Preparation method and application of modified regenerated cellulose sponge

Abstract

The invention discloses a preparation method of modified regenerated cellulose sponge, which comprises the following steps: modifying regenerated cellulose sponge by using N-(2-acylamino ethyl)-acrylamide and nano Cu3N to prepare poly N-(2-acylamino ethyl)-acrylamide / nano Cu3N modified regenerated cellulose sponge; the poly (N-(2-acylaminoethyl)-acrylamide / nano Cu3N modified regenerated cellulose sponge has a loose and porous channel structure and shows excellent water transmission capacity and temperature-control antibacterial effect, and after bacterial liquid is filtered by the sponge, the filtering antibacterial rates of escherichia coli and staphylococcus aureus at 35 DEG C both reach 95% or above; as an organic and inorganic combined antibacterial material, the composite material is helpful for removing bacteria in water, and is suitable for the field of water purification.

Description

Technical Field

[0001] The present invention relates to a process for preparing a composite modified cellulose sponge by modifying agricultural waste straw cellulose and then immobilizing nano-Cu3N, and its application in removing bacteria in water bodies, belonging to the technical field of natural polymer materials. Background Art

[0002] Although the birth of antibiotics and the popularization of vaccines have, to a certain extent, achieved the control of human bacterial infections, the overuse of antibiotic drugs has led to the variation of bacteria, breeding countless new "multi-drug resistant bacteria". Therefore, the research and development of non-antibiotic antibacterial materials with low toxicity, high potency and high timeliness is one of the important current topics.

[0003] Inorganic antibacterial materials are a type of functional materials with the functions of killing and inhibiting the growth and reproduction of bacteria. It has been proven that Cu3N nanoparticles can bind copper ions to the enzymes inside microbial cells, especially those containing sulfhydryl groups (-SH). Sulfhydryl groups are key parts of the active centers of many enzymes, and the binding of copper ions to them will cause the enzymes to become inactivated, thereby interfering with the cell's metabolic processes, such as energy generation and substance synthesis. Copper ions can catalyze the Fenton reaction, converting hydrogen peroxide (H2O2) into highly reactive hydroxyl radicals (·OH). These free radicals will attack DNA, proteins and lipids inside the cell, causing oxidative damage and ultimately leading to cell death. Therefore, it has significant antibacterial and bacteriostatic abilities against both Gram-positive and Gram-negative bacteria, and its antibacterial method is diverse, and the process is different from other metal oxides. This is also the reason why antibacterial materials with Cu3N as the core component have attracted great interest. However, pure Cu3N nanoparticles have disadvantages such as easy aggregation and difficult recovery. In order to overcome such problems and endow metal particles with better dispersibility, antibacterial properties and recyclability, a certain carrier is usually required during the formation of Cu3N nanoparticles.

[0004] As important food cash crops in China, the annual output of by-products such as straw from crops like corn has exceeded 800 million tons. At present, the utilization of straw resources in rural areas still has significant limitations: except for a small amount used as domestic fuel, feed processing or industrial fermentation raw materials, more than 70% of the straw is still disposed of by open-air burning or natural stacking. This extensive disposal not only causes serious air pollution and health hazards, but also leads to a huge waste of renewable biomass resources.

[0005] Currently, there is no report related to the technical solution of the present invention. Summary of the Invention

[0006] Based on the phase transition characteristics of the UCST-type polymer, poly-N-(2-aminoethyl)-acrylamide (PNAEAM), the present invention provides a preparation method of a temperature-responsive cellulose-based antibacterial material, namely a preparation method of poly-N-(2-aminoethyl)-acrylamide / nano-Cu3N modified regenerated cellulose sponge; Cu3N nanoparticles can kill bacteria in water, and the porous structure of the regenerated cellulose sponge is conducive to the passage of water flow. The present invention provides an economical and effective way for the efficient purification of water; moreover, agricultural waste straw, which is rich in resources but has not been deeply developed, is selected as the raw material, and Cu3N nanoparticles are immobilized by a simple chemical precipitation method, and an antibacterial sponge product is prepared by reaction, further expanding the application field of agricultural waste straw, making this green and renewable material of straw be utilized with high added value, and laying a theoretical and new technology foundation for the diversified high-value expansion of agricultural waste straw.

