Cellulose-based material for adsorbing and desorbing micro-plastics as well as preparation method and application of cellulose-based material

Abstract

The invention relates to the technical field of cellulose preparation, and discloses a cellulose-based material for adsorbing and desorbing micro-plastics as well as a preparation method and application of the cellulose-based material. The preparation method comprises the following steps: (1) bamboo is cut off and then placed in alkali liquor to be soaked, washed to be neutral and then placed in a hydrogen peroxide solution to be bleached, and bamboo powder is obtained after the bamboo is taken out, dried and smashed; 2) adding the bamboo powder into a mixed aqueous solution of urea and sodium hydroxide, and stirring to obtain slurry; continuously stirring the slurry at the pressure of 0.5-1.5 MPa and the temperature of 80-120 DEG C, and cooling to room temperature to obtain a mixed solution; and 3) adding the mixed solution into an acetic acid solution to react, filtering, washing and drying to obtain the product. According to the preparation method, the problems that in the prior art, bamboo cellulose is difficult to dissolve, the preparation cost is high, the bamboo cellulose is not friendly to the environment, and the product quality is prone to being affected can be solved, efficient, low-cost and environment-friendly preparation of the high-quality dissolved bamboo cellulose is achieved, and the application range of the bamboo cellulose in adsorption and desorption of micro-plastics is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of cellulose preparation, and particularly relates to a cellulose-based material for adsorbing and desorbing microplastics, a preparation method thereof, and an application thereof. Background Art

[0002] Microplastics generally refer to plastic particles with a diameter less than 5 millimeters, which are widely present in the ocean, fresh water, drinking water, and air, posing a potential threat to human health and the natural environment. Their sources are extensive, including cosmetics, detergents, industrial production processes, and the degradation of large plastics. Microplastics are difficult to degrade, can exist in the environment for a long time, and accumulate through the food chain, causing serious damage to the ecosystem. Therefore, developing efficient and environmentally friendly microplastic removal technologies has important practical significance.

[0003] Currently, the methods for removing microplastics mainly include physical filtration, chemical degradation, and biological adsorption, etc. Although physical filtration methods can remove larger-sized microplastics, they have poor removal effects on nanoscale microplastics; although chemical degradation methods can completely decompose microplastics, they usually require harsh conditions such as strong acids, strong bases, or high temperatures, which are likely to cause secondary pollution; biological adsorption methods use microorganisms or biological materials to adsorb microplastics, but the adsorption efficiency is low, and it is difficult to desorb and recycle microplastics.

[0004] Bamboo cellulose, as a natural polymer material, has shown broad application prospects in many fields such as textiles, papermaking, biomedicine, food packaging, and adsorption materials due to its good biodegradability, biocompatibility, relatively high strength and modulus, etc. However, the efficient dissolution of bamboo cellulose has always been a key problem in this field.

[0005] Traditional bamboo cellulose dissolution methods have many deficiencies. For example, some solvent systems such as cuprammonium solution used not only have a complex preparation process, high cost, but also cause great pollution to the environment. Although ionic liquids have good solubility for cellulose, the synthesis process of ionic liquids is complex, the price is expensive, and the recovery is difficult, which limits their large-scale application. In addition, some chemical dissolution methods may cause great damage to the structure and properties of bamboo cellulose, resulting in a decline in the quality of the final product, and it is difficult to meet the strict requirements for the performance of bamboo cellulose in high-end application fields. The existing methods for preparing dissolved bamboo cellulose are difficult to achieve a balance in terms of production cost, environmental friendliness, and product quality. There is an urgent need to develop a more efficient, environmentally friendly, and product-quality-guaranteed method for preparing dissolved bamboo cellulose, so as to broaden the application of bamboo cellulose in the adsorption and desorption of microplastics. Summary of the Invention

[0006] Aiming at the problems and deficiencies in the existing technology, the purpose of the present invention is to provide a cellulose-based material for adsorbing and desorbing microplastics, and its preparation method and application.

