CN-121991378-A - Straw three-element separation method based on enzyme pretreatment and DES solvent

Abstract

The invention provides a straw three-element separation method based on enzyme pretreatment and DES solvent, belongs to the field of biomass resource utilization, and can solve the problems of high energy consumption, serious environmental pollution and low separation efficiency in the existing straw three-element separation method. The method comprises the steps of crushing straws, carrying out enzymolysis pretreatment by using cellulase and hemicellulase, mixing solid after solid-liquid separation with DES solvent, reacting for 2-4 hours at 120-150 ℃ and 0.5-1.0 MPa to dissolve lignin, centrifuging to obtain DES solvent solution containing lignin and solid sediment containing cellulose and hemicellulose, filtering the DES solvent solution containing lignin through a ceramic membrane, drying to obtain lignin products, treating the solid sediment with hydrogen peroxide solution, carrying out solid-liquid separation, washing and drying to obtain cellulose products, combining the separation liquid and the washing liquid, concentrating, adding ethanol for precipitation, and drying to obtain the hemicellulose products. The invention realizes the step-by-step high-efficiency separation of three elements and improves the separation efficiency and the product purity.

Inventors

• SHI XIAODAN
• ZHANG YING
• ZHENG LU

Assignees

• 上海昶法新材料有限公司

Dates

Publication Date

20260508

Application Date

20260130

Claims (10)

1. 1. The straw three-element separation method based on enzyme pretreatment and DES solvent is characterized by comprising the following steps: (1) Crushing the straw to a particle size of 0.5-2 mm, performing enzymolysis pretreatment by using a mixed enzyme solution of cellulase and hemicellulase, and performing solid-liquid separation to obtain pretreated straw solids; (2) Preparing a eutectic solvent by taking choline chloride and ethylene glycol as raw materials, mixing the pretreated straw solid with the eutectic solvent, and reacting for 2-4 hours under the conditions of 120-150 ℃ and 0.5-1.0 MPa to dissolve lignin in the eutectic solvent; (3) Cooling to room temperature after the reaction is finished, and obtaining eutectic solvent solution containing lignin and solid precipitate containing cellulose and hemicellulose through centrifugal separation; (4) Filtering the eutectic solvent solution containing lignin through a ceramic membrane, and drying the retentate to obtain a lignin product; (5) Treating the solid precipitate with hydrogen peroxide solution, separating solid from liquid, washing, and drying to obtain cellulose product; (6) Evaporating and concentrating the separation liquid and the washing liquid generated in the step (5), adding ethanol into the concentrated liquid, standing and precipitating, and drying the precipitate to obtain a hemicellulose product.
2. 2. The method for separating three straws by three based on enzyme pretreatment and DES solvent according to claim 1, wherein in the step (1), the addition amount of the cellulase is 10-20 IU/g straws, and the addition amount of the hemicellulase is 5-15 IU/g straws; and/or in the step (1), the temperature of the enzymolysis pretreatment is 45-55 ℃, the time is 8-12 h, the enzymolysis process is carried out for 5-10 min at intervals of 1-2h, and the rotating speed is 100-200 r/min.
3. 3. The method for separating three straw elements based on enzyme pretreatment and DES solvent according to claim 1, wherein in the step (2), the mass ratio of the choline chloride to the ethylene glycol is 1:2-1:4; and/or the eutectic solvent reacts for 1-2 hours at the temperature of 60-80 ℃.
4. 4. The method for separating three straw elements based on enzyme pretreatment and DES solvent according to claim 1, wherein in the step (2), the mass ratio of the pretreated straw solid to the eutectic solvent is 1:5-1:10.
5. 5. The method for separating three straw elements based on enzyme pretreatment and DES solvent according to claim 1, wherein in the step (3), the rotation speed of centrifugation is 3000-5000 r/min, and the centrifugation time is 10-20 min.
6. 6. The method for separating three straw elements based on enzyme pretreatment and DES solvent according to claim 1, wherein in the step (4), the pore diameter of the ceramic membrane is 0.1-0.5 μm, and the filtration pressure is 0.1-0.3 MPa.
7. 7. The method for separating three straws by three elements based on enzyme pretreatment and DES solvent according to claim 1, wherein in the step (5), the mass fraction of the hydrogen peroxide solution is 3-5%, the mass ratio of the solid precipitate to the hydrogen peroxide solution is 1:3-1:5, the reaction temperature is 50-70 ℃, and the reaction time is 1-3 hours.
8. 8. The method for separating three straws by using the enzyme pretreatment and the DES solvent according to claim 1, wherein in the step (6), the addition amount of the ethanol is 2-4 times of the concentrated solution, and the mass fraction of the ethanol is 95%; And/or the temperature of the standing treatment is 3-8 ℃ and the time is 8-16 h.
9. 9. The method for separating three straw elements based on enzyme pretreatment and DES solvent according to any one of claims 1 to 8, wherein the eutectic solvent filtered in step (4) and the supernatant solution after standing and precipitation in step (6) are recycled.
10. 10. The method for separating three straws by three based on enzyme pretreatment and DES solvent according to claim 1, wherein the straws are corn straws, the purity of the obtained lignin is more than or equal to 92%, the purity of hemicellulose is more than or equal to 85%, and the purity of cellulose is more than or equal to 88%.

