Ultrasound-assisted enzymatic preparation of fatty acid ethyl ester in deep eutectic solvent

Abstract

In this paper, fatty acid ethyl ester (FAEE) was enzymatically produced from the waste oil and ethanol. It was investigated under three different conditions: ultrasound, deep eutectic solvent (DES) and ultrasound-assisted DES. The effects of lipase dosage, alcohol oil ratio, reaction temperature, ultrasonic power, reaction time and DES dosage on the conversion rate of FAEE were explored. The ultrasonic-assisted DES optimization experiment was carried out through the response surface experiment with five factors and three levels. The experimental results showed that the conversion of FAEE was significantly improved and the reaction time was shortened under the ultrasound-assisted DES system, the ultrasonic power and reaction temperature had synergistic effect on the conversion of FAEE. The conversion rate of FAEE reached 93.61 ± 0.46% on the condition of reaction temperature 59 °C, ultrasonic power 80 W, and reaction time 137 min with addition of 6.4% lipase and 4 mmol alcohol for 1 g oil.