Nano-cellulose and composite cellulase synergistic filtration aiding process

Abstract

The invention relates to the technical field of filtration aiding processes, and provides a nanocellulose and composite cellulase combined filtration aiding process which comprises the following steps: S100, respectively preparing nanocellulose and composite cellulase; s200, pretreating the to-be-filtered liquid, sequentially adding nano cellulose and compound cellulase, and then stirring to obtain the treated to-be-filtered liquid; and S300, sequentially carrying out filtering treatment on the treated to-be-filtered liquid. According to the nanocellulose and composite cellulase synergistic filtration aiding technology, through the synergistic effect of nanocellulose and composite cellulase, the filtration efficiency is improved, the enzyme preparation process is optimized, the stability of the filtration process and the purity of filtrate are improved, and the nanocellulose and composite cellulase synergistic filtration aiding technology is high in environmental friendliness, wide in application range and suitable for industrial production. The problems of low efficiency, high energy consumption, non-ideal filtering effect and the like in a traditional filtering method can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of filter aid technology, and in particular to a filter aid technology of nanocellulose coordinated with composite cellulase. Background Art

[0002] Nanocellulose has the characteristics of large specific surface area and rich surface hydroxyl content. It is a new type of renewable, biodegradable and environmentally friendly material. It is mainly obtained by a series of treatments using pulp fiber as raw material. Pigments are inorganic small molecule particles that can be used as fillers to color paper and increase the opacity of paper. Compared with organic dyes, pigments not only have better light resistance and corrosion resistance, but are also environmentally friendly and will not remain in water for a long time, thereby causing pollution. However, compared with dyes, pigments cannot form chemical reactions with pulp fibers. The existing technology only uses electrostatic action to combine pigment particles with paper fibers by adding retention and filtration aids, resulting in poor retention and extreme instability, and a large amount of pigment particles are lost with white water.

[0003] However, the current traditional filtration methods have the problems of low efficiency, high energy consumption, and unsatisfactory filtration effect. Therefore, a process technology is urgently needed to solve the above technical problems. Summary of the invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems. The present invention provides a nanocellulose synergistic composite cellulase filtration-aid process. The nanocellulose synergistic composite cellulase filtration-aid process provided by the present application, through the synergistic effect of nanocellulose and composite cellulase, not only improves the filtration efficiency, but also optimizes the enzyme preparation process, improves the stability of the filtration process and the purity of the filtrate, and has high environmental friendliness and a wide range of applications. It can solve the problems of low efficiency, high energy consumption, and unsatisfactory filtration effect in traditional filtration methods.

[0005] The present invention provides a nanocellulose-composite cellulase filtration-aiding process, comprising the following steps: S100, preparing nanocellulose and composite cellulase respectively; S200, pre-treating a filtrate, sequentially adding nanocellulose and composite cellulase, and then stirring to obtain a treated filtrate; S300, sequentially filtering the treated filtrate; wherein the nanocellulose comprises a mixture of cellulose nanocrystals and cellulose nanofibers; the composite cellulase comprises cellulase and auxiliary enzymes;

[0006] The preparation method of cellulase comprises: S101, adding a first preservative and a flocculant in sequence to a fermentation liquid of bacillus, filtering to obtain a filtrate; S102, adding a second preservative to the filtrate, adjusting the pH, and sterilizing to obtain cellulase.

[0007] After adopting the technical scheme of the present invention, the following technical effects can be achieved: the nanocellulose synergistic composite cellulase filtration aid process of the present invention effectively improves the efficiency and quality of liquid filtration through the synergistic effect of nanocellulose and composite cellulase, and the nanocellulose includes a mixture of cellulose nanocrystals and cellulose nanofibers, and has a large specific surface area and high hydrophilicity. Under the action of the composite cellulase, impurities in the liquid can be decomposed more efficiently, sedimentation and agglomeration can be reduced, and the filtration effect can be significantly improved, which helps to reduce the blockage that may occur during the filtration process, increase the flux of the filtrate, achieve the purpose of rapid and effective filtration, and significantly improve the clarity and purity of the filtrate; in addition, through a special preparation method, the cellulase is prepared by Bacillus fermentation broth, and combined with the use of preservatives and flocculants, the activity of the enzyme is improved, while maintaining stability during the treatment process, and by adjusting the pH value, adding preservatives and sterilizing, the activity of the enzyme is maximized and not inhibited, and good catalytic activity can be maintained under different environmental conditions, which helps to improve the long-term effectiveness and reliability of the overall process; and, because the auxiliary enzyme in the composite cellulase can further decompose non-cellulose substances in the liquid, such as lignin, pectin, etc., thereby reducing their interference with the filtration effect, the applicability of the enzyme in a variety of liquid systems is improved, especially for those liquids rich in complex organic matter, it can effectively accelerate the decomposition of substances and improve the removal rate of impurities during the filtration process. , reducing sediments and flocculants to achieve higher filtration accuracy; using preservatives and flocculants in the enzyme preparation and filtration aid process effectively avoids enzyme inactivation and secondary deposition of impurities, making the filtration process more controllable, reducing errors and unstable factors in operation, and improving the filtration effect under long-term operation; finally, the process uses nanocellulose and natural enzymes to reduce dependence on chemicals and high energy consumption. Nanocellulose, as an environmentally friendly material, is natural and renewable. Compared with traditional filtration methods, the present invention is excellent in environmental friendliness, reduces the demand for harmful chemicals, and reduces energy consumption in the filtration process, meeting the needs of sustainable development; in general, the nanocellulose synergistic composite cellulase filtration aid process provided by the present application, through the synergistic effect of nanocellulose and composite cellulase, not only improves the filtration efficiency, but also optimizes the enzyme preparation process, improves the stability of the filtration process and the purity of the filtrate, and has high environmental friendliness and a wide range of applications. It can solve the problems of low efficiency, high energy consumption, and unsatisfactory filtration effect in traditional filtration methods.

[0008] In one technical solution of the present invention, the first preservative comprises: potassium sorbate, sodium benzoate and EDTA; and / or the second preservative comprises: potassium sorbate, sodium benzoate and EDTA; and / or the flocculant comprises: disodium hydrogen phosphate and calcium chloride; and / or the pH is adjusted to 8.0-8.5.

