Method for extracting lignin from raw grass

Abstract

The invention provides a method for extracting lignin from raw grass. The method comprises the following steps: 1. preparing steam exploded pulp powder: carrying out necessary truncating or slicing on the collected raw grass, then drying the raw grass, putting the raw grass in a pot to be converted into pulp through steam explosion, and drying and grinding the pulp to prepare the steam exploded pulp powder; 2. extracting coarse lignin: fully mixing the steam exploded pulp powder with an organic solvent which can dissolve lignin in a weight ratio of 1:(10-40), carrying out pressure filtration on the mixture, and concentrating the filtrate, thus obtaining the coarse lignin; and 3. refining the lignin: dissolving the coarse lignin in acetic acid aqueous solution with the weight being 10-30 times that of the coarse lignin and the concentration being 80%, then dropwisely adding the mixture to water with the weight being 10-50 times that of the mixture, precipitating the lignin, centrifugally separating, drying, and then sealing and packaging. The prepared lignin has purity of 95-100% and can be widely applied to the production of lignin-based epoxy resins, lignin adhesives, lignin rubber reinforcing agents and the like. The lignin preparation method has the beneficial effects of energy saving, less procedures, low cost and high purity.

Description

technical field [0001] The invention relates to a method for extracting lignin from slurry powder obtained by using gramineous plants as raw materials through a steam explosion method. Background technique [0002] The wood fiber contains 35-45% cellulose, the rest is hemicellulose (25-35%) and lignin (20-30%), and the pulp with high purity suitable for cellulose derivatives is produced from wood fiber , most of which use sulfite method and pre-hydrolysis method, the process is roughly raw material preparation (peeling, slicing), cooking (immersion in bisulfite sulfurous acid solution, pressurized heating), selection, bleaching, dehydration and dry. During the cooking process, the lignin is degraded and dissolved in the cooking liquor to become black liquor, and the cellulose and lignin are separated. This method seriously pollutes the environment and requires a large drug recovery device. On the other hand, the cooking chemicals in the lignin extracted from black liquor ...

AI Technical Summary

Problems solved by technology

This method has a high reaction temperature and a long time, and the alcohols in the alcohol-water solvent that dissolves lignin have a high boiling point. The alcohols are recovered by vacuum distillation to remove water, and the recovery cost is high.

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