Graphene oxide-chitosan composite membrane, preparation method thereof and application of graphene oxide-chitosan composite membrane in adsorption of copper ions
A graphene oxide-chitosan composite membrane was prepared by aqueous dispersion and vacuum filtration, which solved the problems of easy stacking of graphene oxide and easy dissolution of chitosan. This method achieved efficient adsorption of copper ions, with good mechanical strength and adsorption performance, and is suitable for water treatment devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-03-13
AI Technical Summary
When graphene oxide and chitosan are used alone, graphene oxide tends to stack, which reduces the number of active sites. Chitosan has poor mechanical strength and is easily soluble under acidic conditions. There is a lack of preparation methods that can precisely control the membrane structure and have excellent adsorption performance.
Graphene oxide and chitosan were mixed at a dry mass ratio of 1:5 using an aqueous dispersion method, and a graphene oxide-chitosan composite membrane was prepared by vacuum filtration to form a dense layered structure. The film-forming properties and mechanical support of chitosan were utilized to enhance the stability and adsorption performance of the membrane.
The prepared composite membrane has high adsorption activity and good mechanical strength, and is suitable for wastewater treatment under different concentration and temperature conditions. The adsorption kinetics conform to the pseudo-first-order and pseudo-second-order models, and the copper ion removal rate is as high as 94%.
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Figure CN121648897A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water treatment materials technology, and particularly relates to a graphene oxide-chitosan composite membrane, its preparation method, and its application in adsorbing copper ions. Background Technology
[0002] Copper and its compounds are widely used in industries such as electroplating, electronics, and metallurgy, resulting in copper-containing wastewater that poses a serious threat to the aquatic environment. At the same time, copper is a valuable metallic resource, and recovering copper from wastewater has significant economic and environmental benefits. Adsorption methods are widely used in the treatment of heavy metal wastewater due to their simplicity and low cost.
[0003] Graphene oxide (GO) and chitosan (CS) are two commonly used adsorbent materials. GO has a high specific surface area and abundant oxygen-containing functional groups (such as carboxyl and epoxy groups), while CS molecules contain a large number of amino and hydroxyl groups. Both can bind to copper ions through coordination, electrostatic interactions, and other mechanisms. However, GO alone tends to stack in water, leading to a reduction in active sites and adsorption capacity; while CS alone suffers from poor mechanical strength and easy dissolution under acidic conditions. Combining GO and CS is considered an effective way to solve these problems. However, current technologies lack preparation methods that can precisely control the membrane structure and achieve excellent adsorption performance. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention proposes a graphene oxide-chitosan composite membrane, its preparation method, and its application in adsorbing copper ions.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A method for preparing a graphene oxide-chitosan composite film includes the following steps:
[0007] Chitosan dispersion and graphene oxide dispersion are mixed and stirred to form a composite dispersion;
[0008] The composite dispersion was vacuum filtered onto a microporous membrane to form a film, which was then dried and peeled off to obtain the graphene oxide-chitosan composite membrane.
[0009] Beneficial effects: The preparation process of this invention only uses aqueous phase dispersion, room temperature stirring and vacuum filtration, without the need for high temperature, high pressure or toxic crosslinking agents, making it simple to operate and environmentally friendly; the resulting composite membrane is a self-supporting flexible film that can be directly used in water treatment devices such as fixed beds and membrane filtration, avoiding the problem of difficult recovery of powdered adsorbents.
[0010] Furthermore, the adsorption kinetics of the composite membrane prepared by the method of this invention conform to the pseudo-first-order and pseudo-second-order models (Ri). 2The value >0.92 indicates that the process integrates physical diffusion and chemical complexation mechanisms, adapts to wastewater treatment needs under different concentration and temperature conditions, and has good engineering application prospects.
[0011] In summary, this invention not only solves the performance bottleneck of existing GO or CS when used alone, but also achieves an integrated design of "structure-performance-application" through a precise preparation strategy, providing a new type of functional membrane material for efficient, green, and scalable treatment of heavy metal wastewater.
