2.3 DES pretreatment
Sorghum stover was loaded to a reactor containing DES at a 1:10 (w/w)
biomass-to-solvent ratio. A vortex mixer was used to rigorously mix the
biomass and DES before the reaction. The mixtures were processed at
120–140 °C for 3 h in an oil bath with continuous stirring at 500 rpm.
Upon the end of the pretreatment, the reaction was quenched by adding
ethanol/water 1:1 (v/v) solution and acetone. The solid fraction was
washed with ethanol/water solution 1:1 (v/v). Further solvent washing
was conducted to completely recover the fractionated lignin from the
pretreated biomass.