Tuesday, May 3, 2011
Lignocellulosic biomass that is composed of carbohydrate polymers has a great potential for commercial usage among the renewable alternative energy sources. Especially, rapeseed stalk, which is an organic waste from processing of rapeseed oil extraction or by-product of bio-diesel production, is available and eco-friendly biomass with very low cost and high content of carbohydrate polymers. The main objectives of this research were to seek effective conditions of oxalic acid pretreatment in producing bio-ethanol from rapeseed stalk - which composed of holocellulose 68.32%, lignin 20.99%, fat 1.02% and ash 8.90% - and possible availabilities of bio- refinery residues from the reactions as well. Therefore, this research analyzed the productivity of bio-ethanol obtained from rapeseed stalk by oxalic acid pretreatment and investigated the effects of the several factors, such as pretreatment temperature (120-160°C), pretreatment time (5-30 min), and various concentrations (0.5-2%) of oxalic acid. Along with each level of oxalic acid pretreatment, SSF (Simultaneous Saccharification and Fermentation) process was carried out and SSF conditions were selected according to the previous results. Cellulase (NS50013, Novozymes, Demark) and β-glucosidase (NS50010, Novozymes, Denmark) were used for enzymatic hydrolysis and wild type xylose fermenting Pichia stipitis CBS 6054 was used for fermentation. After bio-ethanol production, HPLC equipped with RI detector was used to analyze yield of bio-ethanol and elemental analyzer was used to analyze chemical components - carbohydrate compounds, proteins, and ash - of its residues.