Description

Straw three-element separation method based on enzyme pretreatment and DES solvent Technical Field The invention belongs to the technical field of biomass resource utilization, and particularly relates to a straw three-element separation method based on enzyme pretreatment and DES solvent. Background Straw is a biomass resource with wide sources, and mainly consists of cellulose, hemicellulose and lignin. The effective separation of the three components is significant for the high-value utilization of the straw. However, the conventional three-element separation method in the prior art generally has the problems of high energy consumption, large environmental pollution, low separation efficiency and the like. For example, chemical separation often uses a large amount of chemical reagents such as strong acid and strong alkali, which are easy to cause equipment corrosion and environmental pollution, and physical laws often have difficulty in realizing ideal separation effect. In recent years, biological enzyme pretreatment and novel solvent separation technologies are widely paid attention to due to the characteristics of environmental protection, high efficiency and the like, wherein a eutectic solvent (DES) as a novel green solvent shows good application prospect in the field of biomass separation, but the technology of combining enzyme pretreatment and DES solvent for straw three-element separation is still not perfect, and particularly, there is room for further improvement in the aspects of separation process optimization and product purity improvement. Disclosure of Invention In order to solve the problems of high energy consumption, serious environmental pollution, low separation efficiency in the existing straw three-element separation method, the invention provides the straw three-element separation method based on enzyme pretreatment and DES solvent, which can realize the efficient separation of cellulose, hemicellulose and lignin in straw and has the advantages of low production cost, small environmental pollution, good separation effect and the like. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: in one aspect of the invention, a method for separating three straw elements based on enzyme pretreatment and DES solvent is provided, which comprises the following steps: (1) Crushing the straw to a particle size of 0.5-2 mm, performing enzymolysis pretreatment by using a mixed enzyme solution of cellulase and hemicellulase, and performing solid-liquid separation to obtain pretreated straw solids; (2) Preparing a eutectic solvent by taking choline chloride and ethylene glycol as raw materials, mixing the pretreated straw solid with the eutectic solvent, and reacting for 2-4 hours under the conditions of 120-150 ℃ and 0.5-1.0 MPa to dissolve lignin in the eutectic solvent; (3) Cooling to room temperature after the reaction is finished, and obtaining eutectic solvent solution containing lignin and solid precipitate containing cellulose and hemicellulose through centrifugal separation; (4) Filtering the eutectic solvent solution containing lignin through a ceramic membrane, and drying the retentate to obtain a lignin product; (5) Treating the solid precipitate with hydrogen peroxide solution, separating solid from liquid, washing, and drying to obtain cellulose product; (6) Evaporating and concentrating the separation liquid and the washing liquid generated in the step (5), adding ethanol into the concentrated liquid, standing and precipitating, and drying the precipitate to obtain a hemicellulose product. According to the invention, in the step (1), through enzyme pretreatment, part of the cell wall structure of the straw can be destroyed, the difficulty of the subsequent separation process is reduced, and the separation efficiency is improved. The DES solvent prepared in the step (2) has good dissolution performance and lower toxicity, has different dissolution capacities on lignin, cellulose and hemicellulose, and provides a basis for subsequent separation. The pretreated straw solid is mixed with the eutectic solvent, so that lignin in the straw is fully dissolved in the DES solvent, and most of cellulose and hemicellulose are remained in the solid, thereby realizing primary separation. In the filtering process, the eutectic solvent DES can penetrate through the ceramic membrane, and lignin is trapped, so that the lignin is extracted efficiently, and the extracted lignin is dried to obtain a lignin product with high purity. And (5) bleaching the cellulose by using a hydrogen peroxide solution to remove residual pigment and impurities, performing solid-liquid separation after the reaction is finished, washing the solid to be neutral, and drying to obtain a high-purity cellulose product. In the step (1), the addition amount of the cellulase is 10-20 IU/g straw, and the addition amount of the hemicellulase is 5-15 IU/g straw. And/or in the step (1), the