RESUMO
This work reports the transesterification of soybean oil with ethanol using two commercial immobilized lipases under the influence of ultrasound irradiation. The experiments were performed in an ultrasonic water bath, following a sequence of experimental designs to assess the effects of temperature, enzyme and water concentrations, oil to ethanol molar ratio and output irradiation power on the reaction yield. Results show that ultrasound-assisted lipase-catalyzed transesterification of soybean oil with ethanol might be a potential alternative route to conventional alkali-catalyzed method, as high reaction yields (~90 wt.%) were obtained at mild irradiation power supply (~100 W), and temperature (60 °C) in a relatively short reaction time, 4h, using Lipozyme RM IM as catalyst. The repeated use of the catalyst under the optimum experimental condition resulted in a decay in both enzyme activity and product conversion after two cycles. The use of Novozym 435 led to lower conversions (about 57%) but the enzyme activity was stable after eight cycles of use, showing, however, a reduction in product conversion after the forth cycle.
Assuntos
Lipase/química , Lipase/efeitos da radiação , Compostos Orgânicos/química , Compostos Orgânicos/efeitos da radiação , Sonicação/métodos , Óleo de Soja/química , Óleo de Soja/efeitos da radiação , Ativação Enzimática/efeitos da radiação , Enzimas Imobilizadas , Esterificação/efeitos da radiação , Proteínas Fúngicas , Ondas de Choque de Alta Energia , Cinética , Doses de Radiação , Solventes/química , Solventes/efeitos da radiação , Especificidade por Substrato/efeitos da radiaçãoRESUMO
The present paper describes a protocol for production of diacylglycerol by the partial hydrolysis of soybean oil catalyzed by lipase under ultrasound irradiation. Better yields and shorter reaction times were obtained under sonication as compared to the thermal process.