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Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: batch and fluidized bed reactor study Svetlana Saponjic Zorica D. Knezevic-Jugovic* Dejan I. Bezbradica Milena G. Zuza Omar Ali Saied Nevenka Boskovic-Vragolovic Dusan Z. Mijin *Corresponding author Keywords: bioreactors, covalent immobilization, ester, non-aqueous system, optimization technique.
Lipase from Candida rugosa was covalently immobilized on sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion (> 99%) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g -1 dry support and in a relatively short time (24 hrs) at 37ºC, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2% yield after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale. |