the membrane, and vice versa. Graphene separation membranes are thin films prepared using graphene materials, which can efficiently separate harmful substances in water such as heavy metal ions and organic pollutants, with excellent properties such as high flux, high selectivity, and high stability, and have great application potential in water treatment. Currently, the most common graphene separation membranes are prepared by orderly stacking graphene nanosheets and have a layered structure. However, the porosity of such graphene separation membranes is very low, resulting in a permeation flux far less than the theoretical value. Therefore, it is of great value and significance to prepare graphene separation membranes with high porosity and ultra-high flux. SUMMARY

[0004] In view of the problem that the porosity of existing graphene separation membranes is low, resulting in a permeation flux far less than the theoretical value, the present application aims to provide a graphene separation membrane with a pleated structure and a preparation method thereof. The basic concept of the present application is to use strong adhesive tape to form a pleated structure of the graphene separation layer, increasing the number of pores per unit membrane area, i.e. increasing the membrane porosity; the pleated graphene has good light-heat conversion capability, which can heat the water on the surface of the membrane under sunlight, significantly reducing the viscosity of the water, thereby further improving the water flux.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] The application provides a preparation method of a graphene separation membrane with a wrinkle structure, comprising the following steps: firstly, preparing a nanofiber dispersion liquid and a graphene dispersion liquid respectively, depositing a nanofiber layer on a porous membrane substrate, then depositing a graphene layer on the nanofiber layer, turning over the obtained material and tightly attaching the graphene layer on a pre-stretched elastic tape, tearing off the porous membrane substrate, and releasing the elastic tape to shrink the nanofiber layer and the graphene layer, then coating an organic polymer casting solution on the shrunk nanofiber layer, immersing in anhydrous ethanol for phase inversion, and finally peeling off the prepared membrane from the elastic tape.

[0007] Based on the above technical scheme, further, the porous membrane substrate is one of polyacrylonitrile membrane, polyvinylidene fluoride membrane, mixed cellulose ester membrane, polypropylene membrane, polycarbonate membrane, polytetrafluoroethylene membrane, polyether sulfone membrane and polysulfone membrane with a flat plate structure, and the pore size ranges from 0.01 to 10.0 microns.

[0008] Based on the above technical scheme, further, the graphene includes graphene obtained by chemically exfoliating graphite and derivatives thereof, and is one or a mixture of two or more of graphene oxide, reduced graphene oxide, hydroxylated graphene, carboxylated graphene, aminated graphene and sulfonated graphene.

[0009] Based on the above technical scheme, further, the nanofiber is carbon material nanofiber, metal nanofiber, metal oxide nanofiber, organic polymer nanofiber or inorganic nitrogen / carbon compound nanofiber.

[0010] Based on the above technical scheme, further, the carbon material nanofiber is one or a mixture of two or more of carbon nanotube and carbon nanofiber; the metal nanofiber is one or a mixture of two or more of gold nanofiber, silver nanofiber, copper nanofiber, cobalt nanofiber, iron nanofiber and nickel nanofiber; the metal oxide nanofiber is one or a mixture of two or more of iron oxide nanofiber, zinc oxide nanofiber, titanium oxide nanofiber, aluminum oxide nanofiber, gallium oxide nanofiber and tin oxide nanofiber; the organic polymer nanofiber is one or a mixture of two or more of poly(p-phenylene terephthalamide) nanofiber and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid); and the inorganic nitrogen / carbon compound nanofiber is one or a mixture of two or more of silicon carbide nanofiber and boron nitride nanofiber.

[0011] Based on the above technical scheme, further, the deposition method is one of vacuum suction filtration, spraying and evaporation self-assembly.

[0012] Based on the above technical scheme, further, the elastic tape is pre-stretched to 150% to 400% of the original length.

[0013] Based on the above technical scheme, further, the organic polymer casting solution is a viscous solution obtained by uniformly stirring a high molecular organic polymer, a pore forming agent and an organic solvent at 40-80 DEG C.

[0014] Based on the above technical scheme, further, the high molecular polymer is one or more than two kinds of mixture of polyacrylonitrile, polyvinylidene fluoride, polyether sulfone and polysulfone; the pore forming agent is one or mixture of two kinds of polyvinylpyrrolidone and polyethylene glycol; the organic solvent is one or more than two kinds of mixture of N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

[0015] Based on the above technical scheme, further, the mass ratio of the high molecular polymer, the pore forming agent and the organic solvent is 1:(0.2-1):5-10.

