Effect On Whiteness And High Value Utilization Of High Yield Bamboo Pulp By Pretreatment

Bamboo is a potential raw material for pulping and papermaking,and its research on high yield pulping has attracted researchers’ attention.In this study,the effects of xylanase pretreatment on high yield bamboo pulp and lignin-carbohydrate complex(LCC)were studied,and the effects of their changes on the whiteness and yellowing of high yield bamboo pulp were explored,which provided a theoretical basis for solving the problem of difficult bleaching and easy yellowing of high yield bamboo pulp.In addition,this paper also discussed the high value utilization of bamboo,using the high yield bamboo pulp as raw material,using cellulase hydrolysis to prepare fermentable sugars and enzymolysis residue adsorption methylene blue.The main conclusions are as follows:(1)The pulping process of bamboo high yield pulp removes a small amount of lignin,mainly the surface lignin.After bleaching,the lignin content in the pulp decreased from 25.23%to 21.24%,and the surface lignin content decreased from 59.24% to 50.19%.Xylanase pretreatment increased the surface lignin concentration(SLC)on the pulp by 5.98%,which was easier to be removed in bleaching,effectively improving the bleaching ability of the pulp and inhibiting the yellowing of the pulp.(2)It was found that the change trend of lignin content in LCC was opposite to that of pulp.The fiber dispersion and porosity of pulp and xylanase pretreatment could improve the yield of LCC.After pulping,the connection between lignin and carbohydrate in LCC was broken,and the weight and number average molecular weight of LCC decreased by 82.67%and 82.83%,respectively.Bleaching process destroyed the chromophore of LCC to a certain extent,but the chromophore content of LCC increases.However,xylanase pretreatment removed more than 50% of the xylan in LCC,reduced the chromophase group in LCC,and increased the connection between lignin and carbohydrate,thus improving the structural stability of LCC.(3)The effects of pretreatment on high yield bamboo pulp showed that the damage degree of fiber surface of Fenton pretreatment was higher than that of hydrogen peroxide and ethanol pretreatment,and the damage degree of SCMP fiber surface was the most serious.The enzymatic efficiency of Fenton pretreatment SCMP was 49.5% higher than that of APMP and CTMP.Pretreatment effectively removed lignin and hemicellulose from high yield pulp fiber,changed the crystallinity and surface lignin content of fiber,and improved the efficiency of enzymatic hydrolysis of high yield pulp.SLC of high yield pulp fiber was positively correlated with enzymatic hydrolysis efficiency.After enzymatic hydrolysis,the removal rate of 400mg/L methylene blue reached more than 90%.