[0007] The object of the present invention is achieved by adopting the following technical solutions: (1) Under a nitrogen atmosphere and ice-water bath conditions, 3-aminopropionamide and ice water are mixed, then ice ether and a 1-3 mol / L K2CO3 solution are added. After stirring and mixing evenly, an ice ether solution of acryloyl chloride is added. After reacting for 3-5 h, the pH of the reaction product is adjusted to 1-3, washed with ether 3-5 times, the aqueous phases are collected and combined, and the pH value is adjusted to neutral. After freeze-drying, the dried product is dissolved in an ethanol-methanol mixed solution, and solid-liquid separation is carried out. The liquid is concentrated by rotary evaporation and recrystallized, and the crystallized product is dried to obtain N-(2-aminoethyl)-acrylamide; The mass ratio of the 3-aminopropionamide to acryloyl chloride is 1-1.5:1 (g:mL), the volume-mass ratio of the K2CO3 solution to 3-aminopropionamide is 3-5.5:1 (mL:g), and the ethanol-methanol mixed solution is prepared by mixing ethanol and methanol at a volume ratio of 3-5:1. (2) After peeling and grinding and screening the dried straw, it is extracted with a benzene-alcohol-dichloromethane mixed solution for defatting and air-dried, and then subjected to delignification and hemicellulose treatment with sodium perchlorate and sodium chlorate. The pulp is washed with water until neutral, filtered, and the filter residue is dried to obtain cellulose powder; the cellulose powder, N,N-dimethylacetamide, and LiCl are mixed and reacted to prepare a cellulose solution. The cellulose solution is regenerated by adding water under a high-speed disperser, filtered and washed, resuspended and transferred to a mold for freeze-drying to obtain a regenerated nano-cellulose sponge; In the benzene-alcohol-dichloromethane mixed solution, the volume ratio of benzene, anhydrous ethanol, and dichloromethane is 2-5:1-2:1-3; the mass ratio of defatted straw to sodium perchlorate is 1:1; the mass-volume ratio of defatted straw to sodium chlorate is 1-1.5:1 (g:mL); the mass ratio of cellulose powder to N,N-dimethylacetamide is 1:20-30; the mass ratio of cellulose powder to LiCl is 2:1; (3) Heat 5 - 15 mL of octadecylamine to 250 - 300 °C, then add 0.2 - 0.4 g of Cu(NO3)2·3H2O powder. After the color of the mixture changes from orange to tan, cool it and separate the solid from the liquid. Wash the solid 4 - 6 times with absolute ethanol, and then wash it 2 - 4 times with a cyclohexane - ethanol mixture (cyclohexane:ethanol = 1:5) to obtain nano - Cu3N; (4) Mix the regenerated nano - cellulose sponge, N-(2 - aminoethyl) - acrylamide, and initiator, and react at 45 - 70 °C for 4 - 12 h. Then, wash the sponge with deionized water for 36 - 48 h and freeze - dry it to obtain the modified cellulose sponge. Immerse the modified cellulose sponge in the nano - Cu3N dispersion liquid, and dry it to obtain the poly N-(2 - aminoethyl) - acrylamide / nano - Cu3N modified regenerated cellulose sponge; The addition amount of N-(2 - aminoethyl) - acrylamide is 0.5 - 2.0% of the mass of the regenerated nano - cellulose sponge; the mass ratio of N-(2 - aminoethyl) - acrylamide to the initiator is 30:1 - 50:1, and the mass ratio of the modified cellulose sponge to nano - Cu3N is 1:1 - 3.

[0008] Another object of the present invention is to apply the PNAEAM / nano - Cu3N modified regenerated cellulose sponge prepared by the above method to the removal of bacteria in water bodies.