[0016] In the second aspect, the application provides a graphene separation membrane with a wrinkle structure prepared by the above preparation method.

[0017] Based on the above technical scheme, further, the graphene separation membrane has a layered structure, including a porous organic polymer base layer, a nanofiber intermediate layer and a wrinkle graphene surface layer.

[0018] Based on the above technical scheme, further, the thickness of the porous organic polymer base layer is 20-200 mu m, the thickness of the nanofiber intermediate layer is 1-50 mu m, and the thickness of the wrinkle graphene surface layer is 1-50 mu m.

[0019] In the third aspect, the application provides the application of the above graphene separation membrane with a wrinkle structure in wastewater treatment.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] The graphene separation membrane with a wrinkle structure prepared by the application has high porosity, excellent separation performance, and can effectively convert sunlight into heat energy to heat the water on the surface of the membrane and reduce the viscosity of the water, thereby further improving the water permeability of the graphene separation membrane with a wrinkle structure. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the application and constitute a part of the specification, and are used to explain the application together with the following specific embodiments, but do not constitute a limitation on the application.

[0023] Figure 1 The low-magnification scanning electron microscope image of the surface of the wrinkle graphene oxide separation membrane prepared in Example 1;

[0024] Figure 2 A high magnification scanning electron microscope image of the surface of the corrugated graphene oxide separation membrane prepared in Example 1;

[0025] Figure 3 A scanning electron microscope image of the cross section of the corrugated graphene separation membrane prepared in Example 2;

[0026] Figure 4 A graph of the results of the photothermal conversion performance of the corrugated graphene separation membrane prepared in Example 3 under the irradiation of 645 W m -2 of sunlight.

[0027] Figure 5 A graph of the results of the pure water permeation rate of the corrugated graphene separation membrane prepared in Example 3 before and after the irradiation of sunlight. DETAILED DESCRIPTION

[0028] In order to further understand the present application, the preferred embodiments of the present application are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, and are not limitations to the claims of the present application.

[0029] Example 1

[0030] (1) Synthesis of graphene oxide: 1.0 g of natural graphite powder and 0.5 g of sodium nitrate were weighed and added to 25 mL of concentrated sulfuric acid, and stirred magnetically for 8 h. Then, 3.0 g of potassium permanganate was slowly added in an ice bath, and stirring was continued for 4 h. Subsequently, the temperature was raised to 35°C, and 46 mL of deionized water was slowly added after stirring for 2 h, and 140 mL of deionized water was added after stirring for 0.5 h. Thereafter, 10 mL of 30% hydrogen peroxide solution was quickly added. The product was centrifuged and washed with water several times, and freeze-dried;

[0031] (2) Preparation of graphene oxide dispersion: 50 mg of graphene oxide solid was weighed and added to 1 L of deionized water, and stirred for 1 h, and then ultrasonically treated in an ultrasonic cleaner for 1 h;

[0032] (3) Preparation of carbon nanotube dispersion: 200 mg of commercially purchased single-walled carbon nanotube powder and 500 mg of sodium dodecyl sulfate were weighed and added to 400 mL of deionized water, and then 3-5 rounds of stirring with a magnetic stirrer for 30 min and ultrasonic treatment with an ultrasonic cell disruptor (ultrasonic on for 3 s / ultrasonic off for 5 s) were alternately performed. The obtained carbon nanotube dispersion was centrifuged at a rotation speed of 8000 rpm for 10 min, and the supernatant was placed in a beaker.

[0033] (4) Put the mixed cellulose ester membrane with pore size of 0.22 μm into a vacuum filtration device, and filter 2 mL of the carbon nanotube dispersion prepared in step (3), and then filter 2 mL of the graphene oxide dispersion prepared in step (2), and dry the prepared material at a temperature not exceeding 80℃;

[0034] (5) Stretch 3M VHB elastic glue by 300%, and then tightly attach the side of the mixed cellulose ester membrane prepared in step (4) with graphene oxide to the elastic glue, and then slowly tear off the mixed cellulose ester membrane and release the elastic tape, to obtain a wrinkled graphene oxide / carbon nanotube layer;

[0035] (6) Put 5.0 g of polyether sulfone powder and 2.5 g of polyvinylpyrrolidone powder into 25.0 g of N-methylpyrrolidone, and stir at 60℃ for 4 h to prepare a casting solution, drop the casting solution onto the wrinkled graphene oxide prepared in step (5), and spin at a speed of 1000 rpm for 20 s; then, immerse it in anhydrous ethanol for phase inversion, and after 30 min, take off the prepared membrane from the elastic glue, to obtain a graphene separation membrane with a wrinkled structure.

