An interfacial polymerization repaired nanoporous reduced graphene oxide membrane, and a preparation method and application thereof

Abstract

This invention belongs to the field of membrane separation technology and discloses an interfacially polymerized repaired nanoporous reduced graphene oxide membrane, its preparation method, and its applications. The preparation method includes the following steps: S1, reducing graphene oxide to obtain reduced graphene oxide; S2, oxidizing and etching the reduced graphene oxide to obtain nanoporous reduced graphene oxide; S3, loading the nanoporous reduced graphene oxide onto a porous support membrane to obtain a nanoporous reduced graphene oxide membrane; S4, wetting the nanoporous reduced graphene oxide membrane with water, then performing an interfacial polymerization reaction with an organic solution containing polyacrylamide chloride monomers, followed by drying to obtain the interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The membrane of this invention possesses high permeation flux, high separation selectivity, and efficient retention capacity for small molecule drugs, and has broad application prospects in pharmaceutical wastewater treatment, solvent recovery, and other fields.

Description

Technical Field

[0001] This invention relates to the field of membrane separation technology, specifically to a nanoporous reduced graphene oxide membrane repaired by interfacial polymerization, its preparation method, and its application. Background Technology

[0002] With the accelerated pace of industrialization and urbanization in my country, water scarcity has become increasingly prominent, making wastewater resource utilization a crucial strategic approach to alleviate the water crisis and achieve water recycling. In the field of industrial wastewater treatment, especially wastewater from industries such as pharmaceuticals and fine chemicals, the wastewater is generally characterized by high organic matter concentration, poor biodegradability, and high salt content, making it extremely difficult to treat. Even after traditional biological treatment, this type of wastewater still retains a large amount of recalcitrant organic matter, requiring further advanced treatment to meet discharge standards or for reuse. Simultaneously, the high concentration of inorganic salts in the wastewater not only inhibits microbial activity, leading to a decrease in biochemical treatment efficiency, but also restricts the discharge of treated effluent into municipal pipe networks or downstream industrial park wastewater treatment plants, further exacerbating the difficulty and pressure of industrial wastewater treatment. Against this backdrop, membrane separation technology, particularly nanofiltration (NF) and reverse osmosis (RO) processes, has been widely applied in advanced industrial wastewater treatment and reuse systems due to its high separation efficiency, becoming one of the core technologies for achieving wastewater resource utilization.

[0003] However, existing membrane separation technologies face many technical bottlenecks in practical applications, severely restricting their industrialization and effectiveness. Specifically, firstly, traditional polyamide-based organic nanofiltration membranes exhibit little difference in retention characteristics for organic matter and inorganic salts, making selective separation difficult. This means they cannot efficiently retain recalcitrant organic matter while allowing inorganic salts to permeate, leading to the simultaneous enrichment of organic matter and salts in the membrane concentrate. Subsequent evaporation and crystallization processes cannot yield high-purity crystalline salts, resulting in mixed salts that must be disposed of as hazardous waste, significantly increasing treatment costs and environmental risks. Secondly, organic pollutants in industrial wastewater readily adsorb and deposit on membrane surfaces, causing severe membrane fouling, leading to decreased flux and increased operating energy consumption. For high-precision organic nanofiltration or reverse osmosis membranes, their poor chemical stability prevents effective flux recovery through backwashing; frequent chemical cleaning not only shortens membrane life but also generates secondary pollution. Although inorganic ceramic membranes offer better fouling resistance and chemical stability, their high manufacturing costs and complex production processes hinder their large-scale application in industrial wastewater treatment. Furthermore, in organic solvent systems in the chemical and bio-fermentation industries, existing nanofiltration membrane materials generally suffer from poor solvent resistance and are prone to swelling and failure, while ceramic membranes often lack sufficient precision, limiting the application of membrane separation technology in solvent recovery and resource utilization.

[0004] In recent years, two-dimensional materials, represented by graphene oxide (GO), have attracted widespread attention in the field of membrane separation due to their unique layered structure, excellent hydrophilicity, and tunable interlayer spacing. Furthermore, the abundant oxygen-containing functional groups on their surface endow the membranes with good hydrophilicity and antifouling capabilities, providing a new technological path for the efficient and selective separation of organic matter and inorganic salts. However, existing graphene oxide-based separation membranes still suffer from problems such as low membrane flux and insufficient separation factor, making it difficult to simultaneously meet the core requirements of industrial applications for high flux, high selectivity, and high stability, and failing to effectively overcome the bottlenecks of existing membrane separation technologies.

