Chitosan-polyacrylonitrile composite material and preparation method and application thereof

Abstract

This application relates to the field of materials technology, providing a chitosan-polyacrylonitrile composite material, its preparation method, and its application. The general structural formula of the chitosan-polyacrylonitrile composite material is as follows: This application uses inexpensive chitosan and polyacrylonitrile fiber as raw materials to develop a novel chitosan-polyacrylonitrile composite material, overcoming the solubility limitation of chitosan under acidic conditions and simultaneously enhancing its adsorption capacity for phenolic compounds and heavy metals. It exhibits higher selectivity for target pollutants, especially among eight different phenolic compounds (phenol, 4-methylphenol, 4-chlorophenol, 4-nitrophenol, hydroquinone, catechol, resorcinol, and phloroglucinol), showing excellent adsorption performance for hydroquinone, with an adsorption capacity as high as 316.84 mg·g⁻¹. ‑1 Furthermore, this application addresses the soft metal ion Hg. 2+ Its adsorption capacity is outstanding, with a maximum adsorption capacity of 237.18 mg·g⁻¹. ‑1 .

Description

Technical Field

[0001] This application belongs to the field of materials technology, and in particular relates to a chitosan-polyacrylonitrile composite material, its preparation method, and its application. Background Technology

[0002] The continued development of the manufacturing industry has significantly exacerbated the discharge of organic waste into aquatic ecosystems, thus worsening water pollution problems. Even at trace concentrations, organic pollutants pose a serious threat to the recycling and sustainable development of water resources. Phenolic compounds, as a typical class of persistent organic pollutants, are widely used in industrial production processes such as plastics, dyes, and pesticides, and possess strong resistance to degradation due to the stability of their chemical structures. Once these compounds enter the environment, they readily accumulate in the food chain, posing potential risks to ecosystems and human health.

[0003] Besides organic pollutants, heavy metals (such as lead, chromium, and mercury) are also among the most significant pollutants in wastewater. The presence of these toxic metals not only significantly degrades the quality of groundwater and surface water but also poses a serious threat to aquatic ecosystems and terrestrial organisms. Furthermore, long-term exposure to heavy metals can cause irreversible damage to vital human organs (such as the liver, kidneys, brain, and nervous system), and may even be carcinogenic or cause acute poisoning under high concentration conditions.

[0004] Among numerous water pollution control technologies, adsorption is widely considered one of the most promising pollutant removal technologies due to its simple operation, low energy consumption, recyclability, and high treatment efficiency. Currently, various highly efficient adsorption materials have been developed for removing organic pollutants and heavy metals from wastewater. However, despite these materials' progress in pollutant removal, they still face the problem of low selectivity, making it difficult to efficiently separate phenolic pollutants and heavy metal ions. Therefore, developing adsorption materials with higher selectivity, larger adsorption capacity, and better regeneration performance remains a core challenge in the field of water pollution control. Summary of the Invention

[0005] The purpose of this application is to provide a chitosan-polyacrylonitrile composite material, which aims to solve the problem that existing high-efficiency adsorption materials have low selectivity and are difficult to efficiently separate phenolic pollutants and heavy metal ions.

[0006] The embodiments of this application are implemented as follows: a chitosan-polyacrylonitrile composite material, wherein the general structural formula of the chitosan-polyacrylonitrile composite material is:

[0007]

[0008] This application also provides a method for preparing the above-mentioned chitosan-polyacrylonitrile composite material, comprising:

[0009] Modified polyacrylonitrile fibers dissolved in N-methylpyrrolidone were uniformly mixed with copper sulfate pentahydrate and sodium L-ascorbate dissolved in water to obtain a first mixture;

[0010] Modified chitosan was added to the first mixture and stirred to react. After filtration and washing, a second mixture was obtained.

[0011] The second mixture was placed in an acid solution and stirred. After filtration, the resulting solid was placed in a sodium carbonate solution and stirred. After filtration, washing, and drying, chitosan-polyacrylonitrile composite material was obtained.

[0012] This application also provides an application of the above-mentioned chitosan-polyacrylonitrile composite material in the adsorption of organic pollutants and heavy metal ions.

