Optimization of OPEFB lignocellulose transformation process through ionic liquid [TEA][HSO(4)] based pretreatment

Research on the transformation of Oil Palm Empty Fruit Bunches (OPEFB) through pretreatment process using ionic liquid triethylammonium hydrogen sulphate (IL [TEA][HSO(4)]) was completed. The stages of the transformation process carried out were the synthesis of IL with the one-spot method, optimization of IL composition and pretreatment temperature, and IL recovery. The success of the IL synthesis stage was analyzed by FTIR, H-NMR and TGA. Based on the results obtained, it showed that IL [TEA][HSO(4)] was successfully synthesized. This was indicated by the presence of IR absorption at 1/λ = 2814.97 cm(−1), 1401.07 cm(−1), 1233.30 cm(−1) and 847.92 cm(−1) which were functional groups for NH, CH(3), CN and SO(2), respectively. These results were supported by H-NMR data at δ (ppm) = 1.217–1.236 (N–CH(2)–CH(3)), 3.005–3.023 (–H), 3.427–3.445 (N–H(+)) and 3.867 (N(+)H(3)). The TGA results showed that the melting point and decomposition temperature of the IL were 49 °C and 274.3 °C, respectively. Based on pretreatment optimization, it showed that the best IL composition for cellulose production was 85 wt%. Meanwhile, temperature optimization showed that the best temperature was 120 °C. In these two optimum conditions, the cellulose content was obtained at 45.84 wt%. Testing of IL [TEA][HSO(4)] recovery performance for reuse has shown promising results. During the pretreatment process, IL [TEA][HSO(4)] recovery effectively increased the cellulose content of OPEFB to 29.13 wt% and decreased the lignin content to 32.57%. The success of the recovery process is indicated by the increasing density properties of IL [TEA][HSO(4)]. This increase occurs when using a temperature of 80–100 °C. The overall conditions obtained from this work suggest that IL [TEA][HSO(4)] was effective during the transformation process of OPEFB into cellulose. This shows the potential of IL [TEA][HSO(4)] in the future in the renewable energy sector.