[0012] Optionally, the mass ratio of graphene oxide in the graphene oxide dispersion to chitosan in the chitosan dispersion is 1:5.
[0013] Beneficial effects: This invention effectively inhibits the stacking of GO sheets in water by compounding graphene oxide and chitosan at a dry mass ratio of 1:5. At the same time, it solves the problems of brittleness and difficulty in handling of pure GO membranes by utilizing the film-forming properties and mechanical support of chitosan. In addition, the introduction of GO significantly enhances the structural stability of chitosan membranes, preventing them from swelling or dissolving in acidic wastewater, thereby obtaining a self-supporting composite membrane with both high adsorption activity and good mechanical strength.
[0014] Furthermore, the concentration of the graphene oxide dispersion is 0.2 mg / mL.
[0015] Furthermore, the preparation process of the graphene oxide dispersion is as follows:
[0016] The graphene oxide stock solution was added to deionized water and ultrasonically treated for 30 minutes under an ultrasonic power of 100 W and an ice-water bath.
[0017] Furthermore, the concentration of the chitosan dispersion is 5 mg / ml.
[0018] Furthermore, the preparation process of the chitosan dispersion is as follows:
[0019] Chitosan powder was added to a 1% acetic acid solution (i.e., 1 ml of acetic acid per 100 ml of acetic acid solution) and magnetically stirred at 300 r / min for 24 hours at 25°C until completely dissolved.
[0020] Furthermore, the chitosan powder has a degree of deacetylation ≥85% and a molecular weight of 200 kDa.
[0021] Optionally, the stirring conditions are: shaking and mixing at 25 °C.
[0022] Optionally, the vacuum filtration conditions are: continuous filtration for 24 hours at a vacuum pressure of -0.08 MPa.
[0023] Beneficial effects: Vacuum filtration promotes the orderly stacking of GO sheets under the bridging of chitosan molecules, forming a dense and regular layered nanostructure. This not only preserves the large specific surface area of GO, but also fully exposes and synergistically interacts carboxyl and epoxy groups (from GO) with amino and hydroxyl groups (from CS), providing a large number of efficient coordination and electrostatic adsorption sites for copper ions.
[0024] Furthermore, the microporous filter membrane is a polyethersulfone filter membrane with a pore size of 0.03 μm and a diameter of 47 mm.
[0025] A graphene oxide-chitosan composite membrane is prepared by the above-described preparation method.
[0026] Optionally, the drying conditions are: drying at 25°C and 40% relative humidity for 12 hours.
[0027] The above-mentioned graphene oxide-chitosan composite membrane is used to adsorb copper ions in wastewater.
[0028] Optionally, the graphene oxide-chitosan composite membrane has a copper ion removal rate of >94%.
[0029] Compared with the prior art, the present invention has the following advantages and technical effects:
[0030] The composite membrane prepared by this invention through precise control of raw material ratio and process parameters has a regular layered structure and good mechanical properties, and can be directly applied to water treatment processes without breaking.
[0031] The composite membrane prepared by this invention exhibits excellent adsorption performance for copper ions. At 25°C, it adsorbs a Cu(II) solution with an initial concentration of 635.5 mg / L for 30 minutes, achieving an adsorption capacity of 193.6 mg / g; at 60°C, the adsorption capacity reaches 5997.5 mg / g (e.g., ...). Figure 6 ).
[0032] The adsorption kinetics of the composite membrane prepared by this invention conform to pseudo-first-order and pseudo-second-order kinetic models, with a correlation coefficient R0. 2 A value greater than 0.92 indicates that the adsorption process is a complex, multi-step process involving multiple mechanisms such as physical diffusion and chemisorption. Furthermore, in practical application tests, the composite membrane prepared in this invention achieved a copper ion removal rate of up to 94% in CPU leaching solution, demonstrating good selectivity and promising application prospects. Attached Figure Description
[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0034] Figure 1 A photograph of the GO / CS5-M composite membrane prepared in Example 1;
[0035] Figure 2 A planar SEM image of the GO / CS5-M composite membrane prepared in Example 1;
[0036] Figure 3 A cross-sectional SEM image of the GO / CS5-M composite membrane prepared in Example 1;
[0037] Figure 4 XRD patterns of the membrane materials prepared in Example 1, Comparative Example 1, and Comparative Example 2;
[0038] Figure 5 The mechanical property test diagrams are for the membrane materials prepared in Example 1, Comparative Example 1, and Comparative Example 2.