[0007] To achieve the purpose of the invention, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention provides a preparation method of a cellulose-based material for adsorbing and desorbing microplastics, comprising the following steps: (1) Cut the bamboo and soak it in an alkali solution, take it out and wash it to neutral, then bleach it in a hydrogen peroxide solution, take it out, dry it, and pulverize it to obtain bamboo powder; (2) Add the bamboo powder to a mixed aqueous solution of urea and sodium hydroxide, stir at -5 to 5 °C to obtain a slurry; continue to stir the slurry at 0.5 to 1.5 MPa and 80 to 120 °C, and cool it to room temperature to obtain a mixed solution; (3) Add the mixed solution to an acetic acid solution for reaction, filter and collect the precipitate, wash it to neutral and then dry it to obtain the cellulose-based material for adsorbing and desorbing microplastics.

[0009] According to the above preparation method of the cellulose-based material for adsorbing and desorbing microplastics, preferably, the alkali solution in step (1) is a sodium hydroxide solution or a potassium hydroxide solution; the concentration of the alkali solution is 3 to 8 wt%; the soaking temperature is 60 to 80 °C; the soaking time is 2 to 3 h.

[0010] According to the above preparation method of the cellulose-based material for adsorbing and desorbing microplastics, preferably, the concentration of the hydrogen peroxide solution in step (1) is 2 to 5 wt%; the bleaching temperature is 50 to 70 °C, and the time is 1 to 3 h.

[0011] According to the above preparation method of the cellulose-based material for adsorbing and desorbing microplastics, preferably, the mesh number of the bamboo powder in step (1) is 60 to 100 mesh.

[0012] According to the above preparation method of the cellulose-based material for adsorbing and desorbing microplastics, preferably, the molar ratio of urea to sodium hydroxide in the mixed aqueous solution in step (2) is (2 to 4):1; based on the total mass of urea and sodium hydroxide, the concentration of the mixed aqueous solution is 10 to 15%; the mass ratio of the bamboo powder to the mixed aqueous solution is 1:(10 to 15).

[0013] According to the above preparation method of the cellulose-based material for adsorbing and desorbing microplastics, preferably, the stirring time at -5 to 5 °C in step (2) is 1 to 3 h; the time for continuous stirring is 0.5 to 2 h.

[0014] According to the method for preparing the cellulose-based material for adsorbing and desorbing microplastics described above, preferably, in step (3), the mass concentration of the acetic acid solution is 5-10%; the volume ratio of the mixed solution to the acetic acid solution is 1:(4-5); the reaction time is 4-5 h; the drying temperature is 40-60 °C.

[0015] The second aspect of the present invention provides a cellulose-based material for adsorbing and desorbing microplastics, which is prepared by the preparation method described in the first aspect of the present invention.

[0016] According to the cellulose-based material for adsorbing and desorbing microplastics described above, the degree of polymerization of the cellulose-based material is 800-900, and the crystallinity is 55-60%.

[0017] The third aspect of the present invention provides an application of the cellulose-based material for adsorbing and desorbing microplastics described in the second aspect above, which is used for adsorbing and desorbing microplastics.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention provides a method for preparing a cellulose-based material for adsorbing and desorbing microplastics, so as to solve the problems of difficult dissolution of bamboo cellulose, high preparation cost, environmental unfriendliness and easy influence on product quality in the prior art, and realize the efficient, low-cost and green preparation of high-quality dissolved bamboo cellulose to broaden its application in adsorbing and desorbing microplastics. Specific embodiments

[0020] The following examples are only applicable to further illustrate the present invention. It should be noted that all the technologies and scientific terms used in the present invention have the same meaning as those in the technical field to which the present invention belongs unless otherwise specified. The experimental methods without specific conditions in the following examples are all conventional technologies in the technical field, or are carried out according to the conditions recommended by the manufacturers; the reagents or instruments without indicating the manufacturers are all conventional products that can be obtained through commercial purchase.