[0036] Figure 1 The low-magnification scanning electron microscope image of the surface of the prepared graphene oxide separation membrane can be seen to have no cracks, holes or other defects on the membrane surface.

[0037] Figure 2 The high-magnification scanning electron microscope image of the surface of the prepared graphene oxide separation membrane can be seen to have a typical wrinkled structure.

[0038] The thickness of the graphene oxide / carbon nanotube layer of the prepared graphene oxide separation membrane with wrinkles is 10 μm, and the thickness of the lower porous polyether sulfone substrate is 55 μm.

[0039] The pure water permeation rate of the graphene oxide separation membrane with a wrinkled structure is 45 L m -2 h -1 bar -1 , and the rejection rate of molecules such as methyl blue and congo red is >99%, showing good separation performance.

[0040] Example 2

[0041] (1) Synthesis of graphene oxide: weigh 1.0 g of natural graphite powder and 0.5 g of sodium nitrate into 25 mL of concentrated sulfuric acid, and magnetically stir for 8 h. Then, slowly add 3.0 g of potassium permanganate in an ice bath, and continue to stir for 4 h. Then, increase the temperature to 35℃, stir for 2 h, slowly add 46 mL of deionized water, and stir for another 0.5 h. Then, quickly add 10 mL of 30% hydrogen peroxide solution. The product is centrifuged and washed with water several times, and then freeze-dried;

[0042] (2) Preparation of graphene dispersion: 50 mg of graphene oxide solid was weighed into 1 L of deionized water, stirred for 1 h and then treated with ultrasonic cleaning instrument for 1 h; 80 mL of the dispersion was measured and poured into a 100 mL polytetrafluoroethylene reaction kettle, and reduced at 120 °C for 6 h;

[0043] (3) Preparation of carbon nanotube dispersion: 200 mg of commercially purchased multi-walled carbon nanotube powder and 500 mg of sodium dodecyl sulfate were weighed into 400 mL of deionized water, then stirred with a magnetic stirrer for 30 min, and treated with an ultrasonic cell crusher for 1 h (ultrasonic opening 3 s / closing 5 s) alternately for 3-5 rounds. The obtained carbon nanotube dispersion was centrifuged at a speed of 8000 rpm for 10 min, and the supernatant was placed in a beaker;

[0044] (4) A polyvinylidene fluoride membrane with a pore size of 0.1 μm was installed in a vacuum filtration device, and 2 mL of the carbon nanotube dispersion prepared in step (3) was filtered, and then 2 mL of the graphene dispersion prepared in step (2) was filtered. The prepared sample was dried under the condition that the temperature did not exceed 80 °C;

[0045] (5) The 3M VHB elastic glue was stretched by 300% around, then the polyvinylidene fluoride membrane with graphene prepared in step (4) was tightly attached to the elastic glue, and then the polyvinylidene fluoride membrane was slowly torn off and the elastic tape was released, to prepare a wrinkled graphene / carbon nanotube layer;

[0046] (6) 5.0 g of polyvinylidene fluoride powder and 5.0 g of polyvinylpyrrolidone powder were added to 25.0 g of N-methylpyrrolidone, and a casting solution was prepared by stirring at 60 °C for 4 h. The casting solution was added dropwise to the wrinkled graphene prepared in step (5), and spin-coated at a speed of 1000 rpm for 20 s; then it was quickly immersed in anhydrous ethanol for phase inversion, and the prepared membrane was peeled off from the elastic glue after 30 min, to obtain a graphene separation membrane with a wrinkled structure.

[0047] Figure 3 The scanning electron microscope image of the cross section of the prepared graphene separation membrane can be seen to have a typical layered structure, the upper layer is a wrinkled graphene / carbon nanotube layer with a thickness of about 12 μm, and the lower layer is a porous polyvinylidene fluoride substrate with a thickness of 75 μm.

