不同氧化剂对禾草类碱木质素结构变化的影响

研究了禾草类碱木质素在O2、H2O2、O3、O2/H2O2、O3/H2O2等不同氧化剂氧化时其结构的变化规律,为更好地利用禾草类碱木质素提供理论依据和工艺方法。研究结果表明,以O2/H2O2氧化禾草类碱木质素时,高用碱量可促进木质素高分子组分氧化降解,分子质量均一化,酚羟基和羧基增加较多,脱甲氧基反应也较强烈;低用碱量时,木质素氧化降解少,并伴有缩合反应;H2O2可促进碱木质素氧化降解,促进酚羟基、羧基的产生和脱甲氧基反应;在O3氧化适宜条件下,添加H2O2可使O3氧化反应缓和,木质素分子发生缩合并均一化,生成较多的酚羟基、羧基和羰基。

Effect of Different Oxidants on Structure Transformation of Alkali Lignin

The effect of different oxidants such as O_2,H_2O_2,O_3,O_2/H_2O_2,O_3/H_2O_2 on structure transformation of straw alkali lignin were studied in the paper,it provided theoretical understanding and technological process to rational application of straw alkali lignin.The results indicated: when O_3/H_2O_2 oxidant was used,high alkali dosage could accelerate oxidizing degradation of the lignin macromolecules and improve the uniformity of the molecular weight distribution,the contents of Ph-OH and-COOH increased evidently,demethoxy reaction was comparative fierce,MW homogenization was improved and more active groups were formed. Accompanying with condensation reaction,the degree of oxidizing degradation was little when low alkali dosage was used.Adding H_2O_2 could degrade alkali lignin and accelerate producing Ph-OH,-COOH and demethoxy reaction;under the apprpriate conditions,adding H_2O_2 could relax the ozone oxidizing reaction and reduce the production of low molecule organic acid and produce more Ph-OH,-COOH and carbonyl groups.So H_2O_2/O_3 oxidant can activate alkali lignin and improve the molecular weight distribution homogenization,it can increase the reaction performance of industrial lignin.