Chiral graphene oxide-based separation membrane, and preparation method and application thereof

Abstract

This invention belongs to the field of membrane separation and functional membrane materials technology, and discloses a chiral graphene oxide-based separation membrane, its preparation method, and its application. The membrane is composed of graphene oxide and / or reduced graphene oxide sheets and a single-stranded DNA-single-walled carbon nanotube complex. The single-stranded DNA helically winds around the outer surface of the single-walled carbon nanotubes to form a one-dimensional chiral nanochannel and intercalates between the sheets, forming a three-dimensional chiral channel network connected in the membrane thickness direction. The preparation method includes: heating and decohexing salmon sperm double-stranded DNA in a urea-containing buffer to obtain single-stranded DNA; dispersing single-walled carbon nanotubes and then complexing them with the single-stranded DNA; further mixing with a graphene oxide or reduced graphene oxide dispersion; and vacuum filtration to form the membrane. This membrane exhibits a high separation factor for chiral enantiomers such as L / D-phenylalanine, with an excess value of up to 99.95% for L-phenylalanine enantiomers after multi-stage separation, making it suitable for the efficient separation of chiral drugs and amino acids.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation and functional membrane materials technology, specifically relating to a chiral graphene oxide-based separation membrane, its preparation method, and its application. Background Technology

[0002] Chiral enantiomers are pairs of molecules with identical atomic connections but mirror-image spatial arrangements. They typically possess very similar physicochemical properties and are difficult to separate and purify under conventional conditions. However, in chiral biological environments, different enantiomers interact significantly with target sites, often exhibiting completely different or even opposite pharmacological activities and toxicities. Therefore, obtaining enantiomers with high optical purity is of great significance in the fields of pharmaceuticals, pesticides, and fine chemicals.

[0003] Currently, commonly used chiral separation methods include chromatography, crystallization, kinetic resolution, and chiral membrane separation. Among these, chiral membrane separation technology has gradually become an important development direction for chiral separation due to its advantages such as low energy consumption, simple operation, continuous operation, and ease of scale-up. However, existing chiral membrane materials generally suffer from the following problems: First, the membrane materials lack stable and high-density chiral recognition sites, resulting in a limited separation factor; second, there is a clear "trade-off" between permeate flux and selectivity, making it difficult to simultaneously achieve high flux and high selectivity; and third, some soft organic chiral materials lack sufficient mechanical strength, making it difficult to meet the stability requirements of engineering applications.

[0004] Graphene oxide (GO), as a typical two-dimensional sheet material, possesses atomically thin layers, high specific surface area, excellent mechanical properties, and abundant oxygen-containing functional groups. It can construct layered composite membranes with various organic and inorganic components through van der Waals forces, hydrogen bonds, or covalent bonds, and has been widely used in nanofiltration, gas separation, and ion sieving. On the other hand, there is a specific non-covalent interaction between double-stranded deoxyribonucleic acid (DNA) and single-walled carbon nanotubes (SWCNTs). Single-stranded deoxyribonucleic acid (ssDNA) can selectively spirally wind onto the SWCNT surface through π-π stacking and electrostatic interactions, and has been widely used in research on the chiral sorting and dispersion stabilization of SWCNTs.

[0005] However, in existing technologies, planar membrane surfaces or porous support layers modified with small molecule chiral selectors, chiral polymers, or chiral metal complexes are often used, making it difficult to construct a controllable one-dimensional chiral channel network inside the membrane. Meanwhile, there are no reports on two-dimensional chiral membranes constructed by GO and DNA / SWCNT synergistically, and their high enantioselective separation and mechanism characterization in amino acid, chiral drug, and other systems.

[0006] Therefore, there is an urgent need to develop a chiral separation membrane system with a finely tunable structure, high mechanical strength, high throughput and high enantioselectivity, to provide new ideas for the engineering application of two-dimensional chiral membranes. Summary of the Invention

[0007] The purpose of this invention is to provide a chiral graphene oxide-based separation membrane, its preparation method, and its application, in order to solve the problems of insufficient chiral recognition sites, difficulty in balancing flux and selectivity, and insufficient mechanical properties in existing chiral separation membrane materials.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A chiral graphene oxide-based separation membrane comprises: a layered framework formed by stacking graphene oxide sheets and / or reduced graphene oxide sheets, and a single-stranded deoxyribonucleic acid (DNA)-single-walled carbon nanotube (CNT) composite dispersed and embedded in the layered framework; the DNA is helically wound around the outer surface of the CNTs to form a shell-core structure of one-dimensional chiral nanochannels; the one-dimensional chiral nanochannels are interconnected in the membrane thickness direction to form a three-dimensional chiral channel network, and are connected to the DNA and / or reduced graphene oxide sheets through the negatively charged phosphate backbone of the DNA; the mass ratio of the DNA and / or reduced graphene oxide, the DNA, and the CNTs is 1:1 to 4:0.1 to 0.4.