[0009] After adopting the technical scheme of the present invention, the following technical effects can be achieved: preservatives are essential for the stability and long-term preservation of enzymes, potassium sorbate and sodium benzoate can inhibit the growth of microorganisms, prevent the degradation or contamination of enzymes during the fermentation process, effectively extend the storage period of enzymes, prevent enzyme preparations from being contaminated by bacteria or other microorganisms, thereby ensuring that the activity of the enzyme is maintained, thereby improving the stability and life of the enzyme, so that cellulase maintains a high catalytic efficiency during long-term storage, and reduces the loss in the production process; EDTA is a commonly used metal ion chelating agent that can combine with metal ions to remove metal ions that may affect the activity of the enzyme. It can effectively prevent the inhibitory effect of metal ions on enzymes, maintain the optimal activity of enzymes, avoid the inhibitory effect of metal ions on enzymes by chelating metal ions, ensure that the activity of the enzyme is not destroyed, and improve the catalytic effect of the enzyme; the role of the flocculant is mainly to promote the aggregation of suspended matter in the liquid, making it easier to remove, thereby improving the filtration efficiency. Disodium hydrogen phosphate can promote the aggregation of particulate matter, so that impurities aggregate into larger particles, which are easy to be removed during the filtration process. By accelerating the aggregation and precipitation of particulate matter, the clogging of impurities during filtration is reduced, and the filtration rate and efficiency are improved. Calcium chloride can work together with disodium hydrogen phosphate to enhance the flocculation effect, and can provide calcium ions to further promote the coagulation of particulate matter, making it easy to precipitate or filter out, thereby enhancing the flocculation effect, especially in high turbidity or high viscosity liquids, which can more effectively remove impurities and improve the clarity and purity of the filtration. During the enzyme preparation and filtration process, the pH is adjusted to optimize the activity and stability of the enzyme. Cellulase usually has the best activity under neutral or slightly alkaline conditions. By adjusting the pH to the range of 8.0-8.5, the cellulase can be placed under the best reaction conditions, thereby enhancing its catalytic efficiency, helping to maintain the activity and stability of the cellulase, avoiding the inactivation of the enzyme due to an acidic or overly alkaline environment, and ensuring the best performance of the enzyme during the filtration process.

[0010] In one technical solution of the present invention, the mass ratio of the first preservative to the fermentation broth of Bacillus is (0.002-0.003):1; and / or the mass ratio of the second preservative to the fermentation broth of Bacillus is (0.004-0.005):1; and / or the mass ratio of the flocculant to the fermentation broth of Bacillus is (2-5):1.

[0011] After adopting the technical scheme of the present invention, the following technical effects can be achieved: by reasonably regulating these proportions, it is possible to ensure that each link in the enzyme preparation process proceeds smoothly, and to improve the activity and filtering effect of the final cellulase; the mass ratio of the first preservative to the fermentation broth of Bacillus (0.002-0.003): 1, which can inhibit the growth and reproduction of microorganisms and prevent enzyme degradation or contamination, and the first preservative can effectively prevent microbial contamination in the enzyme preparation process without excessively affecting the activity of other components or enzymes in the fermentation broth, thereby ensuring the high efficiency of enzyme preparation. At the same time, the use of the preservative prolongs the stability of the cellulase, avoids the loss of enzyme activity during the preparation process, and is conducive to long-term storage and use; the mass ratio of the second preservative to the fermentation broth of Bacillus (0.004-0.005): 1, the fermentation broth is subjected to additional antiseptic treatment before adjusting the pH value to ensure that the microorganisms in the fermentation broth are thoroughly inhibited, which can be achieved during fermentation. The antiseptic effect is further improved in the later stage of liquid treatment, the pollution source is reduced, the purity of cellulase is ensured, and it is ensured that the enzyme is not easily contaminated or degraded by microorganisms during storage and use, thereby extending the validity period of enzyme preparation and the activity of the enzyme; the mass ratio of flocculant to the fermentation liquid of Bacillus is (2-5): 1. The flocculant can promote the aggregation of solid particles in the liquid to form larger flocs, which are convenient for removal in the subsequent filtration process. Within this ratio range, the amount of flocculant added can effectively promote the aggregation and precipitation of particles, ensuring the effective removal of impurities in the fermentation liquid. The appropriate amount of flocculant can effectively promote the sedimentation or aggregation of particles, reduce the blockage of impurities during the filtration process, thereby improving the filtration speed and the clarity of the filtrate. By effectively removing impurities in the fermentation liquid, the purity and activity of the cellulase finally prepared can be improved, and the use of an appropriate amount of flocculant simplifies the subsequent separation process, reduces the processing steps, and makes the overall process more efficient and simple.

[0012] In a technical solution of the present invention, in S102, before adjusting the pH, the method further includes: adding sodium chloride; the mass ratio of sodium chloride to the fermentation liquid of Bacillus is (2-5):1.

[0013] After adopting the technical scheme of the present invention, the following technical effects can be achieved: sodium chloride, as a common salt, can increase the osmotic pressure, help stabilize the extracellular environment, so that cells or enzymes will not be damaged due to too fast changes in osmotic pressure, can change the ionic strength of the fermentation liquid, promote the precipitation and flocculation of certain impurities, and its addition can help remove solid particles in the liquid and reduce the impact on subsequent enzyme activity. It can also enhance the stability of the enzyme by increasing the ionic strength and avoid the impact of pH changes on the enzyme activity; sodium chloride in this ratio can effectively adjust the ionic strength of the fermentation liquid and improve the stability of the solution. By adjusting the salt concentration reasonably, the stable existence of the enzyme in the fermentation liquid can be ensured, and precipitation or activity reduction will not occur due to inappropriate ionic strength. In addition, sodium chloride can enhance the ionic strength, promote the aggregation of suspended particles or impurities, and form larger particles, which is beneficial to the subsequent filtration and separation process. An appropriate amount of sodium chloride has It helps to improve the sedimentation effect of impurities and improve the efficiency of filtration. The addition of sodium chloride can enhance the buffering capacity of the fermentation broth and help balance the unstable changes that may be caused during the pH adjustment process. By maintaining a certain ion concentration, it can prevent excessive fluctuations in the activity of the enzyme during the pH adjustment process. An appropriate amount of sodium chloride can provide a certain salt environment, which helps to stabilize the three-dimensional structure of the enzyme, thereby enhancing its catalytic activity and ensuring that the subsequent cellulase activity is not affected. In general, adding sodium chloride in step S102 and accurately controlling its ratio to the mass of the fermentation broth (2-5:1) can improve the stability of the fermentation broth, ensure that the activity of the enzyme in subsequent treatment is not affected, promote impurity removal, improve filtration and separation efficiency, enhance the stability and catalytic efficiency of the enzyme, thereby improving the quality and effect of the final cellulase, improving the efficiency and stability of the entire process, and ensuring the smooth progress of the enzyme preparation and filtration process.

[0014] In one technical solution of the present invention, the auxiliary enzyme comprises at least one of β-xylosidase, xylanase, mannanase, catalase and laccase.