[0039] Figure 6 The adsorption capacity of the membrane materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 for Cu(II) at different temperatures is shown in the graph.
[0040] Figure 7 The adsorption kinetics fitting curves of Cu(II) on the membrane materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown.
[0041] Figure 8 The graph shows the removal efficiency of CPU leachate treated by the membrane materials prepared in Example 1, Comparative Example 1, and Comparative Example 2. Detailed Implementation
[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0043] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0044] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0045] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.
[0046] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0047] This invention discloses a graphene oxide-chitosan composite membrane, which is prepared by vacuum filtration of graphene oxide and chitosan, wherein the dry basis mass ratio of graphene oxide to chitosan is 1:5, and the thickness of the prepared composite membrane is from tens of μm to tens of nm.
[0048] The graphene oxide-chitosan composite membrane disclosed in this invention has a regular layered structure, high adsorption capacity and good mechanical strength.
[0049] This invention provides a method for preparing the above-mentioned graphene oxide-chitosan composite film, comprising the following steps:
[0050] (1) Preparation of chitosan dispersion: 2.000 g of chitosan powder (degree of deacetylation ≥85%, molecular weight approximately 200 kDa) was accurately weighed using an analytical balance and slowly added to 400 mL of 1% acetic acid solution. The solution was magnetically stirred at 300 r / min for 24 hours at 25℃ until completely dissolved, yielding a chitosan dispersion with a concentration of 5 mg / mL. This dispersion was then sealed and stored at 4℃ for later use.
[0051] (2) Preparation of graphene oxide dispersion: 20 mL of 4 mg / mL graphene oxide stock solution was accurately measured using a pipette and added to 380 mL of deionized water to obtain a 0.2 mg / mL graphene oxide dilution. The dilution was placed in an ultrasonic machine and ultrasonically treated for 30 minutes at 100 W power in an ice-water bath to obtain a uniformly dispersed graphene oxide dispersion.
[0052] (3) Preparation of composite dispersion: Accurately measure 25 mL of the graphene oxide dispersion obtained in step (2) and 5 mL of the chitosan dispersion obtained in step (1) using a pipette, and pour them into a 50 mL centrifuge tube. The dry weight ratio of graphene oxide to chitosan is 1:5; shake the mixture at 25 ℃ to obtain a uniform GO / CS composite dispersion;
[0053] (4) Vacuum filtration to form a membrane: The composite dispersion obtained in step (3) is poured into a vacuum filtration device; a polyethersulfone filter membrane with a pore size of 0.03 μm and a diameter of 47 mm is used to continuously filter under a vacuum pressure of -0.08 MPa for 24 hours; after filtration, the filter membrane with wet film is transferred to a constant temperature and humidity chamber with a temperature of 25℃ and a relative humidity of 40% and left to dry for 12 hours; finally, the self-supporting composite membrane is carefully peeled off from the filter membrane with tweezers to obtain the GO / CS composite membrane.
[0054] Furthermore, this invention also discloses the application of the above-mentioned graphene oxide-chitosan composite membrane in the adsorption of copper ions in wastewater.
[0055] Unless otherwise specified, "room temperature" or "normal temperature" as used in this invention refers to 20-30℃.
[0056] All raw materials used in this invention were purchased from the market.
[0057] The technical solution of the present invention will be further illustrated by the following embodiments.
