Unveiling the potential of water as a co-solvent in microwave-assisted delignification of sugarcane bagasse using ternary deep eutectic solvents

• Published in: Bioresource technology 2022-05, Vol.351, p.127005-127005, Article 127005
• Main Authors: Chourasia, Vallari R., Bisht, Meena, Pant, Kamal K., Henry, Robert J.
• Format: Article
• Language: English
• Subjects: Biomass; Cellulose; Choline; Co-solvent; Deep Eutectic Solvents; Delignification; Edible Grain; Lewis acid; Lignin; Microwave; Microwaves; Saccharum; Solvents; Water
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2022.127005

•Aqueous solution of ternary DESs were used for pre-treatment of SB.•Pre-treatment was performed in 30 mins at 100 °C using microwave heating.•MgCl2 and NiCl2 were integrated with neutral DESs for pre-treatment.•20% aqueous CC:EG:NI achieved 84% delignification and 99% enzyme digestibility.•EG based DESs showed better pre-treatment performance than GLY based DESs. Deep eutectic solvents (DESs) have become popular owing to their biodegradability and recyclability. In this study, the influence of water as a co-solvent is demonstrated to enhance the properties of choline based ternary DESs. A fast and energy-efficient microwave-assisted pre-treatment process was developed for delignification of sugarcane bagasse (SB). The effectiveness of SB fractionation was revealed by incorporating Lewis acids (MgCl2.6H20, NiCl2.6H20) with the DESs for pre-treatment and Choline chloride: Ethylene glycol: NiCl2.6H20 (CC:EG:NI) at a molar ratio 1:2:0.016 with 20w% water as a co-solvent provided the most promising result, with 84% delignification and 99% enzyme digestibility. Water was also employed as an anti-solvent to facilitate lignin solubility and exhibited up to 26w% lignin yield from DES liquor with maximum DES recovery of 95% (w/w). Water distinctly affects the density, viscosity, and intermolecular hydrogen bonding of the DES and its impact on the process dynamics is worth further exploration.