[0009] As one of the plant raw materials, agricultural waste straw contains abundant carbohydrates in its chemical composition analysis. Both of them have many oxygen - containing functional groups such as hydroxyl groups in their macromolecules, which lays a good chemical material foundation for the immobilization of nanoparticles. In addition, agricultural waste straw contains more parenchyma cells. The parenchyma cells are composed of only one primary wall. The microfibrils formed by the co - action of hydrogen bonds and van der Waals forces of low - molecular - weight cellulose molecular chains are arranged disorderly in this cell wall and have fewer crystals. Compared with the fiber - cell cellulose with large molecular weight, high crystallinity, small specific surface area, and compact texture, low - molecular - weight cellulose has the advantages of being soft and plastic, high reaction accessibility, etc., and is more suitable for functional development and research. The cellulose sponge formed after dissolution, regeneration, and cold - dry molding with a mold has a porous structure. These channels are arranged orderly and connected together. This special structure facilitates the penetration and transportation of liquid molecules inside it. This characteristic provides an excellent place for the immobilization of metal nanoparticles, and at the same time provides a greater possibility and convenience for the full contact and reaction of bacteria and copper nitride particles.

[0010] Beneficial effects of the present invention: Using the regenerated cellulose sponge prepared from agricultural waste straw as a carrier, nano-copper nitride particles are co-mixed and immobilized by a simple precipitation modification method, and then the porous structure of the carrier is used to achieve filtration, sterilization and water purification. The antibacterial material is composed of modified regenerated cellulose and nano-copper nitride, which is more concise and energy-saving than traditional antibacterial materials. It is a new type of green and environmentally friendly functional material that is currently the mainstream development and can be applied to the field of water purification; the realization of this sponge filter column provides a feasible solution for the high-value utilization of agricultural waste straw and also lays a certain preliminary foundation for the functional development of agricultural waste straw. Detailed implementation mode

[0011] The technical solutions of the present invention will be further described in detail below through examples. However, the content of the present invention is not limited thereto. In the following examples, the methods are conventional methods unless otherwise specified, and the materials, reagents, etc. are obtained from commercial sources or prepared by conventional methods unless otherwise specified. Example 1: Preparation and application of poly-N-(2-aminoethyl)acrylamide / nano-Cu3N modified regenerated cellulose sponge (1) Under a nitrogen atmosphere, 3.2 g of 3-aminopropionamide was dissolved in 5 mL of ice water in an ice-water bath and then added to a three-necked flask. Subsequently, 17 mL of ice-cold diethyl ether and 9.6 mL of 3 mol / L K2CO3 solution were successively added to the three-necked flask and stirred. Then, a mixture of 2.8 mL of acryloyl chloride and 12 mL of ice-cold diethyl ether was added dropwise to the three-necked flask under an ice-water bath. After reacting for 3 h, the pH of the reaction product was first adjusted to 1 with 5 mol / L hydrochloric acid solution, and then washed 3 times with 100 mL of diethyl ether. The lower aqueous phase was collected and combined, and then the pH was adjusted to neutral with 1 mol / L NaOH solution, and freeze-dried to obtain a crude product. The crude product was dissolved in a 150 mL ethanol / methanol mixture (ethanol / methanol = 3:1), filtered, and the filtrate was rotary evaporated at 35 °C. The concentrated solution was recrystallized at 4 °C for 12 h, and the precipitate was collected. After