[0015] After adopting the technical scheme of the present invention, the following technical effects can be achieved: the use of auxiliary enzymes is to improve the overall catalytic effect and filtering performance of cellulase; beta-xylosidase can hydrolyze xylosidic bonds in xylan and convert them into monosaccharides or smaller oligosaccharide molecules, which helps to reduce the inhibition of xyloside components in wood fiber on cellulase activity, improve the decomposition efficiency of cellulase, and enhance the ability to remove cellulose in filtrate; xylanase can hydrolyze xylan molecules and degrade xylan into smaller sugar substances. It reduces the inhibitory effect of xylan on cellulase by degrading xylan in plant cell walls, increases the contactable surface area and decomposition ability of cellulase, and improves the catalytic efficiency of cellulase. It can also reduce the interference of the wood part and enhance the cellulose removal efficiency during the filtration process; mannanase can hydrolyze mannan molecules so that these polysaccharide components no longer affect the catalytic action of cellulase. By hydrolyzing mannan, the interference of sugar substances on cellulase is reduced, the cellulose degradation process is optimized, and the overall treatment effect is improved; in the catalytic process of cellulase, hydrogen peroxide may be one of the by-products. Catalase can decompose hydrogen peroxide and prevent the accumulation of hydrogen peroxide, thereby protecting the enzyme activity from oxidative damage, thereby reducing its potential destructive effect on cellulase and other enzymes, protecting the activity of the enzyme, and improving the stability of the process; laccase can degrade lignin in plants. Lignin is a complex organic matter in the cell wall of plants, which usually inhibits the action of cellulase. Laccase reduces the effect of lignin on fiber by degrading lignin. The synergistic effect of these auxiliary enzymes on the degradation of cellulose makes cellulase more efficient, thereby improving the efficiency of cellulose removal during the filtration process; thus, these auxiliary enzymes can degrade the complex components in the plant cell wall through synergistic action, thereby reducing the interference of these components on cellulose degradation, and effectively promote the decomposition efficiency of cellulose by cellulase, and by decomposing the inhibitory components in the plant cell wall, cellulase can more easily contact cellulose molecules, thereby improving the catalytic efficiency of cellulase; in general, auxiliary enzymes can enhance the activity and efficiency of cellulase through synergistic action, which not only improves the decomposition efficiency of cellulase on complex plant cell wall components, but also effectively improves the effect of the filtration process and the quality of the filtrate, reduces enzyme consumption, increases the economy and sustainability of the process, and ensures the stability and efficiency of cellulase in practical applications.

[0016] In one technical scheme of the present invention, a method for preparing nanocellulose includes: S111, sequentially subjecting a cellulose raw material to hydrolysis treatment, separation treatment and modification treatment in a sulfuric acid solution to obtain cellulose nanocrystals; S112, dispersing the cellulose in water and subjecting it to high-pressure homogenization treatment to obtain a cellulose nanofiber suspension; S113, adding cellulose nanocrystals and a dispersant to the cellulose nanofiber suspension and subjecting it to ultrasonic dispersion treatment to obtain nanocellulose; wherein, in S111, the modification treatment uses 2,2,6,6-tetramethyl-1-piperidinyloxy or acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy for the modification treatment.

[0017] After adopting the technical scheme of the present invention, the following technical effects can be achieved: the hydrolysis treatment uses sulfuric acid solution to acid-hydrolyze the cellulose raw material, aiming to degrade the raw cellulose into cellulose nanocrystals, and the acidic environment in the sulfuric acid solution promotes the hydrolysis reaction of cellulose, so that the long-chain cellulose molecules are broken to form shorter cellulose nanocrystals with a relatively strong structure, thereby removing most of the non-cellulose impurities in the original cellulose, and converting the cellulose into nano-scale cellulose crystals, increasing the surface area of ​​the cellulose, so that the cellulose nanocrystals formed by its hydrolysis have stronger rigidity and mechanical strength than ordinary cellulose, and are suitable for subsequent nanocellulose preparation; after the hydrolysis treatment, the hydrolysis product of the cellulose needs to be separated to remove excess acid, impurities and incompletely hydrolyzed larger cellulose particles, and the separation treatment can effectively remove the incompletely hydrolyzed larger particles and impurities, ensure that purer cellulose nanocrystals are obtained, and avoid the influence of impurities on the quality of the nanocellulose; after the hydrolysis and separation, the cellulose nanocrystals are modified using 2,2,6,6-tetramethyl-1-piperidinyloxy or acetylamino-2,2,6,6-tetramethyl The cellulose nanocrystals are modified by chemical reagents such as 1-piperidinyloxy, thereby functionalizing the surface of the cellulose nanocrystals, changing their surface properties, making them more hydrophilic, and improving the compatibility of cellulose with water, which is of great significance for the subsequent preparation of suspensions and practical applications, and can effectively improve the dispersibility and stability of nanocellulose, prevent it from agglomerating or settling in the solution, and ensure that it can maintain good performance in various applications. Finally, new functional groups can be introduced on the surface of nanocellulose, making it have more diverse application potential, such as applications in biomedicine, environmentally friendly materials, coatings, composite materials and other fields; cellulose is dispersed in water, and high-pressure homogenization is used to decompose the cellulose nanofibers into a single fiber nanostructure to form a cellulose nanofiber suspension. High-pressure homogenization can decompose larger cellulose particles into nano-sized fibers, increase the specific surface area, and make it have better reactivity and physicochemical properties in subsequent applications, and can be evenly dispersed in water to form a stable suspension, which is convenient for subsequent processing, application and storage; finally, the cellulose nanocrystals are mixed with a dispersant and then ultrasonically dispersed. Ultrasound can further disperse cellulose nanocrystals through high-frequency vibration and shear force, making them more evenly distributed in the suspension to form the final nanocellulose. It can effectively prevent cellulose nanocrystals from agglomerating in the liquid, enhance their dispersibility and stability in the liquid, and make cellulose nanocrystals and dispersants form a more uniform suspension, further improving the performance and application effect of nanocellulose.

[0018] In one technical solution of the present invention, in nanocellulose, the mass ratio of cellulose nanocrystals to cellulose nanofibers is 1:(1-1.2); and / or the dispersant includes: at least one of polyethylene glycol, sodium carboxymethyl cellulose, sodium dodecyl sulfate and polyvinyl alcohol; and / or the high-pressure homogenization treatment is repeated at least 3 times.

[0019] After adopting the technical scheme of the present invention, the following technical effects can be achieved: cellulose nanocrystals have a highly crystalline structure, are generally more rigid and stable, and can provide higher mechanical strength; cellulose nanofibers are composed of long chains of cellulose molecules, have higher surface hydrophilicity and larger specific surface area, and are suitable for increasing compatibility with other substances. By adjusting the mass ratio appropriately to 1: (1-1.2), cellulose nanocrystals provide strength and rigidity, while cellulose nanofibers provide high surface area and enhanced processability. The addition of cellulose nanocrystals can increase the rigidity and strength of cellulose, so that the final product has higher mechanical properties, and cellulose Nanofibers improve their adhesion and compatibility with other materials through their high surface area, and can take into account strength and toughness, rigidity and processability at the same time, ultimately obtaining nanocellulose with good comprehensive performance, which is suitable for a wider range of application scenarios; dispersants are key substances used to reduce the agglomeration of nanocellulose particles and maintain their uniform dispersion. Polyethylene glycol has good dispersibility and lubricity, which can reduce the aggregation force between particles and enhance the dispersion stability of nanocellulose; sodium carboxymethyl cellulose can effectively reduce the mutual attraction between cellulose nanofibers and enhance their water dispersibility; sodium dodecyl sulfate can effectively change the surface charge of cellulose particles, Reduce the aggregation between particles and promote the dispersion of cellulose; polyvinyl alcohol has strong hydrophilicity and adhesion, which helps to improve the dispersibility of cellulose particles and increase their stability; these dispersants can form a stable dispersion system in water, prevent cellulose particles from agglomerating, ensure the uniform distribution of cellulose nanocrystals and nanofibers in the solution, and form a protective layer on the cellulose surface by interacting with the cellulose surface to prevent agglomeration caused by the attraction between particles, thereby improving the stability of cellulose nanofibers and helping to improve the rheological properties of nanocellulose suspensions, making them easier to process and apply, especially in the fields of coatings and membrane materials; high-pressure homogenization Homogenization is a technology that uses high-speed impact, shear and friction of liquid through narrow holes to break down large particles to the nanometer level. High-pressure homogenization can further decompose cellulose particles, reducing their size to the nanometer level while increasing the surface area of ​​cellulose, thereby improving the uniformity and fineness of cellulose nanofibers. The refined nanofibers have a higher specific surface area, enabling them to exhibit better mechanical properties, transparency and reinforcement effects in the fields of composite materials, coatings and films. Repeated high-pressure homogenization process can ensure a more uniform size distribution of nanocellulose, reduce the agglomeration of nanofibers, and improve their long-term storage stability and controllability during processing.

