Different ionic liquids favor different lignocellulosic biomass particle sizes during pretreatment to function efficiently

Abstract

Cotton stalks at four different particles sizes (<0.15 mm, 0.15-0.5 mm, 0.5-1.0 mm and 1.0-2.0 mm) were subjected to ionic liquid pretreatment via 1-ethyl-3-methylimidazolium acetate (EMIMAc) and 1-ethyl-3-methylimidazolium chloride (EMIMCl) followed by the enzymatic hydrolysis of pretreated biomass. The changes in crystalline structure, lignin content and digestibility of the pretreated samples were investigated in addition to the glucose yield obtained from cotton stalks. For EMIMAc pretreatment, the lowest glucose yield (57%) was obtained upon the pretreatment of cotton stalks having the smallest particle size prior to pretreatment (<0.15 mm) while cotton stalks with larger particle sizes gave higher glucose yields of which were at least 71%. On the contrary, EMIMCl pretreatment functioned more efficiently with cotton stalks having smaller particle sizes (<0.15 mm and 0.15-0.5 mm) where increasing the biomass particle size further caused a decrease in the glucose yield from approximately 49% to 33%, unlike the EMIMAc pretreatment. These differences in the glucose yields obtained for different ionic liquids suggest that the ideal particle size of biomass prior to pretreatment may change from one ionic liquid to another.

Characterization of Bamboo after Ionic Liquid-H2O Pretreatment for the Pyrolysis Process

“…Most studies report reduced lignin and hemicellulose content in pretreated biomass, while the glucan fraction, which is mainly cellulose, is usually almost completely recovered. The effect of pH value (Zhang et al 2013), particle sizes (Bahcegul et al 2012;Hou et al 2013), water content, pretreatment time, and other influencing factors (Brandt et al 2011) have been investigated in grasses, hardwood, and softwood. The impact of ILs treatment on the composition of treated biomass was investigated in several studies (Fu et al 2010(Fu et al , 2011).…”

Catalytic Role of Ionic Liquids for Dissolution and Degradation of Biomacromolecules

“…This might be due to extensive depolymerization reactions leading to soluble oligosaccharides. The trend was opposite for [Emim][Cl] solution, where the highest yield was achieved for larger size particles (Bahcegul et al 2012). The transformation from cellulose I to cellulose II was only observed by using [Emim][CH 3 COO] for the smallest particle size studied (< 0.15 mm).…”

“…The glucose recovery percentage was increased almost linearly from 26.2% to 96.7% with the increase of temperature. Another study showed that [Emim][CH 3 COO] was capable of disrupting the lignocellulosic materials in a shorter period of time, resulting in a higher yield of monosaccharaides (Bahcegul et al 2012). The degree of crystallization (DP) of cellulose-rich materials after regeneration was also found to decrease with the increasing pre-treatment time (Sant'Ana Da Silva et al 2011).…”

“…Smaller particle size enhances the surface area and diffusion of chemicals into the lignocellulosic materials. However, the ideal particle size of a certain biomass might vary depending on the type of the IL used (Bahcegul et al 2012). For pretreatment of cotton stalks with [Emim][CH 3 COO] and [Emim][Cl], four different particle sizes (< 0.15 mm, 0.15 to 0.5 mm, 0.5 to 1.0 mm, and 1.0 to 2.0 mm) were used.…”

Thermal Decomposition of Bamboo Phyllostachys Edulis Pretreated with Ionic Liquids-Water Mixtures

“…Adding water or other organic solvent to IL systems can reduce the process cost significantly if pretreatment effectiveness is not compromised. The ILs mixtures have been successful applied in enzymatic hydrolysis [5]- [7]. ILs-water mixtures proved to be highly effective for biomass pretreatment by selective removal of lignin and it was obtained objective results for bio-fuel [8].…”