不同预处理方法对构树脱木质素动力学的影响

Delignification Kinetics of Alkaline and Ethanol Pretreatment of Broussonetia papyrifera

中文关键词:  构树  乙醇预处理  碱法预处理  脱木质素  动力学

Key Words:Broussonetia papyrifera  ethanol pretreatment  alkaline pretreatment  delignification  kinetics

中文摘要:

      以构树为原料，利用碱和乙醇对其进行预处理，通过分析两种预处理方法脱木质素的动力学特性，比较它们在脱木质素速率及活化能方面的差异。结果表明，碱法和乙醇预处理构树脱木质素属于一级反应，脱木质素过程主要由大量脱木质素和残余脱木质素阶段组成。在碱法和乙醇预处理中，进入残余脱木质素阶段的温度分别高于130°C和150°C。脱木质素速率会随着预处理温度的升高而提高，且大量脱木质素阶段的速率高于残余脱木质素阶段。比较两种预处理方法的脱木质素动力学数据发现，低温时，两种预处理方法的脱木质素速率相同，而在中、高温时，碱法预处理的脱木质素速率略高于乙醇预处理。在大量脱木质素阶段，碱法预处理脱木质素的活化能为100.2 kJ/mol，乙醇预处理脱木质素的活化能为82.3 kJ/mol，说明乙醇预处理较碱法预处理更容易脱除木质素。

Abstract:

      The kinetic characteristics of delignification of Broussonetia papyrifera pretreated by sodium hydroxide and ethanol were analyzed in this study to compare their differences in delignification rate and activation energy. Results showed that delignification reactions during alkaline and ethanol pretreatment were a first order reaction. There were two delignification stages during both pretreatment processes， i.e.， bulk delignification and supplement delignification. During the pretreatments with alkaline and ethanol， it entered the supplementary delignification stage as the temperatures were higher than 130℃ and 150℃， respectively. The delignification rate was increased with the increase of pretreatment temperature， and the delignification rate in the bulk delignification stage was higher than that of the supplementary delignification stage. Comparing the delignification kinetics of the two pretreatment processes， it was found that the delignification rates were almost the same at low temperature， while the delignification rate of the alkali pretreatment was slightly higher than that of the ethanol pretreatment at medium and high temperature. It was also found that the activation energies of alkaline and ethanol pretreatments were 100.2 kJ/mol and 82.3 kJ/mol respectively in bulk delignification stages， which indicated that in present study， lignin was easier to be removed during ethanol pretreatment process.