Using deep eutectic solvents to pretreat corncob for the fabrication of sustainable lignocellulose hydrogels

Using agricultural wastes as raw materials to manufacture high value-added materials with green and economical processes is of great significance. In this study, corncob processed by deep eutectic solvents (DESs) pretreatment (80–130 °C) can be successfully prepared into lignocellulose-based hydrogels (LCHs) by a facile and green ZnCl2/CaCl2 solvent system. An appropriate amount of lignin can be well dispersed and filled in the structure of LCHs, thus improving the mechanical properties of the hydrogel. The hydrogel using 120 °C pretreated corncob as starting material reached the best tensile stress (144.4 kPa) and compressive stress (401.4 kPa). Due to the excellent flexibility and the presence of a large number of metal ions, the hydrogels prepared from the 120 °C pretreated corncob were assembled into a capacitor and got an energy density of 110.2 Wh/kg at the power density of 495.0 W/kg. In short, this study provides a simple and green method to prepare LCHs and a novel efficient utilization route of the corncob.