[0048] Example 3

[0049] (1) Synthesis of graphene oxide: 1.0 g of natural graphite powder and 0.5 g of sodium nitrate were weighed into 25 mL of concentrated sulfuric acid and stirred magnetically for 8 h. Then, 3.0 g of potassium permanganate was slowly added in an ice bath and stirring was continued for 4 h. Subsequently, the temperature was raised to 35 °C and stirring was continued for 2 h before 46 mL of deionized water was slowly added. Stirring was continued for 0.5 h before 140 mL of deionized water was added. Then, 10 mL of 30% hydrogen peroxide solution was quickly added. The product was freeze-dried after multiple centrifugation and water washing steps;

[0050] (2) Preparation of graphene dispersion: 10 mg of graphene oxide solid was weighed into 200 mL of deionized water and stirred for 1 h before being sonicated in an ultrasonic cleaner for 1 h. Then, 5 μL of hydrazine hydrate solution and 140 μL of ammonia were added and the reduction was carried out at 60 °C for 10 min to obtain a graphene dispersion;

[0051] (3) Preparation of carbon nanotube dispersion: 200 mg of single-walled carbon nanotube powder and 500 mg of sodium dodecyl sulfate were weighed into 400 mL of deionized water. Then, 30 min of stirring with a magnetic stirrer and 1 h of sonication with an ultrasonic cell disruptor (ultrasonic on for 3 s and off for 5 s) were alternately performed for 3-5 cycles. The obtained carbon nanotube dispersion was centrifuged at 8000 rpm for 10 min and the supernatant was collected in a beaker;

[0052] (4) A polyacrylonitrile membrane with a pore size of 0.22 μm was mounted in a vacuum filtration device and 2 mL of the carbon nanotube dispersion prepared in step (3) was filtered. Then, 2 mL of the graphene dispersion prepared in step (2) was filtered. The obtained sample was dried at a temperature of not more than 80 °C.

[0053] (5) A 3M VHB elastic adhesive was stretched by 400% in all directions. Then, the polyacrylonitrile membrane with graphene prepared in step (4) was tightly attached to the elastic adhesive with the graphene side. Then, the polyacrylonitrile membrane was slowly peeled off and the elastic adhesive was released to obtain a wrinkled graphene / carbon nanotube layer;

[0054] (6) A casting solution was prepared by stirring 5.0 g of polyethersulfone powder and 2.5 g of polyvinylpyrrolidone powder in 25.0 g of N,N-dimethylformamide at 60 °C for 4 h. The casting solution was dropped onto the wrinkled graphene prepared in step (5) and spin-coated at a rotation speed of 1000 rpm for 30 s. Then, the graphene was quickly immersed in anhydrous ethanol for phase inversion. After 30 min, the obtained membrane was peeled off from the elastic adhesive to obtain a graphene separation membrane with a wrinkled structure.

[0055] The thickness of the graphene / carbon nanotube layer of the prepared graphene separation membrane with a wrinkled structure was 25 μm and the thickness of the porous polyethersulfone substrate was 72 μm.

[0056] Figure 4 The surface temperature of the prepared corrugated graphene separation membrane as a function of irradiation time under the irradiation of 645 W m -2 of sunlight. As can be seen from the figure, the surface temperature of the corrugated graphene membrane rises from room temperature 22.4℃ to 52.4℃ within 1 min, showing excellent light-heat conversion capability.

[0057] Figure 5 The pure water permeation rate of the prepared corrugated graphene membrane before and after the irradiation of sunlight. As can be seen from the figure, the pure water permeation rate thereof before the irradiation is 36.5 L m -2 h -1 bar -1 , and significantly rises to 68.4 L m -2 h -1 bar -1 after the irradiation, showing obvious improvement effect of the pure water permeation rate.

[0058] Example 4

[0059] (1) Synthesis of graphene oxide: 1.0 g of natural graphite powder and 0.5 g of sodium nitrate were weighed and added into 25 mL of concentrated sulfuric acid, and magnetically stirred for 8 h, then 3.0 g of potassium permanganate was slowly added in an ice bath, and continuously stirred for 4 h. Subsequently, the temperature was raised to 35℃, and after stirring for 2 h, 46 mL of deionized water was slowly added, and after stirring for 0.5 h, 140 mL of deionized water was added, and then 10 mL of 30% hydrogen peroxide solution was quickly added. The product was centrifuged and washed with water several times, and then freeze-dried;