[0020] In one technical solution of the present invention, in S111, the modification treatment includes: a first modification method: adding NaBr, 2,2,6,6-tetramethyl-1-piperidinyloxy NaCIO solution, adding Na2CO3-NaHCO3 buffer solution with a pH of 10.2 to nano-microcrystalline cellulose in sequence, and then performing ultrasonic dispersion treatment, static reaction treatment, adding anhydrous ethanol for dialysis treatment to obtain nano-microcrystalline cellulose; or a second modification method: adding acetate buffer solution, NaCIO2, 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy and NaCIO solution to nano-microcrystalline cellulose in sequence, stirring treatment, and then adding anhydrous ethanol for dialysis treatment to obtain nano-microcrystalline cellulose.

[0021] After adopting the technical scheme of the present invention, the following technical effects can be achieved: through the two modification treatment methods, the surface properties of cellulose nanocrystals are significantly improved, including enhanced hydrophilicity, dispersibility and surface activity, which can improve the dispersibility of cellulose, enhance its stability in the aqueous phase, introduce functional groups such as carboxyl groups, aldehyde groups, etc., increase compatibility and chemical reactivity with other substances; and improve mechanical properties and surface affinity, providing a better basis for its application in the fields of composite materials, coatings, films, etc.; ensure high purity and high stability, and improve the long-term application stability of nanocellulose; through this surface modification, the performance of cellulose nanocrystals is optimized, suitable for more industrial applications, especially in the development of environmentally friendly and sustainable materials.

[0022] In a technical solution of the present invention, in the first modification method, the amount of NaBr added is 3.0mmol-8.0mmol; and / or in the first modification method, the amount of 2,2,6,6-tetramethyl-1-piperidinyloxy added is 0.005mmol-0.03mmol; and / or in the first modification method, the amount of NaCIO added is 1mmol-15mmol; and / or in the first modification method, the amount of Na2CO3-NaHCO3 buffer solution added is 200mL-250mL; and / or in the first modification method, the amount of anhydrous ethanol added is 10mL-20 mL; and / or in the second modification method, the concentration of the acetate buffer solution is 0.2mol / L-0.3mol / L; and / or in the second modification method, the amount of the acetate buffer solution added is 200mL-300mL; and / or in the second modification method, the amount of NaCIO2 solution added is 5mmol-20mmol; and / or in the second modification method, the amount of 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy added is 0.2mmol-0.5mmol; and / or in the second modification method, the amount of NaCIO added is 1mmol-5mmol.

[0023] After adopting the technical scheme of the present invention, the following technical effects can be achieved: adjusting the addition amount of these chemicals can accurately control the degree of modification reaction, reaction efficiency and performance of the final product; NaBr is mainly used as an auxiliary means of oxidation catalyst in the reaction, which can promote the oxidation reaction of 2,2,6,6-tetramethyl-1-piperidinyloxy and help form carboxyl groups with negative charges; an appropriate amount of NaBr helps to introduce an appropriate amount of carboxyl groups on the surface of cellulose nanocrystals, so that the cellulose nanocrystals have good hydrophilicity and dispersibility; too much NaBr may lead to excessive oxidation, while too little NaBr may lead to excessive oxidation. It can lead to incomplete oxidation; the added amount of 2,2,6,6-tetramethyl-1-piperidinyloxy is a catalyst for the oxidation reaction, which can catalyze the oxidation reaction of cellulose, introduce carboxyl groups, and improve the hydrophilicity of cellulose nanocrystals. An appropriate amount of 2,2,6,6-tetramethyl-1-piperidinyloxy can ensure the introduction of an appropriate amount of functional groups on the surface of cellulose, thereby improving the hydrophilicity and dispersibility of cellulose, making it easier to cross-link with other materials and improving its composite properties; NaCIO, as an oxidant, works together with 2,2,6,6-tetramethyl-1-piperidinyloxy to accelerate the oxidation process of cellulose. It helps to generate more carboxyl groups or other oxidized groups and improve the surface hydrophilicity of cellulose; Na2CO3-NaHCO3 buffer solution is used to adjust the pH of the reaction system and keep it in an appropriate range to ensure that the oxidation reaction can proceed smoothly. The appropriate pH value is crucial to the stability of the 2,2,6,6-tetramethyl-1-piperidinyloxy catalyst and the high efficiency of the oxidation reaction, avoiding the reaction rate being affected by too high or too low pH. By controlling the pH with a buffer solution, the solution can be prevented from being too acidic or too alkaline, thereby reducing the occurrence of side reactions and ensuring the selectivity and efficiency of the reaction; anhydrous ethanol is used for dialysis treatment to help remove impurities or solvents produced in the reaction. After removing the impurities, the stability of the cellulose nanocrystals is improved, avoiding degradation or inconsistent performance caused by impurities; acetic acid The salt buffer solution is used to adjust the pH of the reaction, providing a stable acidic environment for the oxidation reaction and ensuring that the cellulose is not over- or under-oxidized during the oxidation process; the amount of acetate buffer solution controls the overall pH of the reaction system and ensures that the appropriate acidity is maintained during the reaction; NaCIO2 is another oxidant that helps to generate more active oxygen species, further enhancing the oxidation effect of cellulose and increasing the introduction of surface functional groups; 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy is used as a catalyst, and an appropriate amount of 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy can promote the oxidation of cellulose and increase the functional groups of the product; the amount of NaCIO added controls the strength of the oxidant, further promotes the reaction and ensures that the surface of the cellulose is sufficiently modified.

[0024] In one technical solution of the present invention, the whisker length of nanocellulose is 100nm-350nm.

[0025] After adopting the technical scheme of the present invention, the following technical effects can be achieved: the whisker length is an important parameter of the nanocellulose size, and the whisker length affects the mechanical strength, dispersibility, surface properties, etc. of cellulose. When the cellulose whisker length is in the range of 100nm to 350nm, good mechanical properties and surface activity are guaranteed, while avoiding the difficulty in dispersion and processing that may be caused by too long whiskers; the pressure filtration treatment is used to remove unnecessary solid particles or impurities from the filtrate. The pressure filtration treatment can help effectively remove large particle impurities and agglomerates in the liquid, so that the treated filtrate is purer and more uniform.

[0026] After adopting the technical solution of the present invention, the following technical effects can be achieved:

[0027] (1) The synergistic effect of cellulase and nanocellulose significantly improves the efficiency of liquid filtration. Cellulase can destroy cell walls and convert cellulose into soluble sugars, thereby increasing the permeability of the filtrate;

[0028] (2) The process uses natural enzymes and nanocellulose, which reduces dependence on chemicals and meets environmental protection requirements. Cellulase, as a biocatalyst, catalyzes various useful transformations in an environmentally friendly manner and has the advantages of selectivity, specificity and low energy consumption.