[0009] The single-stranded deoxyribonucleic acid was derived from salmon sperm double-stranded deoxyribonucleic acid, which was obtained by thermo-chemical treatment and decoupling in a urea-containing solution.

[0010] The reduced graphene oxide was obtained by heat-treating an aqueous dispersion of graphene oxide at 50–200°C for 0.5–4 hours.

[0011] The thickness of the separation membrane is 2–2.5 μm, and the pure water flux of the separation membrane prepared with graphene oxide is 2–5 L·m⁻¹ under a pressure difference of 0.8 bar. -2 ·h -1 The separation membrane prepared by thermal reduction at 200℃ has a pure water flux of 30–60 L·m⁻¹ under a pressure difference of 0.8 bar. -2 ·h -1 .

[0012] A method for preparing a chiral graphene oxide-based separation membrane includes the following steps: S1: Dissolve double-stranded deoxyribonucleic acid (DDNA) derived from salmon sperm in PBS buffer containing 8 mol / L urea, heat at 80–100 °C for 0.5–2 h, and then dialyze to obtain a single-stranded DDNA solution; S2: Add single-walled carbon nanotubes to a 0.5% (w / w) aqueous solution of polyvinylpyrrolidone, disperse by ultrasonication, centrifuge and collect the supernatant to obtain a single-walled carbon nanotube dispersion; mix the single-walled carbon nanotube dispersion with the single-stranded deoxyribonucleic acid solution from step one at a mass ratio of 1 to 4:1 under stirring conditions, and stir for 1 to 3 hours to obtain a single-stranded deoxyribonucleic acid-single-walled carbon nanotube dispersion; S3: Add graphene oxide powder or reduced graphene oxide powder to water and disperse by ultrasonication to obtain a graphene oxide or reduced graphene oxide dispersion. S4: Mix the dispersion from step S2 with the dispersion from step S3 under stirring for 1-3 hours. Adjust the amount of each component to make the mass ratio of graphene oxide and / or reduced graphene oxide, single-stranded deoxyribonucleic acid and single-walled carbon nanotubes 1:1-4:0.1-0.4 to obtain a film-forming dispersion. Vacuum filter the film-forming dispersion through a polyethersulfone substrate membrane under a pressure difference of 0.8 bar to form a film. Dry at room temperature for 6-24 hours to obtain the chiral graphene oxide-based separation membrane.

[0013] The heating temperature in step S1 is 90℃ and the heating time is 1h; the reduced graphene oxide powder in step S3 is obtained by heat-treating the graphene oxide aqueous dispersion at 50~200℃ for 0.5~4h.

[0014] Chiral enantiomers are separated using a chiral graphene oxide-based separation membrane. A feed liquid and a receiving liquid are added to both sides of the separation membrane, respectively. Driven by the concentration difference, the chiral enantiomers are transported through the separation membrane. The receiving liquid is collected to obtain a product enriched with a specific chiral enantiomer.

[0015] The chiral enantiomer is selected from at least one of phenylalanine, glutamic acid, ibuprofen, propranolol, and 2-methylpiperazine.

[0016] The chiral enantiomers are L-phenylalanine and D-phenylalanine, and the separation membrane is a graphene oxide-single-stranded deoxyribonucleic acid-single-walled carbon nanotube membrane or a graphene oxide-single-stranded deoxyribonucleic acid-single-walled carbon nanotube membrane reduced at 200°C, with a separation factor greater than 6.0.

