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The production of biodiesel was investigated using a new reaction system consisting of a reactor coupled to an adsorption column. The esterification reaction was carried out above the boiling points of methanol and water to evaporate the water produced during the reaction. A condenser placed above the adsorption column was responsible for condensing the water and methanol vapor, returning water-free methanol to the reactor after passing through the adsorption column. The adsorption system was employed to remove the water produced during the reaction to shift the equilibrium toward fatty acid methyl ester production. Biodiesel was produced by the esterification reaction of oleic acid and methanol, using sulfuric acid as catalyst. The results showed that the new reaction system yielded up to 99.7% biodiesel, while the highest yield obtained using the traditional agitated batch reactor was 88.2%. The best operating condition was found when the reactor was operated at 100 °C, 1% catalyst (w/w), and with an oleic acid to methanol ratio of 3:1.

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In this work, the stabilizing effect of bovine serum albumin (BSA), peptone (PEP), and polyethylene glycol (PEG) during immobilization of Candida antarctica lipase on activated carbon was investigated. The influence of enzyme concentration and type of additive, added during the immobilization procedure, was studied using a 2 2 factorial central composite design. The goal was to maximize the synthetic activity of butyl butyrate, using butyric acid and butanol as substrate in n-heptane. An increase of 31-58% in the esterification activity was obtained when enzyme concentration on the supernatant was enhanced from 86.50 U m L -1 to 226.80 U mL -1 . An enhancement in esterification activity of 38-68.95% was observed, depending on the initial enzyme concentration, when PEP was used instead of BSA. No significant increase in the esterification activity was observed when PEP was replaced by PEG. However, thermal stability tests at 50°C showed that PEG had a higher stabilizing effect.