Cellulose-based aerogel as well as preparation process and application thereof

Abstract

The invention discloses cellulose-based aerogel as well as a preparation process and application thereof, and relates to the technical field of ecological restoration of water bodies. The preparation process of the cellulose-based aerogel comprises the following steps: removing impurities from garden wastes, washing, drying and crushing to obtain raw material powder; extracting cellulose from the raw material powder by coupling physical, chemical and enzymolysis modes; the preparation method comprises the following steps: loading carboxyl on cellulose, and combining copper ions, quaternary ammonium salt cations and a high-molecular polymer containing amido with the carboxyl to obtain a gel material; the gel material is subjected to freeze drying treatment, and the cellulose-based aerogel is obtained. The prepared aerogel has excellent effects of organic matter adsorption, heavy metal adsorption and algae resistance.

Description

Technical Field

[0001] This application relates to the field of water body ecological restoration technology, and in particular to a cellulose-based aerogel, its preparation process, and its application. Background Technology

[0002] With continuous economic and technological development, the discharge of industrial wastewater, domestic wastewater, and agricultural runoff is increasing year by year. Wastewater has a complex composition, including organic matter, heavy metals, and phosphorus and nitrogen. Although modern wastewater treatment plants can remove most pollutants, heavy metals, and phosphorus and nitrogen, "compliant discharge" is not the same as "harmless discharge." When this wastewater containing organic matter, heavy metals, and phosphorus and nitrogen is discharged into rivers and lakes, long-term accumulation can easily lead to eutrophication, excessive algae growth, and water quality deterioration. Furthermore, the water contains a certain amount of organic matter and heavy metals.

[0003] Currently, ecological vegetation beds are mainly used to treat water pollution and eutrophication. Ecological vegetation beds, also known as artificial floating beds, are a type of artificial floating island. Targeting polluted and eutrophic water, they utilize ecological engineering principles to degrade organic matter, nitrogen, and phosphorus in the water, and adsorb heavy metals. They primarily use aquatic plants, employing soilless cultivation techniques and polymer materials as carriers and substrates. By leveraging interspecies symbiotic relationships and fully utilizing the spatial and nutrient niches of the water body, they establish a highly efficient artificial ecosystem to reduce the pollution load in the water. This significantly improves water transparency and effectively enhances water quality indicators.

[0004] However, most existing ecological vegetation beds focus on a single function, such as effectively inhibiting algae, but they are poor in heavy metal adsorption and organic matter degradation. They lack the multifunctionality of simultaneously removing organic pollutants, adsorbing heavy metals, and inhibiting algae, making it difficult to meet the emergency treatment needs of complex water pollution. Summary of the Invention

[0005] The main objective of this application is to propose a cellulose-based aerogel, its preparation process, and its application. This cellulose-based aerogel can be installed on an ecological vegetation bed to endow the ecological vegetation bed with excellent organic pollutant removal, heavy metal adsorption, and anti-algae properties, thereby better meeting the emergency treatment needs of complex water pollution.

[0006] Firstly, this application provides a process for preparing cellulose-based aerogels, comprising the following steps: S1. Provide garden waste, and remove impurities, wash, dry and crush the garden waste to obtain raw material powder; S2. Cellulose is extracted from the raw material powder obtained in step S1 by a combination of physical, chemical and enzymatic methods. S3. Carboxyl groups are loaded onto the cellulose obtained in step S2, and copper ions, quaternary ammonium salt cations and amine-containing polymers are combined with the carboxyl groups to obtain a gel material. S4. The gel material obtained in step S3 is freeze-dried to obtain the cellulose-based aerogel.

[0007] By employing the above-mentioned technical solution, garden waste, including tree branches and leaves, is rich in cellulose. When extracting plant cellulose, the garden waste is first pulverized to break down the dense cell walls and lignin layer, making it easier to separate the cellulose that was originally encased within the cells. This also increases the specific surface area of ​​the raw material, allowing subsequent acid / alkali solutions and enzyme preparations to more effectively remove lignin and hemicellulose, resulting in high-yield and high-quality nanocellulose.

[0008] This application employs a coupled physical, chemical, and enzymatic approach to extract cellulose from raw material powder more effectively. Physical methods disrupt the dense structure of plant cell walls, increasing cellulose accessibility and facilitating the penetration of chemical reagents and enzymes. Chemical acid and alkali reagents dissolve and remove lignin and hemicellulose encapsulating the cellulose, exposing the cellulose fibers and performing preliminary purification. Enzymatic hydrolysis converts amorphous cellulose into soluble products and hydrolyzes long-chain fibers into short-chain cellulose, yielding cellulose with high yield and high quality.

[0009] Cellulose possesses a porous structure and excellent biocompatibility. As a backbone, cellulose, rich in hydroxyl groups on its surface, can be converted into carboxyl groups to introduce carboxyl groups into the cellulose backbone. These carboxyl groups serve as core anchors, utilizing electrostatic interactions, coordination effects, and cross-linking mechanisms to bind copper ions, quaternary ammonium cations, and amine-containing polymers within the same network, further enhancing the dispersibility of cellulose. The resulting aerogel exhibits a three-dimensional porous network structure containing negatively charged groups such as carboxyl and hydroxyl groups, positively charged groups such as amine groups, as well as copper ions and quaternary ammonium cations.

[0010] The cellulose matrix serves as a supporting framework, providing a three-dimensional porous structure that facilitates the adsorption, capture, and local concentration of organic matter, heavy metals, and algal cells. Negatively charged groups such as carboxyl and hydroxyl groups effectively adsorb cationic organic matter, including cationic dyes; while positively charged groups containing amine groups effectively adsorb anionic organic matter, including anionic dyes. Copper ions provide sustained antibacterial / antialgal activity. Copper ions can induce oxidative stress within cells, damaging cell membranes and proteins, leading to rapid bacterial and algal death. Under light conditions, the photocatalytic / oxidative effect can be further enhanced. Quaternary ammonium cations endow the material with broad-spectrum antibacterial properties and certain hydrophobic properties. Through electrostatic adsorption and membrane disruption, they produce a rapid permeation-rupture effect on algal cell walls / membranes, complementing the effect of copper ions. Quaternary ammonium salts provide rapid membrane disruption, while copper ions provide deep oxidative killing, effectively killing bacteria and preventing algae. Furthermore, the positive charge of the amine-containing polymer itself can also enhance cell membrane charge adsorption and oxidative stress response in conjunction with copper ions.

