Optimized biodiesel production from Ricinus communis oil using CaO, C/CaO and KOH catalysts under conventional and ultrasonic conditions

Abstract

This paper introduces a cheap local Ricinus communis, which grows in Jahrom, a warm region of southwest Iran, as a renewable energy source. Biodiesel production was investigated by employing CaO and C:CaO as heterogeneous catalysts and KOH as a homogenous catalyst. Conventional and ultrasonic-assisted methods were used considering different methanol to oil molar ratios (4:1, 6:1 and 8:1) and different temperatures (40 ˚C, 50 ˚C and 60 ˚C). The optimized production condition was assessed by response surface methodology (RSM). The results showed that the most suitable catalyst was C:CaO with a methanol to oil molar ratio of 6:1 and temperature of 60 ˚C. Using carbon with CaO increased biodiesel yield by around 20% compared to CaO alone. In all conditions, ultrasonic assistance improved biodiesel yield compared to the conventional method by around 11%. Furthermore, the biodiesel content increased with increasing ultrasonic power from 100 to 400 W. The properties of the produced biodiesel from Iranian castor oil meet the requirements of the EN 14214 biodiesel standard. Optimization of the biodiesel production under ultrasonic condition using RSM shows that the best temperature is 46.81 °C and the methanol to oil molar ratio is 5.25 by Cao:C catalyst.