Lignocellulosic Content and Biofuel Potential of Post-harvest Sugarcane Leaves from Commonly Cultivated Indian Varieties

Sugarcane is one of the most important crops in India and its post-harvest leaves having low fodder value compared to many other agri residues, can be utilized for biofuel production. There is no detailed information on the lignocellulosic content of cane straw from different varieties, which could be helpful for the selection of potential biofuel feedstock and designing suitable pretreatment methods. Hence, in the present study, lignocellulosic content of post-harvest leaves from seventeen Indian cane varieties was analyzed for its better utilization in bioethanol production. Major cell wall polymers such as cellulose, hemicellulose and lignin were estimated in a range of 53.8-38.7%, 34.4-23.6% and 18.9-13.3% dry weight of biomass respectively in these varieties. Cellulose, hemicellulose and lignin contents in Nayana (CO 86032) were found to be 53.8%, 31% and 18.4% respectively. Among the tested varieties, Nayana was selected for further pretreatment studies being one of the candidates widely cultivated in India with high sucrose and cellulose content. 1-ethyl,3-methylimidazolium acetate ([Emim][Ac]) pretreatment at 150°C for 3 hr was found to be effective in biomass depolymerization. Higher degree of delignification was observed in [Emim][Ac] (62.1%) compared to hot water pretreatment (13.4%). FTIR spectra also confirmed the effective depolymerization of the biomass. The biofuel potential of [Emim][Ac] pretreated biomass was assessed in terms of saccharification efficiency and was found 3.8 fold higher compared to untreated biomass at 72 hr of enzymatic hydrolysis.