[0011] The technical solution of this application uses garden waste as raw material, turning "waste" into "treasure." It employs a coupled physical, chemical, and enzymatic hydrolysis method to extract cellulose from the raw material powder relatively fully, with high yield and quality. The hydroxyl groups on the cellulose are converted into carboxyl groups to provide multifunctional anchors, allowing for the sufficient and stable loading of copper ions, quaternary ammonium cations, and amine-containing polymers. The resulting material has a stable structure and possesses the functions of organic matter adsorption, heavy metal adsorption, and bactericidal and anti-algae effects.

[0012] Optionally, in step S2, the extraction of cellulose from the raw material powder using a coupled physical, chemical, and enzymatic approach includes: (1) Mix the raw material powder, deionized water, sodium chlorite and acetic acid, heat under an ultrasonic water bath, separate the solid and liquid to obtain the first solid, and wash the first solid with water. (2) Add the first solid obtained in step (1) to a sodium hydroxide solution, heat it under an ultrasonic water bath, separate the solid and liquid to obtain a second solid, and wash the second solid with water; (3) Add the second solid obtained in step (2) to the enzyme solution, adjust the pH to 4-6, control the temperature to 25-55℃, and after enzymatic hydrolysis, the third solid is obtained by enzyme inactivation and solid-liquid separation. The third solid is washed and dried to obtain cellulose.

[0013] By adopting the above technical solution, mixing raw material powder, deionized water, sodium chlorite and acetic acid, and heating in an ultrasonic water bath can effectively remove lignin; adding the first solid to a sodium hydroxide solution and heating in an ultrasonic water bath can effectively remove hemicellulose; adding the second solid to an enzyme solution for enzymatic hydrolysis can further remove residual lignin and hemicellulose, resulting in cellulose with high yield and quality.

[0014] Optionally, in step (1), the raw material powder, deionized water, sodium chlorite and acetic acid are mixed in a weight ratio of (25-35):(1400-1500):(13-18):(2.9-3.5).

[0015] Optionally, in step (2), the concentration of the sodium hydroxide solution is 4.5 to 6 wt%, and the first solid is mixed with the sodium hydroxide solution at a weight ratio of 1:(13 to 17).

[0016] Optionally, in step (3), the second solid is mixed with the enzyme solution at a weight ratio of 1:(20-30).

[0017] Optionally, in step (1), the conditions for the ultrasonic water bath include: ultrasonic power of 200-500W and water bath temperature of 70-80℃; in step (2), the conditions for the ultrasonic water bath include: ultrasonic power of 200-500W and water bath temperature of 80-95℃. In step (3), the concentration of the enzyme solution is 10-30 U / mL, and the enzymes in the enzyme solution include laccase, xylanase and cellulase, and the concentration ratio of laccase, xylanase and cellulase is (4-6):(4-6):(7-13).

[0018] By employing the above technical solution, under ultrasonic water bath conditions, the "cavitation effect" of ultrasound combined with the "thermal effect" of the water bath can effectively disrupt the dense structure of plant cell walls, increasing cellulose accessibility and creating conditions for the penetration of chemical reagents and subsequent enzymes, thereby obtaining cellulose with high yield and high quality. Furthermore, during enzymatic hydrolysis, laccase, xylanase, and cellulase work synergistically. Laccase effectively degrades lignin, xylanase effectively degrades hemicellulose, and cellulase hydrolyzes cellulose, further improving the cellulose yield and obtaining high-quality cellulose.

[0019] Optionally, in step (3), when performing enzymatic hydrolysis, the temperature is controlled at 25-35℃ for 30-60 min, the temperature is controlled at 40-50℃ for 30-60 min, and the temperature is controlled at 45-55℃ for 120-180 min.

[0020] By adopting the above technical solution, the temperature is controlled in a gradient segment during enzymatic hydrolysis, so that each enzyme can give full play to its own advantages. Laccase effectively degrades lignin, xylanase effectively degrades hemicellulose, and cellulase hydrolyzes cellulose to obtain cellulose with high yield and high quality.

[0021] Optionally, in step (3), after washing the third solid and before drying, the following steps are also included: the washed third solid is enzymatically hydrolyzed again according to the enzymatic hydrolysis method in step (3), and after the second enzymatic hydrolysis, it is subjected to enzyme inactivation, solid-liquid separation and washing.

[0022] By employing the above-mentioned technical solution and performing enzymatic hydrolysis again, the yield and quality of cellulose can be further improved.

[0023] Optionally, in step S3, loading carboxyl groups, copper ions, quaternary ammonium salt cations, and amine-containing polymers onto cellulose includes: Step 1: Carboxyl groups are loaded onto cellulose using an oxidation method to obtain carboxylated cellulose powder. The carboxylated cellulose powder is then added to water to form a cellulose dispersion. Step 2: Mix copper nitrate solution and L-ascorbic acid sodium solution to obtain a first mixture. Add the first mixture to the cellulose dispersion obtained in Step 1 and stir to obtain a first intermediate dispersion system. Step 3: Add the hexadecyltrimethylammonium chloride solution to the first intermediate dispersion system obtained in Step 2, and stir to obtain the second intermediate dispersion system; Step 4: Add the polyethyleneimine solution to the second intermediate dispersion system obtained in Step 3, stir, and let stand to obtain the gel material.

[0024] By employing the above technical solution, cellulose possesses a porous structure and good biocompatibility. Cellulose serves as the backbone, and its surface is rich in hydroxyl groups. These hydroxyl groups are converted into carboxyl groups, introducing carboxyl groups onto the cellulose backbone. These carboxyl groups act as core anchor points, utilizing electrostatic interactions, coordination effects, and cross-linking mechanisms to bind copper ions, quaternary ammonium cations, and amine-containing polymers within the same network. This also enhances the dispersibility of cellulose. The resulting material is a three-dimensional porous network material with a stable structure, possessing the functions of organic matter adsorption, heavy metal adsorption, and bactericidal and anti-algae properties.

