Investigation of sugar extraction capability from rice paddy straw for potential use of bioethanol production towards energy security

Abstract

ABSTRACT Over the past decades, bioethanol has emerged as an important alternative to fossil fuels. Moreover, bioethanol reduces the overall CO2 emission (greenhouse gas emission) compared to petroleum fuels as these are plant derived. Bioethanol will also provide energy security in the regions/countries where fossil fuels are in scarcity. Bioethanol is produced widely using edible resources like sugarcane, rice, and corn grains, etc. It has been a concern that the edible sources may create problem in food security. With these concerns, non-edible feedstock such as rice paddy straw and corn straw-based lignocellulose biomass has drawn tremendous attention toward the second generation (2G) ethanol production as a sustainable bioenergy source for internal combustion (IC) engine. Cellulose and hemicellulose contents are higher in biomass, which can be used as a source of reducing sugar to produce ethanol. Higher concentration of lignin fibers in the non-edible raw materials makes the sugar extraction challenging. The use of acidic medium such as hydrochloric acid (HCl) and sulfuric acid (H2SO4) makes it easier to break down the lignin fibers and enhances the sugar extraction. In this work, varying concentrations of HCl and H2SO4 were used to examine and maximize the sugar extraction from rice paddy straw. HCl was observed to provide higher yielding of sugar compared to H2SO4. Furthermore, a temperature-variation study (during the hydrolysis process) was also performed to evaluate the variation in sugar yielding with 2.0% HCl (v/v).