[0029] (3) Due to the improvement of filtration efficiency, the energy consumption during operation is relatively reduced, while the purification process is simplified, the purification time is shortened, and the cost is reduced. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention provides a nanocellulose-composite cellulase filtration-aiding process, comprising the following steps:

[0032] S100, preparing nanocellulose and composite cellulase respectively;

[0033] The preparation method of cellulase comprises:

[0034] S101, after adding the first portion of preservative and flocculant to the fermentation broth of Bacillus in sequence, filtering to obtain a filtrate; preparing cellulase through the fermentation broth of Bacillus, and combining the use of preservatives and flocculants to improve the activity of the enzyme, while maintaining stability during the treatment process, on the one hand, because Bacillus is an alkali-resistant strain, the extracted cellulase also has a certain alkali resistance, suitable for industrial application, and by adjusting the pH value, adding preservatives and sterilizing, it is ensured that the activity of the enzyme is maximized and not inhibited, and good catalytic activity can be maintained under different environmental conditions, which helps to improve the long-term effectiveness and reliability of the overall process;

[0035] Preferably, the first preservative includes: potassium sorbate, sodium benzoate and EDTA. Preservatives are crucial to the stability and long-term preservation of enzymes. Potassium sorbate and sodium benzoate can inhibit the growth of microorganisms, prevent the degradation or contamination of enzymes during fermentation, effectively extend the storage period of enzymes, and prevent enzyme preparations from being contaminated by bacteria or other microorganisms, thereby ensuring that the activity of the enzyme is maintained, thereby improving the stability and life of the enzyme, allowing cellulase to maintain a high catalytic efficiency during long-term storage, and reducing losses during the production process; EDTA is a commonly used metal ion chelating agent that can bind to metal ions to remove metal ions that may affect enzyme activity.

[0036] Flocculants include: disodium hydrogen phosphate and calcium chloride; the main function of flocculants is to promote the aggregation of suspended matter in the liquid, making it easier to remove, thereby improving the filtration efficiency. Disodium hydrogen phosphate can promote the aggregation of particulate matter, so that impurities aggregate into larger particles, which are easier to remove during the filtration process. By accelerating the aggregation and precipitation of particulate matter, it reduces the blockage of impurities during filtration and improves the filtration rate and efficiency; calcium chloride can work together with disodium hydrogen phosphate to enhance the flocculation effect, and can provide calcium ions to further promote the coagulation of particulate matter, making it easier to precipitate or filter out, thereby enhancing the flocculation effect, especially in high turbidity or high viscosity liquids, can more effectively remove impurities and improve the clarity and purity of the filtration;

[0037] The mass ratio of flocculant to the fermentation liquid of Bacillus is (2-5):1. The flocculant can promote the aggregation of solid particles in the liquid to form larger flocs, which are convenient for removal in the subsequent filtration process. Within this ratio range, the amount of flocculant added can effectively promote the aggregation and precipitation of particles, ensuring the effective removal of impurities in the fermentation liquid. The right amount of flocculant can effectively promote the sedimentation or aggregation of particles, reduce the blockage of impurities in the filtration process, thereby increasing the filtration speed and the clarity of the filtrate. By effectively removing impurities in the fermentation liquid, the purity and activity of the cellulase finally prepared can be improved. The use of the right amount of flocculant simplifies the subsequent separation process, reduces the processing steps, and makes the overall process more efficient and simple.

[0038] Furthermore, the mass ratio of the first preservative to the fermentation broth of Bacillus is (0.002-0.003): 1, which can inhibit the growth and reproduction of microorganisms and prevent the degradation or contamination of enzymes. In addition, the first preservative can effectively prevent microbial contamination during the enzyme preparation process without excessively affecting the activity of other components of the fermentation broth or enzymes, thereby ensuring the high efficiency of enzyme preparation. At the same time, the use of the preservative prolongs the stability of cellulase, avoids the loss of enzyme activity during the preparation process, and is conducive to long-term storage and use.

[0039] S102, adding a second portion of preservative to the filtrate, adjusting the pH, and then sterilizing to obtain cellulase.

[0040] Preferably, the second preservative includes potassium sorbate, sodium benzoate and EDTA; the pH is adjusted to 8.0-8.5; during the enzyme preparation and filtration process, the pH is adjusted to optimize the activity and stability of the enzyme. Cellulase usually has the best activity under neutral or slightly alkaline conditions. By adjusting the pH to the range of 8.0-8.5, the cellulase can be placed under the best reaction conditions, thereby enhancing its catalytic efficiency, helping to maintain the activity and stability of the cellulase, avoiding enzyme inactivation due to an acidic or overly alkaline environment, and ensuring the best performance of the enzyme during the filtration process; the ratio of the second preservative to the mass of the fermentation broth of Bacillus (0.004-0.005): 1, the fermentation broth is subjected to additional preservative treatment before the pH value is adjusted to ensure that the microorganisms in the fermentation broth are thoroughly inhibited, which can further improve the preservative effect in the later stage of the fermentation broth treatment, reduce pollution sources, ensure the purity of the cellulase, and ensure that the enzyme is not easily contaminated or degraded by microorganisms during storage and use, thereby extending the shelf life of the enzyme preparation and the activity of the enzyme;

[0041] Furthermore, before adjusting the pH, the method further includes: adding sodium chloride; the mass ratio of sodium chloride to the fermentation liquid of Bacillus is (2-5):1, which can improve the stability of the fermentation liquid, ensure that the activity of the enzyme in subsequent treatment is not affected, promote the removal of impurities, improve the filtration and separation efficiency, enhance the stability and catalytic efficiency of the enzyme, thereby improving the quality and effect of the final cellulase, improving the efficiency and stability of the entire process, and ensuring the smooth progress of the enzyme preparation and filtration process.

[0042] The preparation method of nanocellulose comprises:

[0043] S111, sequentially performing hydrolysis treatment, separation treatment and modification treatment on the cellulose raw material sulfuric acid solution to obtain cellulose nanocrystals;

[0044] Preferably, the modification treatment includes: a first modification method: adding NaBr and 2,2,6,6-tetramethyl-1-piperidinyloxy NaCl O solution to the nano-microcrystalline cellulose in sequence, adding a Na2CO3-NaHCO3 buffer solution with a pH of 10.2, and then sequentially performing ultrasonic dispersion treatment, static reaction treatment, and adding anhydrous ethanol for dialysis treatment to obtain nano-microcrystalline cellulose;

[0045] The role of NaBr and 2,2,6,6-tetramethyl-1-piperidinyloxy is to oxidatively modify cellulose nanocrystals. 2,2,6,6-tetramethyl-1-piperidinyloxy is a widely used oxidation catalyst that can help introduce negative charges on the surface of cellulose nanocrystals and improve their dispersibility and hydrophilicity. Through the synergistic effect of the two, carboxyl groups can be generated on the surface of cellulose nanocrystals. These functional groups provide surface hydrophilicity and enhance the stability of cellulose particles in water. By introducing negatively charged carboxyl groups, the modified nanocrystalline cellulose has stronger hydrophilicity and can be more easily dispersed in water to avoid agglomeration. The introduction of carboxyl groups makes cellulose nanocrystals carry negative charges, which will enhance the repulsive force between particles, thereby effectively preventing the aggregation or agglomeration of cellulose particles in water. Nanocellulose with negative charges on the surface is more likely to interact with other positively charged substances or polymers, thereby improving its compatibility with other materials.