[0025] Optionally, in step one, carboxylated cellulose powder is added to water to obtain a cellulose solution with a concentration of 0.5-2.0 wt%, the pH of the cellulose solution is adjusted to 3.5-4.5, and ultrasonically dispersed to obtain a cellulose dispersion. In step two, the concentration of copper nitrate solution is 8-12 mmol / L, the concentration of L-ascorbic acid sodium aqueous solution is 80-120 mmol / L, the copper nitrate solution and L-ascorbic acid sodium aqueous solution are mixed at a volume ratio of (0.5-1.5):(1-1.5), and the first mixture is mixed with cellulose dispersion at a volume ratio of (2.0-2.5):1. In step three, the concentration of the hexadecyltrimethylammonium chloride solution is 0.1–0.3 mol / L, and the hexadecyltrimethylammonium chloride solution is mixed with the first intermediate dispersion system at a volume ratio of (0.5–0.7):3.2. In step four, the concentration of the polyethyleneimine solution is 8-12 wt%, and the polyethyleneimine solution is mixed with the second intermediate dispersion system obtained in step three at a volume ratio of (0.32-0.37):1.

[0026] By adopting the above technical solution and controlling the amount of raw materials used in each step, carboxyl groups, copper ions, quaternary ammonium salt cations and amine-containing polymers can be loaded onto the cellulose backbone in a more sufficient and stable manner.

[0027] Optionally, in step S4, the gel material is placed in a container, the bottom of the container is directly in contact with liquid nitrogen for 1 to 2 hours, frozen at -25 to -35°C, and dried under vacuum at 25 to 35°C to obtain cellulose-based aerogel.

[0028] By employing the above technical solution, the gel material is placed in a container, with the bottom of the container directly in contact with liquid nitrogen. This strong cooling method prevents the formation of a disordered porous structure due to inconsistent temperature gradients during cooling. The liquid nitrogen contact results in an ordered porous structure, improving the material's specific surface area and ensuring the stable loading of carboxyl groups, copper ions, quaternary ammonium cations, and amine groups onto the cellulose matrix.

[0029] Secondly, the cellulose-based aerogel provided in this application is prepared using the cellulose-based aerogel preparation process described in any one of the above claims.

[0030] By adopting the above technical solution, the cellulose-based aerogel obtained has a three-dimensional porous network structure, which is stable and has the functions of adsorbing organic matter, adsorbing heavy metals, and sterilizing and anti-algae.

[0031] Thirdly, this application provides the application of a cellulose-based aerogel as described above in the ecological restoration of aquatic bodies.

[0032] By adopting the above technical solution, the cellulose-based aerogel prepared in this application is installed on an ecological vegetation bed. When the cellulose-based aerogel comes into contact with water, it can effectively adsorb organic pollutants and heavy metals in the water and has excellent anti-algae effect.

[0033] In summary, this application includes at least one of the following beneficial technical effects: 1. The technical solution of this application uses garden waste as raw material and employs a coupled physical, chemical, and enzymatic hydrolysis method to extract cellulose from the raw material powder relatively fully, resulting in high yield and quality of extracted cellulose. Furthermore, the hydroxyl groups on the cellulose are converted into carboxyl groups to provide multifunctional anchors, enabling the full and stable loading of copper ions, quaternary ammonium cations, and amine-containing polymers. The resulting material has a stable structure and possesses the functions of organic matter adsorption, heavy metal adsorption, and bactericidal and anti-algae effects.

[0034] 2. Cellulose serves as a supporting framework, providing a three-dimensional porous structure that facilitates the adsorption and capture of organic matter, heavy metals, and algal cells. Negatively charged groups such as carboxyl and hydroxyl groups effectively adsorb cationic organic matter. Positively charged groups containing amine groups effectively adsorb anionic organic matter, such as anionic dyes. Copper ions achieve sustained antibacterial / antialgal activity. Copper ions can generate oxidative stress within cells, damaging cell membranes and proteins, leading to rapid death of bacteria and algae. Under light conditions, the photocatalytic / oxidative effect can be further enhanced. Quaternary ammonium cations endow the material with broad-spectrum antibacterial properties and certain hydrophobic properties. Through electrostatic adsorption and membrane disruption, they produce a rapid permeation-rupture effect on algal cell walls / cell membranes, complementing the effect of copper ions: quaternary ammonium salts provide rapid membrane disruption, while copper ions provide deep oxidative killing, effectively killing bacteria and preventing algae. Furthermore, the positive charge of the amine-containing polymer itself can also enhance the charge adsorption and oxidative stress of the cell membrane, in conjunction with copper ions. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the embodiments.

[0036] Raw material description: Laccase: Shanghai Yuanye Biotechnology Co., Ltd., specification: 120U / g; Xylanase: Shanghai Yuanye Biotechnology Co., Ltd., specification: 300,000 U / g; Cellulase: Shanghai Yuanye Biotechnology Co., Ltd., specification: 400U / mg; Polyethyleneimine: Shanghai Aladdin Biochemical Technology Co., Ltd., 70,000 MW.

[0037] Example 1 A process for preparing cellulose-based aerogel includes the following steps: Step 1: Provide garden waste, and remove impurities, wash, dry and crush the garden waste to obtain raw material powder.

[0038] (1) The garden waste consists of branches and leaves of camphor trees, osmanthus trees, ginkgo trees and bamboo from Xiamen and Fujian. After removing impurities from the garden waste, the total mass of the camphor tree branches and leaves is m1, the total mass of the osmanthus tree branches and leaves is m2, the total mass of the ginkgo tree branches and leaves is m3, and the total mass of the bamboo branches and leaves is m4. The garden waste is mixed in the ratio of m1:m2:m3:m4 = 4:1:1:2 to obtain the mixture. (2) Wash the mixture obtained in step (1) three times with deionized water and air dry it under natural conditions until the moisture content is 12wt%. Crush the air-dried garden waste and sieve the crushed material to obtain raw material powder with a particle size of 60 mesh.

[0039] Step 2: Extracting cellulose from the raw material powder obtained in Step 1 using a combination of physical, chemical, and enzymatic methods.