[0060] (2) Preparation of sulfonated graphene dispersion: 200 mL of graphene oxide dispersion with a concentration of 100 mg L -1 was prepared, and the pH value was adjusted to 9-10 with 5 wt% sodium carbonate solution, and then 600 mg of sodium borohydride was added. The mixture was reacted at 80℃ for 1 h under stirring. The generated precipitate was separated by centrifugation, washed with water several times, and then redispersed in water by ultrasonic. 46 mg of p-aminobenzenesulfonic acid and 18 mg of sodium nitrite were weighed and added into an ice-bath-cooled HCl solution to prepare an aryl diazonium salt; then the diazonium salt solution was added to the above partially reduced graphene oxide dispersion, and reacted for 2 h under ice-bath conditions; the product was separated by centrifugation, washed several times, and then redispersed in water. After adding 5 μL of hydrazine hydrate, the mixture was reacted at 100℃ for 12 h to obtain a sulfonated graphene dispersion.

[0061] (3) Preparation of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) dispersion: 10 mL of commercially purchased poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) dispersion with a concentration of 1 wt% was diluted to 100 mL with deionized water;

[0062] (4) Put a polycarbonate membrane with a pore size of 0.1 μm into a vacuum filtration device, and filter 1 mL of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) dispersion prepared in step (3) and then filter 2 mL of the sulfonated graphene dispersion prepared in step (2), and dry the prepared sample at a temperature not higher than 80 °C;

[0063] (5) Stretch 3M VHB elastic tape by 300%, and then tightly attach the polycarbonate membrane with sulfonated graphene prepared in step (4) to the elastic tape, and then slowly tear off the polycarbonate membrane and release the elastic tape to prepare a wrinkled graphene / poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) layer;

[0064] (6) Add 5.0 g of polyethersulfone powder and 2.5 g of polyvinylpyrrolidone powder into 25.0 g of N-methylpyrrolidone, and stir at 60 °C for 4 h to prepare a casting solution, drop the casting solution onto the wrinkled sulfonated graphene prepared in step (5), and spin coat at a rotation speed of 1000 rpm for 20 s. Subsequently, immerse it in anhydrous ethanol for phase inversion, and after 30 min, peel off the prepared membrane from the elastic tape to obtain a graphene separation membrane with a wrinkled structure.

[0065] The thickness of the sulfonated graphene / poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) layer of the prepared graphene separation membrane with a wrinkled structure is 6 μm, and the thickness of the porous polyethersulfone substrate is 72 μm.

[0066] Example 5

[0067] (1) Synthesis of graphene oxide: weigh 1.0 g of natural graphite powder and 0.5 g of sodium nitrate into 25 mL of concentrated sulfuric acid, and magnetically stir for 8 h, then slowly add 3.0 g of potassium permanganate in an ice bath, and continue to stir for 4 h. Subsequently, increase the temperature to 35 °C, stir for 2 h, then slowly add 46 mL of deionized water, and stir for another 0.5 h before adding 140 mL of deionized water. Then, quickly add 10 mL of 30% hydrogen peroxide solution. The product is centrifuged and washed with water several times, and then freeze-dried;

[0068] (2) Preparation of graphene oxide dispersion: weigh 500 mg of graphene oxide solid into 1 L of deionized water, stir for 1 h, and then ultrasonically treat in an ultrasonic cleaner for 1 h;

[0069] (3) Preparation of silver nanowire dispersion: weigh 10 mL of a commercially purchased silver nanowire dispersion with a concentration of 10 mg mL -1 Dilute the silver nanowire dispersion to 100 mL with deionized water;

[0070] (4) Place the mixed cellulose ester membrane with a pore size of 0.45 μm on a glass plate, and use a spray gun to spray the silver nanofiber dispersion prepared in step (3) onto the mixed cellulose ester membrane, and then naturally dry or dry at a temperature of not higher than 80°C, and then use a spray gun to spray the graphene oxide dispersion prepared in step (2) onto the silver nanofiber, and then naturally dry or dry at a temperature of not higher than 80°C.

[0071] (5) Stretch the 3M VHB elastic adhesive by 300%, and then tightly attach the mixed cellulose ester membrane with graphene oxide prepared in step (4) to the elastic adhesive, and then slowly tear off the mixed cellulose ester membrane and release the elastic adhesive tape, to obtain a wrinkled graphene / silver nanowire layer.

[0072] (6) Add 5.0 g of polyacrylonitrile and 2.5 g of polyethylene glycol powder into 25.0 g of N,N-dimethylacetamide, and stir at 70°C for 4 h to prepare a casting solution. Drop the casting solution onto the wrinkled graphene oxide prepared in step (5), and spin coat at a speed of 1000 rpm for 20 s. Then, quickly immerse it in anhydrous ethanol for phase inversion, and after 30 min, peel off the prepared membrane from the elastic adhesive, to obtain a graphene separation membrane with a wrinkled structure.

