Pretreatment with [EMIM]Ac/DMAc Co-solvent to Improve Enzymatic Saccharification of Pussy Willow (Salix gracilistyla Miq.)

Song-Yi Han, Chan-Woo Park, Fauzi Febrianto, Nam-Hun Kim, Seung-Hwan Lee

Abstract


Pretreatment of Salix gracilistyla Miq. with 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) together with N,N-dimethylacetamide (DMAc) as a co-solvent achieved an improvement in enzymatic saccharification yield in comparison to the raw material without pretreatment. The effects of the [EMIM]Ac/DMAc ratio (7:3, 5:5, and 3:7), pretreatment temperature (80 to 140°C), and pretreatment time (1 to 3 h) on enzyme saccharification were investigated. Acremonium cellulase and Optimash BG were used as the enzyme cocktail. With addition of DMAc to [EMIM]Ac, the viscosity of the co-solvent was drastically decreased. With increasing pretreatment temperature and time, the water soluble fraction increased at all [EMIM]Ac/DMAc ratios. The cellulose crystallinity also increased with increasing amount of DMAc in the co-solvent but decreased with increasing pretreatment temperature. The yields of glucose and xylose increased with increasing [EMIM]Ac amounts in the co-solvent, varying from 72.8% to 84.3% and 75.3% to 88.1%, respectively, for all [EMIM]Ac/DMAc ratios. These values were markedly higher than the glucose and xylose yields of 25.7% and 8.4%, respectively, obtained with DMAc alone and comparable to the 86.7% and 83.9% yields, respectively, obtained with [EMIM]Ac alone. The highest glucose and xylose yields obtained under the investigated pretreatment conditions were 84.3% and 88.1%, respectively.

Keywords


Pretreatment; Ionic liquid; 1-Ethyl-3-methylimidazolium acetate ([EMIM]Ac); N,N-Dimethylacetamide (DMAc); Enzymatic saccharification

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