[0005] Therefore, developing a novel membrane material that combines high flux, high organic matter rejection rate, high inorganic salt permeability, and excellent fouling resistance to solve the application problems of existing membrane separation technology in industrial wastewater treatment has become a key technological direction for promoting the resource utilization of industrial wastewater and expanding the application of membrane separation technology in organic solvent systems. This is of great significance for alleviating the water resource crisis and promoting the development of green and low-carbon industries. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a nanoporous reduced graphene oxide membrane for interfacial polymerization repair, its preparation method, and its application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing an interfacially polymerized repaired nanoporous reduced graphene oxide membrane, comprising the following steps: S1. Reduce graphene oxide to obtain reduced graphene oxide; S2. The reduced graphene oxide is subjected to oxidation etching treatment to obtain nanoporous reduced graphene oxide. S3. Load the nanoporous reduced graphene oxide onto a porous support membrane to obtain a nanoporous reduced graphene oxide membrane. S4. After wetting the nanoporous reduced graphene oxide membrane with water, it undergoes an interfacial polymerization reaction with an organic solution containing polyacrylamide monomers, and is then dried to obtain the interfacially polymerized and repaired nanoporous reduced graphene oxide membrane.

[0008] As a preferred embodiment of the preparation method of the interface polymerization repair nanoporous reduced graphene oxide film of the present invention, in step S1, the reduction treatment is ultraviolet light irradiation reduction or hydrothermal reduction.

[0009] Preferably, the ultraviolet light wavelength for the ultraviolet light irradiation reduction is 254nm, the power is 10W, and the irradiation time is 10min-120min; and / or, the hydrothermal reduction temperature is 90℃-120℃, and the time is 1h-2h.

[0010] More preferably, the irradiation time for the ultraviolet light irradiation reduction is 30 minutes.

[0011] More preferably, the hydrothermal reduction temperature is 100°C and the time is 1 hour.

[0012] In a preferred embodiment of the method for preparing the interfacial polymerization-repaired nanoporous reduced graphene oxide film of the present invention, in step S2, the oxidation etching treatment is as follows: the reduced graphene oxide and potassium persulfate are mixed and treated at 80℃-120℃ for 25min-45min, cooled, and then hydrogen peroxide is added, and treated at 80℃-120℃ for 1h-2h; the concentration of potassium persulfate in the reaction system is 0.8mg / mL-1.5mg / mL; and the volume of hydrogen peroxide is 1.5%-3% of the total volume of the reaction system.

[0013] Preferably, the oxidation etching process is as follows: the reduced graphene oxide and potassium persulfate are mixed and treated at 100°C for 30 min, cooled, and then hydrogen peroxide is added and treated at 100°C for 1 h.

[0014] Preferably, the concentration of potassium persulfate in the reaction system is 1 mg / mL.

[0015] Preferably, the volume of the hydrogen peroxide is 2% of the total volume of the reaction system.

[0016] As a preferred embodiment of the preparation method of the interface polymerization repair nanoporous reduced graphene oxide membrane of the present invention, before step S3, a pretreatment step of cleaning and hydrophilic modification of the porous support membrane is further included.

[0017] As a preferred embodiment of the preparation method of the nanoporous reduced graphene oxide membrane with interface polymerization repair described in this invention, in step S3, the porous support membrane is a microfiltration membrane or an ultrafiltration membrane, and its material is selected from any one of polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, alumina, zirconium oxide, silicon oxide, titanium oxide, zeolite, and silicon carbide.

[0018] As a preferred embodiment of the preparation method of the interface polymerization repair nanoporous reduced graphene oxide membrane of the present invention, in step S3, the loading includes the following steps: (1) dispersing the nanoporous reduced graphene oxide in a sodium tetraborate solution to prepare a raw material solution; (2) using cross-flow filtration to deposit the nanoporous reduced graphene oxide in the raw material solution onto the surface of the porous support membrane to form a nanoporous reduced graphene oxide layer; the deposition is performed by pressure filtration with a transmembrane pressure difference of 0.1 MPa-1 MPa; the concentration of the sodium tetraborate solution is 2 mmol / L-10 mmol / L.

[0019] Preferably, the concentration of the sodium tetraborate solution is 5 mmol / L.

[0020] As a preferred embodiment of the preparation method of the nanoporous reduced graphene oxide membrane repaired by interface polymerization according to the present invention, the polyacrylamide chloride monomer includes at least one of pyromellitic trimethylolpropionate, tridecanoic acid chloride, and isophthaloyl chloride; the mass concentration of the organic solution containing the polyacrylamide chloride monomer is 0.1wt%-2wt%.

[0021] Preferably, the polyacrylamide chloride monomer includes pyromellitic trimethylolpropionate chloride.

[0022] Preferably, the solvent of the organic solution containing polyacrylamide chloride monomer includes at least one of hexane, toluene, and carbon tetrachloride.

[0023] Preferably, the organic solution containing polyacrylamide chloride monomer has a mass concentration of 0.5 wt%.

[0024] In a preferred embodiment of the method for preparing the interface-polymerized repaired nanoporous reduced graphene oxide film of the present invention, in step S4, the drying temperature is 45℃-200℃ and the time is 10min-60min.

[0025] Preferably, the drying temperature is 60°C and the time is 15 minutes.

[0026] Secondly, the present invention provides an interfacially polymerized repaired nanoporous reduced graphene oxide membrane prepared by the aforementioned preparation method.

