柳枝稷超高压爆破前处理研究

Studies on Pretreatment of Switchgrass by Ultra-high Pressure Explosion with a High-pressure Homogenizer

关键词:  超高压爆破  前处理  柳枝稷

Key words:  ultra-high pressure explosion  pretreatment  switchgrass

摘要:

应用高压均质技术对柳枝稷(Panicum virgatum)进行超高压爆破前处理。柳枝稷秸秆粉碎后用0.5%的NaOH加热处理,保持悬浮状态下通过高压均机进行100MPa爆破。结果表明,超高压爆破使柳枝稷颗粒悬浮液变为粘稠流体,粒度显著变小,超微结构由纤维状变为疏松的中空多孔状,木质素、灰分含量显著减少,碱消耗量显著增加,但对纤维素的结晶指数影响很小。处理后每克材料用4.7FPU的纤维素酶,5.3IU的木聚糖酶和0.4CBU的β-葡萄糖苷酶水解48h,酶解率97.6%,较未爆破对照提高21.1%。超高压爆破显著提高酶解率的主要原因是破坏了木质纤维的超微结构,增大了酶的作用面积,是一种有潜力的木质纤维材料前处理方法。

Abstract:

Switchgrass was treated by using a homogenizer in a constant suspended state, a process termed as ultra-high pressure explosion (UHPE).The stalk of switchgrass was grinded to powder, heated in 0.5% NaOH solution, and then 100MPa UHPE-treated through a homogenizer under a suspended state.The results verified that UHPE changed the suspension solution of powder into a stick fluid.The granularity analysis and scanning electron microscope (SEM) observation confirm that UHPE can decrease the granularity significantly and disrupt the microstructure of lignocellulosic from a rigid and highly ordered fibril to a distorted, poly-porous and "center empty" structure.The contents of lignin and ash were decreased significantly.The NaOH consuming was enhanced.However, the effect by UHPE on CrI was minor.After pretreatment, the switchgrass was near completely hydrolyzed to digestibility of 97.6% within 48 hours by a low enzymes loading, 4.7FPU of cellulase, 5.3IU of xylanase and 0.4CBU of β-glucosidase per gram substrate, 21.1% higher than that of NaOH treated control sample.The major mechanism for UHPE enhancing the digestibility is by disrupting the microstructure of biomass, enlarging the accessible area for enzyme attack, which was not observed in previous investigation.Therefore, UHPE is argued to be a potential alternative technology for pretreatment of lignocellulosic biomass.