[0040] (1) 30 parts by weight of the raw material powder obtained in step one, 16 parts by weight of sodium chlorite and 3.2 parts by weight of anhydrous acetic acid were added to 1450 parts by weight of deionized water in sequence. The mixture was heated for 1 hour in an ultrasonic water bath (ultrasonic power of 250W and water bath temperature of 75℃). The solution was removed by suction filtration to obtain the first solid. The first solid was rinsed with deionized water until the pH of the washing solution was 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 5 wt% at a weight ratio of 1:15, heated in an ultrasonic water bath (ultrasonic power of 300W, water bath temperature of 90℃) for 2 hours, the solution is removed by suction filtration to obtain the second solid, and the second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 20 U / mL (laccase 5 U / mL, xylanase 5 U / mL, cellulase 10 U / mL, and the remainder is deionized water) at a weight ratio of 1:25. The pH is adjusted to 5.0 with 0.1 mol / L acetic acid solution, the temperature is controlled at 30℃, the enzyme is hydrolyzed for 30 min, the temperature is controlled at 45℃, the enzyme is hydrolyzed for 40 min, the temperature is controlled at 50℃, the enzyme is hydrolyzed for 2.5 h, and the enzyme is inactivated by heating at 100℃ for 5 min. The solution is removed by filtration to obtain the third solid. The third solid is washed with deionized water until the pH of the washing solution is 7.0. The washed third solid is dried at 80℃ for 4 h to obtain cellulose.

[0041] Step 3: Load carboxyl groups onto the cellulose obtained in Step 2, and combine copper ions, quaternary ammonium salt cations, and amine-containing polymers with the carboxyl groups to obtain a gel material.

[0042] (1) Take 5 parts by weight of the cellulose obtained in step two and 0.1 parts by weight of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxygen radical, chemical formula C9H). 18 NO) and 0.8 parts by weight of sodium bromide were added to 320 parts by weight of deionized water, and 0.6 parts by weight of sodium hypochlorite were added to adjust the pH to 10. The mixture was stirred at 200 rpm for 4 hours. During the stirring process, a 0.5 wt% sodium hydroxide solution was added dropwise to maintain the pH of the reaction system at 10. After the reaction was completed, the solution was filtered to obtain a solid. The solid was washed with deionized water until the pH of the washing solution was 7.0. The washed solid was dried at 80°C for 4 hours to obtain carboxylated cellulose powder. (2) Add 10 parts by weight of the carboxylated cellulose powder obtained in step (1) to deionized water to obtain a cellulose solution with a concentration of 1 wt%. Adjust the pH of the cellulose solution to 4 with 0.3 mol / L hydrochloric acid and sonicate at 1000 W for 30 min to obtain a cellulose dispersion. (3) Add copper nitrate to deionized water to obtain a copper nitrate solution with a concentration of 10 mmol / L. Mix the copper nitrate solution, acetonitrile (purity 99 wt%) and L-ascorbic acid sodium aqueous solution (concentration 100 mmol / L) in a volume ratio of 4:1:4 and stir at a stirring speed of 200 rpm for 10 min to obtain the first mixture. Mix the first mixture with the cellulose dispersion obtained in step (2) in a volume ratio of 2.2:1 and stir at a stirring speed of 200 rpm for 1 h to obtain the first intermediate dispersion system. (4) Add hexadecyltrimethylammonium chloride (CTAC) to an ethanol solution (anhydrous ethanol and deionized water mixed at a volume ratio of 1:1) to obtain a CTAC solution with a concentration of 0.2 mol / L. Mix the CTAC solution with the first intermediate dispersion system obtained in step (3) at a volume ratio of 0.6:3.2 and stir at a stirring rate of 200 rpm for 1 h to obtain the second intermediate dispersion system. (5) Add polyethyleneimine to deionized water to obtain a PEI solution with a concentration of 10wt%. Mix the PEI solution and the second intermediate dispersion system obtained in step (4) at a volume ratio of 0.35:1. Stir at a stirring rate of 200rpm for 30min and let stand at 25℃ for 2h to obtain the gel material.

[0043] Step 4: Freeze-dry the gel material obtained in Step 3 to obtain cellulose-based aerogel.

[0044] The gel material obtained in step three was poured into a cylindrical container (5.5 cm high and 2.5 cm in diameter of the cavity). The outer wall of the container was covered with an insulation layer, and a copper base was placed at the bottom of the container. The copper base was brought into contact with liquid nitrogen (about -196°C) for 1 hour, and then frozen at -30°C for 5 hours. Finally, it was dried at a pressure of 20 Pa and a temperature of 30°C for 6 hours to obtain cellulose-based aerogel.

[0045] Examples 2-5 Examples 2-5 are based on Example 1, except that the conditions for extracting cellulose in step two are changed, while the other steps remain the same as in Example 1. Specifically, step two of Example 2 is as follows: (1) 25 parts by weight of the raw material powder obtained in step one, 13 parts by weight of sodium chlorite and 2.9 parts by weight of anhydrous acetic acid were added to 1400 parts by weight of deionized water in sequence. The mixture was heated for 1 hour in an ultrasonic water bath (ultrasonic power of 200W and water bath temperature of 70℃). The solution was removed by suction filtration to obtain the first solid. The first solid was rinsed with deionized water until the pH of the washing solution was 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 4.5 wt% at a weight ratio of 1:13, heated in an ultrasonic water bath (ultrasonic power of 250W, water bath temperature of 85℃) for 2 hours, the solution is removed by suction filtration to obtain the second solid, and the second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 20 U / mL (laccase 5 U / mL, xylanase 5 U / mL, cellulase 10 U / mL, and the remainder is deionized water) at a weight ratio of 1:25. The pH is adjusted to 5.0 with 0.1 mol / L acetic acid solution, the temperature is controlled at 30℃, the enzyme is hydrolyzed for 30 min, the temperature is controlled at 45℃, the enzyme is hydrolyzed for 40 min, the temperature is controlled at 50℃, the enzyme is hydrolyzed for 2.5 h, and the enzyme is inactivated by heating at 100℃ for 5 min. The solution is removed by filtration to obtain the third solid. The third solid is washed with deionized water until the pH of the washing solution is 7.0. The washed third solid is dried at 80℃ for 4 h to obtain cellulose.