[0027] Thirdly, the present invention provides the application of the interface-polymerized repaired nanoporous reduced graphene oxide membrane in fluid separation.

[0028] Compared with existing technologies, the beneficial effects of this invention are as follows: The nanoporous reduced graphene oxide membrane repaired by interfacial polymerization of this invention significantly improves the flux of the graphene oxide directional separation membrane through the interfacial polymerization repair process. Compared with ordinary graphene oxide membranes without pore modification, the flux increase can reach several times, while maintaining a high separation factor, achieving efficient and selective separation of organic matter and inorganic salts. Secondly, the nanoporous reduced graphene oxide membrane repaired by interfacial polymerization of this invention exhibits excellent retention performance for small molecule drugs, especially in complex systems containing organic solvents (such as pharmaceutical wastewater), it can still maintain a high drug retention rate, while overcoming the shortcomings of traditional nanofiltration membranes or reverse osmosis membranes in the insufficient separation selectivity of organic matter / inorganic salt mixed systems. Furthermore, the interface-polymerized repair layer of the nanoporous reduced graphene oxide membrane of this invention exhibits excellent chemical stability and structural integrity. It maintains a dense separation layer structure in organic solvent environments, effectively suppressing swelling and defect propagation. This overcomes the shortcomings of traditional polymer membranes, such as easy solvent swelling and poor selectivity of unrepaired nanoporous membranes, thus ensuring its long-term effectiveness and reliability in practical applications and avoiding rapid degradation of membrane performance and non-selective leakage of the target solute. In addition, the preparation process of this invention is mild, with controllable operation steps, and all key parameters can be precisely adjusted, facilitating large-scale production and batch stability control, demonstrating excellent prospects for industrial application. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the reaction apparatus for preparing reduced graphene oxide by ultraviolet light irradiation in Example 1 of the present invention; Figure 2 Comparative images of the appearance of reduced graphene oxide prepared under different ultraviolet light irradiation times in Examples 1-4 and Comparative Examples 3-5 of the present invention; Figure 3 X-ray photoelectron spectra of Examples 1-4 and Comparative Examples 3-5 prepared under different ultraviolet light irradiation times are shown below; wherein, (a) graphene oxide (ultraviolet light irradiation time is 0 min); (b) Comparative Example 3 (ultraviolet light irradiation time is 1 min); (c) Example 2 (ultraviolet light irradiation time is 10 min); (d) Example 1 (ultraviolet light irradiation time is 30 min); (e) Example 3 (ultraviolet light irradiation time is 60 min); (f) Example 4 (ultraviolet light irradiation time is 120 min); (g) Comparative Example 4 (ultraviolet light irradiation time is 240 min); (h) Comparative Example 5 (ultraviolet light irradiation time is 360 min); Figure 4The images are scanning transmission electron microscope images of the products at different preparation stages of the present invention; wherein, (a) raw material graphene oxide; (b) reduced graphene oxide prepared in step (1) of Example 1; (c) nanoporous reduced graphene oxide prepared in step (2) of Example 1; and (d) nanoporous reduced graphene oxide film repaired by interfacial polymerization prepared in Example 1. Figure 5 The images are scanning electron microscope images of the products at different preparation stages of the present invention; wherein, (a) a single-channel tubular ceramic membrane; (b) a graphene oxide membrane prepared using step (1) of Comparative Example 2; (c) a reduced graphene oxide membrane prepared using step (1) of Comparative Example 3; (d) a nanoporous reduced graphene oxide membrane prepared using Comparative Example 1; and (e) a nanoporous reduced graphene oxide membrane repaired by interfacial polymerization prepared using Example 1. Detailed Implementation

[0030] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0031] The following description, in conjunction with specific embodiments, illustrates the practical effects of the present invention.

[0032] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials, reagents, equipment, etc. used are all commercially available unless otherwise specified.

[0033] The preparation method of the graphene oxide dispersion used in this invention includes the following steps: (1) Under ice bath conditions, add 3g of graphite powder and 1.5g of sodium nitrate to 69mL of concentrated sulfuric acid and stir thoroughly to make the raw materials fully contact the concentrated sulfuric acid; then, slowly add 9g of potassium permanganate to the reaction system and continue stirring for 30min.

[0034] (2) Transfer the reaction system to a heat-collecting constant temperature magnetic stirring oil bath at 35°C and continue stirring for 30 min. Then, slowly add 138 mL of deionized water to the reaction system for dilution, while raising the oil bath temperature to 98°C and maintaining it at this temperature for 15 min to allow the oxidation reaction to proceed fully.

[0035] (3) After the reaction is completed, the reaction system is removed from the oil bath and placed in a water bath environment to cool for 10 min to control the cooling rate. Then, 420 mL of deionized water is added to the system to terminate the oxidation reaction, and 3 mL of 30% hydrogen peroxide is added to remove other unreacted products to obtain graphene oxide (GO) dispersion. The dispersion is quantitatively analyzed and prepared into a graphene oxide dispersion with a concentration of 0.1 g / L.