[0017] Based on Arrhenius relation fitting, the diffusion activation energy of L-phenylalanine in the separation membrane is lower than that of D-phenylalanine.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This invention constructs a shell-core structured one-dimensional chiral nanochannel by winding ssDNA helices obtained through thermal / chemical unwinding onto the outer surface of SWCNTs. These channels are then intercalated between GO / rGO sheets, forming a three-dimensional interconnected and stable one-dimensional chiral channel network within the membrane. Compared to control membranes containing only GO, GO-DNA (GD), or GO-SWCNT (GS), this invention achieves high throughput and high chiral selectivity while maintaining high mechanical strength. Under suitable GO thickness and ssDNA / SWCNT ratio conditions, the GDS membrane achieves a pure water flux of approximately 2.28 L·m⁻¹. -2 ·h -1 ·bar -1 At this temperature, the ideal selectivity for L / D-Phe can reach approximately 6.24, and the separation factor can be further improved by adjusting the degree of GO reduction (selectivity can reach approximately 13.94). With moderate reduction at 200℃, the ee value (%) of L-Phe after cascade separation can reach approximately 99.95%. This membrane system not only efficiently separates L / D-Phe and L / D-Glu, but also exhibits excellent separation capabilities for various chiral drugs and intermediates such as R / S-propranolol, R / S-ibuprofen, and R / S-2-methylpiperazine. The ideal selectivity of some systems can reach as high as approximately 14.39 and 11.84, which is superior to some previously reported chiral membranes and chromatographic systems. Furthermore, by measuring L / D-Phe within the range of 5–30℃... The permeation rate of D-Phe and the Arrhenius relationship fitting showed that the transmembrane diffusion activation energy of L-Phe was significantly lower than that of D-Phe. Combined with the results of increased interlayer spacing, electrochemical double-layer capacitance Cdl difference, and significant changes in stress-strain curves after L-Phe immersion, it is proved that the membrane material of this invention, after introducing ssDNA-SWCNT chiral channels in the GO / rGO interlayer, not only possesses excellent mechanical and thermal stability, but also constructs a chiral microenvironment conducive to L-type enantiomer transport. Furthermore, it provides a new characterization method for evaluating the membrane-solute interaction strength by Cdl and changes in mechanical properties, providing a new technical path for the study of chiral membrane separation mechanisms and the screening of high-performance chiral membrane materials. Attached Figure Description

[0019] Figure 1 Cross-sectional SEM images of GO membrane, GO+DNA (GD) membrane, GO+SWCNT (GS) membrane, GO+DNA+SWCNT (GDS) membrane, and rGO+DNA+SWCNT (rGDS-200) chiral membrane obtained by thermal reduction at 200℃.

[0020] Figure 2 Comparison charts of the separation performance of GDS membrane / rGDS-T and comparative series membranes for L / D-Phe, and comparison charts of membrane water flux.

[0021] Figure 3Arrhenius fitting curves of L / D-Phe permeation rate for GDS membrane and rGDS-200 membrane at different temperatures.

[0022] Figure 4 CD spectra of ssDNA, SWCNT, ssDNA-SWCNT and their complexation with GO / rGO.

[0023] Figure 5 XRD patterns of GDS and GO membranes before and after immersion in different chiral solutions.

[0024] Figure 6 This graph shows the variation of the ee value of L-Phe in the permeate of each stage as a function of the number of separation stages when using the rGDS-200 optimal chiral separation membrane for multi-stage tandem separation of racemic L / D-Phe solutions. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0027] For ease of description, the GO-DNA-SWCNT chiral membrane will be referred to as GDS in this invention, and the membranes obtained by thermal reduction of it at 50℃, 150℃, and 200℃ will be referred to as rGDS-50, rGDS-150, and rGDS-200, respectively.

[0028] Example 1: Preparation of ssDNA DNA derived from salmon sperm was dissolved in PBS buffer (pH=7.4, containing 137 mM NaCl) with 8 mol / L urea at a concentration of 5, 10, or 20 mg / mL. The solution was heated at 90°C with stirring for 1 h to unwind the double-stranded DNA into ssDNA. The resulting solution was transferred to a dialysis bag and dialyzed against deionized water at room temperature to remove the PBS buffer salts, yielding the ssDNA solution.

[0029] Example 2: SWCNT dispersion and ssDNA Preparation of SWCNT composite solution Weigh an appropriate amount of SWCNT and add it to a 0.5% PVP aqueous solution. Disperse the solution by sonication for 10 min, centrifuge at 7000 rpm for 5 min, discard the precipitate, and take the supernatant to obtain a stable SWCNT dispersion.

