Synergistic effect in the catalytic activity of lipase Rhizomucor miehei immobilized on zeolites for the production of biodiesel

Gismondine (P) ion exchanged with Cu2+, Zn2+, and Ni2+ were used as solid supports for the immobilization of the lipase Rhizomucor miehei enzyme. Physicochemical characterization of the zeolite-enzyme complexes were performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR). These bio-catalysts were used for the transesterification reaction of soybean oil to biodiesel. Divalent cation species and thermal treatment of the zeolitic supports had different effects on several parameters under investigation. In terms of the enzyme activity, the zeolite-enzyme complexes prepared with Ni-P were superior in comparison to the other ones and a synergistic effect for the zeolite-enzyme complex (Ni-P/200-ENZ) was observed for the transesterification reactions of soybean oil to biodiesel. The total amount of methyl esters produced by the complex Ni-P/200-ENZ was of 56.2%, while the same concentration of the immobilized enzyme in its free form yielded only 39.3% of methyl esters, and Ni-P/200 in its pure form also yielded a very low amount of methyl esters (20%). The other zeolite-enzyme complexes (Zn-P/200-ENZ, Cu-P/200-ENZ, and Na-P/200-ENZ) presented a completely different behavior in comparison to the Ni-P/200-ENZ complexes. The total yields of methyl esters generated by these biocatalysts were very low and no synergistic effects were observed. A correlation between the cation atomic radius and the enzymatic activity of the zeolite-enzyme complexes was observed. It was noticed that the bigger the atomic radius of the extra-framework cation, smaller was the experimental enzymatic activity coefficient. (C) 2012 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Enzymatic transesterification of soybean oil with ethanol using lipases immobilized on highly crystalline PVA microspheres

Polyvinyl alcohol (PVA) microspheres with different degree of crystallinity were used as solid supports for Rhizomucor miehei lipase immobilization, and the enzyme-PVA complexes were used as biocatalysts for the transesterification of soybean oil to fatty acid ethyl esters (FAEE). The amounts of immobilized enzyme on the polymeric supports were similar for both the amorphous microspheres (PVA4) and the high crystalline microspheres (PVA25). However, the enzymatic activity of the immobilized enzymes was depended on the crystallinity degree of the PVA microspheres: enzymes immobilized on the PVA4 microspheres have shown low enzymatic activity (6.13 U mg-1), in comparison with enzymes immobilized on the high crystalline PVA25 microspheres (149.15 U mg-1). A synergistic effect was observed for the enzyme-PVA25 complex during the transesterification reaction of soybean oil to FAEE: transesterification reactions with free enzyme with the equivalent amount of enzyme that were immobilized onto the PVA25 microspheres (5.4 U) have yielded only 20% of FAEE, reactions with the pure highly crystalline microsphere PVA25 have not yielded FAEE, however reactions with the enzyme-PVA25 complexes have yielded 66.3% of FAEE. This synergistic effect of an immobilized enzyme on a polymeric support has not been observed before for transesterification reaction of triacylglycerides into FAEE. Based on ATR-FTIR, 23Na- and 13C-NMR-MAS spectroscopic data and the interaction of the polymeric network intermolecular hydrogen bonds with the lipases residual amino acids a possible explanation for this synergistic effect is provided. © 2013 Elsevier Ltd. All rights reserved