A method for preparing a chitosan hollow fiber conductive membrane

Abstract

The application discloses a preparation method of a chitosan hollow fiber conductive membrane, which comprises the following steps: reducing graphene oxide into phosphatized reduced graphene oxide by using phytic acid as a reducing agent; and making the phosphatized reduced graphene oxide as a crosslinking agent and an ion conductor, so as to be tightly combined with a chitosan hollow fiber membrane through intermolecular hydrogen bonds under the auxiliary action of residual phytic acid in the system, and thus the chitosan hollow fiber conductive membrane is prepared. The chitosan hollow fiber conductive membrane has the advantages of high conductivity and good stability, and can be used as a membrane sensor for human motion monitoring, so that the problems of poor dispersibility, poor interface compatibility and poor conductivity of graphene in a fiber matrix are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of textile materials, and particularly relates to a preparation method of a chitosan hollow fiber conductive membrane. BACKGROUND

[0002] Hollow fiber membranes have a tubular cavity structure, high packing density, and self-supporting properties, and are widely used in the fields of membrane separation, membrane distillation, ultrafiltration, membrane sensing, and gas separation. The materials for hollow fiber membranes mainly include polyacrylonitrile, polyimide, cellulose, cellulose acetate, polyvinyl chloride, and polypropylene, but have performance defects such as easy pollution, poor hydrophilicity, and poor organic solvent resistance, which limit their application fields. Therefore, it is of great significance to develop a hydrophilic hollow fiber membrane material.

[0003] Natural high molecular chitosan has strong hydrophilicity, and has good film-forming property, organic solvent resistance, biodegradability, and good biocompatibility, and can be used as an ideal material for developing a new type of hollow fiber membrane applied in the field of membrane sensing. In the application of membrane sensing, the conductivity of the hollow fiber membrane is also required to a certain extent. Therefore, it is a key problem to endow the chitosan hollow fiber membrane with conductivity. Although graphene oxide has ion conduction capacity, the ion conduction rate is low and difficult to meet the actual application requirements. If the graphene oxide is reduced and a proton carrier is introduced at the same time by using a chemical method, the conductivity can be greatly improved. Meanwhile, if the graphene oxide is loaded on the chitosan hollow fiber membrane, the conductivity and mechanical properties of the chitosan hollow fiber membrane can be effectively improved. SUMMARY

[0004] In view of the problems of single function, poor mechanical property, and lack of conductivity of the existing chitosan hollow fiber membrane, the present application provides a method for preparing a chitosan hollow fiber conductive membrane by using phosphonated reduced graphene oxide generated by reducing graphene oxide with phytic acid as a crosslinking agent and an ion conductor, and with the auxiliary action of the remaining phytic acid in the system.

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

[0006] A chitosan hollow fiber conductive membrane, and a preparation method thereof, specifically includes the following steps:

[0007] (1) graphene oxide is added to distilled water, ultrasonic dispersion is performed to form a graphene oxide water dispersion liquid, then phytic acid is added, heating reaction is performed, and ultrasonic dispersion is performed again to form a phosphonated reduced graphene oxide water dispersion liquid;

[0008] (2) chitosan and polyethylene glycol 2000 are added to a 3vol% acetic acid solution, stirring and dissolution are performed at 60 DEG C to form a spinning solution, vacuum degassing is performed, spinning is performed, and sodium hydroxide solution is used as an internal and external gel bath to make the chitosan hollow fiber membrane coagulate into a membrane, then washing is performed in distilled water until the chitosan hollow fiber membrane is neutral, and a chitosan hollow fiber membrane is formed.

[0009] (3) placing the chitosan hollow fiber membrane prepared in step (2) into the phosphated reduced graphene oxide aqueous dispersion solution of step (1), after freeze-thaw circulation, sequentially immersing in distilled water, anhydrous ethanol, n-hexane, and drying at room temperature to obtain a chitosan hollow fiber conductive membrane.

[0010] Further, the concentration of the graphene oxide aqueous dispersion solution in step (1) is 2-6 mg / mL, and the volume ratio of the graphene oxide aqueous dispersion solution to the used phytic acid is 40:1-40:5.