[0046] Step two of Example 3 is as follows: (1) 35 parts by weight of the raw material powder obtained in step one, 18 parts by weight of sodium chlorite and 3.5 parts by weight of anhydrous acetic acid were added to 1500 parts by weight of deionized water in sequence. The mixture was heated for 1 hour in an ultrasonic water bath (ultrasonic power of 300W and water bath temperature of 80℃). The solution was removed by suction filtration to obtain the first solid. The first solid was rinsed with deionized water until the pH of the washing solution was 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 6 wt% at a weight ratio of 1:17, heated in an ultrasonic water bath (ultrasonic power of 350W, water bath temperature of 95℃) for 2 hours, the solution is removed by suction filtration to obtain the second solid, and the second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 20 U / mL (laccase 5 U / mL, xylanase 5 U / mL, cellulase 10 U / mL, and the remainder is deionized water) at a weight ratio of 1:25. The pH is adjusted to 5.0 with 0.1 mol / L acetic acid solution, the temperature is controlled at 30℃, the enzyme is hydrolyzed for 30 min, the temperature is controlled at 45℃, the enzyme is hydrolyzed for 40 min, the temperature is controlled at 50℃, the enzyme is hydrolyzed for 2.5 h, and the enzyme is inactivated by heating at 100℃ for 5 min. The solution is removed by filtration to obtain the third solid. The third solid is washed with deionized water until the pH of the washing solution is 7.0. The washed third solid is dried at 80℃ for 4 h to obtain cellulose.

[0047] Step two of Example 4 is as follows: (1) 30 parts by weight of the raw material powder obtained in step one, 16 parts by weight of sodium chlorite and 3.2 parts by weight of anhydrous acetic acid were added to 1450 parts by weight of deionized water in sequence. The mixture was heated for 1 hour in an ultrasonic water bath (ultrasonic power of 250W and water bath temperature of 75℃). The solution was removed by suction filtration to obtain the first solid. The first solid was rinsed with deionized water until the pH of the washing solution was 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 5 wt% at a weight ratio of 1:15, heated in an ultrasonic water bath (ultrasonic power of 300W, water bath temperature of 90℃) for 2 hours, the solution is removed by suction filtration to obtain the second solid, and the second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 15 U / mL (laccase 4 U / mL, xylanase 4 U / mL, cellulase 7 U / mL, and the remainder is deionized water) at a weight ratio of 1:20. The pH is adjusted to 5.0 with a concentration of 0.1 mol / L acetic acid solution, the temperature is controlled at 30℃, the enzyme is hydrolyzed for 30 min, the temperature is controlled at 45℃, the enzyme is hydrolyzed for 40 min, the temperature is controlled at 50℃, the enzyme is hydrolyzed for 2.5 h, the enzyme is inactivated by heating at 100℃ for 5 min, the solution is removed by filtration, and the third solid is obtained. The third solid is washed with deionized water until the pH of the washing solution is 7.0. The washed third solid is dried at 80℃ for 4 h to obtain cellulose.

[0048] Step two of Example 5 is as follows: (1) 30 parts by weight of the raw material powder obtained in step one, 16 parts by weight of sodium chlorite and 3.2 parts by weight of anhydrous acetic acid were added to 1450 parts by weight of deionized water in sequence. The mixture was heated for 1 hour in an ultrasonic water bath (ultrasonic power of 250W and water bath temperature of 75℃). The solution was removed by suction filtration to obtain the first solid. The first solid was rinsed with deionized water until the pH of the washing solution was 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 5 wt% at a weight ratio of 1:15, heated in an ultrasonic water bath (ultrasonic power of 300W, water bath temperature of 90℃) for 2 hours, the solution is removed by suction filtration to obtain the second solid, and the second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 25 U / mL (laccase 6 U / mL, xylanase 6 U / mL, cellulase 13 U / mL, and the remainder is deionized water) at a weight ratio of 1:30. The pH is adjusted to 5.0 with a concentration of 0.1 mol / L acetic acid solution, the temperature is controlled at 30℃, the enzyme is hydrolyzed for 30 min, the temperature is controlled at 45℃, the enzyme is hydrolyzed for 40 min, the temperature is controlled at 50℃, the enzyme is hydrolyzed for 2.5 h, and the enzyme is inactivated by heating at 100℃ for 5 min. The solution is removed by filtration to obtain the third solid. The third solid is washed with deionized water until the pH of the washing solution is 7.0. The washed third solid is dried at 80℃ for 4 h to obtain cellulose.

[0049] Examples 6-7 Examples 6 and 7 are based on Example 1, except that the conditions for loading carboxyl groups, copper ions, quaternary ammonium salt cations, and amine-containing polymers onto cellulose in step three are changed; the other steps remain the same as in Example 1. Specifically, Step three of Example 6 is as follows: (1) Take 4 parts by weight of the cellulose obtained in step two and 0.08 parts by weight of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxy free radical, chemical formula C9H) 18 NO) and 0.6 parts by weight of sodium bromide were added to 310 parts by weight of deionized water, and 0.5 parts by weight of sodium hypochlorite were added to adjust the pH to 9.5. The mixture was stirred at 200 rpm for 4 hours. During the stirring process, a 0.5 wt% sodium hydroxide solution was added dropwise to maintain the pH of the reaction system at 9.5. After the reaction was completed, the solution was filtered to obtain a solid. The solid was washed with deionized water until the pH of the washing solution was 7.0. The washed solid was dried at 70°C for 4 hours to obtain carboxylated cellulose powder. (2) Add 8 parts by weight of the carboxylated cellulose powder obtained in step (1) to deionized water to obtain a cellulose solution with a concentration of 0.8 wt%. Adjust the pH of the cellulose solution to 4 with 0.3 mol / L hydrochloric acid and sonicate at 1000 W for 25 min to obtain a cellulose dispersion. (3) Add copper nitrate to deionized water to obtain a copper nitrate solution with a concentration of 8 mmol / L. Mix the copper nitrate solution, acetonitrile (purity 99 wt%) and L-ascorbic acid sodium aqueous solution (concentration 80 mmol / L) in a volume ratio of 4:1:4 and stir at a stirring speed of 200 rpm for 10 min to obtain the first mixture. Mix the first mixture with the cellulose dispersion obtained in step (2) in a volume ratio of 2:1 and stir at a stirring speed of 200 rpm for 1 h to obtain the first intermediate dispersion system. (4) Add hexadecyltrimethylammonium chloride (CTAC) to an ethanol solution (anhydrous ethanol and deionized water mixed at a volume ratio of 1:1) to obtain a CTAC solution with a concentration of 0.2 mol / L. Mix the CTAC solution with the first intermediate dispersion system obtained in step (3) at a volume ratio of 0.5:3.2 and stir at a stirring rate of 200 rpm for 1 h to obtain the second intermediate dispersion system. (5) Add polyethyleneimine to deionized water to obtain a PEI solution with a concentration of 8wt%. Mix the PEI solution and the second intermediate dispersion system obtained in step (4) at a volume ratio of 0.32:1. Stir at a stirring rate of 200 rpm for 30 min and let stand at 20°C for 2 h to obtain the gel material.

