Choline Chloride-Based Deep Eutectic Solvent-Treated Wood

Abstract

Due to their adaptability and low preparation costs, deep eutectic solvents (DESs) have been widely used in a variety of applications. For some potential industrial applications, developing new low-cost DESs is critical. Oxalic acid (OA), acetic acid (AA), urea (Ur), and glycerol (GL) were mixed in various molar ratios to make DES solutions, with choline chloride (ChCL) acting as the hydrogen bond acceptor (HBA). In this work, DES solutions were applied to wood samples of Oriental spruce (Picea orientalis) at 150 °C. The chemical structures of wood samples were significantly altered after impregnation with DES solutions, as revealed by Fourier transform infrared spectroscopy (FTIR). The hemicellulose and cellulose peaks increased around 1700 cm−1, while the lignin peak disappeared completely around 1500 cm−1. After the decay test, mass losses were lower than in the control samples. The decay tests revealed that the leached wood samples were more resistant to decay. DES-treated wood samples, on the other hand, decomposed at lower temperatures.