Preparation Of Medicinal Microcrystalline Cellulose By SO₃ Micro-explosion And Enzyme Catalyzed H₂O₂ Oxidized Rice Straw

The rice straw structure,which is intertwined with cellulose,hemicellulose and lignin,is dense and complex.It limits the development and application of rice straw in the field of microcrystalline cellulose.It must be pretreated to prepare high value microcrystalline cellulose.Based on the pretreatment method of SO₃ / NH₃ combined dilute alkali solution,a pretreatment method of SO₃ microburst / enzyme catalyzed H₂O₂ oxidation combined with dilute alkali solution was proposed.The method can significantly improve the removal rate of lignin,The loss rate of holocellouse is almost constant,and the waste water discharge is reduced.Based on the enzyme-catalyzed H₂O₂ oxidation of lignin,a new process for the preparation of microcrystalline cellulose by enzymatic oxidation of H₂O₂ with Na ClO2 was extended.The resulting microcrystalline cellulose had a whiteness of about 84%,a crystallinity of about 87% and a content of about 98%,and in addition to burning residue exceeded,but also meet the 2015 version of "Chinese Pharmacopoeia" in the requirements of microcrystalline cellulose.The following conclusions can be drawn from this study:1 After SO₃ / NH₃ combined with dilute alkali solution on the rice straw pretreatment conditions optimization,the lignin residue was 5.5⁶.5%,the loss rate of holocellouse was 5⁸%,the yield was 54 56%.The optimum conditions were as follows: the rod straw with the length of 3cm and the water content of 6% was selected as the raw material,the SO₃ micro-thermal explosion temperature was 60℃,the time was 90 min,and the alkali treatment was carried out at 60℃for 3.5h.2 SO₃ micro-thermal explosion / enzyme catalyzed H₂O₂ oxidation combined with dilute alkali solution pretreatment straw straw,Compared with the semi-solid liquid treating method,the enzyme is more easily adsorbed on the surface of the straw,catalytic H₂O₂ oxidative degradation of surface lignin in situ,Oxidation efficiency is higher,the pretreatment effect is better.The lignin residue is between 3.2 and 4.5%,the loss rate of the holocellouse is basically the same,and the waste water is reduced by about half.The optimum conditions were as follows: the adsorption time was90 min at 55 ℃,and then allowed to stand for 2h after hydrogen peroxide spray.3 Compared with the rice straw microcrystalline cellulose prepared by NaClO2 bleaching method,the whiteness was 84%,the content was 98%,the crystallinity was for 87%,are higher than 2015 version of "Chinese Pharmacopoeia" standard.