[0030] Under stirring conditions, the ssDNA solution (Example 1) and the SWCNT dispersion were mixed at a mass ratio of (1-4):1 and stirred for 2 hours, so that the ssDNA would spirally wrap around the outer surface of the SWCNT through π-π stacking and electrostatic interaction, thus obtaining the ssDNA-SWCNT dispersion.

[0031] Example 3: Preparation of chiral separation membrane for GDS 5 mg of GO lyophilized powder was weighed and added to 10 mL of deionized water for ultrasonic dispersion to obtain a GO dispersion. The ssDNA-SWCNT dispersion (Example 2) prepared by mixing 10 mg of ssDNA and 1 mg of SWCNT was mixed with the GO dispersion under stirring for 2 h. The resulting film-forming dispersion was vacuum filtered through a polyethersulfone substrate membrane at a pressure difference of 0.8 bar, and then naturally dried for 12 h to obtain a GDS chiral separation membrane with a thickness of approximately 2–2.5 μm and a pure water flux of approximately 2.28 L·m⁻¹. -2 ·h -1 ·bar -1 .

[0032] Example 4: Preparation of rGDS-T chiral separation membrane Based on Example 3, only the degree of reduction of the GO sheets was changed. The GO aqueous dispersion was heat-treated at 50℃, 150℃, and 200℃ for 3 hours to obtain rGO-50, rGO-150, and rGO-200 powders with different degrees of reduction. These powders were then mixed with ssDNA-SWCNT composite solution under the same conditions as in Example 3, filtered, and used to form membranes, resulting in rGDS-50, rGDS-150, and rGDS-200 membranes.

[0033] Example 5: Preparation of control membranes (GO, GD, GS membranes) To compare the performance of the chiral separation membrane of the present invention, the following control samples were prepared: GOM: Membrane formed solely by GO, without the addition of DNA and SWCNT; GDM: GO and ssDNA are blended to form a membrane without the addition of SWCNT; GSM: GO and SWCNT are blended to form a membrane without adding ssDNA; SEM results showed that GO and GD exhibited a typical "book-like" layered structure, and SWCNT hybrids were observed forming a three-dimensional interconnected network between GO / rGO layers in GS, GDS, and rGDS-T films. Figure 1 ).

[0034] Example 6: Chiral enantiomer separation experiment The membranes prepared in Examples 3-5 were fixed in the middle of the separation device. 50 mL of chiral enantiomer solution was added to the left chamber, and an equal volume of deionized water was added to the right chamber. The permeation experiment was carried out at room temperature under magnetic stirring. 1 mL of solution was taken from each side at regular intervals, and the enantiomer concentration was determined by UV-Vis or high-performance liquid chromatography. The concentration was converted according to the standard curve, and the permeability and separation factor were calculated according to the pre-set formula.

[0035] In GDS membrane separation experiments, when the feed was an equimolar racemic L / D-Phe solution (3 g / L), the ideal selectivity for L / D-Phe was approximately 7.39. Under the same conditions, the GDS membrane exhibited high selectivity for L / D-Glu and R / S-Ibuprofen, with separation factors of approximately 9.8 and 6.1, respectively. It also showed separation ability for R / S-Propranolol and R / S-2-methylpiperazine, but the overall selectivity was relatively weak. For non-equimolar mixed feeds, competitive transport could further amplify the selectivity; for example, the separation factor for the Propranolol system could increase to 14.4 at S:R = 9:1. These results demonstrate that the chiral separation membrane of this invention has good enantiomeric separation ability for various amino acids and chiral drugs, and exhibits high selectivity in some systems. To further investigate the effect of GO reduction on chiral separation performance, under isostatic racemic Phe (3 g / L) conditions, the separation factors for L / D-Phe of GDS, rGDS-50, rGDS-150, and rGDS-200 membranes were approximately 7.39, 3.00, 11.0, and 12.59, respectively, indicating that moderate reduction can significantly improve the chiral selectivity of the membrane. Figure 2 ).

[0036] Furthermore, to evaluate the purification capability of the rGDS-200 chiral separation membrane under engineering conditions, the rGDS-200 membrane prepared in Example 4 was used to perform multi-stage tandem separation of the racemic L / D-Phe solution. The initial feed solution contained 3 g / L concentrations of both L-Phe and D-Phe. The concentrations of L-Phe and D-Phe in the permeate of each stage were measured, and the ee value of L-Phe was calculated. The results are as follows: Figure 6 As shown.

