摘要
本研究采用当今木素化学领域中较好的木素分离法——纤维素酶解法,制备出荻纤维素酶木素,并对纤维素酶的酶解条件进行了探索;进而采用化学分析和一系列现代测试技术,对荻纤维素酶木素的化学和结构特性作了详细研究,同时与荻研磨木素作了比较。实验结果表明,采用纤维素酶分离木素的方法,可以在满足碳水化合物达到最大降解的条件下,取得更多代表性强的木素。选定的酶解优化条件为:酶的浓度Ce,0.5％;底物浓度Cs,5％;酶解时间t,2×3天(3天酶解一次,分两次进行)。
The cellulose enzymatic hydrolysis, considered to be the best lignin isolation method in current lignin chemistry is used to prepare cellulolytic enzyme lignin from amur silver grass. Cellulosic enzymolysis conditions are being studied. The ACEL (celluiolytic enzyme lignin from silver amur grass), along with, MGL-A(milled grass lignin of amur silver grass) are compared for their elemental compositions, functional group contents, ratio of three structural units, molecular weights and their distributions, phenolic acids and lignin structures through chemical analyses, IR-, UV-, GC-, GPC-, ~1H-NIMR, ^(13)C-NMR spectral methods and other chemical treatments, such as alkaline nitrobenzene oxidation, alkaline hydrolysis and sodium borohydride reduction. With the help of orthogonal experimentation and monofactor variance analysis, experiments were carried out on the enzymolysis conditions of cellulase TC originated from T. Reesei. The following conclusions were being drawn: enzyme conc. 0.5%, substrate conc.5%, Reaction time 2×3 days (once every three days) leading to maximum enzymatic degradation of carbohydrates and hence higher ligning yield and more representativeness. Results obtained indicate that higher average molecular weights, slightly lower phenolic-hydroxyl contents, and greater extent of condensation in the ACEL with less degradation are due to shorter ball milling time compared with the MGL-A. In addition, the ACEL can be obtained in relatively higher yield to the greater extent of carbohydrate removal resulted from enzymolysis. Therefore, ACEL ismore representative of the protolignin in the raw material, and it is prefeted for lignin characterization studies. It is also suggested that ACEL and MGL both posses quaiacyl-, syringyl-, and p-hydroxylphenylpropane units, and a very close association between lignin and polysaccharides is confirmed. The residual carbohyrate composition of both lignins shows that sugars originated from hemicellulose, especially arabinoglucuronoxylans are predominating. The amount of phenolic acid ester, linked with lignins are determined by its alkaline hydrolysis products and UV spectroscopy.
出处
《中国造纸学报》
CAS
CSCD
北大核心
1990年第1期54-65,共12页
Transactions of China Pulp and Paper
