Phenolic Compound Removal Technique For Efficient Biobutanol Production Using Oil Palm Fronds Hydrolysate

Oil Palm Frond (OPF) juice has been the focus of Malaysian bioenergy producers through acetone-butanol-ethanol (ABE) fermentation. However, due to the high concentration of phenolic compounds in the hydrolysate, usually gallicacid and ferulic acids, the fermentation medium turns acidic which hinders the growth of most microorganisms. A suitable method of phenolic compound removal with a minimal effect on the sugar stability of OPF juice has been employed using Amberlite XAD-4 resin. During the detoxification process, the effects of temperature and pH on the removal of phenolic compounds and sugar stability were also assessed. The Amberlite XAD-4 resin managed to adsorb about 32% of phenolic compound from the OPF hydrolysate at an optimum temperature of 50 °C and hydrogen ion concentration (pH) of 6. In addition, it maintained as much as 93.7 % of the sugar in the OPF juice. The effect of detoxifying OPF hydrolysate was further tested for biobutanol production in batch culture using strain Clostridium acetobutylicum SR1, L2, and A1. Strain L2 gave the highest improvement in biobutanol and total solvent production by 22.7% and 14.41%, respectively, in medium with detoxified OPF juice. Meanwhile, compared to non-detoxified OPF juice, the acid production of strain L2 significantly decreased by 2.99-fold when using detoxified OPF juice, despite a 1.2-fold increase in sugar consumption. Conclusively, using Amberlite XAD-4 resin to detoxify OPF hydrolysate at pH 6 and 50 °C removed the phenolic compound while increasing the strain L2 capability to improve biobutanol and total solvent production.