Softening beech wood with Fe3+ auxiliary deep eutectic solvent (DES)

Deep eutectic solvents (DES) offer advantages such as environmental friendliness, recyclability, and biocompatibility, demonstrating promising applications in functional materials, chemical reactions, and electrochemistry. This study investigated the softening effect of DES on beech with the assistance of FeCl3, considering different treatment durations (1, 2, 3, and 4 h) on varying thicknesses (1, 2.5, 3.5, and 5 mm). Results indicate that longer treatment time leads to better softening effects on beech wood at the same thickness. FeCl3 acts as an active site providing acidic protons, thereby enhancing the softening efficiency of DES. Wood treated with Fe3+-assisted DES removes 86% of the lignin and 48% of the hemicelluloses, resulting in enhanced flexibility. Scanning electron microscopy reveals that most of the vessel lumens, cell lumens, and intercellular spaces of beech wood treated with Fe3+-assisted DES are filled with DES, reducing the wood's porosity. Color difference analysis and energy-dispersive X-ray spectroscopy demonstrate that wood color darkens gradually with prolonged treatment time, correlating with the addition of FeCl3. Thermal analysis indicates an improvement in the flame retardancy of the treated wood. This research methodology significantly enhances wood utilization and diversifies the aesthetic possibilities of wood products, thereby may expanding their applications in architecture and furniture.