vacuum drying the precipitate, white NAEAM powder was obtained. (2) 5 mL of octadecylamine (ODA) was heated to 250 °C, and then 0.2 g of Cu(NO3)2·3H2O powder was quickly added. After 10 min, the color of the solvent changed from orange to yellow-brown, and then cooled. The solid was washed 4 times with absolute ethanol and 2 times with a cyclohexane / ethanol mixture (cyclohexane / ethanol = 1:5) to obtain nano-Cu3N. (3)After peeling the air-dried corn straw, grind it and pass through a 60-mesh sieve to collect the material below the sieve, and then pass through an 80-mesh sieve to collect the material above the sieve; weigh 10 g of the straw powder, pack it and put it into a Soxhlet extractor, add 250 mL of a benzene-ethanol-dichloromethane mixture (volume ratio of benzene to absolute ethanol is 2:1, volume ratio of benzene to dichloromethane is 1:1), and siphon and circulate 3 times per hour in the extractor. After extracting repeatedly for 24 h, air-dry it naturally. Add 50 mL of deionized water, 1 mL of sodium chlorate, and 1 g of sodium perchlorate to 1 g of the air-dried raw material after extraction, mix well, and place it in a constant temperature water bath at 30 °C until the raw material turns white. Wash the slurry repeatedly by suction filtration with deionized water until the material is neutral, filter, and freeze-dry the filter residue to obtain cellulose with a purity of 80%; according to the mass ratio of cellulose powder to N,N-dimethylacetamide of 1:25, take 2 g of cellulose and add it to DMAc. Stir and react at 105 °C and 200 r / min for 1 h, then add 1 g of LiCl, adjust the temperature of the oil bath to 95 °C, continue to react for 1 h, and then put it in the refrigerator for refrigeration to obtain a cellulose solution. Use a syringe to extract 2 mL of the cellulose solution, start the high-speed disperser with a rotation speed of 5000 rpm, and inject the solution into 200 mL of water at a speed of 2 mL / min. After complete injection, continue to disperse for 5 s to complete the regeneration and dispersion process; filter the regenerated nanocellulose suspension with a microporous membrane with a pore size of 0.2 μm, wash it twice with deionized water, and then redisperse the washed material in 5 mL of deionized water; continuously stir the suspension with a magnetic stirrer for 0.5 h, then transfer the mixed solution to a mold and freeze-dry it to obtain a regenerated nanocellulose sponge; (4)Mix the regenerated nanocellulose sponge, N-(2-aminoethyl)-acrylamide, and the initiator KPS, where the addition amount of N-(2-aminoethyl)-acrylamide is 0.5% of the mass of the regenerated nanocellulose sponge; the mass ratio of N-(2-aminoethyl)-acrylamide to the initiator is 30:1. React at 45 °C for 4 h, then wash the sponge with deionized water for 36 h, and freeze-dry it to obtain a modified cellulose sponge; immerse the modified cellulose sponge in 20 mL of a nanoscale Cu3N dispersion (mass ratio of modified cellulose sponge to nanoscale Cu3N is 1:1), and dry it to obtain a poly-N-(2-aminoethyl)-acrylamide / nanoscale Cu3N modified regenerated cellulose sponge; (5)Product characteristics Use multi-dimensional characterization methods to systematically analyze the agricultural waste straw-based composite material: First, determine the loading amount of copper nitride in the material by inductively coupled plasma optical emission spectrometry (ICP-OES). The results show that the copper nitride content in the sponge per unit mass is 200 mg / g. Subsequently, use mercury intrusion porosimetry to characterize the pore structure characteristics of the material, and the measured average pore diameter is 5.6 μm, and the porosity is as high as 94.6%. Supported by this porous structure, the material exhibits excellent water flux performance (178×10 3 L·m-2 ·h -1 ). Further analysis by nitrogen adsorption - desorption tests showed that the regenerated cellulose sponge loaded with copper nitride had a specific surface area of 22.6 m 2 / g, which provided favorable conditions for the exposure of reactive sites.