[0036] Example 1: This embodiment prepares a nanoporous reduced graphene oxide, and the preparation method includes the following steps: (1) Preparation of reduced graphene oxide 100 mL of a 0.1 g / L graphene oxide dispersion was placed in a circular quartz column and sonicated for 10 min. Then, the quartz column was placed in a constant-temperature water bath at 25°C, and a magnetic stirrer was added to the container, with pre-stirring for 30 min. Next, a low-pressure ultraviolet mercury lamp (10 W, 254 nm wavelength) with a glass sleeve was inserted below the surface of the graphene oxide dispersion, and the stirring rate was kept constant while continuously irradiating with ultraviolet light for 30 min to obtain a reduced graphene oxide dispersion. A schematic diagram of the specific reaction apparatus is shown below. Figure 1 As shown.

[0037] (2) Preparation of nanoporous reduced graphene oxide The reduced graphene oxide dispersion obtained in step (1) was transferred to a sealed pressure-resistant glass container and placed in a magnetic stirrer rotor. Then, potassium persulfate was added to it (so that the final concentration of potassium persulfate in the system was 1 mg / mL), and the mixture was heated and stirred in a water bath at 100°C for 30 min, and then rapidly cooled to room temperature. Next, hydrogen peroxide with a mass concentration of 30% (the amount of hydrogen peroxide added was 2% of the total volume of the system) was added to the mixture, and the mixture was heated and stirred in a water bath at 100°C for 1 h. Finally, the mixture was cooled to room temperature to obtain a nanoporous reduced graphene oxide dispersion.

[0038] Example 2: This embodiment prepared a nanoporous reduced graphene oxide. The only difference between the preparation method and that in Example 1 is that the ultraviolet light irradiation time in step (1) is 10 min.

[0039] Example 3: This embodiment prepared a nanoporous reduced graphene oxide. The only difference between the preparation method and that in Example 1 is that the ultraviolet light irradiation time in step (1) is 60 min.

[0040] Example 4: This embodiment prepared a nanoporous reduced graphene oxide. The only difference between the preparation method and that in Example 1 is that the ultraviolet light irradiation time in step (1) is 120 min.

[0041] Example 5: This embodiment prepares a nanoporous reduced graphene oxide, and the preparation method includes the following steps: (1) Preparation of reduced graphene oxide Take 100 mL of graphene oxide dispersion with a concentration of 0.1 g / L, put it into a high-temperature and high-pressure flat-bottomed glass tube with a threaded end, place a magnetic stirring rotor into it, tighten the threaded cap, and sonicate for 10 min; then place the sealed glass tube on an instrument with heating and stirring functions, heat and stir at 100℃ for 1 h, and after cooling, obtain reduced graphene oxide dispersion.

[0042] (2) Preparation of nanoporous reduced graphene oxide The reduced graphene oxide obtained in step (1) was transferred to a sealed pressure-resistant glass container and placed in a magnetic stirrer rotor. Then, potassium persulfate was added to the mixture (to make the final concentration of potassium persulfate in the system 1 mg / mL), and the mixture was heated and stirred in a water bath at 100°C for 30 min, and then rapidly cooled to room temperature. Next, hydrogen peroxide with a mass concentration of 30% (the amount of hydrogen peroxide added was 2% of the volume of the dispersion) was added to the mixture, and the mixture was heated and stirred in a water bath at 100°C for 1 h. Finally, the mixture was cooled to room temperature to obtain a nanoporous reduced graphene oxide dispersion.

[0043] Comparative Example 1: This comparative example prepared a reduced graphene oxide, and the preparation method includes the following steps: 100 mL of a 0.1 g / L graphene oxide dispersion was placed into a circular quartz column and sonicated for 10 min. Then, the quartz column was placed in a constant temperature water bath at 25 °C, and a magnetic stirrer was added to the container and stirred for 30 min. Next, a low-pressure ultraviolet mercury lamp (10 W power, 254 nm main wavelength) with a glass sleeve was inserted below the surface of the graphene oxide dispersion. The stirring rate was kept constant, and the mixture was continuously irradiated with ultraviolet light for 30 min to obtain a reduced graphene oxide dispersion.

[0044] Comparative Example 2: This comparative example prepared a nanoporous graphene oxide, and the preparation method includes the following steps: 100 mL of a 0.1 g / L graphene oxide dispersion was transferred to a sealed, pressure-resistant glass container and placed in a magnetic stirrer rotor. Potassium persulfate was then added (to bring the final concentration of potassium persulfate in the system to 1 mg / mL), and the mixture was heated and stirred in a 100°C water bath for 30 min, then rapidly cooled to room temperature. Next, 30% hydrogen peroxide (2% of the dispersion volume) was added to the mixture, and the mixture was heated and stirred in a 100°C water bath for 1 h. Finally, the mixture was cooled to room temperature to obtain a nanoporous graphene oxide dispersion.

[0045] Comparative Example 3: This comparative example prepared a nanoporous reduced graphene oxide. The only difference between the preparation method and Example 1 is that the ultraviolet light irradiation time in step (1) is 1 min.