[0013] This application successfully developed a novel chitosan-polyacrylonitrile composite material using inexpensive chitosan and polyacrylonitrile fibers as raw materials. This material overcomes the solubility limitations of chitosan under acidic conditions and simultaneously enhances its adsorption capacity for phenolic compounds and heavy metals. Compared to chitosan, this chitosan-polyacrylonitrile composite material has a more compact internal structure, mainly due to the structural confinement effect of polyacrylonitrile. This structural modification endows the chitosan-polyacrylonitrile composite material with higher selectivity for target pollutants, especially among eight different phenolic compounds (phenol, 4-methylphenol, 4-chlorophenol, 4-nitrophenol, hydroquinone, catechol, resorcinol, and phloroglucinol). Hydroquinone exhibits superior adsorption performance, with an adsorption capacity as high as 316.84 mg·g⁻¹. -1 Furthermore, this chitosan-polyacrylonitrile composite material is effective against soft metal ions such as Hg. 2+ Its adsorption capacity is also outstanding, with a maximum adsorption capacity of 237.18 mg·g⁻¹. -1 . Attached Figure Description

[0014] Figure 1 TEM images of PAN-CS and CS provided in Embodiment 1 of this application;

[0015] Figure 2 Infrared spectra of different functionalized materials provided in Embodiment 1 of this application. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0017] This application provides a chitosan-polyacrylonitrile composite material, the general structural formula of which is:

[0018]

[0019] In this embodiment, the chitosan-polyacrylonitrile composite material (PAN-CS) is formed by chemically bonding modified chitosan and modified polyacrylonitrile, and is used for the adsorption and removal of phenolic pollutants and heavy metal ions. This material not only combines the high adsorption performance of chitosan and the acid resistance of polyacrylonitrile fibers, but also significantly improves the structural stability and pollutant selectivity of the material.

[0020] Chitosan, a natural polymer derived from chitin, has attracted considerable attention in environmental protection and industrial applications due to its excellent biocompatibility, biodegradability, efficient adsorption performance, and promising functionalization potential. However, the application of chitosan is limited under certain environmental conditions, especially in weakly acidic solutions where it is prone to acid degradation and gelation. This reduces its dispersibility in aqueous solutions and affects its ability to complex metal ions through hydroxyl and amino groups, thus limiting its adsorption performance.

[0021] Polyacrylonitrile fiber (PANF) is an acid-resistant material with a surface rich in cyano groups, which can be chemically modified to form various functional groups. Studies have shown that functionalized PANF exhibits high selective adsorption capacity for specific pollutants in water pollution control, providing important scientific evidence for its precise application in wastewater treatment. Therefore, by rationally designing functionalized PANF and optimizing its interaction mechanism with pollutants, its application value in the field of water pollution control is expected to be further enhanced.

[0022] This application also provides a method for preparing the above-mentioned chitosan-polyacrylonitrile composite material, including the following steps:

[0023] Step S1: Dissolve the modified polyacrylonitrile fiber (PAN) in N-methylpyrrolidone. P F) is uniformly mixed with copper sulfate pentahydrate and sodium L-ascorbate dissolved in water to obtain the first mixture.

[0024] Step S2: Add modified chitosan (BNCS) to the first mixture and stir to react. After filtration and washing, a second mixture (PAN-BCS) is obtained.

[0025] Step S3: The second mixture is placed in an acid solution for mixing and stirring. After filtration, the resulting solid is placed in a sodium carbonate solution for mixing and stirring. After filtration, washing, and drying, chitosan-polyacrylonitrile composite material (PAN-CS) is obtained.

[0026] The reaction route is shown below:

[0027]

[0028] Optionally, the method for preparing the modified polyacrylonitrile fiber includes: mixing polyacrylonitrile fibers (PAN) into... P F), propargylamine, and deionized water were stirred and reacted under boiling reflux conditions. After the reaction was completed, the fibers were removed, washed, and dried to obtain modified polyacrylonitrile fibers (PAN). P F). The reaction pathway is shown below:

[0029]

[0030] More specifically, the preparation method of the modified polyacrylonitrile fiber includes: adding 1.00g of polyacrylonitrile fiber, 10.0mL of propargylamine and 30.0mL of deionized water into a round-bottom flask, stirring the mixture under boiling reflux conditions for 24 hours, and after the reaction is completed, removing the fiber, washing it repeatedly with ethanol, and drying it to obtain the modified polyacrylonitrile fiber.

