Ultrasound-assisted interesterification method from coconut oil for biodiesel production via heterogeneous catalyst: Characterization and optimization

Abstract

Ultrasound-assisted interesterification is a new approach for biodiesel production, and in this study, coconut oil was selected as the raw material to produce biodiesel using this technology. Therefore, this study aims to produce biodiesel from the reaction of coconut oil with ethyl acetate via ultrasound-assisted interesterification method with heterogeneous catalysts by characterization and optimization. This study begins by characterizing the eggshell CaO catalyst for 2 h at 900 °C through calcination. Next, the ultrasound-assisted interesterification process was conducted with the parameters of temperature (35 °C, 45 °C, 55 °C), molar ratio (1:6, 1:9, 1:12 w/w), and process time (1, 5, and 10 min). After obtaining biodiesel yield, physicochemical characteristics, gas chromatography-mass spectroscopy, and optimization of three parameters using Design Expert with face-centered central composite design type of 17 experimental designs were analyzed. The biodiesel composition products are fatty acid ethyl ester, triacetin, and diacetin were 21.69%, 1.09%, and 0.61% with density, viscosity, water content, acid value, and flash point of 0.961 g/mL; 5.902 cSt; 0.048%; 0.112 mg KOH/gr of oil; and 142 °C, respectively. The optimization results showed that the quadratic model was suggested with high precision (R${}^2=0.9890$) by obtaining a peak biodiesel yield of 81.17% with a temperature of 55 °C, molar ratio of 1:9.7 (w/w) and process time of 6.03 min.