[0046] Comparative Example 4: This comparative example prepared a nanoporous reduced graphene oxide. The only difference between the preparation method and Example 1 is that the ultraviolet light irradiation time in step (1) is 240 min.

[0047] Comparative Example 5: This comparative example prepared a nanoporous reduced graphene oxide. The only difference between the preparation method and Example 1 is that the ultraviolet light irradiation time in step (1) is 360 min.

[0048] Test Example 1: This test example uses X-ray photoelectron spectroscopy (XPS) to analyze the chemical state changes and reduction degree of functional groups on the surface of graphene oxide (GO) in step (1) of Examples 1-4 and Comparative Examples 3-5 of this invention under different ultraviolet (UV) irradiation times.

[0049] like Figure 2 As shown, with the extension of ultraviolet light irradiation time, the color of the graphene oxide dispersion gradually deepens from the initial yellow, indicating that ultraviolet light irradiation of the present invention can effectively reduce graphene oxide, and with the increase of the degree of reduction, the conjugated structure is gradually restored, the optical band gap decreases, and the macroscopic manifestation is a deepening of color. like Figure 3 As shown, after ultraviolet irradiation, the epoxy bonds of graphene oxide break to form hydroxyl bonds, and the relative content of carboxyl groups is further increased. However, when the ultraviolet irradiation time exceeds 120 min, or even reaches 360 min, excessive reduction will lead to local defects in the carbon skeleton or even the absence of carbon atoms, which is not conducive to maintaining the mechanical integrity and layered stacking order of graphene nanosheets. Moreover, the dispersibility of excessively reduced graphene oxide in water will also decrease significantly, and irreversible aggregation is likely to occur, affecting the uniformity of subsequent films.

[0050] Application Example 1: This application example demonstrates the preparation of an interfacially polymerized repaired nanoporous reduced graphene oxide, the preparation method of which includes the following steps: (1) Preparation of nanoporous reduced graphene oxide membrane (I) Selection and pretreatment of support membrane A single-channel tubular ceramic membrane with a pore size of 0.05 μm was selected as the support membrane (inner diameter 7.4 mm, length 1 m, effective membrane area 0.023236 m²). 2 The selected membrane tube was cleaned according to the following steps: ultrasonic cleaning in pure water bath four times, soaking in 1mol / L sulfuric acid for 24h, ultrasonic cleaning in pure water bath four times, soaking in NaOH (1g / L) + SDS (0.3g / L) mixed solution for 24h, and finally ultrasonic cleaning in pure water bath four times.

[0051] (II) Membrane tank installation and cleaning After cleaning, the membrane tubes are placed in a dedicated membrane tank. First, they are rinsed once with 4L of ultrapure water using a cross-flow method, and then rinsed once with 4L of ultrapure water using a membrane-passing method.

[0052] (III) Preparation of raw material solution Prepare a 2 L sodium tetraborate solution with a concentration of 5 mmol / L and filter it using a 0.22 μm filter membrane; Based on the target number of deposition layers (10 layers) and the theoretical areal density of a single-layer nanosheet (0.144 μg / cm³), 2 First, calculate the total mass of the required nanoporous reduced graphene oxide, taking into account the effective area of ​​the supporting membrane. m = number of target deposition layers × theoretical areal density of single-layer nanosheets × effective area of ​​the supporting film = 10 × 0.144 μg / cm² 2 ×0.023236m 2 =0.33mg; Based on the required total mass of nanoporous reduced graphene oxide, take the corresponding volume of the nanoporous reduced graphene oxide dispersion prepared in Example 1 (the concentration of which was obtained through quantitative analysis) and add it to the prepared sodium tetraborate solution. Stir until homogeneous to obtain the raw material solution.

[0053] (IV) Cross-flow filter assembly Pour the raw material liquid into the inlet tank, turn on the cross-flow filtration device, collect the effluent in a clean container, and return the cross-flow circulating water to the inlet tank. After the dispersion in the inlet tank has been filtered, pour the solution in the effluent tank back into the inlet tank. Repeat this circulation operation three times. After that, insert the product water pipe into the inlet tank and circulate for 30 minutes.

[0054] (V) Multi-layer assembly and post-processing: Repeat steps (III) and (IV) three times, gradually increasing the operating pressure to 0.5 MPa during each of the three preparation processes; after the three assembly processes are completed, place the product water pipe into the water inlet tank, increase the pressure to 1 MPa, and circulate for 2 hours.

[0055] (VI) Drying The membrane tube was removed and placed in a forced-air drying oven, heated to 90°C and dried for 2 hours to obtain a nanoporous reduced graphene oxide membrane.

[0056] (2) Preparation of nanoporous reduced graphene oxide membranes repaired by interfacial polymerization (I) Aqueous phase wetting The nanoporous reduced graphene oxide membrane prepared in step (1) was placed in a water bath and soaked in deionized water for 60 minutes to fully wet the membrane layer, so that the oxygen-containing functional groups (mainly hydroxyl groups) on its surface could unfold and form an aqueous interface.

