An Evaluation of the Alkaline Pretreatment and Hydrolysis on the Production of Bioethanol using Durio zibethinus (Durian) Husks

Mapúa Malayan Colleges Mindanao, College of Engineering and Architecture, Davao City, 8000 Philippines

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Abstract

Growing energy crisis and alarming environmental concerns make the development of biofuels an essential alternative to fossil fuels. Durian, a tropical fruit native to Southeast Asia, is a lignocellulosic biomass suitable for use as feedstock. Despite the increasing interest in bioethanol production, studies on the use of durian husks as feedstock remain limited. In this study, alkaline pretreatment and alkaline hydrolysis using sodium hydroxide (NaOH) were used to produce bioethanol. The NaOH concentrations used for pretreatment/hydrolysis were 1.5M/0.5M, 2.0M/1.0M, and 2.5M/1.5M. The samples were fermented, distilled, and analyzed. The distillates were qualitatively measured using refractometry and quantitatively measured using gas chromatography. The highest results were obtained from the 2.5M/1.5M alkaline group, which produced 44.67 mL of distillate and bioethanol concentration of 82.59%. The amount of distillate and bioethanol concentration increased as the pretreatment and hydrolysis concentrations increased. One-way ANOVA revealed a significant difference among the alkaline concentration groups in bioethanol production. However, Tukey Post-Hoc test showed that the difference in distillate volume and bioethanol concentration between the samples from 2.0M/1.0M and 2.5M/1.5M alkaline groups were not significant. Therefore, the results from the 2.0M/1.0M alkaline group are considered to deliver the optimum product of 42 mL distillate with 79.83% bioethanol concentration.