Tuesday, May 3, 2011
The limited resources of fossil fuels, increasing prices of crude oil, and environmental concerns are some reasons for exploring the use of vegetable oils as alternative fuels. Biodiesel is a promising nontoxic and biodegradable renewable fuel comprised of mono-alkyl esters of long chain fatty acids, which can be produced by an enzymatic alcoholysis reaction of vegetable oils using lipases. These enzymes constitute an important group of biotechnologically valuable enzymes, mainly because of the versatility of their properties and ease of mass production. In this work lipase from Pseudomonas fluorescens (LPF) was immobilized by interfacial hydrophobic adsorption on two matrices, i.e., commercial polystyrene functionalized with aromatic groups and macro porous silica functionalized with octyl groups. The immobilization yields were 82.5% and 37.2% respectively to silica and polystyrene supports. The recovered activities were 105% and 21%, respectively to silica and polystyrene supports. Biodiesel was produced by ethanolysis of babassu oil using the “home-made” biocatalysts. The reaction was performed at 40oC, molar ratio oil:ethanol of 1:7, and 10% (m/m) of biocatalyst. The ethyl esters were quantified by gas chromatography. Maximum yield (100%) was achieved after 24h when LPF immobilized on silica-octyl was used. Moreover, a yield of 98.7% was achieved after 48h when LPF immobilized on commercial aromatic polystyrene was used. These results show the great potential of the silica-octyl-LPF biocatalyst in the alcoholysis of babassu oil in order to produces biodiesel fuel.