Combining Ultrasound with Mild Alkaline Solutions as an Effective Pretreatment to Boost the Release of Sugar Trapped in Sugarcane Bagasse for Bioethanol Production

Abstract

AbstractThe aim of this work was to develop and optimize process parameters in ultrasound and sono‐assisted alkaline pretreatment of sugarcane bagasse prior to hydrolysis and bioethanol fermentation processes. Following the optimization of ultrasound time and temperature, the influence of concentration of NaOH solution was examined. The optimal condition in ultrasound pretreatment (35 kHz) was achieved at 5 min and 65C. Ultrasound pretreatment of bagasse prior to hydrolysis step resulted in increased sugar concentration from 3.62 g/L (control, 25C) to 5.78 g/L (65C, 5 min). The micromorphology and cellulose crystallinity for native and pretreated bagasse were investigated by scanning electron microscopy and X‐ray diffraction, respectively. The maximum glucan conversion and bioethanol production of 50% and 0.38 g/g glucose were achieved following sono‐assisted alkaline pretreatment (3% NaOH concentration), respectively. The findings indicate that sono‐assisted alkaline pretreated bagasse can be used as a potential feedstock in bioethanol production.Practical ApplicationsCurrent bioethanol production uses food crops such as sugarcane and maize. Large amounts of sugar molecules are present in the lignocellulose of plant material and current research aims to “unlock” the fermentable sugars in agricultural or forestry wastes and residues. The objective of the present research was to find an optimum pretreatment method by combining ultrasound with various concentrations of mild alkaline solution in order to make use of a greater proportion of lignocellulose materials from the sugarcane bagasse for bioethanol production. The development of an efficient pretreatment to increase the cellulose digestibility and fermentability potential of biomass may be of interest in bioethanol industries.