Abstract
Waste bleaching earths from crude vegetable oil refining process contains approximately 40% of its weight as oil. Production of fatty acid alkyl esters by lipase-catalyzed alcoholysis of waste vegetable oil from oil processing industry with primary alcohols in an organic solvent system was investigated. Lipase from Candida cylindracea showed very stable in organic solvent having as high as its hydrophobicity. When n-hexane, diesel oil, and kerosene were used as organic solvent in alcoholysis of waste activated bleaching earth at 10% of lipase concentration, during the first 4 hours of reaction more than 80±6% (w/w) fatty acid alkyl ester with short chain length alcohols was attained. Effect of lipase concentration on maximum fatty acid methyl ester production rate (%/h) is experimentally represented as follow,
maximum fatty acid methyl ester production rate (%/h)=aebx
where a and b are constants, and x denote enzyme concentration (% of waste bleaching earth weight). Constant b in n-hexane, diesel oil, and kerosene was approximately similar. Three types of fatty acid alkyl ester were analyzed as biodiesel fuel. Standard properties were similar compared to diesel fuel, but sulfur content of fatty acid methyl ester was below 0.0001 % (w/w). Considering the blend of fatty acid methyl ester with diesel fuel, use of diesel oil or kerosene in fatty acid methyl ester production leads to reduce the production cost and these results show a promising reutilization method of industrial waste resources containing waste vegetable oils for the production of biodiesel.