[0050] Step three of Example 7 is as follows: (1) Take 6 parts by weight of the cellulose obtained in step two and 0.12 parts by weight of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxy free radical, chemical formula C9H) 18 NO) and 1 part by weight of sodium bromide were added to 330 parts by weight of deionized water, and 0.7 parts by weight of sodium hypochlorite were added to adjust the pH to 10.5. The mixture was stirred at 200 rpm for 4 hours. During the stirring process, a 0.5 wt% sodium hydroxide solution was added dropwise to maintain the pH of the reaction system at 10.5. After the reaction was completed, the solution was filtered to obtain a solid. The solid was washed with deionized water until the pH of the washing solution was 7.0. The washed solid was dried at 85°C for 4 hours to obtain carboxylated cellulose powder. (2) Add 12 parts by weight of the carboxylated cellulose powder obtained in step (1) to deionized water to obtain a cellulose solution with a concentration of 1.2 wt%. Adjust the pH of the cellulose solution to 4 with 0.3 mol / L hydrochloric acid and sonicate at 1000 W for 35 min to obtain a cellulose dispersion. (3) Add copper nitrate to deionized water to obtain a copper nitrate solution with a concentration of 12 mmol / L. Mix the copper nitrate solution, acetonitrile (purity 99 wt%) and L-ascorbic acid sodium aqueous solution (concentration 120 mmol / L) in a volume ratio of 4:1:4 and stir at a stirring speed of 200 rpm for 10 min to obtain the first mixture. Mix the first mixture with the cellulose dispersion obtained in step (2) in a volume ratio of 2.4:1 and stir at a stirring speed of 200 rpm for 1 h to obtain the first intermediate dispersion system. (4) Add hexadecyltrimethylammonium chloride (CTAC) to an ethanol solution (anhydrous ethanol and deionized water mixed at a volume ratio of 1:1) to obtain a CTAC solution with a concentration of 0.2 mol / L. Mix the CTAC solution with the first intermediate dispersion system obtained in step (3) at a volume ratio of 0.7:3.2 and stir at a stirring rate of 200 rpm for 1 h to obtain the second intermediate dispersion system. (5) Add polyethyleneimine to deionized water to obtain a PEI solution with a concentration of 12wt%. Mix the PEI solution and the second intermediate dispersion system obtained in step (4) at a volume ratio of 0.37:1. Stir at a stirring rate of 200rpm for 30min and let stand at 30℃ for 2h to obtain the gel material.

[0051] Example 8 This embodiment is based on Example 1, with the difference being that the enzymatic hydrolysis is performed twice in step two, while the other steps remain the same as in Example 1. Specifically, step two of this embodiment is as follows: (1) 30 parts by weight of the raw material powder obtained in step one, 16 parts by weight of sodium chlorite and 3.2 parts by weight of anhydrous acetic acid were added to 1450 parts by weight of deionized water in sequence. The mixture was heated for 1 hour in an ultrasonic water bath (ultrasonic power of 250W and water bath temperature of 75℃). The solution was removed by suction filtration to obtain the first solid. The first solid was rinsed with deionized water until the pH of the washing solution was 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 5 wt% at a weight ratio of 1:15, heated in an ultrasonic water bath (ultrasonic power of 300W, water bath temperature of 90℃) for 2 hours, the solution is removed by suction filtration to obtain the second solid, and the second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 20 U / mL (laccase 5 U / mL, xylanase 5 U / mL, cellulase 10 U / mL, and the remainder is deionized water) at a weight ratio of 1:25. The pH is adjusted to 5.0 with acetic acid solution with a concentration of 0.1 mol / L, the temperature is controlled at 30℃, the enzyme is hydrolyzed for 30 min, the temperature is controlled at 45℃, the enzyme is hydrolyzed for 40 min, the temperature is controlled at 50℃, the enzyme is hydrolyzed for 2.5 h, and the enzyme is inactivated by heating at 100℃ for 5 min. The solution is removed by filtration to obtain the third solid. The third solid is washed with deionized water until the pH of the washing solution is 7.0. (4) The third solid obtained in step (3) is subjected to enzymatic hydrolysis, solid-liquid separation and washing again in the same manner as in step (3). The washed solid is dried at 80°C for 4 hours to obtain cellulose.

[0052] Comparative Example 1 This comparative example is based on Example 1, the difference being that ultrasonic extraction is not included in step two during the cellulose extraction process. All other steps remain the same as in Example 1. Specifically, step two of this comparative example is as follows: (1) Add 30 parts by weight of the raw material powder obtained in step one, 16 parts by weight of sodium chlorite and 3.2 parts by weight of anhydrous acetic acid to 1450 parts by weight of deionized water in sequence, heat in a water bath (water bath temperature is 75℃) for 1 hour, filter to remove the solution, and obtain the first solid. Rinse the first solid with deionized water until the pH value of the washing solution is 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 5 wt% at a weight ratio of 1:15, heated in a water bath (water bath temperature is 90℃) for 2 hours, filtered to remove the solution, and the second solid is obtained. The second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 20 U / mL (laccase 5 U / mL, xylanase 5 U / mL, cellulase 10 U / mL, and the remainder is deionized water) at a weight ratio of 1:25. The pH is adjusted to 5.0 with 0.1 mol / L acetic acid solution, the temperature is controlled at 30℃, the enzyme is hydrolyzed for 30 min, the temperature is controlled at 45℃, the enzyme is hydrolyzed for 40 min, the temperature is controlled at 50℃, the enzyme is hydrolyzed for 2.5 h, and the enzyme is inactivated by heating at 100℃ for 5 min. The solution is removed by filtration to obtain the third solid. The third solid is washed with deionized water until the pH of the washing solution is 7.0. The washed third solid is dried at 80℃ for 4 h to obtain cellulose.