[0046] Na2CO3-NaHCO3 buffer solution is used to adjust the pH of the solution to ensure pH stability during the oxidation reaction. A pH value of 10.2 is an optimized value that helps the stability and reaction efficiency of the TEMPO catalyst. Under appropriate pH conditions, the oxidation reaction is more efficient, and the introduction of carboxyl groups can be better controlled, making the modification process more precise and controllable. The buffer solution helps maintain the stability of the reaction system and avoids possible side reactions under acidic or overly alkaline conditions.

[0047] Ultrasonic dispersion treatment uses high-frequency sound waves to act on the solution to further refine and evenly disperse the cellulose nanoparticles and reduce aggregation between particles. The static reaction treatment provides the cellulose nanoparticles with sufficient time to react to ensure uniform modification. By using anhydrous ethanol to wash and remove residual substances in the solution, the purity of the cellulose nanocrystals is ensured, which can increase the storage stability of cellulose and avoid degradation or deterioration that may occur during long-term storage.

[0048] As an oxidant, NaCl O can further increase the degree of oxidation of cellulose and promote surface chemical reactions. This process can introduce more oxidized groups, thereby improving the surface properties of cellulose nanocrystals. The oxidation reaction increases the chemical functional groups on the surface of cellulose, such as aldehyde and carboxyl groups, which not only improves the hydrophilicity of cellulose, but also provides functional groups for further cross-linking or composite material applications, enhancing reactivity: the introduction of these surface functional groups makes cellulose more likely to react with other chemicals, improving its application in composite materials, coatings, membrane materials, etc.

[0049] The second modification method is to add acetate buffer solution, NaClO2, 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy and NaClO solution to nano-microcrystalline cellulose in sequence, stir the mixture, and then add anhydrous ethanol for dialysis to obtain nano-microcrystalline cellulose.

[0050] NaClO2 and 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy as oxidants and catalysts can initiate the oxidation reaction of cellulose and introduce carboxyl groups. NaClO solution provides an oxidizing environment to further promote the reaction. Through the combination of different oxidants and buffer solutions, the oxidation degree and surface functionalization of cellulose can be controlled. Through the combination of different chemicals, the reaction conditions in the modification process can be precisely controlled to optimize the properties of cellulose nanocrystals.

[0051] S112, dispersing cellulose in water and performing high-pressure homogenization treatment to obtain a cellulose nanofiber suspension;

[0052] Preferably, the high-pressure homogenization treatment is repeated at least 3 times. High-pressure homogenization is a technology that performs high-speed impact, shearing and friction on a liquid through a narrow hole, which can refine large particles to the nanometer level. High-pressure homogenization can further decompose cellulose particles, reduce their size to the nanometer level, and increase the surface area of ​​cellulose, thereby improving the uniformity and fineness of cellulose nanofibers. The refined nanofibers have a higher specific surface area, so that they exhibit better mechanical properties, transparency and enhancement effects in the fields of composite materials, coatings and films. Repeated high-pressure homogenization processes can ensure that the size distribution of nanocellulose is more uniform, reduce the agglomeration of nanofibers, and improve their long-term storage stability and controllability during processing.

[0053] S113, adding cellulose nanocrystals and a dispersant into a cellulose nanofiber suspension and performing ultrasonic dispersion treatment to obtain nanocellulose;

[0054] The dispersant includes: at least one of polyethylene glycol, sodium carboxymethyl cellulose, sodium dodecyl sulfate and polyvinyl alcohol. The dispersant can form a stable dispersion system in water, prevent cellulose particles from agglomerating, ensure the uniform distribution of cellulose nanocrystals and nanofibers in the solution, and form a protective layer on the cellulose surface by interacting with the cellulose surface to prevent agglomeration caused by attraction between particles, thereby improving the stability of cellulose nanofibers, helping to improve the rheological properties of nanocellulose suspensions, making them easier to process and apply, especially in the fields of coatings and membrane materials;

[0055] S200, pre-treating the filtrate, adding nanocellulose and composite cellulase in sequence, and stirring to obtain a treated filtrate;

[0056] S300, filtering the treated filtrate in sequence;

[0057] Preferably, the whisker length of nanocellulose is 100nm-350nm; the length of whiskers affects the mechanical strength, dispersibility, surface properties, etc. of cellulose. The length of cellulose whiskers is in the range of 100nm to 350nm, which ensures good mechanical properties and surface activity, while avoiding the difficulty of dispersion and processing caused by too long whiskers. The appropriate whisker length helps the stable dispersion of nanocellulose in aqueous solution or other media. Too long nanocellulose may affect its dispersibility due to mutual entanglement or formation of large agglomerates, making it difficult to process. By controlling the whisker length, it is possible to ensure good dispersion of cellulose in liquid; whiskers of appropriate length have a higher specific surface area, which can enhance its interaction with other materials, especially in combination with other components in the composite material, providing stronger mechanical properties; shorter whisker length provides larger surface active sites, which is easy to carry out functionalization treatment, thereby optimizing the reactivity of cellulose. For example, the introduction of functional groups such as surface carboxyl and hydroxyl groups can further improve its chemical properties, hydrophilicity and compatibility with other materials.

[0058] Furthermore, the filtration treatment is a pressure filtration treatment (0.1-0.3MPa). Pressure filtration treatment is a commonly used separation technology for removing unwanted solid particles or impurities from the filtrate. It can not only efficiently push the liquid through the filter medium, but also will not cause excessive losses or filter membrane clogging due to excessive pressure. Appropriate pressure can promote the liquid to pass through the filter membrane, increase the filtration rate, and thus speed up the treatment process. Moderate pressure helps to achieve efficient filtration without damaging the cellulose structure; through pressure filtration, large particles, unreacted chemical reagents and other impurities in the liquid can be removed to ensure higher quality of the final product. The filtered nanocellulose solution or suspension is more uniform and pure, suitable for subsequent applications; after pressure filtration, cellulose nanocrystals can be better dispersed and uniform, reducing the presence of large particles, ensuring its stable performance in subsequent use. Especially for processes involving the application of nano-scale materials, the nanocellulose obtained after filtration is more in line with application requirements.