[0021] In order to enable those skilled in the art to more clearly understand the technical solutions of the present invention, the technical solutions of the present invention will be described in detail below with specific examples. Example 1

[0022] A method for preparing a cellulose-based material for adsorbing and desorbing microplastics includes the following steps: (1) Take fresh bamboo, remove the outer skin and pith, and cut it into small sections. Put the bamboo sections into a sodium hydroxide solution with a mass fraction of 3%, soak at 60 °C for 4 hours for delignification treatment. After rinsing with water until neutral, put it into a hydrogen peroxide solution with a mass fraction of 2%, and bleach at 50 °C for 3 hours. Dry the bleached bamboo and crush it into bamboo powder with a mesh size of 60.

[0023] (2) Mix urea and sodium hydroxide in a molar ratio of 2:1, add deionized water to prepare a mixed aqueous solution with a mass fraction of 10%. Add bamboo powder to the mixed aqueous solution, with the mass ratio of bamboo powder to the mixed aqueous solution being 1:15, and stir at -5°C for 3 hours to form a homogeneous slurry; transfer the slurry to a high-pressure reactor and react at a pressure of 0.5 MPa and a temperature of 80°C for 2 hours. After the reaction, cool to room temperature and slowly release the pressure to obtain a mixed solution.

[0024] (3) According to the volume ratio of the mixed solution to the acetic acid solution being 1:4, pour the dissolved mixed solution into a 5% acetic acid solution for regeneration for 4 h, filter the precipitate, wash it with deionized water until neutral, and dry it in vacuo at 40°C to obtain a dissolved bamboo cellulose product. After testing, the degree of polymerization of this product is 800 and the crystallinity is 55%. Example 2

[0025] A preparation method of a cellulose-based material for adsorbing and desorbing microplastics, comprising the following steps: (1) Take fresh bamboo, cut it into small sections after removing the outer skin and pith. Put the bamboo sections into a 5% sodium hydroxide solution and soak at 70°C for 3 hours for delignification treatment. After rinsing with water until neutral, put it into a 3% hydrogen peroxide solution and bleach at 60°C for 2 hours. Dry the bleached bamboo and crush it into bamboo powder with a mesh size of 80.

[0026] (2) Mix urea and sodium hydroxide in a molar ratio of 3:1, add deionized water to prepare a mixed aqueous solution with a mass fraction of 12%. Add bamboo powder to the mixed aqueous solution, with the mass ratio of bamboo powder to the mixed aqueous solution being 1:12, and stir at 0°C for 2 hours to form a homogeneous slurry; transfer the slurry to a high-pressure reactor and react at a pressure of 1 MPa and a temperature of 100°C for 1 hour. After the reaction, cool to room temperature and slowly release the pressure to obtain a mixed solution.

[0027] (3) According to the volume ratio of the mixed solution to the acetic acid solution being 1:5, pour the dissolved mixed solution into a 7% acetic acid solution for regeneration for 5 h, filter the precipitate, wash it with deionized water until neutral, and dry it in vacuo at 50°C to obtain a dissolved bamboo cellulose product. After testing, the degree of polymerization of this product is 900 and the crystallinity is 60%. Example 3

[0028] A preparation method of a cellulose-based material for adsorbing and desorbing microplastics, comprising the following steps: (1) Take fresh bamboo, cut it into small sections after removing the outer skin and pith. Put the bamboo sections into a sodium hydroxide solution with a mass fraction of 8%, soak them at 80 °C for 2 hours for delignification treatment. After rinsing with water until neutral, put them into a hydrogen peroxide solution with a mass fraction of 5%, and bleach them at 70 °C for 1 hour. Dry the bleached bamboo and crush it into bamboo powder with a mesh size of 100.

[0029] (2) Mix urea and sodium hydroxide in a molar ratio of 4:1, add deionized water to prepare a mixed aqueous solution with a mass fraction of 15%. Add the bamboo powder to the mixed aqueous solution, and the mass ratio of the bamboo powder to the mixed aqueous solution is 1:10. Stir at 5 °C for 1 hour to form a homogeneous slurry; transfer the slurry to a high-pressure reactor and react at a pressure of 1.5 MPa and a temperature of 120 °C for 0.5 hour. After the reaction, cool to room temperature and slowly release the pressure to obtain a mixed solution.