[0058] Example 1: (GO / CS5-M membrane material)
[0059] A method for preparing a graphene oxide-chitosan composite membrane (GO / CS composite membrane) includes the following steps:
[0060] (1) Preparation of chitosan dispersion: 2.000 g of chitosan powder (degree of deacetylation ≥85%, molecular weight approximately 200 kDa) was accurately weighed using an analytical balance and slowly added to 400 mL of 1% acetic acid solution. The solution was magnetically stirred at 300 r / min for 24 hours at 25℃ until completely dissolved, yielding a chitosan dispersion with a concentration of 5 mg / mL. This dispersion was then sealed and stored at 4℃ for later use.
[0061] (2) Preparation of graphene oxide dispersion: 20 mL of 4 mg / mL graphene oxide stock solution was accurately measured using a pipette and added to 380 mL of deionized water to obtain a 0.2 mg / mL graphene oxide dilution. The dilution was placed in an ultrasonic machine and ultrasonically treated for 30 minutes at 100 W power in an ice-water bath to obtain a uniformly dispersed graphene oxide dispersion.
[0062] (3) Preparation of composite dispersion: Accurately measure 25 mL of the graphene oxide dispersion obtained in step (2) and 5 mL of the chitosan dispersion obtained in step (1) using a pipette, and pour them into a 50 mL centrifuge tube. The dry weight ratio of graphene oxide to chitosan is 1:5; shake the mixture at 25 °C to obtain a uniform GO / CS composite dispersion;
[0063] (4) Vacuum filtration to form a membrane: The composite dispersion obtained in step (3) is poured into a vacuum filtration apparatus; a polyethersulfone filter membrane with a pore size of 0.03 μm and a diameter of 47 mm is used, and filtration is carried out continuously for 24 hours under a vacuum pressure of -0.08 MPa; after filtration, the filter membrane with the wet membrane attached is transferred to a constant temperature and humidity chamber at a temperature of 25℃ and a relative humidity of 40% and left to dry for 12 hours; finally, the self-supporting composite membrane is carefully peeled off from the filter membrane with tweezers to obtain the GO / CS composite membrane, denoted as GO / CS5-M. The composite membrane has a smooth surface and self-supporting properties.
[0064] Comparative Example 1 (Single Graphene Oxide Film Material)
[0065] The difference from Example 1 is that a single graphene oxide film material was prepared, and the specific preparation process is as follows:
[0066] A method for preparing a graphene oxide (GO) film material includes the following steps:
[0067] (1) Accurately measure 20 mL of graphene oxide stock solution with a concentration of 4 mg / mL using a pipette, and add it to 380 mL of deionized water to obtain a graphene oxide dilution with a concentration of 0.2 mg / mL. Place the dilution in an ultrasonic machine and sonicate it for 30 minutes at 100 W power under ice-water bath conditions to obtain a uniformly dispersed graphene oxide dispersion;
[0068] (2) Accurately measure 25 mL of the graphene oxide dispersion obtained in step (1) using a pipette and pour it into a 50 mL centrifuge tube. Shake well at 25 °C; then pour it into a vacuum filtration device; use a polyethersulfone filter membrane with a pore size of 0.03 μm and a diameter of 47 mm, and continuously filter under a vacuum pressure of -0.08 MPa for 24 hours; after filtration, transfer the filter membrane with the wet membrane to a constant temperature and humidity chamber at 25 °C and 40% relative humidity, and let it stand and dry for 12 hours; finally, carefully peel the self-supporting composite membrane off the filter membrane with tweezers to obtain the GO membrane.
[0069] Comparative Example 2 (GO / CS) 10 -M membrane material)
[0070] The difference from Example 1 is that the dry mass ratio of graphene oxide to chitosan is 1:10, and the specific preparation process is as follows:
[0071] A method for preparing a graphene oxide-chitosan composite membrane (GO / CS composite membrane) includes the following steps:
[0072] (1) Preparation of chitosan dispersion: 2.000 g of chitosan powder (degree of deacetylation ≥85%, molecular weight approximately 200 kDa) was accurately weighed using an analytical balance and slowly added to 400 mL of 1% acetic acid solution. The solution was magnetically stirred at 300 r / min for 24 hours at 25℃ until completely dissolved, yielding a chitosan dispersion with a concentration of 5 mg / mL. This dispersion was then sealed and stored at 4℃ for later use.