[0059] First embodiment

[0060] This embodiment provides a nanocellulose-composite cellulase filtration-aiding process, comprising the following steps:

[0061] S100, preparing nanocellulose and composite cellulase respectively;

[0062] S200, pre-treating the filtrate, adding the nanocellulose and the composite cellulase in sequence, and stirring to obtain a treated filtrate;

[0063] S300, performing filtering treatment at 0.2 MPa on the treated filtrate in sequence;

[0064] Wherein, the nanocellulose comprises: a mixture of cellulose nanocrystals and cellulose nanofibers;

[0065] The composite cellulase comprises: cellulase, β-xylosidase and xylanase;

[0066] The preparation method of the cellulase comprises:

[0067] S101. After adding potassium sorbate, sodium benzoate, EDTA, disodium hydrogen phosphate and calcium chloride to the fermentation broth of Bacillus in sequence, filtering to obtain a filtrate, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of Bacillus is 0.002:1; the mass ratio of the sum of disodium hydrogen phosphate and calcium chloride to the fermentation broth of Bacillus is 3:1;

[0068] S102, adding potassium sorbate, sodium benzoate and EDTA to the filtrate, adjusting the pH to 8.0, and sterilizing to obtain the cellulase, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of the Bacillus is 0.004:1; the mass ratio of sodium chloride to the fermentation broth of the Bacillus is 2:1;

[0069] The preparation method of the nanocellulose comprises:

[0070] S111, sequentially performing a hydrolysis treatment, a separation treatment and a first modification treatment on a cellulose raw material sulfuric acid solution to obtain the cellulose nanocrystals;

[0071] S112, dispersing cellulose in water and subjecting it to high-pressure homogenization treatment three times to obtain the cellulose nanofiber suspension;

[0072] S113, adding the cellulose nanocrystals and polyethylene glycol to the cellulose nanofiber suspension and performing ultrasonic dispersion treatment to obtain the nanocellulose, wherein the mass ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:1;

[0073] Among them, the first modification treatment includes: adding 8.0mmol of NaBr, 0.03mmol of 2,2,6,6-tetramethyl-1-piperidinyloxy, and 15mmol of NaCIO solution in sequence to the nano-microcrystalline cellulose, adding 250mL of Na2CO3-NaHCO3 buffer solution with a pH of 10.2, and then performing ultrasonic dispersion treatment and static reaction treatment in sequence, adding 20mL of anhydrous ethanol for dialysis treatment to obtain the nano-microcrystalline cellulose.

[0074] Second embodiment

[0075] This embodiment provides a nanocellulose-composite cellulase filtration-aiding process, comprising the following steps:

[0076] S100, preparing nanocellulose and composite cellulase respectively;

[0077] S200, pre-treating the filtrate, adding the nanocellulose and the composite cellulase in sequence, and stirring to obtain a treated filtrate;

[0078] S300, performing filtering treatment at 0.1 MPa on the treated filtrate in sequence;

[0079] Wherein, the nanocellulose comprises: a mixture of cellulose nanocrystals and cellulose nanofibers;

[0080] The composite cellulase comprises: cellulase, mannanase and catalase;

[0081] The preparation method of the cellulase comprises:

[0082] S101. After adding potassium sorbate, sodium benzoate, EDTA, disodium hydrogen phosphate and calcium chloride in sequence to the fermentation broth of Bacillus, filtering is performed to obtain a filtrate, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of Bacillus is 0.003:1; the mass ratio of the sum of disodium hydrogen phosphate and calcium chloride to the fermentation broth of Bacillus is 2:1;

[0083] S102, adding potassium sorbate, sodium benzoate and EDTA to the filtrate, adjusting the pH to 8.5, and sterilizing to obtain the cellulase, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of the Bacillus is 0.005:1; the mass ratio of sodium chloride to the fermentation broth of the Bacillus is 3:1;

[0084] The preparation method of the nanocellulose comprises:

[0085] S111, sequentially performing a hydrolysis treatment, a separation treatment and a first modification treatment on a cellulose raw material sulfuric acid solution to obtain the cellulose nanocrystals;

[0086] S112, dispersing cellulose in water and subjecting it to high-pressure homogenization treatment three times to obtain the cellulose nanofiber suspension;

[0087] S113, adding the cellulose nanocrystals and sodium carboxymethyl cellulose to the cellulose nanofiber suspension and performing ultrasonic dispersion treatment to obtain the nanocellulose, wherein the mass ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:1;

[0088] Among them, the first modification treatment includes: adding 3.0mmol of NaBr, 0.005mmol of 2,2,6,6-tetramethyl-1-piperidinyloxy, and 1mmol of NaCIO solution in sequence to the nano-microcrystalline cellulose, adding 200mL of Na2CO3-NaHCO3 buffer solution with a pH of 10.2, and then performing ultrasonic dispersion treatment and static reaction treatment in sequence, adding 10mL of anhydrous ethanol for dialysis treatment to obtain the nano-microcrystalline cellulose.

[0089] Third embodiment

[0090] This embodiment provides a nanocellulose-composite cellulase filtration-aiding process, comprising the following steps:

[0091] S100, preparing nanocellulose and composite cellulase respectively;

[0092] S200, pre-treating the filtrate, adding the nanocellulose and the composite cellulase in sequence, and stirring to obtain a treated filtrate;

[0093] S300, performing filtering treatment at 0.3 MPa on the treated filtrate in sequence;

[0094] Wherein, the nanocellulose comprises: a mixture of cellulose nanocrystals and cellulose nanofibers;

[0095] The composite cellulase comprises: cellulase and laccase;

[0096] The preparation method of the cellulase comprises:

[0097] S101. After adding potassium sorbate, sodium benzoate, EDTA, disodium hydrogen phosphate and calcium chloride to the fermentation broth of Bacillus in sequence, filtering to obtain a filtrate, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of Bacillus is 0.002:1; the mass ratio of the sum of disodium hydrogen phosphate and calcium chloride to the fermentation broth of Bacillus is 4:1;

[0098] S102, adding potassium sorbate, sodium benzoate and EDTA to the filtrate, adjusting the pH to 8.0, and sterilizing to obtain the cellulase, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of the Bacillus is 0.004:1; the mass ratio of sodium chloride to the fermentation broth of the Bacillus is 4:1;

[0099] The preparation method of the nanocellulose comprises:

[0100] S111, sequentially performing a hydrolysis treatment, a separation treatment and a first modification treatment on a cellulose raw material sulfuric acid solution to obtain the cellulose nanocrystals;

[0101] S112, dispersing cellulose in water and subjecting it to high-pressure homogenization treatment three times to obtain the cellulose nanofiber suspension;

[0102] S113, adding the cellulose nanocrystals and sodium dodecyl sulfate to the cellulose nanofiber suspension for ultrasonic dispersion treatment to obtain the nanocellulose, wherein the mass ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:1.2;

[0103] Among them, the second modification treatment includes: adding an acetate buffer solution with a concentration of 0.2 mol / L, 5 mmol of NaCIO2, 0.2 mmol of 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy and 1 mmol of NaCl O solution to the nano-microcrystalline cellulose in sequence, stirring, and then adding anhydrous ethanol for dialysis treatment to obtain the nano-microcrystalline cellulose.

