Mild pretreatment and enzymatic saccharification of cellulose with recycled ionic liquids towards one-batch process

► Ionic liquids allow short time and room/mild temperature cellulose pretreatment. ► IL-recycling can be performed in maintaining their efficiency to pretreat cellulose. ► Trichoderma reesei cellulase is compatible with [Emim]+[MeO(H)PO2]− (up to 40%, v/v). ► [Emim]+[MeO(H)PO2]− pretreatment and enzymatic saccharification can be combined. The development of second-generation bioethanol involves minimizing the energy input throughout the processing steps. We report here that efficient ionic liquid pretreatments of cellulose can be achieved with short duration times (20min) at mild temperature (45°C) with [Emim]+[MeO(H)PO2]− and at room temperature (25°C) with [Emim]+[CH3COO]−. In these conditions, yields of glucose were increased by a factor of 3. In addition, the recycling of these two imidazolium-based ILs can be performed in maintaining their efficiency to pretreat cellulose. The short time and mild temperature of cellulose solubilization allowed a one-batch processing of [Emim]+[MeO(H)PO2]− IL-pretreatment and saccharification. In the range from 0 to 100% IL in an aqueous enzymatic medium, the glucose yields were improved at IL proportions between 10 and 40%. The maximum yield at 10% IL is very promising to consider one batch process as efficient as two-step process.