Understanding physicochemical changes in pretreated and enzyme hydrolysed hemp (Cannabis sativa) biomass for biorefinery development

The physicochemical properties of hemp biomass structure to pretreatment and enzymatic hydrolysis were investigated to improve upon reducing sugar production for biofuel development. Sodium hydroxide pretreated biomass (SHPB) yielded maximum conversion of holocellulose into reducing sugar (72 %). Scanning electron microscopy (SEM) revealed that enzymatic hydrolysis generated regular micropores in the fragmented biomass structure. The thermogravimetric analysis (TGA) curve suggested the degradation of hemicellulose and cellulose, which conformed well to the subsequent nuclear magnetic resonance (NMR) studies indicating the presence of alpha- and beta-glucose (28.4 %) and alpha- and beta-xylose (10.7 %), the major carbohydrate components commonly found in hydrolysis products of hemicellulose and cellulose. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra showed stretching modes of the lignin acetyl group, suggesting the loosening of the polymer matrix and thus the exposure of the cellulose polymorphs. X-ray diffraction pattern indicated that enzymatic hydrolysis caused a higher crystallinity index (36.71), due to the fragmentation of amorphous cellulose leading to the reducing sugar production suitable for biofuel development.