Solid acid facilitated deep eutectic solvents extraction of high-purity and antioxidative lignin production from poplar wood.

Pure deep eutectic solvents (DESs) system of choline chloride (ChCl)/Lactic acid (Lac) were demonstrated to be an effective strategy for extraction of lignin. In this study, two kinds of different promising solid acid (SA) with DESs were designed to promote the pretreatment of lignocellulose. The SA of phosphotungstic acid (HOPW) and iron bromide (FeBr) were introduced into DESs to extract poplar wood lignin and evaluate the antioxidant activity.