[0037] After six-stage tandem separation using the rGDS-200 membrane, the enantiomeric excess of L-Phe was increased to 99.95%. During 168 h of continuous operation, the rGDS-200 membrane maintained a stable ee value of 84.6%–87.3%, with the L-Phe flux remaining between 41.1 and 43.8 mmol·m⁻¹. -2 ·h -1The D-Phe flux remained between 2.9 and 3.5 mmol·m⁻². -2 ·h -1 .

[0038] Example 7: Characterization of transport energy barrier (diffusion activation energy), circular dichroism spectroscopy, and membrane-solute interaction Permeation experiments were conducted on equimolar racemic L / D-Phe solutions at 5, 10, 15, 20, 25, and 30 °C using deionized water as the driving fluid and employing GDS and rGDS-200 chiral separation membranes. The permeation rate P at different temperatures was recorded, and the slope of the linear equation lnP = lnα - Ea / (RT) was plotted using the Arrhenius equation. The activation energy Ea was then calculated. Figure 3 The results showed that the diffusion activation energy of L-Phe was lower than that of D-Phe in both GDS and rGDS-200 films; among them, the ΔEa of rGDS-200 was 9.74 kcal / mol. -1 GDS ΔEa = 3.55 kcal mol -1 This indicates that L-Phe has a lower energy barrier to overcome in the rGDS-200 membrane, making it easier to penetrate the membrane layer and preferentially transported within the membrane.

[0039] CD spectroscopy was performed on ssDNA, SWCNT, ssDNA-SWCNT and the membrane obtained by combining them with GO / rGO. Figure 4 The results showed that the CD signal of ssDNA and SWCNT and its complex exhibited a significant chiral response. After ssDNA-SWCNT complexed with GO, the CD signal was significantly enhanced and redshifted, proving that chiral information was transferred from ssDNA to SWCNT and its membrane structure, achieving effective chiral assembly. The comparison of CD intensity of membranes with different reduction degrees showed that the CD signal of rGDS-50 was the weakest, followed by GDS, rGDS-150, and rGDS-200, which increased in turn, indicating that moderate reduction is beneficial to constructing a stronger chiral microenvironment.

[0040] Furthermore, GDS and rGDS-T series membranes were immersed in L-Phe solution, D-Phe solution, L / D-Phe mixed solution, and pure water for a certain period of time. After 24 hours, they were removed, the surface free solutes were gently rinsed off, and after drying, XRD was performed. Figure 5Electrochemical and mechanical performance tests were conducted. Compared with the GO membrane immersed in pure water, the interlayer spacing changed significantly, indicating that L-phenylalanine is more easily transported through the membrane. Electrochemical tests were performed using a three-electrode system, with the membrane used as the working electrode modification layer. The interfacial double-layer capacitance Cdl was measured by cyclic voltammetry. The results showed that after immersion in L-Phe, D-Phe, and a racemic mixture, the interlayer spacing of the GDS membrane was approximately 2.10, 2.39, and 2.24 nm, respectively, exhibiting a trend of d(D) > d(Mix) > d(L). Electrochemical results indicated that, in the same membrane sample, the double-layer capacitance after D-Phe treatment was lower than that after L-Phe treatment; in the rGDS-200 membrane, the interfacial charge transfer resistance increased to 3.9 Ω after D-Phe treatment. Mechanical tests showed that the membrane soaked in D-Phe exhibited higher tensile stress, indicating that D-Phe interacted more strongly with the chiral interface building units, forming a more significant interfacial barrier. In contrast, L-Phe retained a lower migration barrier and achieved faster permeation. The aforementioned trends in Cdl and mechanical properties are consistent with the results of separation experiments and diffusion activation energy analysis, jointly demonstrating the preferential transport mechanism of L-Phe by the chiral membrane of this invention from three aspects: transport barrier, chiral environment, and membrane-solute interaction.

Claims

1. A chiral graphene oxide-based separation membrane, characterized in that, include: A layered framework formed by stacking graphene oxide sheets and / or reduced graphene oxide sheets, and a single-stranded deoxyribonucleic acid-single-walled carbon nanotube composite dispersed and embedded in the layered framework; The single-stranded deoxyribonucleic acid helix is ​​wound around the outer surface of the single-walled carbon nanotube to form a one-dimensional chiral nanochannel with a shell-core structure. The one-dimensional chiral nanochannels are interconnected in the film thickness direction to form a three-dimensional chiral channel network, and are connected to the graphene oxide sheets and / or reduced graphene oxide sheets through the negatively charged phosphate backbone of the single-stranded deoxyribonucleic acid. The mass ratio of the graphene oxide and / or reduced graphene oxide, the single-stranded deoxyribonucleic acid, and the single-walled carbon nanotubes is 1:1 to 4:0.1 to 0.

