Valorization of oil palm Biomass: Investigating ChCl:Lactic Acid deep eutectic solvents for efficient furfural production

This study investigated the production of furfural from oil palm empty fruit bunches (EFBs) and oil palm fronds (OPFs) using choline chloride:lactic acid (ChCl:Lactic Acid) deep eutectic solvents (DESs). The effects of temperature (120–170 °C), reaction time (15–60 min), water content (0–10 wt%), biomass type, and DES molar ratio (1:2 and 1:4) on the furfural yield were systematically evaluated. Maximum yields of 76.93 % and 68.45 % were obtained from EFB and OPF, respectively, at 170 °C, 60 min, 5 wt% water, and 1:2 ChCl:Lactic Acid. The 1:2 M ratio demonstrated superior catalytic performance compared to 1:4, attributed to its lower viscosity, higher acidity, and improved thermal properties, supported by physicochemical characterization (density, refractive index, decomposition/freezing point, pH, and viscosity). Water addition enhanced hemicellulose solubilization and furfural formation by modulating DES polarity and reducing viscosity. Excess water (10 wt%) decreased yield due to DES structural disruption and side reactions. Compared to OPF, EFB exhibited higher furfural productivity, likely due to differences in lignocellulosic structure, xylan content, and cellulose crystallinity. Reaction selectivity was maintained under all conditions, with minimal humin formation, highlighting the stability of ChCl:LA in thermal and acidic environments. This study confirmed the dual role of ChCl:Lactic Acid as a solvent and catalyst, enabling efficient hemicellulose depolymerization and furfural synthesis. This study contributes to the development of sustainable biorefinery pathways by demonstrating the efficacy of biodegradable DESs for high-yield furfural production from underutilized lignocellulosic residues.