Optimization of cellulose yield from oil palm trunks with deep eutectic solvents using response surface methodology

Oil palm trunk (OPT) is widely studied as an underutilized material with large cellulose and lignin contents. As an environmentally friendly solvent, deep eutectic solvents (DESs) can be employed to extract cellulose. The main objective of this study was to evaluate both basic and acidic DES and to optimize cellulose yield from OPT extraction. The type of DES used were choline chloride (ChCl)-urea, ChCl-lactic acid, ChCl-levulinic acid, and ChCl-glycerol. For the optimization, response surface methodology with three-level factorial Box-Behnken design was used with mass ratio solid/liquid in the range of 5-10 g sample/g DES, temperature between 80 and 110 degrees C, and extraction time in the range of 1-4 h. The results showed that the optimal condition for ChCl-levulinic acid was a mass ratio of 5.05%, a temperature of 104.2 degrees C, and a reaction time of 3.76 h with a cellulose yield of 91.29%. It is shown that acidic DESs produce a higher cellulose yield than basic DES. This experiment also offers an important understanding of fractionation and optimization to improve OPT utilization with green solvents.