Characterizations of lignocellulose waxes and study of their effects on enzymatic saccharification for biofuel production

Abstract

Wax is considered to be by-products of biofuel production from lignocellulosic biomass and agricultural processing plants. Although, attempts to find applications of waxes obtained from these sources have been made, yet, little proportions of cases were successfully practical in industrial applications due to lacking of wax characterization data. This research aims to characterize wax properties of three types of lignocellulose biomass; Rice straw (RS), Sugarcane bagasse (SB) and Napier grass (NG); obtained from Soxhlet extraction technique with hexane solvent. The chemical and physical properties of waxes were analysed by Fourier Transform Infrared analysis (FT-IR) analysis and Differential Scanning Calorimeter (DSC) suggesting the similarity of properties between NG and SB waxes. To test the effect of wax on biofuel production, both dewaxed and non-dewaxed biomass were pretreated with diluted alkali and enzymatically hydrolysed by cellulase. The results showed that the combination of dewaxing and alkali pretreatment increased the cellulose proportions in biomass compared to alkali pretreatment for 21.8%, 10.1% and 16.1% in RS, NG and SB, respectively. Additionally, the combined dewaxing and pretreatment improved the saccharification yields of RS, NG and SB for 5.84%, 35.03% and 26.10%, respectively. Altogether, the existence of wax clearly showed the negative effect on biofuel production, thus dewaxing process should be further considered to be included to improve the biorefining process.