[0011] Further, the heating reaction time in step (1) is 12-20 h, and the temperature is 80-110℃.

[0012] Further, the content of chitosan in the spinning solution in step (2) is 3wt%-5wt%, and the content of polyethylene glycol 2000 is 8wt%-10wt%.

[0013] Further, the concentration of the sodium hydroxide solution in step (2) is 15wt%-20wt%.

[0014] Further, the mass ratio of the chitosan hollow fiber membrane to the phosphated reduced graphene oxide aqueous dispersion solution used in step (3) is 1:50-1:200.

[0015] Further, the freeze-thaw circulation in step (3) is freezing at-50℃ for 12 h, then thawing at room temperature for 12 h, and repeating the above process for 6 times.

[0016] The significant advantages of the present application are:

[0017] The present application reduces graphene oxide to phosphated reduced graphene oxide with phytic acid as a reducing agent, and the obtained phosphated reduced graphene oxide has abundant hydroxyl and phosphate groups on the surface, so that it can be used as a crosslinking agent and an ion conductor, and tightly combined with the chitosan hollow fiber membrane through intermolecular hydrogen bonds under the auxiliary action of the remaining phytic acid in the system, to prepare a chitosan hollow fiber conductive membrane. The preparation process of the present application is simple and efficient, the prepared chitosan hollow fiber conductive membrane has high conductivity and good stability, and can be used as a membrane sensor for human motion monitoring, solving the problems of poor dispersibility, poor interfacial compatibility and poor conductivity of graphene in the fiber matrix. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Figure is the resistance change diagram of the chitosan hollow fiber conductive membrane obtained in Example 1 for monitoring the elbow joint movement;

[0019] Figure 2 Figure is the resistance change diagram of the chitosan hollow fiber conductive membrane obtained in Example 2 for walking monitoring. DETAILED DESCRIPTION

[0020] A preparation method of a chitosan hollow fiber conductive membrane, comprising the following steps:

[0021] (1) adding graphene oxide into distilled water, and dispersing by ultrasonic to form a graphene oxide water dispersion liquid with a concentration of 2-6 mg / mL, then adding phytic acid into the graphene oxide water dispersion liquid at a volume ratio of 40:1-40:5, and reacting at 80-110 ℃ for 12-20 h, and then dispersing by ultrasonic to form a phosphorized reduced graphene oxide water dispersion liquid;

[0022] (2) adding chitosan and polyethylene glycol 2000 into a 3vol% acetic acid solution, dissolving by stirring at 60 ℃ to form a spinning solution containing 3wt%-5wt% chitosan and 8wt%-10wt% polyethylene glycol 2000, vacuum degassing, and then spinning, and using a 15wt%-20wt% sodium hydroxide solution as an internal and external gel bath to solidify the chitosan hollow fiber membrane, and then washing in distilled water until neutral to form a chitosan hollow fiber membrane;

[0023] (3) placing the chitosan hollow fiber membrane prepared in step (2) into the phosphorized reduced graphene oxide water dispersion liquid prepared in step (1) at a mass ratio of 1:50-1:200, freezing at-50 ℃ for 12 h, then melting at room temperature for 12 h, repeating the above steps for 6 times, and then sequentially immersing in distilled water, anhydrous ethanol and n-hexane, and drying at room temperature to obtain a chitosan hollow fiber conductive membrane.

[0024] In order to make the content of the application more convenient to understand, the technical solutions of the application will be further described below in combination with specific embodiments, but the application is not limited thereto.

[0025] Example 1

[0026] (1) taking 3 g of graphene oxide, adding into 500 mL of distilled water, and dispersing by ultrasonic to form a graphene oxide water dispersion liquid, then adding 50 mL of phytic acid into the graphene oxide water dispersion liquid, reacting at 80 ℃ for 12 h, and then dispersing by ultrasonic to form a phosphorized reduced graphene oxide water dispersion liquid;

[0027] (2) taking 10 g of chitosan and 20 g of polyethylene glycol 2000, adding into 170 g of a 3vol% acetic acid solution, dissolving by stirring at 60 ℃ to form a spinning solution, vacuum degassing, and then spinning, using a 20wt% sodium hydroxide solution as an internal and external gel bath to solidify the chitosan hollow fiber membrane, and then washing in distilled water until neutral to form a chitosan hollow fiber membrane;

[0028] (3) 2 g of chitosan hollow fiber membrane was added to 400 g of the phosphonated reduced graphene oxide aqueous dispersion, first frozen at -50 ℃ for 12 h, then thawed at room temperature for 12 h, and repeated for 6 times, and then sequentially soaked with distilled water, ethanol, and n-hexane, and dried at room temperature to obtain the chitosan hollow fiber conductive membrane.

