Tuesday, April 20, 2010
10-43

Biolubricants production using enzymatic catalysis: Synthesis of estolides

Erika C. G. Aguieiras1, Claudia O. Veloso2, Juliana V. Bevilaqua3, Danielle O. Rosas4, and Marta A. P. Langone2. (1) Pós-graduação em Tecnologia dos Processos Químicos e Bioquímicos, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, (2) Ppgeq, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524 / PHLC/ Sala 427, Rio de Janeiro, Brazil, (3) Petrobras, Rio de Janeiro, Brazil, (4) Pdab/Hpe, Cenpes/Petrobras, Av. Horácio Macedo, 950 - Cidade Universitária, Rio de Janeiro, Brazil

Estolide is a generic name for linear oligomeric polyesters that can be formed when the carboxylic acid functionality of one fatty acid links to the site of insaturation of another fatty acid or  the carboxyl group and hydroxyl group of hydroxyl fatty acids are dehydrated to form oligomers. Estolides from oleic acid, castor oil, or any source of hydroxy fatty acids have been explored and show promise as cosmetics, coatings, viscosity controller for chocolate, emulsifiers in margarine and biodegradable lubricants. Chemically synthesized estolides present problems of coloration and odor due to the high reaction temperature required. As an alternative, the enzymatic synthesis of estolides by the catalytic action of lipase (E.C. 3.1.1.3), which acts in mild reaction conditions, can be used. In this work, the synthesis of estolides from oleic acid and methyl ricinoleate (biodiesel from castor oil) was investigated using immobilized commercial lipase. The influence of reaction temperature, enzyme concentration, molar ratio of reactants, reaction time, and the use of molecular sieves to remove water from the reaction medium on the conversion was investigated. Reaction temperature had a positive effect on the conversion. Best results of conversion (30%) were achieved using temperatures higher than 70°C. A linear relation between catalyst concentration and conversion was found. However, an amount of lipase up to 14 wt. % is already enough to saturate the enzyme-substrate system. The addition of 500 mg of molecular sieves after 6 hours of reaction resulted in a conversion of 43.7% after 48 h.