Green Deep Eutectic Solvents for Microwave-Assisted Biomass Delignification and Valorisation
Giorgio Grillo, Emanuela Calcio Gaudino, Roberto Rosa, Cristina Leonelli, Ana Timonina, Saulius Grygiškis, Silvia Tabasso, Giancarlo Cravotto
Abstract
Aiming to fulfil the sustainability criteria of future biorefineries, a novel biomass pretreatment combining natural deep eutectic solvents (NaDESs) and microwave (MW) technology was developed. Results showed that NaDESs have a high potential as green solvents for lignin fractionation/recovery and sugar release in the following enzymatic hydrolysis. A new class of lignin derived NaDESs (LigDESs) was also investigated, showing promising effects in wheat straw delignification. MW irradiation enabled a fast pretreatment under mild condition (120 °C, 30 min). To better understand the interaction of MW with these green solvents, the dielectric properties of NaDESs were investigated. Furthermore, a NaDES using the lignin recovered from biomass pretreatment as hydrogen bond donor was prepared, thus paving the way for a "closed-loop" biorefinery process.