[0030] (3) According to the volume ratio of the mixed solution to the acetic acid solution of 1:4.5, pour the dissolved mixed solution into a 10% acetic acid solution for regeneration for 4.5 h, filter the precipitate, wash it with deionized water until neutral, and dry it under vacuum at 60 °C to obtain a dissolved bamboo cellulose product. After testing, the degree of polymerization of this product is 850 and the crystallinity is 58%.

[0031] The above embodiments are specific implementation manners of the present invention, but the implementation manners of the present invention are not limited by the above embodiments. Any combination, change, modification, substitution, simplification that does not exceed the design idea of the present invention falls within the protection scope of the present invention.

Claims

1. A preparation method of a cellulose-based material for adsorbing and desorbing microplastics, characterized in that, It includes the following steps: (1) Cut the bamboo and soak it in an alkali solution. After taking it out, wash it until neutral, then bleach it in a hydrogen peroxide solution. After taking it out, dry and crush it to obtain bamboo powder; (2) Add the bamboo powder to an aqueous solution mixture of urea and sodium hydroxide, stir at -5 to 5 °C to obtain a slurry; continue to stir the slurry at 0.5 to 1.5 MPa and 80 to 120 °C, and cool to room temperature to obtain a mixed solution; (3) Add the mixed solution to an acetic acid solution for reaction, filter and collect the precipitate, wash it until neutral and then dry it to obtain the cellulose-based material for adsorbing and desorbing microplastics.

2. The preparation method of the cellulose-based material for adsorbing and desorbing microplastics according to claim 1, characterized in that In step (1), the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution; the concentration of the alkali solution is 3 to 8 wt%; the soaking temperature is 60 to 80 °C; the soaking time is 2 to 3 h.

3. The preparation method of the cellulose-based material for adsorbing and desorbing microplastics according to claim 1, characterized in that, In step (1), the concentration of the hydrogen peroxide solution is 2 to 5 wt%; the bleaching temperature is 50 to 70 °C, and the time is 1 to 3 h.

4. The preparation method of the cellulose-based material for adsorbing and desorbing microplastics according to claim 1, characterized in that, In step (1), the mesh number of the bamboo powder is 60 to 100 mesh.

5. The preparation method of the cellulose-based material for adsorbing and desorbing microplastics according to claim 1, characterized in that, In step (2), the molar ratio of urea to sodium hydroxide in the aqueous solution mixture is (2 to 4):1; based on the total mass of urea and sodium hydroxide, the concentration of the aqueous solution mixture is 10 to 15%; the mass ratio of the bamboo powder to the aqueous solution mixture is 1:(10 to 15).

6. The preparation method of the cellulose-based material for adsorbing and desorbing microplastics according to claim 1, characterized in that, In step (2), the stirring time at -5 to 5 °C is 1 to 3 h; the time for continued stirring is 0.5 to 2 h.

7. The preparation method of the cellulose-based material for adsorbing and desorbing microplastics according to claim 1, wherein In step (3), the mass concentration of the acetic acid solution is 5 to 10%; the volume ratio of the mixed solution to the acetic acid solution is 1:(4 to 5); the reaction time is 4 to 5 h; the drying temperature is 40 to 60 °C.

8. A cellulose-based material for adsorbing and desorbing microplastics, characterized in that, Prepared by the preparation method according to any one of claims 1 to 7 of the cellulose-based material for adsorbing and desorbing microplastics.

9. The cellulose-based material for adsorbing and desorbing microplastics according to claim 8, characterized in that, The degree of polymerization of the cellulose-based material is 800 to 900, and the crystallinity is 55 to 60%.

10. Use of the cellulose-based material for adsorbing and desorbing microplastics according to claim 8, characterized in that For adsorbing and desorbing microplastics.