氢氧化钠-尿素水溶液高温处理对桉木枝桠材纤维酶解性能的影响

Effect of Treatment with NaOH-urea Aqueous Solution at High Temperature on Enzyme Hydrolysis Property of Eucalyptus Branch Fibers

本研究利用氢氧化钠-尿素水溶液(氢氧化钠∶尿素∶去离子水=6∶4∶90,质量比)在高温条件下处理桉木枝桠材纤维以求改善其酶解(纤维素酶、木聚糖酶和纤维二糖酶的混合酶)性能。酶解工艺条件为:纤维绝干质量2 g、酶解浓度5%、底物酶用量(以纤维素酶活计)10 FPU/g、酶解转速150 r/min、酶解温度50℃、酶解时间72 h,利用单因素实验探究最佳处理工艺。结果表明,在用碱量(以氢氧化钠计)11%、处理温度140℃、保温时间50 min的条件下,该体系对桉木枝桠材纤维酶解性能的改善效果最佳。在最佳条件下,纤维中苯-醇抽出物、木质素和综纤维素的脱除率分别为64.59%、56.45%和15.20%,同时处理后纤维中酶解总糖含量和总糖转化率分别为50.9%和81.18%,与经热水处理后纤维的上述两项指标相比分别提高了约133.5%。

In this study,the NaOH-urea aqueous solution(NaOH∶urea∶H2O=6∶4∶90,mass ratio)was used to treat the eucalyptus branch fibers at high temperature for improving its enzyme hydrolysis property with the mixed enzyme aqueous solution of cellulose,xylanase and cellobiase.The conditions for enzyme hydrolysis were as follows:the oven-dried fiber weight of 2 g,enzyme hydrolysis concentration of 5%,mixed enzyme(calculated by cellucase)dosage of 10 FPU/g fiber,enzyme hydrolysis rotation speed at 150 r/min,enzyme hydrolysis temper⁃ature of 50℃,enzyme hydrolysis time of 72 h,and the process was optimized by single factor tests.The results showed that alkali dosage(measured by NaOH)of 11%,treating at 140℃for 50 min(impregation time of 15 min,liquor ratio of 1∶4)were chosen as the optimal con⁃ditions.Under the above conditions,the removal rates of solvent extract,lignin and holocellulose were 64.59%,56.45%and 15.20%,re⁃spectively.Besides,the content of hydrolyzed total sugar and the conversion rate of the total sugar were 50.90%and 81.18%respectively,which were increased by 133.5%compared with those of the fibers treated with hot water,respectively.