Effect of post-pretreatment washing on saccharification and co-fermentation from bagasse pretreated with biocompatible cholinium ionic liquid

Choline acetate (ChOAc), a cholinium ionic liquid (IL), was used for biomass pretreatment; thereafter, saccharification of the pretreated biomass and glucose/xylose co-fermentation were conducted with different number of post-pretreatment washes (1-5 and 10 washes). Besides saccharification and co-fermentation data, the inhibitory effect of ChOAc on the biocatalyst was compared with that of 1-ethyl-3-methylimidazolium acetate (EmimOAc). ChOAc showed less inhibitory effect on cellulase and yeast activity compared with EmimOAc. The cellulose and hemicellulose saccharification percentages of the IL-pretreated bagasse were approximately 90% and 60%, respectively, irrespective of ChOAc and EmimOAc with sufficient post-pretreatment washes. The cellulose and hemicellulose saccharification percentages after 5 washes were 82% and 59%, respectively, in the case of ChOAc and 51% and 13%, respectively, in the case of EmimOAc. The overall ethanol yields on the original bagasse basis after saccharification and co-fermentation of the IL-pretreated bagasse when washed 5 times were 54% and 22% in the case of ChOAc and EmimOAc, respectively. ChOAc-pretreated bagasse could be saccharified and co-fermented with fewer washes than EmimOAc-pretreated bagasse.