Comparative study of corn stover pretreated by dilute acid and cellulose solvent‐based lignocellulose fractionation: Enzymatic hydrolysis, supramolecular structure, and substrate accessibility

Abstract

Liberation of fermentable sugars from recalcitrant biomass is among the most costly steps for emerging cellulosic ethanol production. Here we compared two pretreatment methods (dilute acid, DA, and cellulose solvent and organic solvent lignocellulose fractionation, COSLIF) for corn stover. At a high cellulase loading [15 filter paper units (FPUs) or 12.3 mg cellulase per gram of glucan], glucan digestibilities of the corn stover pretreated by DA and COSLIF were 84% at hour 72 and 97% at hour 24, respectively. At a low cellulase loading (5 FPUs per gram of glucan), digestibility remained as high as 93% at hour 24 for the COSLIF-pretreated corn stover but reached only $60% for the DA-pretreated biomass. Quantitative determinations of total substrate accessibility to cellulase (TSAC), cellulose accessibility to cellulase (CAC), and non-cellulose accessibility to cellulase (NCAC) based on adsorption of a nonhydrolytic recombinant protein TGC were measured for the first time. The COSLIF-pretreated corn stover had a CAC of 11.57 m 2 /g, nearly twice that of the DA-pretreated biomass (5.89 m 2 /g). These results, along with scanning electron microscopy images showing dramatic structural differences between the DA-and COSLIF-pretreated samples, suggest that COSLIF treatment disrupts microfibrillar structures within biomass while DA treatment mainly removes hemicellulose. Under the tested conditions COSLIF treatment breaks down lignocellulose structure more extensively than DA treatment, producing a more enzymatically reactive material with a higher CAC accompanied by faster hydrolysis rates and higher enzymatic digestibility.

Application of Response Surface Methodology to Optimize Alkali Concentration, Corn Stover Particle Size, and Extruder Parameters for Maximum Sugar Recovery

“…It could be observed from the table that dilute acid (Yan et al, 2009), maleic acid (Lu & Mosier, 2008), lactic and/ acetic acid (Xu et al, 2009), controlled pH hot water (Mosier et al, 2005), steam (Bura et al, 2009), and steam explosion ) had comparable yield of this extrusion pretreatment. The present results were higher than dilute sulfuric acid Zhu et al, 2009), formic acid (Xu et al, 2009a), soaking in ethanol and aqueous ammonia , and steam explosion (Mosier et al, 2005); however, it was lower than dilute acid (Zhu et al, 2005), inorganic salt-FeCl 3 (Liu et al, 2009), cellulose solvent and organic solvent based lignocelluloses fractionation (Zhu et al, 2009). It could be noted that the particle size of corn stover used in most of the pretreatment listed in the table was lower than the extrusion pretreatment, and the higher enzyme dose was employed.…”

Obtaining high purity silica from rice hulls

“…This can be understood by the fact that hemicellulose is more accessible to acid hydrolysis than cellulose because of its amorphous nature. 17 The carboxylic acid component at 1729 cm -1 in the infrared spectra of Figure 3 also increases in intensity. The aqua-regia treatment eliminates phytate efficiently, which could be separated to be used as a metal sequestering agent.…”

Comparative Evaluation of Physiochemical Properties of a Solid Fuel Derived from Adansonia digitata Trunk using Torrefaction

“…2b). Some lignin polymers along with some carbohydrates also may have been deposited onto the surface of the cellulose fibers (Zhu et al 2009). At lower temperatures, the microfibrils of the BT sample were not entirely separated, initially, but they were somewhat twisted due to the partial removal of hemicellulose and lignin.…”