Biodiesel production catalyzed by immobilized lipases offers the possibility of easy reuse of the catalyst, which is very important to minimize costs and to make this process economically feasible. In this study, the reuse of three commercial immobilized lipases (Novozym 435, Lipozyme RM IM, and Lipozyme TL IM) was investigated in ethanolysis of soybean oil. The effect of the use of solvents (ethanol, butanol, and hexane) to wash the immobilized lipases before the enzyme reuse was evaluated, as well as the lipase reuse without solvent washing. The washing with butanol and ethanol led to the lowest decrease in ester yield after the first batch and allowed the highest glycerol removal (>85 %) from biocatalysts. The biocatalysts were incubated at 50 °C for 2 h in these three solvents. Esterification activities of the enzyme preparations, scanning electron microscopy (SEM) analyses of the beads, and protein content in organic phase were evaluated before and after incubation in the solvent. SEM analysis showed a significant change in beads morphology of Novozym 435 after contact with hexane. For Lipozyme TL IM lipase, this effect was visualized with ethanol.
RESUMO -Biodiesel é um biocombustível obtido a partir da reação de transesterificação de óleos vegetais com alcoóis de cadeia curta, que pode ser catalisada por lipases imobilizadas. Para diminuir o custo do processo, o biocatalisador pode ser recuperado, lavado com solvente e reutilizado. Assim, foram avaliados os efeitos do solvente (etanol, n-butanol e n-hexano) em três lipases comerciais imobilizadas (Novozym 435, Lipozyme RM IM, Lipozyme TL IM). Os biocatalisadores foram incubados nos solventes por 2 h a 50 ºC. A suspensão foi centrifugada e com o sobrenadante foi realizada a análise do teor de proteínas. A atividade de esterificação da preparação enzimática, bem como a análise de Microscopia Eletrônica de Varredura, antes e após incubação no solvente foram determinadas. A análise por MEV mostrou uma alteração significativa da estrutura da Novozym 435 após incubação em n-hexano, enquanto que para a lipase Lipozyme TL IM, esse efeito foi visualizado, principalmente, com etanol.
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