[0029] The obtained chitosan hollow fiber conductive membrane was adhered at the elbow joint, and the relative resistance change was tested with the swinging of the arm, and the results are shown in Figure 1 Figure 1 It can be known from

[0030] Example 2

[0031] (1) 1.2 g of graphene oxide was added to 300 mL of distilled water, and ultrasonic dispersion was performed to form an aqueous graphene oxide dispersion, and then 15 mL of phytic acid was added, and ultrasonic dispersion was performed after reaction at 100 ℃ for 18 h to form an aqueous phosphonated reduced graphene oxide dispersion;

[0032] (2) 4 g of chitosan and 9 g of polyethylene glycol 2000 were added to 87 g of 3 vol% acetic acid solution, and stirring was performed at 60 ℃ to dissolve to form a spinning solution, and after vacuum degassing, spinning was performed, and after solidification into a membrane with 17 wt% sodium hydroxide solution as the internal and external gelation bath, washing was performed in distilled water until neutral to form a chitosan hollow fiber membrane;

[0033] (3) 2 g of chitosan hollow fiber membrane was added to 200 g of the phosphonated reduced graphene oxide aqueous dispersion, first frozen at -50 ℃ for 12 h, then thawed at room temperature for 12 h, and repeated for 6 times, and then sequentially soaked with distilled water, ethanol, and n-hexane, and dried at room temperature to obtain the chitosan hollow fiber conductive membrane.

[0034] The obtained chitosan hollow fiber conductive membrane was adhered at the foot, and the relative resistance change was tested with the walking of the human body, and the results are shown in Figure 2 Figure 2 It can be known from

[0035] Comparative Example 1

[0036] (1) 3 g of graphene oxide was added to 500 mL of distilled water, and ultrasonic dispersion was performed to form an aqueous graphene oxide dispersion, and then 50 mL of phosphoric acid was added, and ultrasonic dispersion was performed after reaction at 80 ℃ for 12 h to form an aqueous phosphonated reduced graphene oxide dispersion;

[0037] ​​(2) 10 g of chitosan and 20 g of polyethylene glycol 2000 were added to 170 g of 3 vol% acetic acid solution, and stirred at 60°C to dissolve, forming a spinning solution. After vacuum degassing, spinning was performed, and a 20 wt% sodium hydroxide solution was used as an internal and external gel bath to solidify the membrane. After washing in distilled water until neutral, a chitosan hollow fiber membrane was formed;

[0038] (3) 2 g of chitosan hollow fiber membrane was added to 400 g of phosphonated reduced graphene oxide aqueous dispersion, and was frozen at -50°C for 12 h, then thawed at room temperature for 12 h. This was repeated 6 times, and then sequentially immersed in distilled water, ethanol, and n-hexane, and dried at room temperature to obtain a chitosan hollow fiber conductive membrane.

[0039] Comparative Example 2

[0040] (1) 3 g of reduced graphene oxide was added to 500 mL of distilled water, and was dispersed by ultrasonic to form a reduced graphene oxide aqueous dispersion;

[0041] (2) 10 g of chitosan and 20 g of polyethylene glycol 2000 were added to 170 g of 3 vol% acetic acid solution, and stirred at 60°C to dissolve, forming a spinning solution. After vacuum degassing, spinning was performed, and a 20 wt% sodium hydroxide solution was used as an internal and external gel bath to solidify the membrane. After washing in distilled water until neutral, a chitosan hollow fiber membrane was formed;

[0042] (3) 2 g of chitosan hollow fiber membrane was added to 400 g of reduced graphene oxide aqueous dispersion, and was frozen at -50°C for 12 h, then thawed at room temperature for 12 h. This was repeated 6 times, and then sequentially immersed in distilled water, ethanol, and n-hexane, and dried at room temperature to obtain a chitosan hollow fiber conductive membrane.