4.

2. The chiral graphene oxide-based separation membrane according to claim 1, characterized in that, The single-stranded deoxyribonucleic acid was derived from salmon sperm double-stranded deoxyribonucleic acid, which was obtained by thermo-chemical treatment and decoupling in a urea-containing solution.

3. The chiral graphene oxide-based separation membrane according to claim 1, characterized in that, The reduced graphene oxide was obtained by heat-treating an aqueous dispersion of graphene oxide at 50–200°C for 0.5–4 hours.

4. The chiral graphene oxide-based separation membrane according to claim 1, characterized in that, The thickness of the separation membrane is 2–2.5 μm, and the pure water flux of the separation membrane prepared with graphene oxide is 2–5 L·m⁻¹ under a pressure difference of 0.8 bar. -2 ·h -1 The separation membrane prepared by thermal reduction at 200℃ has a pure water flux of 30–60 L·m⁻¹ under a pressure difference of 0.8 bar. -2 ·h -1 .

5. A method for preparing the chiral graphene oxide-based separation membrane according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Dissolve double-stranded deoxyribonucleic acid (DDNA) derived from salmon sperm in PBS buffer containing 8 mol / L urea, heat at 80–100 °C for 0.5–2 h, and then dialyze to obtain a single-stranded DDNA solution; S2: Add single-walled carbon nanotubes to a 0.5% (w / w) aqueous solution of polyvinylpyrrolidone, disperse by ultrasonication, centrifuge and collect the supernatant to obtain a single-walled carbon nanotube dispersion; mix the single-walled carbon nanotube dispersion with the single-stranded deoxyribonucleic acid solution from step one at a mass ratio of 1 to 4:1 under stirring conditions, and stir for 1 to 3 hours to obtain a single-stranded deoxyribonucleic acid-single-walled carbon nanotube dispersion; S3: Add graphene oxide powder or reduced graphene oxide powder to water and disperse by ultrasonication to obtain a graphene oxide or reduced graphene oxide dispersion. S4: Mix the dispersion from step S2 with the dispersion from step S3 under stirring for 1-3 hours. Adjust the amount of each component to make the mass ratio of graphene oxide and / or reduced graphene oxide, single-stranded deoxyribonucleic acid and single-walled carbon nanotubes 1:1-4:0.1-0.4 to obtain a film-forming dispersion. Vacuum filter the film-forming dispersion through a polyethersulfone substrate membrane under a pressure difference of 0.8 bar to form a film. Dry at room temperature for 6-24 hours to obtain the chiral graphene oxide-based separation membrane.

6. The method according to claim 5, characterized in that, The heating temperature in step S1 is 90℃ and the heating time is 1h; the reduced graphene oxide powder in step S3 is obtained by heat-treating the graphene oxide aqueous dispersion at 50~200℃ for 0.5~4h.

7. A method for separating chiral enantiomers using the chiral graphene oxide-based separation membrane according to any one of claims 1-4, characterized in that, Feed liquid and receiving liquid are added to both sides of the separation membrane, respectively. Driven by the concentration difference, the chiral enantiomer is transported through the separation membrane. The receiving liquid is collected to obtain a product enriched with a certain chiral enantiomer.

8. The method according to claim 7, characterized in that, The chiral enantiomer is selected from at least one of phenylalanine, glutamic acid, ibuprofen, propranolol, and 2-methylpiperazine.

9. The method according to claim 8, characterized in that, The chiral enantiomers are L-phenylalanine and D-phenylalanine, and the separation membrane is a graphene oxide-single-stranded deoxyribonucleic acid-single-walled carbon nanotube membrane or a graphene oxide-single-stranded deoxyribonucleic acid-single-walled carbon nanotube membrane reduced at 200°C, with a separation factor greater than 6.

0.

10. The method according to claim 7, characterized in that, Based on Arrhenius relation fitting, the diffusion activation energy of L-phenylalanine in the separation membrane is lower than that of D-phenylalanine.

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