Rice straw and sugarcane bagasse degradation mimicking lignocellulose decay in nature: An alternative approach to biorefinery

Rice straw (Oryza sativa) and sugarcane bagasse (Saccharum spp.) were subjected to catalytic oxidation. An oxidative cleavage of lignocellulose agro-residues was based on ferric ions and hydrogen peroxide driven by 2,5-dihydroxybenzoic acid (DHB) in weak acidic condition at room temperature. Alteration of inter- and intra-molecular bonding of cellulose and change in cellulose crystallinity which led to influence enzymatic susceptibility were investigated. By means of Fourier transform infrared spectroscopy, functional groups and chemical bonding modification in cellulosic, non-cellulosic, and lignin constituents of rice straw and sugarcane bagasse were characterized. Transformation of crystalline cellulose I-alpha, and I-beta forms was observed after the oxidative reaction. The catalytic oxidative reaction by the Fe3+/DHB/H2O2 system accelerated the modification of cellulose I-alpha to cellulose I-beta phase of sugarcane bagasse. However, the addition of DHB barely affected the oxidative degradation of rice straw. In addition, the crystallinity index of rice straw and sugarcane bagasse that decreased after oxidative reaction caused increases of hydrolytic enzyme accessibilities of treated samples.