Effect of particle size based separation of milled corn stover on AFEX pretreatment and enzymatic digestibility
Effect of particle size based separation of milled corn stover on AFEX pretreatment and enzymatic digestibility
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DOI：
10.1002/bit.21132
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发表时间：
2007-02-01
影响因子：
3.8
通讯作者：
Dale, Bruce E.
中科院分区：
文献类型：
--
作者：
Chundawat, Shishir P. S.;Venkatesh, Balan;Dale, Bruce E.
颗粒大小和组成变化对氨纤维爆炸(AFEX)前处理和木质纤维生物质的酶解有很大影响。玉米秸秆被碾磨并分级成不同组成的颗粒。较大粒度组分(富含玉米芯和秸秆部分)比较小粒度组分(富含叶和壳部分)更难水解。用化学分析电子能谱(ESCA)和傅里叶变换红外光谱(FTIR)分别对生物质表面和本体成分进行了分析。ESCA分析结果表明，预处理后生物质表面的氧碳比下降了15-30%，表明生物质表面的疏水性增强了。FTIR结果证实AFEX处理组分的木质素-碳水化合物复合体(LCC)发生了裂解。光谱结果表明，AFEX可以将裂解的木质素、酚类碎片和其他细胞壁抽提物提取到生物质表面。AFEX处理组分的水洗去除了一些疏水抽出物，导致13%的重量损失(干重)。用改进的普鲁士蓝(MPB)法测定洗涤液酚含量。与未洗涤的样品相比，水洗去除AFEX处理过的生物质中的木酚抽出物大大提高了葡聚糖的转化率。底物颗粒尺寸的减小也影响AFEX过程和水解率。讨论了秸秆颗粒大小、组成和酚类碎片对综合生物精炼的抑制作用。
Particle size and compositional variance are found to have a substantial influence on ammonia fiber explosion (AFEX) pretreatment and enzymatic hydrolysis of lignocellulosic biomass. Corn stover was milled and fractionated into particle sizes of varying composition. The larger particle size fractions (rich in corn cob and stalk portions) were found to be more recalcitrant to hydrolysis compared to the smaller size fractions (rich in leaves and husk portion). Electron spectroscopy for chemical analysis (ESCA) and Fourier transform infrared spectroscopy (FTIR) were used for biomass surface and bulk compositional analysis, respectively. The ESCA results showed a 15-30% decrease in the O/C (oxygen to carbon) ratio after the pretreatment indicating an increase in the hydrophobic nature of biomass surface. FTIR results confirmed cleavage of the lignin-carbohydrate complex (LCC) for the AFEX-treated fractions. The spectroscopic results indicate the extraction of cleaved lignin phenolic fragments and other cell wall extractives to the biomass surface upon AFEX. Water washing of AFEX-treated fractions removed some of the hydrophobic extractives resulting in a 13% weight loss (dry weight basis). Phenolic content of wash stream was evaluated by the modified Prussian blue (MPB) method. Removal of ligno-phenolic extractives from the AFEX-treated biomass by water washing vastly improved the glucan conversion as compared to the unwashed samples. Reduction in the substrate particle size was found to affect the AFEX process and rate of hydrolysis as well. Implications of the stover particle size, composition, and inhibitory role of the phenolic fragments on an integrated biorefinary are discussed.