based on three-step methanolysis of vegetable oil using Candida antarctica lipase immobilized on the acrylic resin (Novozyme 435) was designed, improving the reaction rate and yield. However, the enzyme stability was rather low and the system could not be used repeatedly, which was attributed to a partial deactivation of the lipase by methanol.This work was aimed to explore the feasibility of producing biodiesel from sunflower oil using the immobilized C. antarctica lipase in a solvent-free system. In an attempt to improve enzyme stability and to convert the starting triglycerides directly to the esters, novel acyl acceptors were tested for biodiesel production with respect to their effects on enzyme activity and stability. Although satisfactory performance for several acyl acceptors was achieved, the highest reaction rate was attained with methyl acetate as acyl acceptor. The process was optimized in the industrially feasible batch stirred tank and packed bed reactor systems confirming the importance of using an excess of acyl acceptor compared to the stoichiometric amount for maximum conversion (methyl acetate/oil molar ratio of 12:1).It appears that the use of methyl acetate as an acyl acceptor has significantly improved the operational stability of the immobilized system at solvent-free conditions, which retained around 80% of initial activity after 12 sequential batches, revealing the biocatalyst half-life of 1723 hours. Although satisfactory performance in a batch stirred tank reactor was achieved, kinetics in a packed bed reactor system seems to have a slightly better profile (93.6 ± 3.75% biodiesel yield after eight to ten hours), corresponding to a volumetric productivity of 48.5 g/(dm 3 hour). The stability of the immobilized system in a packed bed reactor also proved to be very attractive with eight consecutive ten hours uses with a residual activity of 94%, implying that the proposed process and the immobilized system could provide a promising solution for the biodiesel synthesis at the industrial scale.Laccase (EC 1.10.3.1) catalyse the oxidation by molecular oxygen of phenols up to phenoxyl radicals. The spatial structure of laccase from Trametes versicolor (LAC) has been determined by several authors and it is commercially available. The broad substrate selectivity and the high oxidation potential of LAC have lead to applications on healthcare, agricultural, industrial and environmental biotechnology.2,4,6-Trichlorophenol (TCP) is a pesticide, antiseptic and wood preservative, classified as environmental pollutant and probable human carcinogen by the USEPA. The airborne fungi can convert TCP into 2,4,6-trichloroanisole (TCA), chief cause of cork taint from polluted cork stoppers to wines.There are few studies about the enzymatic biodegradation of TCP by LAC, mainly focused on the identification of the oxidation product, 2,6-dichloro-1,4-benzoquinone (DCBQ), by MS and NMR. The aim of this work is the kinetic optimization of the assay conditions for this enzymatic reaction, with separation and determ...
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