Effect of ionic liquid weight ratio on pretreatment of bamboo powder prior to enzymatic saccharification

► Biomass was pretreated with different ionic liquid (IL)/biomass ratios (0–10g/g). ► Cholinium IL (less expensive and less toxic than conventional IL) was used. ► An IL/biomass ratio of 3g/g was critical for sufficient biomass pretreatment. ► At an IL/biomass ratio of 3g/g, biomass was not liquid but solid. ► The solid-state biomass pretreatment using IL can reduce cost and waste water. The pretreatment efficiency of weight ratios ranging from 0 to 10 of the ionic liquid, cholinum IL, to bamboo powder was investigated. An IL/biomass ratio of 3g/g was critical to obtain a cellulose saccharification ratio of 80%. At this ratio, the treated bamboo powder remained as a solid. The solid-state pretreatment required a minimum amount of cholinium IL, which could reduce the cost of IL-assisted pretreatment and reduce the amount of wastewater generated in the process.