[0104] Fourth embodiment

[0105] This embodiment provides a nanocellulose-composite cellulase filtration-aiding process, comprising the following steps:

[0106] S100, preparing nanocellulose and composite cellulase respectively;

[0107] S200, pre-treating the filtrate, adding the nanocellulose and the composite cellulase in sequence, and stirring to obtain a treated filtrate;

[0108] S300, performing filtering treatment at 0.3 MPa on the treated filtrate in sequence;

[0109] Wherein, the nanocellulose comprises: a mixture of cellulose nanocrystals and cellulose nanofibers;

[0110] The composite cellulase comprises: cellulase and β-xylosidase, xylanase, mannanase, and catalase;

[0111] The preparation method of the cellulase comprises:

[0112] S101. After adding potassium sorbate, sodium benzoate, EDTA, disodium hydrogen phosphate and calcium chloride to the fermentation broth of Bacillus in sequence, filtering to obtain a filtrate, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of Bacillus is 0.003:1; the mass ratio of the sum of disodium hydrogen phosphate and calcium chloride to the fermentation broth of Bacillus is 5:1;

[0113] S102, adding potassium sorbate, sodium benzoate and EDTA to the filtrate, adjusting the pH to 8.5, and sterilizing to obtain the cellulase, wherein the mass ratio of the sum of potassium sorbate, sodium benzoate and EDTA to the fermentation broth of the Bacillus is 0.005:1; the mass ratio of sodium chloride to the fermentation broth of the Bacillus is 5:1;

[0114] The preparation method of the nanocellulose comprises:

[0115] S111, sequentially performing a hydrolysis treatment, a separation treatment and a first modification treatment on a cellulose raw material sulfuric acid solution to obtain the cellulose nanocrystals;

[0116] S112, dispersing cellulose in water and subjecting it to high-pressure homogenization treatment for 5 times to obtain the cellulose nanofiber suspension;

[0117] S113, adding the cellulose nanocrystals and polyvinyl alcohol into the cellulose nanofiber suspension and performing ultrasonic dispersion treatment to obtain the nanocellulose, wherein the mass ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:1.2;

[0118] Among them, the second modification treatment includes: adding an acetate buffer solution with a concentration of 0.3 mol / L, 300 mmol of NaCIO2, 0.5 mmol of 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy and 5 mmol of NaClO solution to the nano-microcrystalline cellulose in sequence, stirring, and then adding anhydrous ethanol for dialysis treatment to obtain the nano-microcrystalline cellulose.

[0119] Performance Testing

[0120] The retention rate, light transmittance and haze of the first to fourth examples are statistically shown in the following table:

[0121] project Water filtration time Retention rate Light transmittance Haze Second embodiment 74 95 85 66 Second embodiment 85 93 88 73 Third embodiment 86 93 87 72 Fourth embodiment 79 92 86 69

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nanocellulose-composite cellulase filtration-aid process, characterized in that: The nanocellulose-composite cellulase filtration-aiding process comprises the following steps: S100, preparing nanocellulose and composite cellulase respectively; S200, pre-treating the filtrate, adding the nanocellulose and the composite cellulase in sequence, and stirring to obtain a treated filtrate; S300, filtering the treated filtrate in sequence; Wherein, the nanocellulose comprises: a mixture of cellulose nanocrystals and cellulose nanofibers; The composite cellulase comprises: cellulase and auxiliary enzyme; The preparation method of the cellulase comprises: S101, adding the first preservative and the flocculant to the fermentation liquid of Bacillus in sequence, and filtering to obtain a filtrate; S102, adding a second portion of preservative to the filtrate, adjusting the pH, and then performing sterilization treatment to obtain the cellulase.

2. The nanocellulose-composite cellulase filtration-aiding process according to claim 1, characterized in that: The first preservative comprises: potassium sorbate, sodium benzoate and EDTA; and / or The second preservative comprises: potassium sorbate, sodium benzoate and EDTA; and / or The flocculant comprises: disodium hydrogen phosphate and calcium chloride; and / or The pH was adjusted to 8.0-8.

5.

3. The nanocellulose-composite cellulase filtration-aiding process according to claim 2, characterized in that: The mass ratio of the first preservative to the fermentation broth of the Bacillus is (0.002-0.003):1; and / or The mass ratio of the second preservative to the fermentation broth of the Bacillus is (0.004-0.005):1; and / or The mass ratio of the flocculant to the fermentation liquid of the bacillus is (2-5):

1.

4. The nanocellulose-composite cellulase filtration-aiding process according to claim 1, characterized in that: In the S102, before adjusting the pH, the method further includes: Add sodium chloride; The mass ratio of the sodium chloride to the fermentation liquid of the bacillus is (2-5):

1.

5. The nanocellulose-composite cellulase filtration-aiding process according to claim 1, characterized in that: The auxiliary enzyme comprises at least one of β-xylosidase, xylanase, mannanase, catalase and laccase.

6. The nanocellulose-composite cellulase filtration-aiding process according to claim 1, characterized in that: The preparation method of the nanocellulose comprises: S111, sequentially performing hydrolysis treatment, separation treatment and modification treatment on a cellulose raw material sulfuric acid solution to obtain the cellulose nanocrystals; S112, dispersing cellulose in water and performing high-pressure homogenization treatment to obtain the cellulose nanofiber suspension; S113, adding the cellulose nanocrystals and the dispersant into the cellulose nanofiber suspension and performing ultrasonic dispersion treatment to obtain the nanocellulose; Among them, in the S111, the modification treatment is carried out using 2,2,6,6-tetramethyl-1-piperidinyloxy or acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy.

7. The nanocellulose-composite cellulase filtration-aiding process according to claim 6, characterized in that: In the nanocellulose, the mass ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:(1-1.2); and / or The dispersant comprises: at least one of polyethylene glycol, sodium carboxymethyl cellulose, sodium dodecyl sulfate and polyvinyl alcohol; and / or The high pressure homogenization process was repeated at least 3 times.

8. The nanocellulose-composite cellulase filtration-aiding process according to claim 6, characterized in that: In S111, the modification process includes: The first modification method: NaBr and 2,2,6,6-tetramethyl-1-piperidinyloxy NaClO solution are sequentially added to the nano-microcrystalline cellulose, and a Na2CO3-NaHCO3 buffer solution with a pH of 10.2 is added, and then ultrasonic dispersion treatment and static reaction treatment are sequentially performed, and anhydrous ethanol is added for dialysis treatment to obtain the nano-microcrystalline cellulose; or The second modification method is to sequentially add acetate buffer solution, NaClO2, 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy and NaClO solution to the nano-microcrystalline cellulose, stir the mixture, and then add anhydrous ethanol to perform dialysis to obtain the nano-microcrystalline cellulose.

9. The nanocellulose-composite cellulase filtration-aiding process according to claim 8, characterized in that: In the first modification method, the amount of NaBr added is 3.0 mmol-8.0 mmol; and / or In the first modification method, the amount of 2,2,6,6-tetramethyl-1-piperidinyloxy added is 0.005 mmol-0.03 mmol; and / or In the first modification method, the amount of NaClO added is 1 mmol-15 mmol; and / or In the first modification method, the amount of the Na2CO3-NaHCO3 buffer solution added is 200mL-250mL; and / or In the first modification method, the amount of anhydrous ethanol added is 10 mL-20 mL; and / or In the second modification method, the concentration of the acetate buffer solution is 0.2 mol / L-0.3 mol / L; and / or In the second modification method, the amount of the acetate buffer solution added is 200 mL-300 mL; and / or In the second modification method, the amount of the NaClO2 solution added is 5 mmol-20 mmol; and / or In the second modification method, the amount of 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy added is 0.2 mmol-0.5 mmol; and / or In the second modification method, the amount of NaClO added is 1 mmol-5 mmol.

10. The nanocellulose-composite cellulase filtration-aiding process according to claim 1, characterized in that: The whisker length of the nanocellulose is 100nm-350nm.