[0012] The plate - coating method was used to quantitatively evaluate the bacterial interception efficiency of the regenerated cellulose sponge loaded with copper nitride. Specifically: typical pathogenic bacteria Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) were selected as the research objects. After being cultured to the logarithmic growth phase in Luria broth (LB) liquid medium, a high - concentration bacterial suspension of 5×10 8 CFU / mL was prepared by gradient dilution. In the dynamic filtration test simulating actual natural light, at 15 °C, 25 °C, and 35 °C respectively, the regenerated cellulose sponge loaded with copper nitride was used to continuously filter 100 mL of the bacterial solution at a flow rate of 20 mL·min -1 . Then, 100 μL of the filtrate was evenly spread on an agar plate and incubated at 37 °C for 15 h, and the colony - forming units (CFU) were counted. By comparing the colony base number of the unfiltered original solution, the antibacterial rate was calculated. The results showed that at 35 °C, the interception efficiency of the filter column for E. coli , S. aureus was the highest, reaching 97% and 96% respectively; the interception rates at 15 °C were 85% and 83% respectively; the interception rates at 25 °C were 87% and 86% respectively.

[0013] Example 2: Preparation and application of poly(N - (2 - aminoethyl) - acrylamide) / nano - Cu3N modified regenerated cellulose sponge (1) Under a nitrogen atmosphere, 6.4 g of 3 - aminopropionamide was dissolved in 6 mL of ice - water in an ice - water bath and then added to a three - necked flask. Subsequently, 18 mL of ice - cold diethyl ether and 25.6 mL of 2 mol / L K2CO3 solution were successively added to the three - necked flask and stirred. Then, a mixture of 5.3 mL of acryloyl chloride and 24 mL of ice - cold diethyl ether was added dropwise to the three - necked flask under an ice - water bath. After reacting for 4 h, the pH of the reaction product was first adjusted to 2 with 4 mol / L hydrochloric acid solution, then washed 4 times with 150 mL of diethyl ether, and the lower aqueous phase was collected and combined. Then, the pH was adjusted to neutral with 2 mol / L NaOH solution, and the crude product was obtained by freeze - drying. The crude product was dissolved in a 300 mL ethanol - methanol mixture (ethanol / methanol = 4:1), filtered, the filtrate was rotary - evaporated at 35 °C, the concentrated solution was recrystallized at 5 °C for 18 h, the precipitate was collected, and the precipitate was dried in vacuo to obtain white NAEAM powder; (2) Heat 10 mL of octadecylamine (ODA) to 275 °C and quickly add 0.3 g of Cu(NO3)2·3H2O powder. After 15 min, when the solvent color changes from orange to yellowish-brown, cool it, filter it, wash the solid 5 times with absolute ethanol, and wash it 3 times with a mixed solution of cyclohexane and ethanol (cyclohexane / ethanol = 1:5) to obtain nano-Cu3N; (3) After peeling the air-dried corn straw, grind it and pass it through a 150-mesh sieve to collect the undersize material, and then pass it through a 180-mesh sieve to collect the oversize material; Weigh 20 g of the straw powder, pack it and put it into a Soxhlet extractor, add 550 mL of a mixed solution of benzene-ethanol-dichloromethane (volume ratio of benzene to absolute ethanol is 3:1, and the volume ratio of benzene to dichloromethane is 1:2), and let it circulate and siphon 4 times per hour in the extractor. After extracting repeatedly for 36 h, air-dry it naturally. Add 60 mL of deionized water, 1.5 mL of sodium chlorate, and 2 g of sodium perchlorate to 2 g of the air-dried raw material after extraction, mix well, and place it in a constant temperature water bath at 50 °C until the raw material turns white. Wash the slurry repeatedly with deionized water by suction filtration until the material is neutral, filter it, and freeze-dry the filter residue to obtain cellulose with a purity of 90%; According to the mass ratio of cellulose powder to N,N-dimethylacetamide of 1:25, take 3 g of cellulose and add it to DMAc. Stir and react at 110 °C and 250 r / min for 2 h, then add 1.5 g of LiCl, adjust the temperature of the oil bath to 100 °C, continue to react for 1.5 h, and then put it in the refrigerator for refrigeration to obtain a cellulose solution. Use a syringe to extract 5 mL of the cellulose solution, start a high-speed disperser with a rotation speed of 10,000 rpm, and inject the solution into 350 mL of water at a speed of 7 mL / min. After complete injection, continue to disperse for 30 s to complete the regeneration and dispersion process; Filter the regenerated nano-cellulose suspension with a microporous filter membrane with a pore size of 0.5 μm, wash it 3 times with deionized water, and then redisperse the washed material in 25 mL of deionized water; Continuously stir the suspension with a magnetic stirrer for 1 h, then transfer the mixed solution to a mold and freeze-dry it to obtain a regenerated nano-cellulose sponge; (4) Mix the regenerated nano-cellulose sponge, N-(2-aminoethyl)-acrylamide, and initiator KPS, where the addition amount of N-(2-aminoethyl)-acrylamide is 1% of the mass of the regenerated nano-cellulose sponge; The mass ratio of N-(2-aminoethyl)-acrylamide to the initiator is 40:1. After reacting at 55 °C for 8 h, wash the sponge with deionized water for 40 h and dry it by freeze-drying to obtain a modified cellulose sponge; Immerse the modified cellulose sponge in 30 mL of nano-Cu3N dispersion (mass ratio of modified cellulose sponge to nano-Cu3N is 1:2), and dry it to obtain a poly-N-(2-aminoethyl)-acrylamide / nano-Cu3N modified regenerated cellulose sponge; (5) Product characteristics A multi-dimensional characterization method was used to systematically analyze the agricultural waste straw-based composite material: First, the loading amount of copper nitride in the material was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the copper nitride content in the sponge per unit mass was 456 mg / g. Subsequently, the mercury intrusion method was used to characterize the pore structure characteristics of the material. The average pore diameter was measured to be 5.8 μm, and the porosity was as high as 91.1%. Supported by this porous structure, the material exhibited excellent water flux performance (113×10 3 L·m -2 ·h -1 ). Further nitrogen adsorption-desorption test analysis showed that the regenerated cellulose sponge loaded with copper nitride had a specific surface area of 26.6 m 2 / g, which provided favorable conditions for the exposure of reactive sites.

