Delignification and enzymatic hydrolysis kinetics of KOH microwave-assisted pretreated banana stem for bioethanol production

Biomass pretreatment is essential to facilitate lignin removal and enhance cellulose concentration for optimal bioethanol production. Therefore, this research aimed to determine the effects of conventional KOH (KP) and Combined KOH microwave-assisted (CKMP) pretreatment on the banana stem (BS) composition, analyzing the kinetics of lignin removal at various temperatures and KOH concentrations for 25 min. Kinetics variables were calculated by fitting experimental data and cellulose was hydrolyzed to produce reducing sugars. The results showed that the highest lignin removal for KP and CKMP were 37.11%, and 40.39%, respectively, with CKMP having the lowest activation energy of approximately 2.688 kJ mol- 1. CMCase and FPase activity were 1988.3474 and 1605.4187 U mL(-1), respectively, which were significantly higher than the values reported in previous research. The maximum concentration of reducing sugars achieved was 17.69 g L-1, with an enzyme concentration of 50% (v/w), pH 5, and a hydrolysis duration of 25 h. Michaelis constant varied from 0.0037 to 0.0079, and the maximal rate ranged from 1.28 x 10(-6) to 2.76 x 10(-6) Mol L-1 s(-1) when computing the reaction rate using the Michaelis-Menten kinetics model.