Alkaline pretreatment of Durio sp. residual biomass enhances cellulose accessibility for efficient bioethanol production

The reliance on fossil fuels for energy generation has led to significant environmental, social, and economic challenges, necessitating the exploration of sustainable alternatives. Bioethanol, derived from renewable sources such as agricultural waste, presents a promising substitute. This study investigates the potential of durian skin, an abundant agricultural byproduct, as a raw material for bioethanol production. Alkaline pretreatment using NaOH significantly altered the chemical composition and structural properties of durian skin, increasing cellulose content and removing lignin. The cellulose content of the outer durian skin (ODS) and deep durian skin (DDS) increased by 57.53% and 59.28%, respectively, after pretreatment. The X-ray diffraction and Fourier transform infrared spectroscopy of cellulose and lignin provide significant information. Using 30 FPU enzymes to load the substrate results in DDS producing 126 g/L of glucose and 42.8 g/L of ethanol. The optimal conditions are 15% NaOH pretreatment, 150 °C, 4 bars pressure, and 90 min. The study demonstrates the economic viability and environmental benefits of utilising durian skin for bioethanol production, offering insights into sustainable energy sources and waste valorisation. These findings contribute to the global shift towards renewable energy and highlight the importance of pretreatment in enhancing bioethanol production efficiency from agricultural biomass waste.