Comparison of autohydrolysis and ionic liquid 1-butyl-3-methylimidazolium acetate pretreatment to enhance enzymatic hydrolysis of sugarcane bagasse

Abstract

The aim of this work was to evaluate the efficiency of an ionic liquid (IL) 1-butyl-3-methylimidazolium acetate ([Cmim][OAc]) pretreatment (110°C for 30min) in comparison to high severity autohydrolysis pretreatment in terms of delignification, cellulose crystallinity and enzymatic digestibility. The increase in severity of autohydrolysis pretreatment had positive effect on glucan digestibility, but was limited by the crystallinity of cellulose. [Cmim][OAc] pretreated sugarcane bagasse exhibited a substantial decrease in lignin content, reduced cellulose crystallinity, and enhanced glucan and xylan digestibility. Glucan and xylan digestibility was determined as 97.4% and 98.6% from [Cmim][OAc] pretreated bagasse, and 62.1% and 57.5% from the bagasse autohydrolyzed at 205°C for 6min, respectively. The results indicated the improved digestibility and hydrolysis rates after [Cmim][OAc] pretreatment when compared against a comparable autohydrolyzed biomass.

Enhanced Production of Bioethanol by Fermentation of Autohydrolyzed and C4mimOAc-Treated Sugarcane Bagasse Employing Various Yeast Strains

“…Many studies have confirmed the same effect of hightemperature autohydrolysis on the reduction of hemicellulose content [21,23]. It was mentioned in our previous study that C4mimOAc also had a significant effect on hemicellulose; however, compositional analysis and Fourier transform infrared spectroscopy (FTIR) data of pretreated bagasse revealed that the effect of ionic liquid on hemicellulose was still milder as compared to autohydrolysis [19].…”

“…The major effect found by autohydrolysis on lignocellulosic material was removing the hemicellulose and thus reducing its hindrance, and improving the access of enzymes to the cellulose [20,21]. This effect can be clearly observed in Figure 1, where increased pretreatment temperature during autohydrolysis enhanced glucose release during enzymatic hydrolysis but xylose concentration was reduced because some amount of xylan had already been removed during autohydrolysis [19]. Reduction in xylose concentration at 205 • C can be attributed to the removal of some hemicellulose content during high temperature autohydrolysis, while low xylose concentration at 110 • C might be due to more lignin hindrance [19,22].…”

“…This study is the continuation of our previous study that investigated the effects of 1-n-butyl-3-methylimidazolium acetate (C 4 mimOAc) pretreatment versus autohydrolysis on sugarcane bagasse [19]. The aim was to study differently pretreated and enzymatically hydrolyzed bagasse to determine the effects of C 4 mimOAc pretreatment on sugar release [19].…”

“…The aim was to study differently pretreated and enzymatically hydrolyzed bagasse to determine the effects of C 4 mimOAc pretreatment on sugar release [19]. To clarify this further, different yeast strains were compared to find out which of the strains was working efficiently with a newly-designed C 4 mimOAc pretreatment strategy.…”

“…Our previous study examined sugar release upon cellulase treatment from pretreated bagasse [19], while the current study elaborates on the release of glucose and xylose in terms of concentration (mg/mL), considering that the greater content of glucose in the hydrolysate ultimately leads to improved ethanol production. Variations in glucose and xylose concentration from the enzymatic hydrolysis of sugarcane bagasse pretreated with different strategies are shown in Figures 1 and 2.…”