摘要
研究了氧化剂种类,包括H2O2、Na2S2O8、O2、CH3COOOH、(NH4)2S2O8和DMD(dimethyldioxirane),对固载型漆酶和Co(salen)/NaY一锅法催化氧化木素的影响,通过正交和单因素实验对反应条件进行优化,通过GC-MS和GPC、31P-NMR技术分别对芳香类木素降解产物和木素结构进行表征。结果显示,不同氧化剂存在下木素的三种基本结构单元发生了不同程度的降解,降解产物主要为香草醛和丁香醛,其中,Na2S2O8氧化效果最好;一锅法催化氧化木素反应存在有效的协同效应,使一锅法催化氧化效率明显优于单独催化;另外,乙醇在木素催化降解中起到了积极作用。最终的一锅法最佳工艺为:木素用量100 mg,催化剂总用量6 mg,Na2S2O8用量0.4 g,催化剂比例2:1,乙醇用量为0.04 mL,反应时间4 h,pH8。GPC和31P-NMR分析表明,一锅法降解残余木素的分子量显著降低、多分散性趋于1,脂肪族羟基减少,酚羟基含量增加,缩合结构被降解。
The effect of oxidants, including H2O2, Na2S2O8, O2, CH3COOOH,(NH4)2S2O8 and DMD(dimethyldioxirane),on immobilized laccase and Co(salen)/NaY catalytic oxidation of lignin by one-pot process was studied. At the same time, the reaction conditions were optimized by using the orthogonal and single factor experiments. The aromatic degradation products of lignin and the structure of lignin were characterized by GC-MS, GPC and 31P-NMR technique, and the results showed that three kinds of basic structure units of lignin had experienced varying degradation depending on the used oxidants, in which vanillin and syringaldehyde were found to be the main degradation products, and Na2S2O8 showed the best oxidation efficiency. The one-pot catalytic oxidation was more efficient than the single-catalyst catalysis in the catalytic oxidation of lignin, showing effective synergistic effect. In addition, ethanol played an active role in catalytic degradation of lignin. The ultima optimal condition of one-pot process was also obtained as follows: 100 mg lignin, 6 mg catalyst, 0.4 g Na2S2O8, 2:1 catalyst ratio, 0.04 mL ethanol, 4 h, pH 8. GPC and 31 P-NMR analysis showed that the molecular weight of residual lignin was degraded significantly and polydispersity tended to 1 in one-pot, aliphatic hydroxyl group decreased, phenolic hydroxyl content increased, and condensation structure was degraded.
作者
马雪梅
周学飞
MA Xue-mei;ZHOU Xue-fei(Faculty of Chemical Engineering,Kunming University of Science and Technology,Kunming 650500,China;State Key Laboratory of Non Food Biomass and Enzyme Technology,Nanning 530226,China)
出处
《纤维素科学与技术》
CAS
CSCD
2019年第4期8-17,共10页
Journal of Cellulose Science and Technology
基金
国家自然科学基金（21766015）
昆明理工大学分析测试基金（2018M20172208046）
非粮生物质酶解国家重点实验室开放基金（2018-15-Z03-10）