[0053] Comparative Example 2 This comparative example is based on Example 1, the difference being that the enzymatic hydrolysis conditions during cellulose extraction in step two have changed, while the other steps remain the same as in Example 1. Specifically, step two of this comparative example is as follows: (1) 30 parts by weight of the raw material powder obtained in step one, 16 parts by weight of sodium chlorite and 3.2 parts by weight of anhydrous acetic acid were added to 1450 parts by weight of deionized water in sequence. The mixture was heated for 1 hour in an ultrasonic water bath (ultrasonic power of 250W and water bath temperature of 75℃). The solution was removed by suction filtration to obtain the first solid. The first solid was rinsed with deionized water until the pH of the washing solution was 7.0. (2) The first solid obtained in step (1) is mixed with a sodium hydroxide solution with a concentration of 5 wt% at a weight ratio of 1:15, heated in an ultrasonic water bath (ultrasonic power of 300W, water bath temperature of 90℃) for 2 hours, the solution is removed by suction filtration to obtain the second solid, and the second solid is rinsed with deionized water until the pH value of the washing solution is 7.0. (3) The second solid obtained in step (2) is mixed with an enzyme solution with a concentration of 20 U / mL (laccase 10 U / mL, cellulase 10 U / mL, and the remainder is deionized water) at a weight ratio of 1:25. The pH is adjusted to 5.0 with a concentration of 0.1 mol / L acetic acid solution, the temperature is controlled at 50℃, and the enzyme is hydrolyzed for 2.5 h. The enzyme is then heated at 100℃ for 5 min to inactivate it. The solution is removed by filtration to obtain the third solid. The third solid is washed with deionized water until the pH of the washing solution is 7.0. The washed third solid is dried at 80℃ for 4 h to obtain cellulose.

[0054] Comparative Example 3 This comparative example is based on Example 1, except that copper ions are not loaded onto the cellulose in step three. The other steps are the same as in Example 1. Specifically, step three of this comparative example is as follows: (1) Take 5 parts by weight of the cellulose obtained in step two and 0.1 parts by weight of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxygen radical, chemical formula C9H). 18 NO) and 0.8 parts by weight of sodium bromide were added to 320 parts by weight of deionized water, and 0.6 parts by weight of sodium hypochlorite were added to adjust the pH to 10. The mixture was stirred at 200 rpm for 4 hours. During the stirring process, a 0.5 wt% sodium hydroxide solution was added dropwise to maintain the pH of the reaction system at 10. After the reaction was completed, the solution was filtered to obtain a solid. The solid was washed with deionized water until the pH of the washing solution was 7.0. The washed solid was dried at 80°C for 4 hours to obtain carboxylated cellulose powder. (2) Add 10 parts by weight of the carboxylated cellulose powder obtained in step (1) to deionized water to obtain a cellulose solution with a concentration of 1 wt%. Adjust the pH of the cellulose solution to 4 with 0.3 mol / L hydrochloric acid and sonicate at 1000 W for 30 min to obtain a cellulose dispersion. (3) Add hexadecyltrimethylammonium chloride (CTAC) to an ethanol solution (anhydrous ethanol and deionized water mixed at a volume ratio of 1:1) to obtain a CTAC solution with a concentration of 0.2 mol / L. Mix the CTAC solution with the cellulose dispersion obtained in step (2) at a volume ratio of 0.6:3.2 and stir at a stirring rate of 200 rpm for 1 h to obtain the second intermediate dispersion system. (4) Polyethyleneimine was added to deionized water to obtain a PEI solution with a concentration of 10wt%. The PEI solution and the second intermediate dispersion system obtained in step (4) were mixed at a volume ratio of 0.35:1. The mixture was stirred at a stirring rate of 200rpm for 30min and allowed to stand at 25℃ for 2h to obtain the gel material.

[0055] Performance testing The aerogels prepared in Examples 1-8 and Comparative Examples 1-3 were subjected to organic matter adsorption tests, heavy metal adsorption tests, and anti-algae tests. The test results are shown in Table 1 below.

[0056] Organic matter adsorption test: Aerogel (3 cm high, 2.5 cm in cross-sectional diameter) was added to a dye solution with an initial concentration of 1000 mg / L to form a test sample. The mass ratio of the aerogel to the volume of the dye solution was 0.5 mg / L. The dye solution contained CR (Congo Red, chemical formula C). 32 H 22 The initial concentration of N6Na2O6S2) was 500 mg / L, and SY (Sunset Yellow, chemical formula C) was... 16 H 10 The initial concentration of N2Na2O7S2) was 500 mg / L; 50 mL of test sample was taken and placed on a shaker at 25 ℃ and 120 rpm for organic adsorption test. The adsorption time was 1 h. The concentration of dye in the dye solution after adsorption was detected to obtain the removal rate (%) of CR dye and SY dye.

[0057] Wherein, the dye removal rate = [(C0-C1) / C0]×100%. In the formula, C1 is the corresponding concentration of CR dye and SY dye in the dye solution after the adsorption test; C0 is the corresponding initial concentration of CR dye and SY dye in the dye solution before the adsorption test. In this experiment, the initial concentration of CR dye is 500 mg / L and the initial concentration of SY dye is 500 mg / L.

[0058] Heavy metal adsorption experiment: Aerogel (3 cm high, 2.5 cm cross-sectional diameter) was added to a heavy metal solution with an initial concentration of 100 mg / L (50 mg / L for lead nitrate and 50 mg / L for copper nitrate), with a mass ratio of aerogel to heavy metal solution volume of 0.25 mg / mL. The pH of the mixture formed by the aerogel and heavy metals was adjusted to 6.0 with 1 mol / L NaOH solution to obtain the test solution. 30 mL of the test solution was placed on a shaker at 25℃ and 150 rpm for heavy metal adsorption experiment for 1 hour. After the experiment, the heavy metal content in the heavy metal solution was measured to obtain the removal rate of heavy metal ions.

[0059] The removal rate of heavy metal ions = [(ρ0-ρ1) / ρ0]×100%. Where ρ1 is the concentration of Pb(II) and Cu(II) in the heavy metal solution after the adsorption experiment; ρ0 is the initial concentration of Pb(II) and Cu(II) in the heavy metal solution before the adsorption experiment. In this experiment, the initial concentration of Pb(II) was 50 mg / L, and the initial concentration of Cu(II) was 50 mg / L.