[0014] The spread plate method was used to quantitatively evaluate the bacterial retention efficiency of the filter column. Specifically: The typical pathogenic bacteria Escherichia coli ( E. coli ), and Staphylococcus aureus ( S. aureus ) were selected as the research objects. After being cultured to the logarithmic growth phase in Luria broth (LB) liquid medium and then gradient diluted, a high-concentration bacterial suspension of 5×10 8 CFU / mL was prepared. In the dynamic filtration test simulating actual natural light, at 15 °C, 25 °C, and 35 °C respectively, the regenerated cellulose sponge loaded with copper nitride was used to continuously filter 100 mL of the bacterial solution at a flow rate of 20 mL·min -1 . Subsequently, 100 μL of the filtered liquid was evenly spread on the agar plate. After incubation at 37 °C for 15 h, the colony forming units (CFU) were counted. By comparing the colony base of the unfiltered original solution, the antibacterial rate was calculated. The results showed that at 35 °C, the retention efficiency of the filter column for E. coli , S. aureus was the highest, reaching 98% and 99% respectively, and the retention rates at 15 °C were 86% and 84% respectively; the retention rates at 25 °C were 89% and 88% respectively.

[0015] Example 3: Preparation and application of poly-N-(2-aminoethyl)-acrylamide / nano-Cu3N modified regenerated cellulose sponge (1) Under a nitrogen atmosphere, 12.6 g of 3-aminopropionamide was dissolved in 7 mL of ice water in an ice-water bath and then added to a three-necked flask. Subsequently, 19 mL of ice-cold diethyl ether and 67.2 mL of 1 mol / L K2CO3 solution were successively added to the three-necked flask and stirred. Then, 8.4 mL of acryloyl chloride was mixed with 36 mL of ice-cold diethyl ether and added dropwise to the three-necked flask under an ice-water bath. After reacting for 5 h, the pH of the reaction product was first adjusted to 3 with 7 mol / L hydrochloric acid solution, and then washed 5 times with 200 mL of diethyl ether. The lower aqueous phase was collected and combined, and then the pH was adjusted to neutral with 3 mol / L NaOH solution. The crude product was obtained by freeze-drying. The crude product was dissolved in a 400 mL ethanol-methanol mixture (ethanol / methanol = 5:1), filtered, and the filtrate was rotary evaporated at 35 °C. The concentrated solution was recrystallized at 6 °C for 24 h, and the precipitate was collected. After vacuum drying the precipitate, a white NAEAM powder was obtained. (2) 15 mL of octadecylamine (ODA) was heated to 300 °C, and then 0.4 g of Cu(NO3)2·3H2O powder was quickly added. After 20 min, when the color of the solvent changed from orange to yellow-brown, it was cooled and filtered. The solid was washed 6 times with absolute ethanol and 4 times with a cyclohexane-ethanol mixture (cyclohexane / ethanol = 1:5) to obtain nano-Cu3N. (3) After air-dried corn straw was peeled, it was ground and passed through a 250-mesh sieve to collect the undersize, and then passed through a 300-mesh sieve to collect the oversize. 30 g of the straw powder was weighed, packaged, and placed in a Soxhlet extractor. 700 mL of a benzene-ethanol-dichloromethane mixture (volume ratio of benzene to absolute ethanol is 5:2, and volume ratio of benzene to dichloromethane is 2:3) was added to the extractor and siphoned 5 times per hour for 48 h of repeated extraction. After natural air-drying, 70 mL of deionized water, 2 mL of sodium chlorate, and 3 g of sodium perchlorate were added to 3 g of the air-dried raw material after extraction. After mixing evenly, it was placed in a constant-temperature water bath at 70 °C until the raw material turned white. The slurry was repeatedly filtered and washed with deionized water until the material was neutral. After filtration, the filter residue was freeze-dried to obtain cellulose with a purity of 99.99%. According to the mass ratio of cellulose powder to N,N-dimethylacetamide of 1:25, 3 g of cellulose was taken and added to DMAc. After stirring and reacting at 115 °C and 300 r / min for 3 h, 2 g of LiCl was added. The temperature of the oil bath was adjusted to 105 °C, and the reaction continued for 2 h. Then it was placed in the refrigerator for refrigeration to obtain a cellulose solution. 