Experimental investigation of ionic liquid pretreatment of sugarcane bagasse with 1,3-dimethylimadazolium dimethyl phosphate

• [Mmim][DMP]-pretreatment of SCB highly increased enzymatic hydrolysis.
• The crystallinity of SCB reduced greatly after treatment with [Mmim][DMP].
• The best IL-pretreatment in the range investigated caused 70.38% sugar conversion.
• Non-aqueous [Mmim][DMP] performs better than the aqueous one for SCB pretreatment.

In this study, an imidazolium-based ionic liquid (IL), 1,3-dimethylimidazolium dimethyl phosphate ([Mmim][DMP]), was applied for pretreating sugarcane bagasse to produce bioethanol. The main goal of this study was to investigate the feasibility of bagasse pretreatment with this IL, and to verify the effect of different operational parameters on the pretreatment process. Results indicated that temperature and duration of IL-pretreatment have optimum values. Within the range investigated, a maximum fermentable sugar conversion of 70.38% was achieved with this IL at 120 °C and 120 min. The corresponding value was 28.65% for the untreated biomass. The main cause for the observed enhancement in enzymatic hydrolysis was the reduction of cellulose crystallinity in the IL-pretreated biomass, as compared to the untreated sample, because it resulted in higher accessibility of the enzymes to the biomass after pretreatment. Moreover, the results indicated that aqueous [Mmim][DMP] mixtures are not as effective for pretreatment as the pure IL.