Enhanced biomass processing towards acetone-butanol-ethanol fermentation using a ternary deep eutectic solvent

This work evaluated the effectiveness of ternary deep eutectic solvents (DES) composed of cholinium chloride (ChCl), lactic acid (LA) and a diol (ethylene glycol - EG, or 1,6-hexanediol - HEX) in the pretreatment of rice straw (RS) towards the production of biobutanol. The most promising results were obtained with ChCl:LA:EG 1:5:5 at 120 degrees C for 4 h, which enabled the highest conversion of biomass polysaccharides into glucose and xylose up to 89.3 % and 53.6 % yields, respectively. Subsequently, the produced sugars were efficiently converted into biobutanol through the acetone-butanol-ethanol (ABE) fermentation process, resulting in the production of 95.7 g butanol/kg RS as one of the highest values reported in literature. Thus, the application of the ternary DES ChCl: LA:EG 1:5:5 represents a competitive and environmentally friendly pathway for RS valorization in comparison to conventional processes.