[0057] (II) Interfacial polymerization reaction One end of the aqueous-wetted nanoporous reduced graphene oxide membrane was sealed with a solvent-resistant material, and a 0.5 wt% hexane solution of trimesoyl chloride (TMC) was poured into the other end until the nanoporous reduced graphene oxide layer covering the inner surface of the membrane tube was filled to form an organic phase. This end was then sealed as well. The sealed ceramic membrane tube was then completely immersed in deionized water to create a high-pressure environment to prevent the organic phase from permeating. After the interfacial polymerization reaction was completed for 10 minutes, the membrane tube was removed and the hexane solution was discarded.

[0058] (III) Post-processing The interfacially polymerized nanoporous reduced graphene oxide membrane was placed in a vacuum drying oven at 60°C and fixed for 15 minutes. Then, the membrane tube was thoroughly rinsed with deionized water to remove unreacted monomers and residues. It was then vacuum dried at room temperature to obtain the interfacially polymerized and repaired nanoporous reduced graphene oxide membrane.

[0059] Application Example 2: This application example prepares an interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The only difference between this preparation method and application example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of example 1 is replaced with the nanoporous reduced graphene oxide dispersion of example 2.

[0060] Application Example 3: This embodiment prepares an interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The only difference between the preparation method and application example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of example 1 is replaced with the nanoporous reduced graphene oxide dispersion of example 3.

[0061] Application Example 4: This application example prepares an interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The only difference between this preparation method and application example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of example 1 is replaced with the nanoporous reduced graphene oxide dispersion of example 4.

[0062] Application Example 5: This application example prepares an interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The only difference between this preparation method and application example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of example 1 is replaced with the nanoporous reduced graphene oxide dispersion of example 5.

[0063] Application Comparative Example 1: This application comparatively prepared a nanoporous reduced graphene oxide membrane. The only difference between its preparation method and application example 1 is that the interfacial polymerization repair in step (2) is not performed.

[0064] Application Comparative Example 2: This application comparative example prepared an interfacial polymerization repair graphene oxide film. The only difference between the preparation method and application example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of example 1 was replaced with a graphene oxide dispersion.

[0065] Application Comparative Example 3: This application comparative example prepared an interfacial polymerization repaired reduced graphene oxide film. The only difference between the preparation method and application example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of example 1 was replaced with the reduced graphene oxide dispersion of comparative example 1.

[0066] Application Comparative Example 4: This application comparative example prepared an interfacial polymerization repair nanoporous graphene oxide membrane. The only difference between the preparation method and application example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of example 1 was replaced with the nanoporous graphene oxide dispersion of comparative example 2.

[0067] Application Comparative Example 5: This comparative example prepared an interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The only difference between its preparation method and that of Application Example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of Example 1 was replaced with the nanoporous reduced graphene oxide dispersion of Comparative Example 3.

[0068] Application Comparative Example 6: This comparative example prepared an interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The only difference between its preparation method and that of Application Example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of Example 1 was replaced with the nanoporous reduced graphene oxide dispersion of Comparative Example 4.

[0069] Application Comparative Example 7: This comparative example prepared an interfacially polymerized repaired nanoporous reduced graphene oxide membrane. The only difference between its preparation method and that of Application Example 1 is that in step (1), the nanoporous reduced graphene oxide dispersion of Example 1 was replaced with the nanoporous reduced graphene oxide dispersion of Comparative Example 5.

[0070] Test Example 2: In this test example, the morphology of the reduced graphene oxide in step (1) of Example 1, the nanoporous reduced graphene oxide in step (2), and the nanoporous reduced graphene oxide film repaired by interface polymerization in Example 1 were characterized by scanning electron microscopy and scanning transmission electron microscopy (STEM). The results were compared with the raw material graphene oxide (GO) to investigate the influence of different preparation processes on the pore structure of the graphene oxide nanosheets.

[0071] like Figure 4 As shown, Figure 4 (a) is a scanning transmission electron microscope image of the raw material graphene oxide. As can be seen from the image, the surface of ordinary graphene oxide nanosheets is flat and the number of pores is extremely small. Almost no obvious nanoscale penetrating pores can be observed. Figure 4 (b) is a scanning transmission electron microscope image of the reduced graphene oxide obtained in step (1) of Example 1. It can be seen from the image that after ultraviolet reduction, the number and size of pores on the surface of the reduced graphene oxide obtained do not increase significantly compared with the raw material. Figure 4 (c) is a scanning transmission electron microscope image of the nanoporous reduced graphene oxide obtained in step (2) of Example 1. As can be seen from the image, after thermochemical oxidation and drilling (using potassium persulfate and hydrogen peroxide in combination), the number of pores on the surface of the obtained nanoporous reduced graphene oxide increases significantly, and the pore size is significantly larger than the former two, showing a typical nanoporous structure. This indicates that the etching process of the present invention (using potassium persulfate and hydrogen peroxide in combination for thermochemical oxidation) can effectively penetrate the graphene sheets and form penetrating nanopores, thereby shortening the water passage of the nanoporous reduced graphene oxide film. Figure 4 (d) is a scanning transmission electron microscope image of the nanoporous reduced graphene oxide film repaired by interfacial polymerization in Example 1. As can be seen from the figure, after interfacial polymerization repair, the pore size of the nanoporous reduced graphene oxide film is greatly reduced, indicating that the interfacial polymerization process can effectively repair the retention rate loss caused by non-directional drilling.