[0073] (2) Preparation of graphene oxide dispersion: 20 mL of graphene oxide stock solution with a concentration of 4 mg / mL was accurately measured with a pipette and added to 380 mL of deionized water to obtain a graphene oxide dilution with a concentration of 0.2 mg / mL; the dilution was placed in an ultrasonic machine and ultrasonically treated for 30 minutes at a power of 100 W under ice-water bath conditions to obtain a uniformly dispersed graphene oxide dispersion.
[0074] (3) Preparation of composite dispersion: Accurately measure 25 mL of the graphene oxide dispersion obtained in step (2) and 10 mL of the chitosan dispersion obtained in step (1) using a pipette, and pour them into a 50 mL centrifuge tube. The dry weight ratio of graphene oxide to chitosan is 1:10; shake the mixture at 25 °C to obtain a uniform GO / CS composite dispersion;
[0075] (4) Vacuum filtration to form a membrane: The composite dispersion obtained in step (3) is poured into a vacuum filtration apparatus; a polyethersulfone filter membrane with a pore size of 0.03 μm and a diameter of 47 mm is used, and filtration is carried out continuously for 24 hours under a vacuum pressure of -0.08 MPa; after filtration, the filter membrane with wet film is transferred to a constant temperature and humidity chamber at 25℃ and 40% relative humidity, and left to dry for 12 hours; finally, the self-supporting composite membrane is carefully peeled off from the filter membrane with tweezers to obtain the GO / CS composite membrane, denoted as GO / CS. 10 -M.
[0076] Effect verification
[0077] Example 1: Composite membrane adsorption performance test
[0078] The membrane materials prepared in Example 1 and the comparative example were accurately weighed and placed in 50 mL beakers. 20 mL of CuCl2 solution with an initial concentration of 635.5 mg / L was added, and the mixture was stirred at 150 r / min in a magnetic stirrer at 25 °C for adsorption. The copper ion concentration in the solution was measured using an ion meter, and the copper ion concentration at different time points (1, 3, 5, 10, 15, 30, and 60 minutes) was recorded. The real-time adsorption capacity was calculated based on the concentration.
[0079] Experimental results show that the composite membrane reaches adsorption equilibrium within 30 minutes, with an equilibrium adsorption capacity of 193.6 mg / g. At 60 °C, the equilibrium adsorption capacity reaches 5997.5 mg / g.
[0080] Example 2: Actual wastewater treatment test
[0081] CPU leaching solution stock solution provided by Guangdong Lijiang Environmental Protection Co., Ltd., containing multiple competing ions, was used. Membrane materials prepared in Example 1 and the comparative example were immersed in 15 mL of CPU leaching solution for 1 hour for adsorption. Samples were taken to determine the residual copper ion concentration, and the copper ion removal rate was calculated to be 94.07%.
[0082] Figure 1 A photograph of the GO / CS composite membrane prepared in Example 1.
[0083] Figure 2 The image shown is a planar SEM image of the GO / CS composite membrane prepared in Example 1.
[0084] Figure 3 The image shows a cross-sectional SEM image of the GO / CS composite membrane prepared in Example 1.
[0085] from Figure 1-3 It can be seen that the GO / CS composite membrane prepared in Example 1 has a smooth surface, regular structure, and a stable layered structure.
[0086] Figure 4 XRD patterns of the membrane materials prepared in Example 1, Comparative Example 1, and Comparative Example 2. Figure 4 It can be seen that the interlayer spacing of the composite chitosan is greatly improved compared with that of graphene oxide. The larger interlayer spacing is conducive to the entry of Cu(II) ions and the adsorption of ions.
