超临界二氧化碳偶合超声预处理强化玉米秸秆酶水解(英)

Enzymatic hydrolysis enhancement of corn lignocellulose by supercritical CO_2 combined with ultrasound pretreatment

提出了一个木质纤维素生物质预处理的全绿色加工过程.以玉米秸秆和玉米芯为原料,以超临界CO_2和超声偶合法对木质纤维素进行预处理.超临界CO_2预处理条件为:压力15-25 MPa,温度120_170℃,含水量50%,反应时间0.5_4 h.超声场功率600W,温度80℃,作用时间2-8 h.用纤维素酶水解反应获得的还原糖总量来评价预处理效果.结果表明,单纯超临界CO_2和超临界CO_2偶合超声预处理都能够提高生物质水解反应还原糖产量.对于玉米芯,超临界CO_2预处理(170℃,20 MPa,3 0min)后,还原糖产率为62%(未预处理的为12%).对于玉米秸秆(170℃,20 MPa,2.5 h),还原糖产率为46.4%.对于玉米芯,超临界CO_2偶合超声预处理(600 W,80℃下超声处理6 h,然后用170℃,20 MPa超临界CO_2预处理30 min)后,还原糖产率为87%.对于玉米秸秆,超临界CO_2偶合超声预处理(600 W,80℃下超声处理8 h,然后用170℃,20 MPa超临界CO_2预处理1 h)后,还原糖产率为25.5%.与未处理生物质相比,X射线衍射结果表明玉米秸秆和玉米芯在超临界CO_2和超声预处理后其结晶度没有明显变化.扫描电镜分析则发现木质纤维素的表面积显著增加.

Supercritical carbon dioxide （scCO2） combined with an ultrasound method using 15-25 MPa and the temperature range of 120-170℃ for 0.5-4 h was proposed as a pretreatment for corn cob and corn stalk with moisture contents of 50%. The results showed that both scCO2 pretreatment and scCO2 combined with ultrasound pretreatment could improve the total reducing sugar yields of the two materials. Enzymatic hydrolysis of both corn cob and corn stalk sugar using scCO2 pretreatment was increased by 50%and 29.8%compared with the control samples, respectively, while they were increased by 75%and 13.4%, respectively, using the scCO2 combined with ultrasound pretreatment under our experimental conditions. Following treatment from the two pretreatment processes, X-ray diffraction results indicated no significant change in crystallinity of the two materials. How-ever, scanning electron microscopy images demonstrated that the microscopic structure of ligno-cellulose changed considerably and the surface area of lignocellulose increased significantly.