[0031] Optionally, the modified polyacrylonitrile fiber dissolved in N-methylpyrrolidone is uniformly mixed with copper sulfate pentahydrate and sodium L-ascorbate dissolved in water to obtain a first mixture, comprising:

[0032] 1.00 g of modified polyacrylonitrile fiber was dissolved in 50.0 mL of N-methylpyrrolidone at 130 °C. After the solution was cooled to room temperature, 0.32 g of copper sulfate pentahydrate and 0.52 g of sodium L-ascorbate dissolved in 1.0 mL of water were added and stirred until homogeneous to obtain the first mixture.

[0033] Optionally, the preparation method of the modified chitosan includes: dissolving chitosan (CS) in acetic acid solution, adding methanol for uniform mixing, then slowly adding benzaldehyde-methanol solution for mixing and reaction. After the reaction is complete, slowly adding sodium hydroxide solution until no more white precipitate is produced in the solution. After washing and drying, a first modified product (BCS) is obtained. The first modified product is placed in sodium hydroxide solution for swelling treatment, and then slowly added to a p-toluenesulfonyl chloride-chloroform solution for stirring and reaction. After filtration and washing, a second modified product (BTCS) is obtained. The second modified product, sodium azide, and N,N-dimethylformamide are stirred and reacted. After filtration and washing, modified chitosan (BNCS) is obtained. The reaction route is shown below:

[0034]

[0035] More specifically, the preparation method of the modified chitosan includes: dissolving chitosan in acetic acid solution, adding methanol and stirring until the solution is uniformly mixed, then slowly adding benzaldehyde-methanol solution, heating to 60°C, reacting for 3 hours, after the reaction is completed, slowly adding sodium hydroxide solution until no more white precipitate is produced in the solution, washing and drying to obtain the first modified product; after the first modified product is swollen in sodium hydroxide solution for 1 hour, p-toluenesulfonyl chloride-chloroform solution is slowly added dropwise at 0°C, and the reaction is stirred at 0°C for 1 hour, the reaction mixture is then transferred to 30°C, and the reaction is continued to be stirred for 10 hours, filtered and washed to obtain the second modified product; the second modified product, sodium azide and N,N-dimethylformamide are added to a round-bottom flask equipped with a reflux condenser, and the reaction is stirred at 80°C for 4 hours, filtered and washed to obtain modified chitosan.

[0036] Optionally, the step of adding modified chitosan to the first mixture and stirring the reaction, followed by filtration and washing, yields a second mixture comprising:

[0037] Add 0.67 g of modified chitosan to the first mixture, and continue stirring at 30 °C for 24 hours. After the reaction is complete, pour the mixture into 100.0 mL of water, filter, and wash the solid with water and ethanol to obtain the second mixture.

[0038] Optionally, the second mixture is placed in an acid solution for mixing and stirring, filtered, and the resulting solid is placed in a sodium carbonate solution for mixing and stirring. After filtration, washing, and drying, a chitosan-polyacrylonitrile composite material is obtained, comprising:

[0039] The second mixture was placed in 40.0 mL of 2.0 M hydrochloric acid solution, stirred at 40 °C for 4 hours, and then filtered. The resulting solid was placed in 40.0 mL of 1.0 M sodium carbonate solution, stirred at room temperature for 1 hour, filtered, washed with water and ethanol, and dried at 60 °C to obtain chitosan-polyacrylonitrile composite material.

[0040] This application also provides an application of the above-mentioned chitosan-polyacrylonitrile composite material in the adsorption of organic pollutants and heavy metal ions.