[0043] The properties of the chitosan hollow fiber conductive membranes obtained in each example and comparative example were tested, and the results are shown in Table 1.

[0044] Table 1. Performance test of different chitosan hollow fiber conductive membranes

[0045]

[0046] As can be seen from Table 1, the conductivity of the chitosan hollow fiber conductive membrane obtained in the examples can reach 11 S / m, having good conductive performance. In Comparative Example 1, due to the lack of the auxiliary crosslinking effect of phytic acid, the binding force of the phosphonated reduced graphene oxide and the chitosan hollow fiber membrane is weak, resulting in poor tensile strength of the chitosan hollow fiber conductive membrane. The conductivity of the chitosan hollow fiber conductive membrane obtained in Comparative Example 2 is much lower than that in the examples, which is mainly due to the fact that the conductivity of the phosphonated reduced graphene oxide reduced by phytic acid in the examples is greatly improved compared with that of the reduced graphene oxide, and the phosphonated reduced graphene oxide can act as a crosslinking agent under the auxiliary action of phytic acid in the system, and is tightly combined with the chitosan hollow fiber membrane through intermolecular hydrogen bonds, thereby improving the dispersion stability of the phosphonated reduced graphene oxide, reducing the porosity of the chitosan hollow fiber conductive membrane, and improving the tensile strength of the chitosan hollow fiber conductive membrane.

[0047] The above description is only the preferred embodiment of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the present application.

Claims

1. A method for preparing a chitosan hollow fiber conductive film, characterized in that: Includes the following steps: (1) Add graphene oxide to distilled water and disperse it by ultrasonication to form an aqueous dispersion of graphene oxide. Then add phytic acid to it, heat it to react, and then disperse it by ultrasonication to form an aqueous dispersion of phosphorylated reduced graphene oxide. (2) Chitosan and polyethylene glycol 2000 were added to a 3 vol% acetic acid solution and stirred at 60°C to form a spinning solution. After vacuum degassing, the solution was spun and solidified into a film using sodium hydroxide solution as an inner and outer gel bath. The film was then washed in distilled water until neutral to form a chitosan hollow fiber membrane. (3) The chitosan hollow fiber membrane prepared in step (2) is placed in the phosphorylated reduced graphene oxide aqueous dispersion in step (1), and after freeze-thaw cycles, it is soaked in distilled water, anhydrous ethanol and n-hexane in sequence, and dried at room temperature to obtain the chitosan hollow fiber conductive membrane.

2. The method for preparing a chitosan hollow fiber conductive film according to claim 1, characterized in that: The concentration of the graphene oxide aqueous dispersion in step (1) is 2-6 mg / mL, and the volume ratio of the graphene oxide aqueous dispersion to the phytic acid used is 40:1-40:

5.

3. The method for preparing a chitosan hollow fiber conductive film according to claim 1, characterized in that: The heating reaction in step (1) takes 12-20 hours and the temperature is 80-110℃.

4. The method for preparing a chitosan hollow fiber conductive film according to claim 1, characterized in that: In step (2), the content of chitosan in the spinning solution is 3wt%-5wt%, the content of polyethylene glycol 2000 is 8wt%-10wt%, and the concentration of sodium hydroxide solution is 15wt%-20wt%.

5. The method for preparing a chitosan hollow fiber conductive film according to claim 1, characterized in that: The mass ratio of chitosan hollow fiber membrane to phosphorylated reduced graphene oxide aqueous dispersion used in step (3) is 1:50-1:

200.

6. The method for preparing a chitosan hollow fiber conductive film according to claim 1, characterized in that: The freeze-thaw cycle described in step (3) involves freezing at -50°C for 12 hours and then thawing at room temperature for 12 hours, and repeating this process 6 times.

7. A chitosan hollow fiber conductive film prepared by any one of claims 1-6.

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