Bioresource Technology, Vol.115, 208-214, 2012
Scaling up of ethanol production from sugar molasses using yeast immobilized with alginate-based MCM-41 mesoporous zeolite composite carrier
Microporous and mesoporous zeolites, including ZSM-5, H-beta, H-Y, and MCM-41, were modified with 3-aminopropyl-triethoxysilane (APTES), then inorganic fillers, such as abovementioned zeolites or mesoporous materials, (alpha-AlOOH or gamma-Al2O3), were mixed with alginate embedded with yeast; and finally these carriers were cross-linked through the double oxirane. The alginate-based immobilized yeast with MCM-41 exhibited much shorter fermentation time and higher ethanol concentration than pure alginate and other composite carriers with the highest cell concentration of 4.8 x 10(9) cells/mL. The composite carrier maintains the highest ethanol productivity of 6.55 g/L/h for 60 days in continuous fermentation process, implying good operational durability for commercial applications. The reason for the higher bio-catalytical function of the immobilized yeast might lay in the uniformly yeast distribution in the bio-reactor and high yeast cell concentration, which contributed by the improved transmission of fermentation media and combined effects of yeast adsorption by MCM-41 and embedment by alginate. (C) 2011 Elsevier Ltd. All rights reserved.