Enhanced Enzymatic Conversion of Durian Peel by Sulfuric Pretreatment for Biofuel Production

Abstract

Burning of agricultural waste after harvesting seasons leads to persistent environmental pollution, especially PM2.5 and PM10. Utilization of agricultural waste by conversion to value-added product or biofuel is a solution for this problem, however, breaking down of lignocellulosic biomass in agricultural waste has a limiting factor due to its inappropriate physical and chemical properties. In this work, durian peel, as lignocellulosic biomass, was pretreated with diluted sulfuric acid to disintegrate the lignocellulosic fibrils and to promote enzymatic saccharification. To optimize this acid pretreatment, three pretreatment parameters, including temperature (60-140°C), time (20-100mins), and acid concentration (0.5-3.5%) were designed and varied based on Response Surface Methodology (RSM) using Box-Behnken design. After pretreatment, pretreated biomass was enzymatic hydrolyzed, and pretreatment efficiency was determined based on amounts of reducing sugars. The mathematical model representing the correlation of each pretreatment factor and reducing sugars was generated to calculate the optimized pretreatment condition. At predicted optimal pretreatment condition, 127.14°C, 74.13 minutes, 2.75%, the result showed that the reducing sugar was obtained at 553.1 mg/g-durian peel, which was 1.88 folds higher compared to unpretreated durian peel. This work suggested the necessity of pretreatment in bio-conversion of agricultural waste to produce biofuels and value-added products.