8 mL of the cellulose solution was extracted with a syringe, the high-speed disperser was started at a speed of 20,000 rpm, and the solution was injected into 400 mL of water at a speed of 15 mL / min. After complete injection, it was continuously dispersed for 60 s to complete the regeneration and dispersion process. The regenerated nanocellulose suspension was filtered through a microporous membrane with a pore size of 0.8 μm, washed 5 times with deionized water, and then the washed material was redispersed in 50 mL of deionized water. After continuously stirring the suspension with a magnetic stirrer for 1 h, the mixed solution was transferred to a mold and freeze-dried to obtain a regenerated nanocellulose sponge. (4) Mix the regenerated nanocellulose sponge, N-(2-aminoethyl)-acrylamide, and the initiator KPS. The addition amount of N-(2-aminoethyl)-acrylamide is 2% of the mass of the regenerated nanocellulose sponge; the mass ratio of N-(2-aminoethyl)-acrylamide to the initiator is 50:1. After reacting at 70 °C for 12 h, wash the sponge with deionized water for 45 h, and freeze-dry to obtain the modified cellulose sponge; Immerse the modified cellulose sponge in 40 mL of the nano-Cu3N dispersion (the mass ratio of the modified cellulose sponge to nano-Cu3N is 1:3), and dry to obtain the poly-N-(2-aminoethyl)-acrylamide / nano-Cu3N modified regenerated cellulose sponge; (5) Product characteristics Use multi-dimensional characterization methods to systematically analyze the agricultural waste straw-based composite material: First, determine the loading amount of copper nitride in the material by inductively coupled plasma spectroscopy (ICP-OES). The results show that the copper nitride content in the sponge per unit mass is 713 mg / g. Subsequently, use the mercury intrusion method to characterize the pore structure characteristics of the material. The measured average pore diameter is 5.2 μm, and the porosity is as high as 93.3%. Supported by this porous structure, the material exhibits excellent water flux performance (90×10 3 L·m -2 ·h -1 ). Further analysis by nitrogen adsorption-desorption tests shows that the regenerated cellulose sponge loaded with copper nitride has a specific surface area of 33.4 m 2 / g, which provides favorable conditions for the exposure of reactive sites.

[0016] Use the spread plate method to quantitatively evaluate the bacterial retention efficiency of the filter column. Specifically: Select typical pathogenic bacteria Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) as the research objects. After expanding and culturing to the logarithmic growth phase through Luria broth (LB) liquid medium and then gradient diluting, prepare a high-concentration bacterial suspension of 5×10 8 CFU / mL. In the dynamic filtration test simulating actual natural light, at 15 °C, 25 °C, and 35 °C respectively, use the regenerated cellulose sponge loaded with copper nitride to continuously filter 100 mL of the bacterial solution at a flow rate of 20 mL·min -1 . Then take 100 μL of the filtered liquid and evenly spread it on the agar plate. After incubating at 37 °C for 15 h, count the colony forming units (CFU). Calculate the antibacterial rate by comparing with the colony base number of the unfiltered original solution. The results show that at 35 °C, the retention efficiency of the filter column for E. coli , S. aureus is the highest, reaching 99.6% and 99.9% respectively, and the retention rates at 15 °C are 81% and 80% respectively; the retention rates at 25 °C are 90% and 89% respectively.