[0060] Anti-algae test: The test was conducted according to the anti-algae test method in GB / T 24127-2009. The sample was a disc with a cross-sectional diameter of 2.5 cm and a height of 2.5 cm. The anti-algae grade was obtained from 0 to 4. As the anti-algae grade increased, the anti-algae effect decreased. For example, 0 represents excellent anti-algae effect, and 4 represents almost no anti-algae effect.

[0061] Table 1 Results of organic matter adsorption and heavy metal anti-algae activity of aerogels As shown in Table 1, the experimental results of this application demonstrate that the technical solution, using garden waste as raw material and employing a coupled physical, chemical, and enzymatic hydrolysis method, can effectively extract cellulose from the raw material powder, resulting in a high yield and good quality of extracted cellulose. Furthermore, the hydroxyl groups on the cellulose are converted into carboxyl groups to provide multifunctional anchors, enabling the sufficient and stable loading of copper ions, quaternary ammonium cations, and amine-containing polymers. The resulting aerogel exhibits excellent adsorption properties for organic matter, heavy metals, and algae.

[0062] The embodiments described herein are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are indicated by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be included within the scope of protection of this application.

Claims

1. A process for preparing cellulose-based aerogels, characterized in that, Includes the following steps: S1. Provide garden waste, and remove impurities, wash, dry and crush the garden waste to obtain raw material powder; S2. Cellulose is extracted from the raw material powder obtained in step S1 by a combination of physical, chemical and enzymatic methods. S3. Carboxyl groups are loaded onto the cellulose obtained in step S2, and copper ions, quaternary ammonium salt cations and amine-containing polymers are combined with the carboxyl groups to obtain a gel material. S4. The gel material obtained in step S3 is freeze-dried to obtain the cellulose-based aerogel.

2. The preparation process of cellulose-based aerogel according to claim 1, characterized in that, In step S2, the extraction of cellulose from the raw material powder using a coupled physical, chemical, and enzymatic approach includes: (1) Mix the raw material powder, deionized water, sodium chlorite and acetic acid, heat under an ultrasonic water bath, separate the solid and liquid to obtain the first solid, and wash the first solid with water; (2) Add the first solid obtained in step (1) to a sodium hydroxide solution, heat it under an ultrasonic water bath, separate the solid and liquid to obtain a second solid, and wash the second solid with water; (3) Add the second solid obtained in step (2) to the enzyme solution, adjust the pH to 4~6, control the temperature to 25~55℃, and after enzymatic hydrolysis, the third solid is obtained by enzyme inactivation and solid-liquid separation. The third solid is washed and dried to obtain cellulose.

3. The preparation process of cellulose-based aerogel according to claim 2, characterized in that, In step (1), the conditions for the ultrasonic water bath include: ultrasonic power of 200~500W and water bath temperature of 70~80℃; in step (2), the conditions for the ultrasonic water bath include: ultrasonic power of 200~500W and water bath temperature of 80~95℃. In step (3), the concentration of the enzyme solution is 10~30U / mL, and the enzymes in the enzyme solution include laccase, xylanase and cellulase, and the concentration ratio of laccase, xylanase and cellulase is (4~6):(4~6):(7~13).

4. The preparation process of cellulose-based aerogel according to claim 3, characterized in that, In step (3), when performing enzymatic hydrolysis, the temperature is controlled at 25~35℃ for 30~60 min, the temperature is controlled at 40~50℃ for 30~60 min, the temperature is controlled at 45~55℃ for 120~180 min.

5. The preparation process of cellulose-based aerogel according to claim 2, characterized in that, In step (3), after washing the third solid material and before drying it, the following steps are also included: The washed third solid was subjected to enzymatic hydrolysis again according to the enzymatic hydrolysis method in step (3). After the second enzymatic hydrolysis, the solid was deactivated, separated from the solid and washed.

6. The preparation process of cellulose-based aerogel according to claim 1, characterized in that, In step S3, loading carboxyl groups, copper ions, quaternary ammonium salt cations, and amine-containing polymers onto cellulose includes: Step 1: Carboxyl groups are loaded onto cellulose using an oxidation method to obtain carboxylated cellulose powder. The carboxylated cellulose powder is then added to water to form a cellulose dispersion. Step 2: Mix copper nitrate solution and L-ascorbic acid sodium solution to obtain a first mixture. Add the first mixture to the cellulose dispersion obtained in Step 1 and stir to obtain a first intermediate dispersion system. Step 3: Add the hexadecyltrimethylammonium chloride solution to the first intermediate dispersion system obtained in Step 2, and stir to obtain the second intermediate dispersion system; Step 4: Add the polyethyleneimine solution to the second intermediate dispersion system obtained in Step 3, stir, and let stand to obtain the gel material.

7. The preparation process of cellulose-based aerogel according to claim 6, characterized in that, In step one, carboxylated cellulose powder is added to water to obtain a cellulose solution with a concentration of 0.5~2.0wt%, the pH of the cellulose solution is adjusted to 3.5~4.5, and ultrasonically dispersed to obtain a cellulose dispersion. In step two, the concentration of copper nitrate solution is 8~12 mmol / L, the concentration of L-ascorbic acid sodium aqueous solution is 80~120 mmol / L, the copper nitrate solution and L-ascorbic acid sodium aqueous solution are mixed at a volume ratio of (0.5~1.5):(1~1.5), and the first mixture is mixed with cellulose dispersion at a volume ratio of (2.0~2.5):

1. In step three, the concentration of the hexadecyltrimethylammonium chloride solution is 0.1~0.3 mol / L, and the hexadecyltrimethylammonium chloride solution is mixed with the first intermediate dispersion system at a volume ratio of (0.5~0.7):3.

2. In step four, the concentration of the polyethyleneimine solution is 8-12 wt%, and the polyethyleneimine solution is mixed with the second intermediate dispersion system obtained in step three at a volume ratio of (0.32-0.37):

1.

8. The preparation process of cellulose-based aerogel according to claim 1, characterized in that, In step S4, the gel material is placed in a container, the bottom of the container is directly in contact with liquid nitrogen for 1-2 hours, frozen at -25 to -35°C, and dried under vacuum at 25 to 35°C to obtain cellulose-based aerogel.

9. A cellulose-based aerogel, characterized in that, It is prepared by the preparation process of cellulose-based aerogel as described in any one of claims 1 to 8.

10. The application of the cellulose-based aerogel as described in claim 9 in the ecological restoration of aquatic bodies.

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