[0041] The following detailed description of chitosan-polyacrylonitrile composite materials, their preparation methods, and applications is provided with specific examples, as shown below. Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0042] Example 1: Preparation of chitosan-polyacrylonitrile composite material

[0043] Chitosan (CS, 0.75 g) with a degree of deacetylation of 93.4% was dissolved in a 2 wt% acetic acid solution and placed in a 100 mL round-bottom flask. Then, methanol (70.0 mL) was added, and the mixture was stirred with a magnetic stirrer until homogeneous. Next, benzaldehyde (2.00 g) was diluted in methanol (30.0 mL), and this solution was slowly added dropwise to the chitosan-methanol solution. The mixture was heated to 60 °C and reacted for 3 hours. After the reaction was complete, 5% sodium hydroxide solution was slowly added until no more white precipitate formed. The mixture was then stirred for another 30 minutes, filtered, and the solid was washed alternately with water and methanol. Finally, the solid was dried at 60 °C to obtain a white solid BCS (0.98 g).

[0044] BCS (0.76 g) was swollen in 1% sodium hydroxide solution (10.0 mL) for 1 hour. Then, p-toluenesulfonyl chloride (2.90 g) dissolved in chloroform (50.0 mL) was slowly added dropwise to the swollen BCS solution at 0 °C, and the reaction was stirred at this temperature for 1 hour. The reaction mixture was then transferred to 30 °C, and the reaction was continued with stirring for 10 hours. After the reaction was complete, the solid was filtered and washed with ethanol, and finally dried at 60 °C to give a white solid BTCS (0.70 g).

[0045] BTCS (0.62 g), sodium azide (0.30 g), and N,N-dimethylformamide (30.0 mL) were added to a round-bottom flask equipped with a reflux condenser, and the mixture was stirred at 80 °C for 4 hours. After the reaction was complete, the mixture was filtered and the solid was washed with water and ethanol. Finally, the solid was dried at 60 °C to obtain a pale yellow solid, BNCS (0.48 g).

[0046] Dry PANF (1.00 g), propargylamine (10.0 mL), and deionized water (30.0 mL) were added to a round-bottom flask. The mixture was stirred and reacted under boiling reflux for 24 hours. After the reaction was complete, the fibers were removed, washed repeatedly with ethanol, and then dried in an oven at 60°C for at least 8 hours to obtain orange PAN fibers. P F.

[0047] PAN PF (1.00 g) was dissolved in 50.0 mL of N-methylpyrrolidone at 130 °C. After the solution was cooled to room temperature (25 °C), CuSO4·5H2O (0.32 g) dissolved in 1.0 mL of water and L-sodium ascorbate (0.52 g) were added and stirred until homogeneous. Subsequently, BNCS (0.67 g) was added, and stirring was continued at 30 °C for 24 hours. After the reaction was complete, the mixture was poured into 100.0 mL of water, filtered, and the solid was washed with water and ethanol to obtain a brown powder, PAN-BCS. Next, PAN-BCS was placed in 40.0 mL of 2.0 M HCl solution and stirred at 40 °C for 4 hours, then filtered. Subsequently, the solid was placed in 40.0 mL of 1.0 M Na2CO3 solution and stirred at room temperature for 1 hour. The solid was filtered, washed with water and ethanol, and finally dried at 60°C to obtain a brown powder of chitosan-polyacrylonitrile composite material PAN-CS (1.39 g).

[0048] TEM tests were performed on the chitosan CS and the chitosan-polyacrylonitrile composite material PAN-CS in Example 1, and the test results are as follows: Figure 1 As shown, where, Figure 1 (a)-(c) are TEM images of PAN-CS. Figure 1 (d)-(f) are TEM images of the CS. From Figure 1 As can be seen, PAN-CS particles are more densely packed than CS particles. This phenomenon can be attributed to the regioconstriction effect exerted by the modified polyacrylonitrile polymer segments on the chitosan molecular segments during the reaction process. This effect promotes a more compact arrangement of polymer segments, resulting in a more compact structure.