Claims

1. A method for preparing a modified regenerated cellulose sponge, characterized in that, The steps are as follows: (1) Under a nitrogen atmosphere and in an ice-water bath, 3-aminopropionamide and ice water are mixed, then ice ether and a 1-3 mol / L K2CO3 solution are added. After stirring and mixing evenly, an ice ether solution of acryloyl chloride is added. After reacting for 2-4 h, the pH of the reaction product is adjusted to 1-3, and it is washed with ether 2-4 times. The aqueous phases are collected and combined, and the pH value is adjusted to neutral. After freeze-drying, the dried product is dissolved in a mixed solution of ethanol and methanol, followed by solid-liquid separation. The liquid is concentrated by rotary evaporation and recrystallized, and the crystals are dried to obtain N-(2-aminoethyl)-acrylamide; (2) After peeling the dried straw, it is ground and sieved, then extracted with a mixed solution of benzene, alcohol, and dichloromethane for defatting and air-dried. Then, sodium perchlorate and sodium chlorate are used for delignification and hemicellulose treatment. The pulp is washed with water until neutral, filtered, and the filter residue is dried to obtain cellulose powder. The cellulose powder, N,N-dimethylacetamide, and LiCl are mixed and reacted to prepare a cellulose solution. The cellulose solution is regenerated by adding water under a high-speed disperser, filtered and washed, resuspended, and transferred to a mold for freeze-drying to obtain a regenerated nanocellulose sponge; (3) The regenerated nanocellulose sponge, N-(2-aminoethyl)-acrylamide, and an initiator are mixed and reacted at 45-70 °C for 4-12 h. Then, the sponge is rinsed with deionized water for 36-48 h and freeze-dried to obtain a modified cellulose sponge. The modified cellulose sponge is immersed in a nanoscale Cu3N dispersion liquid and dried to obtain a poly-N-(2-aminoethyl)-acrylamide / nanoscale Cu3N modified regenerated cellulose sponge.

2. The preparation method of the modified regenerated cellulose sponge according to claim 1, characterized in that: The mass-volume ratio of 3-aminopropionamide to acryloyl chloride is 1-1.5:1 g:mL, the volume-mass ratio of the K2CO3 solution to 3-aminopropionamide is 3-5.5:1 mL:g, and the mixed solution of ethanol and methanol is prepared by mixing ethanol and methanol at a volume ratio of 3-5:

1.

3. The preparation method of the modified regenerated cellulose sponge according to claim 1, wherein: Nanoscale Cu3N is prepared by heating 5-15 mL of octadecylamine to 250-300 °C, adding 0.2-0.4 g of Cu(NO3)2·3H2O powder. After the color of the mixture changes from orange to yellowish-brown, it is cooled, and solid-liquid separation is carried out. The solid is washed with absolute ethanol 4-6 times and then washed with a mixed solution of cyclohexane and ethanol 2-4 times.

4. The preparation method of the modified regenerated cellulose sponge according to claim 1, characterized in that: In the mixed solution of benzene, alcohol, and dichloromethane, the volume ratio of benzene to absolute ethanol is 2-5:1-2, and the volume ratio of benzene to dichloromethane is 1-2:1-3.

5. The preparation method of the modified regenerated cellulose sponge according to claim 1, characterized in that: The mass ratio of defatted straw to sodium perchlorate is 1:1; the mass-volume ratio of defatted straw to sodium chlorate is 1-1.5:1 g:mL.

6. The preparation method of the modified regenerated cellulose sponge according to claim 1, wherein: The mass-volume ratio of cellulose powder to N,N-dimethylacetamide is 1:20-30 g:mL; the mass ratio of cellulose powder to LiCl is 2:

1.

7. The preparation method of the modified regenerated cellulose sponge according to claim 1, wherein: The addition amount of N-(2-aminoethyl)-acrylamide is 0.5-2.0% of the mass of the regenerated nanocellulose sponge; the mass ratio of N-(2-aminoethyl)-acrylamide to the initiator is 30:1-50:1, and the mass ratio of the modified cellulose sponge to nanoscale Cu3N is 1:1-3.

8. Use of a poly-N-(2-aminoethyl)-acrylamide / nano-Cu3N modified regenerated cellulose sponge prepared by the preparation method of the modified regenerated cellulose sponge described in any one of claims 1-7 in removing bacteria in water bodies.