[0072] like Figure 5 As shown, Figure 5 (a) is a scanning electron microscope image of a single-channel tubular ceramic membrane. Figure 5 (b) A scanning electron microscope image of the graphene oxide film prepared using step (1) of Comparative Example 2. Figure 5 (c) is a scanning electron microscope image of the reduced graphene oxide film prepared using step (1) of Comparative Example 3. Figure 5 (d) is a scanning transmission electron microscope image of the nanoporous reduced graphene oxide film prepared using Comparative Example 1. Figure 5 (e) is a scanning transmission electron microscope image of the nanoporous reduced graphene oxide membrane repaired by interfacial polymerization prepared in Example 1. As can be seen from the figure, the nanoporous reduced graphene oxide membrane repaired by interfacial polymerization of the present invention is based on the nanoporous reduced graphene oxide membrane. First, it is wetted with water to fully expand the surface hydroxyl groups, and then it undergoes an interfacial polymerization reaction with a hexane solution of trimesoyl chloride (TMC). A cross-linked polyamide repair layer is formed in situ on the surface of the nanosheets and in the pores. After the interfacial polymerization repair, the large number of nanopores that were clearly visible before have basically disappeared. The membrane surface has become very dense and smooth, and almost no defects or pores can be observed. The polyamide layer uniformly covers the surface of the nanoporous rGO and effectively fills the through holes generated by etching, forming a composite structure of "rGO base layer + polyamide repair layer". This repair strategy retains the advantage of short mass transfer path brought by etching and blocks non-selective pores through the cross-linked polyamide network, which greatly improves the retention performance of organic matter and small molecule drugs.

[0073] Test Example 3: This test example demonstrates the performance of the nanoporous reduced graphene oxide membranes prepared in Application Examples 1-5 and Comparative Examples 1-7.

[0074] (1) Membrane flux test Test method: The membrane to be tested is installed in the membrane housing, and residual substances are washed away by cross-flow rinsing and pressurized membrane filtration; then the device is used to filter ultrapure water, and after stable operation for 1 hour, the pure water flux of the membrane to be tested is tested at a transmembrane pressure of 0.5 MPa.

[0075] (2) Selectivity test of organic matter and inorganic salts Test method: After completing the membrane flux test, the feed solution was switched to a mixed solution of polyethylene glycol (PEG3350) and magnesium sulfate (PEG3350 mass concentration was 0.1 g / L, and magnesium sulfate mass concentration was 3 g / L) to test the separation performance of the membrane for organic matter and inorganic salts. The test conditions were: transmembrane pressure difference 0.5 MPa, crossflow velocity 0.8 m / s, and temperature 25℃; The concentration of PEG3350 was characterized by chemical oxygen demand (COD) and the concentration of magnesium sulfate was characterized by conductivity.

[0076] (3) Simulated pharmaceutical wastewater test Test method: Simulated pharmaceutical wastewater was used as the feed solution to test the retention performance of the membrane under test for small molecule drugs in an organic solvent environment; The simulated pharmaceutical wastewater consists of an ethanol-water mixture, wherein the volume fraction of ethanol is 25%, the mass concentration of moxifloxacin is 1 g / L, and the mass concentration of sodium chloride is 3 g / L. The test conditions were: transmembrane pressure difference 1.0 MPa, crossflow velocity 2.0 m / s, and temperature 25℃; Moxifloxacin concentration was determined by high performance liquid chromatography (HPLC).

[0077] The test results are shown in Table 1: Table 1. Performance test results of nanoporous reduced graphene oxide films in Application Examples 1-5 and Comparative Examples 1-7. As shown in Table 1, the interface polymerization-repaired nanoporous reduced graphene oxide membrane of the present invention exhibits significant comprehensive advantages in separation performance. Through a synergistic design of "first creating pores, then repairing," it successfully overcomes the contradiction between flux and selectivity in traditional separation membranes, achieving a balance of high flux, high selectivity, and good solvent resistance. Specifically, the UV reduction treatment of the present invention retains some oxygen-containing functional groups to maintain hydrophilicity, while improving interlayer spacing and further promoting water molecule transport across the membrane. This results in excellent retention capacity for high molecular weight organics and very low retention rate for inorganic salts, demonstrating an extremely high organic / inorganic salt separation factor. Secondly, the nanopores formed by thermochemical etching in the present invention greatly shorten the transport path of water molecules, multiplying the permeate flux. In contrast, in non-porous graphene-based membranes (whether original graphene oxide or simple reduction products), water molecules mainly rely on the tortuous nanochannels between layers for transport, resulting in long mass transfer paths, high resistance, and generally low permeate flux, making it difficult to meet the actual requirements of efficient separation. Furthermore, the introduction of the interfacial polymerization repair layer in this invention effectively seals defective pores, significantly improving the membrane's selectivity and achieving synergistic optimization of flux and selectivity. While unrepaired nanoporous substrates possess high water permeability, the non-selective pores created by etching result in low solute rejection rates, making it difficult to meet the requirements of fine separation. In addition, the membrane of this invention maintains high efficiency in intercepting small molecule drugs in simulated pharmaceutical wastewater containing alcohol, with stable organic solvent flux. Unrepaired membranes, however, suffer from drug leakage due to defects. Other non-porous or unreduced control membranes, although possessing some rejection rates, have extremely low fluxes and lack practical application value.