[0049] Furthermore, regarding CS, BCS, BTCS, BNCS, PANF, and PAN in Example 1... P Infrared spectroscopy tests were performed on F, PAN-BCS, and PAN-CS respectively. The test results are as follows: Figure 2 As shown. From Figure 2 From this, we can see that at 1639cm -1 At 755 cm⁻¹, the BCS shows an absorption peak for the stretching vibration of the C=N bond. -1 and 690cm -1 The characteristic absorption peak of the monosubstituted benzene ring appeared at 818 cm⁻¹, indicating the successful formation of the imine bond. -1 The absorption peak at the para-benzene ring bending vibration at 2106 cm⁻¹ confirmed the introduction of the p-toluenesulfonyl group. In the BNCS spectrum, the peak at 2106 cm⁻¹... -1 The stretching vibration absorption peak at 2244 cm⁻¹ indicates the successful introduction of the azide group. In the PANF spectrum, the peak at 2244 cm⁻¹... -1 There is an absorption peak at the stretching vibration of the C≡N bond. PAN PF shows 1660cm -1 The absorption peak of the C=O stretching vibration at that point is observed in the PAN-BCS spectrum. p The characteristic peak of F (C≡N, 2244 cm⁻¹) -1 It also has the characteristic peak of BNCS (-OH, 3500 cm⁻¹). -1 Aromatic ring, 755cm -1 and 690cm -1 After hydrolysis of the imine, the bending vibration absorption peak of the monosubstituted benzene ring disappears in the PAN-CS spectrum.

[0050] Example 2: Adsorption of phenolic compounds by PAN-CS

[0051] 10 mg of dried PAN-CS was immersed in a solution containing phenolic contaminants (volume 40 mL, initial concentration 1 mmol / L). -1 After stirring at room temperature until adsorption equilibrium was reached, the absorbance of each pollutant was measured at its maximum absorption wavelength using a UV spectrophotometer, and the corresponding concentration was calculated based on the corresponding standard curve. The adsorption performance of PAN-CS for phenolic pollutants was calculated based on the decrease in concentration before and after adsorption. The results are shown in Table 1. The formula for calculating the adsorption capacity is as follows:

[0052]

[0053] q e This is the equilibrium adsorption capacity (mg / g) of PAN-CS for phenolic pollutants. -1 ), C0 and C e These correspond to the initial and final adsorption concentrations (mg / L), respectively. -1 V is the volume of the pollutant (L), and m is the mass of PAN-CS (g).

[0054] Table 1. Adsorption capacity of PAN-CS for different phenolic substances

[0055] Adsorbed substances <![CDATA[Adsorption capacity (mmol g -1 )]]> 1 phenol 0 2 phloroglucinol 0.01 3 catechol 0.01 4 resorcinol 0.03 5 4-Methylphenol 0.05 6 4-Chlorophenol 0.11 7 4-Nitrophenol 0.33 8 hydroquinone 2.81

[0056] Example 3: Adsorption of heavy metal ions by PAN-CS

[0057] 10 mg of dried PAN-CS was immersed in a solution containing heavy metal ions (volume 40 mL, initial concentration 1 mmol / L). -1 After stirring at room temperature until adsorption equilibrium is reached, the absorbance is measured using ICP-OES, and the corresponding concentration is calculated based on the relevant standard curve. The adsorption performance of PAN-CS for heavy metal ions is calculated based on the decrease in the concentration of the substance before and after adsorption. The formula for calculating the adsorption capacity is the same as above.

[0058] Table 2. Adsorption capacity of PAN-CS for different heavy metal ions

[0059]

[0060]

[0061] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a chitosan-polyacrylonitrile composite material, characterized in that, include: Modified polyacrylonitrile fibers dissolved in N-methylpyrrolidone were uniformly mixed with copper sulfate pentahydrate and sodium L-ascorbate dissolved in water to obtain a first mixture; Modified chitosan was added to the first mixture and stirred to react. After filtration and washing, a second mixture was obtained. The second mixture was placed in an acid solution and stirred. After filtration, the resulting solid was placed in a sodium carbonate solution and stirred. After filtration, washing, and drying, chitosan-polyacrylonitrile composite material was obtained. The method for preparing the modified polyacrylonitrile fiber includes: Polyacrylonitrile fiber, propargylamine, and deionized water were stirred and reacted under boiling reflux conditions. After the reaction was completed, the fiber was removed, washed, and dried to obtain modified polyacrylonitrile fiber. The method for preparing the modified chitosan includes: Chitosan was dissolved in acetic acid solution and then methanol was added for uniform mixing. Benzaldehyde-methanol solution was then slowly added dropwise for further mixing and reaction. After the reaction was complete, sodium hydroxide solution was slowly added until no more white precipitate was produced in the solution. After washing and drying, the first modified product was obtained. The first modified compound was swollen in a sodium hydroxide solution, and then a p-toluenesulfonyl chloride-chloroform solution was slowly added and stirred. After filtration and washing, the second modified compound was obtained. The second modified material, sodium azide, and N,N-dimethylformamide were stirred and reacted, and after filtration and washing, modified chitosan was obtained.