[0073] The thickness of the prepared graphene separation membrane with wrinkles is 22 μm, and the thickness of the porous polyethersulfone substrate is 60 μm.

[0074] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications should also be considered as falling within the scope of protection of the present application.

Claims

1. A method for producing a graphene separation membrane having a corrugated structure, characterized by, The method comprises the following steps: First, a nanofiber dispersion liquid and a graphene dispersion liquid are prepared respectively, a nanofiber layer is deposited on a porous membrane substrate, a graphene layer is deposited on the nanofiber layer, the obtained material is turned over and the graphene layer is tightly attached to a pre-stretched elastic tape, the porous membrane substrate is torn off, and the elastic tape is released to shrink the nanofiber layer and the graphene layer, then a layer of organic polymer casting solution is coated on the shrunk nanofiber layer, and the organic polymer casting solution is immersed in anhydrous ethanol for phase inversion, finally the prepared membrane is peeled off from the elastic tape to obtain the graphene separation membrane with wrinkle structure.

2. The production method according to claim 1, characterized by, The porous membrane substrate is one of polyacrylonitrile membrane, polyvinylidene fluoride membrane, mixed cellulose ester membrane, polypropylene membrane, polycarbonate membrane, polytetrafluoroethylene membrane, polyethersulfone membrane or polysulfone membrane with a flat plate structure, and the pore size ranges from 0.01 to 10.0 μm.

3. The preparation method according to claim 1, characterized in that, The graphene is one or a mixture of two or more of graphene oxide, reduced graphene oxide, hydroxylated graphene, carboxylated graphene, aminated graphene or sulfonated graphene; and the nanofiber is one or a mixture of two or more of carbon material nanofiber, metal nanofiber, metal oxide nanofiber, organic polymer nanofiber or inorganic nitrogen / carbonide nanofiber.

4. The production method according to claim 3, characterized by, The carbon material nanofiber is one or a mixture of two of carbon nanotube or carbon nanofiber; the metal nanofiber is one or a mixture of two or more of gold nanofiber, silver nanofiber, copper nanofiber, cobalt nanofiber, iron nanofiber or nickel nanofiber; the metal oxide nanofiber is one or a mixture of two or more of iron oxide nanofiber, zinc oxide nanofiber, titanium oxide nanofiber, aluminum oxide nanofiber, gallium oxide nanofiber or tin oxide nanofiber; the organic polymer nanofiber is one or a mixture of two of poly(p-phenyleneterephthalamide) nanofiber or poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid); and the inorganic nitrogen / carbonide nanofiber is one or a mixture of two of silicon carbide nanofiber or boron nitride nanofiber.

5. The preparation method according to claim 1, characterized in that, The deposition method is one of vacuum suction filtration, spraying or evaporation self-assembly; and the elastic tape is pre-stretched to 150% to 400% of the original length.

6. The method of claim 1, wherein, The organic polymer casting solution is a viscous solution obtained by uniformly stirring a high molecular organic polymer, a pore-forming agent and an organic solvent at 40 to 80 ℃.

7. The production method according to claim 6, characterized by, The high molecular organic polymer is one or a mixture of two or more of polyacrylonitrile, polyvinylidene fluoride, polyethersulfone or polysulfone; the pore-forming agent is one or a mixture of two of polyvinylpyrrolidone or polyethylene glycol; the organic solvent is one or a mixture of two or more of N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone; and the mass ratio of the high molecular polymer, the pore-forming agent and the organic solvent is 1:(0.2 to 1):5 to 10.

8. The graphene separation membrane with wrinkle structure prepared by the preparation method in any one of claims 1 to 7.

9. The graphene separation membrane having a corrugated structure according to claim 8, characterized by, The graphene separation membrane has a layered structure, comprising a porous organic polymer base layer, a nanofiber intermediate layer and a wrinkled graphene surface layer; the thickness of the porous organic polymer base layer is 20-200 μm, the thickness of the nanofiber intermediate layer is 1-50 μm, and the thickness of the wrinkled graphene surface layer is 1-50 μm.

10. Use of the graphene separation membrane with a wrinkled structure according to claim 8 or 9 in wastewater treatment.

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