[0087] Figure 5 The graphs show the mechanical properties of the membrane materials prepared in Example 1, Comparative Example 1, and Comparative Example 2. (From...) Figure 5It can be seen that the mechanical properties of the membrane after being composited with a certain proportion of chitosan (GO / CS5-M prepared in Example 1 with a mass ratio of graphene oxide and chitosan of 1:5) were improved compared with pure GO (Comparative Example 1), with the Young's modulus increasing from 1.78 GPa to 2.9 GPa. However, the excessive amount of chitosan added (GO / CS5-M in Comparative Example 2) resulted in a certain improvement in the mechanical properties of the membrane compared with pure GO (Comparative Example 1). 10 -M) can lead to excessive cross-linking, affecting the mechanical properties of the membrane.
[0088] Figure 6 The graph shows the adsorption capacity of Cu(II) for the membrane materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 at different temperatures. Figure 6 It can be seen that the adsorption behavior of the composite membrane prepared in Example 1 of this invention exhibits thermodynamically optimal adsorption conditions. In comparison, the effect of Comparative Example 1 is far inferior to that of Example 1.
[0089] Dynamic fitting was performed using OriginPro software. Figure 7 The figures show the fitted curves of the adsorption kinetics of Cu(II) for each membrane material in Example 1. From... Figure 7 It can be seen that the R-value of the quasi-first-order kinetic model of the composite membrane prepared in Example 1 is... 2 The value is 0.94, and the R-value of the pseudo-second-order dynamic model is... 2 The value is 0.92, which means that the adsorption of Cu(II) in the composite membrane prepared in Example 1 follows first-order and second-order kinetics, indicating that its adsorption process is a complex multi-step process involving multiple mechanisms such as physical diffusion and chemical adsorption.
[0090] Figure 8 This is a graph showing the removal efficiency of CPU leachate treated with different membrane materials in Example 2. From... Figure 8 It can be seen that the composite membrane prepared in Example 1 can still achieve a Cu(II) removal efficiency of 94.07% in a complex system with multi-ion competition. However, the effect of GO is poor.
[0091] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a graphene oxide-chitosan composite film, characterized in that, Includes the following steps: Chitosan dispersion and graphene oxide dispersion are mixed and stirred to form a composite dispersion; The composite dispersion was vacuum filtered onto a microporous membrane to form a film, which was then dried and peeled off to obtain the graphene oxide-chitosan composite membrane.
2. The method for preparing a graphene oxide-chitosan composite film according to claim 1, characterized in that, The mass ratio of graphene oxide in the graphene oxide dispersion to chitosan in the chitosan dispersion is 1:
5.
3. The method for preparing a graphene oxide-chitosan composite film according to claim 1, characterized in that, The concentration of the graphene oxide dispersion is 0.2 mg / mL.
4. The method for preparing a graphene oxide-chitosan composite film according to claim 3, characterized in that, The preparation process of the graphene oxide dispersion is as follows: The graphene oxide stock solution was added to deionized water and ultrasonically treated for 30 minutes under an ultrasonic power of 100 W and an ice-water bath.
5. The method for preparing a graphene oxide-chitosan composite film according to claim 1, characterized in that, The concentration of the chitosan dispersion is 5 mg / ml.
6. The method for preparing a graphene oxide-chitosan composite film according to claim 5, characterized in that, The preparation process of the chitosan dispersion is as follows: Chitosan powder was added to an acetic acid solution and magnetically stirred at 300 r / min for 24 hours at 25°C until completely dissolved.
7. The method for preparing a graphene oxide-chitosan composite film according to claim 6, characterized in that, The chitosan powder has a degree of deacetylation ≥85% and a molecular weight of 200 kDa.
8. The method for preparing a graphene oxide-chitosan composite film according to claim 1, characterized in that, The stirring conditions are: shaking and mixing at 25 °C; and / or, The vacuum filtration conditions are: filtration for 24 hours at a vacuum pressure of -0.08 MPa.
9. A graphene oxide-chitosan composite membrane, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.
10. The application of the graphene oxide-chitosan composite membrane as described in claim 9 in the adsorption of copper ions in wastewater.