2. The method for preparing the chitosan-polyacrylonitrile composite material according to claim 1, characterized in that, The method for preparing the modified polyacrylonitrile fiber includes: 1.00 g of polyacrylonitrile fiber, 10.0 mL of propargylamine and 30.0 mL of deionized water were added to a round-bottom flask. The mixture was stirred and reacted under boiling reflux for 24 hours. After the reaction was completed, the fiber was removed, washed repeatedly with ethanol, and dried to obtain modified polyacrylonitrile fiber.

3. The method for preparing the chitosan-polyacrylonitrile composite material according to claim 1, characterized in that, The method for preparing the modified chitosan includes: Chitosan was dissolved in acetic acid solution, methanol was added and stirred until the solution was uniformly mixed, then benzaldehyde-methanol solution was slowly added dropwise, the mixture was heated to 60 °C and reacted for 3 hours. After the reaction was completed, sodium hydroxide solution was slowly added until no more white precipitate was produced in the solution. After washing and drying, the first modified product was obtained. After the first modified compound swelled in sodium hydroxide solution for 1 hour, p-toluenesulfonyl chloride-chloroform solution was slowly added dropwise at 0°C, and the reaction was stirred at 0°C for 1 hour. The reaction mixture was then transferred to 30°C and stirred for another 10 hours. After filtration and washing, the second modified compound was obtained. The second modified material, sodium azide, and N,N-dimethylformamide were added to a round-bottom flask equipped with a reflux condenser and stirred at 80°C for 4 hours. After filtration and washing, modified chitosan was obtained.

4. The method for preparing the chitosan-polyacrylonitrile composite material according to claim 1, characterized in that, The modified polyacrylonitrile fiber dissolved in N-methylpyrrolidone is uniformly mixed with copper sulfate pentahydrate and sodium L-ascorbate dissolved in water to obtain a first mixture comprising: 1.00 g of modified polyacrylonitrile fiber was dissolved in 50.0 mL of N-methylpyrrolidone at 130 °C. After the solution was cooled to room temperature, 0.32 g of copper sulfate pentahydrate and 0.52 g of sodium L-ascorbate dissolved in 1.0 mL of water were added and stirred until homogeneous to obtain the first mixture.

5. The method for preparing the chitosan-polyacrylonitrile composite material according to claim 4, characterized in that, The process involves adding modified chitosan to the first mixture and stirring the mixture, followed by filtration and washing to obtain a second mixture, comprising: Add 0.67 g of modified chitosan to the first mixture, and continue stirring at 30 °C for 24 hours. After the reaction is complete, pour the mixture into 100.0 mL of water, filter, and wash the solid with water and ethanol to obtain the second mixture.

6. The method for preparing the chitosan-polyacrylonitrile composite material according to claim 5, characterized in that, The second mixture is placed in an acid solution for mixing and stirring, filtered, and the resulting solid is placed in a sodium carbonate solution for mixing and stirring. After filtration, washing, and drying, a chitosan-polyacrylonitrile composite material is obtained, comprising: The second mixture was placed in 40.0 mL of 2.0 M hydrochloric acid solution, stirred at 40 °C for 4 hours, and then filtered. The resulting solid was placed in 40.0 mL of 1.0 M sodium carbonate solution, stirred at room temperature for 1 hour, filtered, washed with water and ethanol, and dried at 60 °C to obtain chitosan-polyacrylonitrile composite material.

7. A chitosan-polyacrylonitrile composite material, characterized in that, The chitosan-polyacrylonitrile composite material is prepared by any one of the preparation methods described in claims 1-6.

8. The application of the chitosan-polyacrylonitrile composite material according to claim 7 in the adsorption of organic pollutants and heavy metal ions.

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