[0078] In summary, the interfacial polymerization repaired nanoporous reduced graphene oxide membrane constructed in this invention, through the organic combination of structural regulation (controllable reduction and efficient pore formation) and functional repair (interfacial polymerization), significantly improves the selective retention capacity of organic matter and small molecule drugs while ensuring high throughput, and also has excellent solvent resistance. It exhibits comprehensive performance that surpasses traditional and comparative membranes in fields such as pharmaceutical wastewater treatment, material concentration and separation, and has clear prospects for industrial application.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a nanoporous reduced graphene oxide membrane repaired by interfacial polymerization, characterized in that, Includes the following steps: S1. Reduce graphene oxide to obtain reduced graphene oxide; S2. The reduced graphene oxide is subjected to oxidation etching treatment to obtain nanoporous reduced graphene oxide. S3. Load the nanoporous reduced graphene oxide onto a porous support membrane to obtain a nanoporous reduced graphene oxide membrane. S4. After wetting the nanoporous reduced graphene oxide membrane with water, it undergoes an interfacial polymerization reaction with an organic solution containing polyacrylamide monomers, and is then dried to obtain the interfacially polymerized and repaired nanoporous reduced graphene oxide membrane.

2. The method for preparing the interfacially polymerized repaired nanoporous reduced graphene oxide film as described in claim 1, characterized in that, In step S1, the reduction process is either ultraviolet light irradiation reduction or hydrothermal reduction.

3. The method for preparing the interfacially polymerized repaired nanoporous reduced graphene oxide membrane as described in claim 2, characterized in that, The ultraviolet light wavelength for the ultraviolet light irradiation reduction is 254nm, the power is 10W, and the irradiation time is 10min-120min; and / or, the hydrothermal reduction temperature is 90℃-120℃, and the time is 1h-2h.

4. The method for preparing the interfacially polymerized repaired nanoporous reduced graphene oxide film as described in claim 1, characterized in that, In step S2, the oxidation etching process is as follows: the reduced graphene oxide and potassium persulfate are mixed and treated at 80℃-120℃ for 25min-45min. After cooling, hydrogen peroxide is added and the mixture is treated at 80℃-120℃ for 1h-2h. The concentration of potassium persulfate in the reaction system is 0.8mg / mL-1.5mg / mL. The volume of hydrogen peroxide is 1.5%-3% of the total volume of the reaction system.

5. The method for preparing the interfacially polymerized repaired nanoporous reduced graphene oxide film as described in claim 1, characterized in that, In step S3, the porous support membrane is a microfiltration membrane or an ultrafiltration membrane, and its material is selected from any one of polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, alumina, zirconium oxide, silicon oxide, titanium oxide, zeolite, and silicon carbide.

6. The method for preparing the interfacially polymerized repaired nanoporous reduced graphene oxide film as described in claim 1, characterized in that, In step S3, the loading includes the following steps: (1) dispersing the nanoporous reduced graphene oxide in a sodium tetraborate solution to prepare a raw material solution; (2) using cross-flow filtration to deposit the nanoporous reduced graphene oxide in the raw material solution onto the surface of the porous support membrane to form a nanoporous reduced graphene oxide layer; the deposition is performed by pressure filtration with a transmembrane pressure difference of 0.1 MPa-1 MPa; the concentration of the sodium tetraborate solution is 2 mmol / L-10 mmol / L.

7. The method for preparing the interfacially polymerized repaired nanoporous reduced graphene oxide film as described in claim 1, characterized in that, In step S4, the polyacrylamide chloride monomer includes at least one of pyromellitic trimethylolpropionate, tridecanoic acid chloride, and isophthaloyl chloride; the mass concentration of the organic solution containing the polyacrylamide chloride monomer is 0.1wt%-2wt%.

8. The method for preparing the interfacially polymerized repaired nanoporous reduced graphene oxide film as described in claim 1, characterized in that, In step S4, the drying temperature is 45℃-200℃ and the time is 10min-60min.

9. The interfacially polymerized repaired nanoporous reduced graphene oxide membrane prepared by any of the preparation methods described in claims 1-8.

10. The application of the interface-polymerized repaired nanoporous reduced graphene oxide membrane according to claim 9 in fluid separation.

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