Biodiesel Production from High FFA Degummed Rice Bran Oil by a Two-Step Process Using Ethanol/Methanol and a Green Catalyst

Degummed rice bran oil (DRBO) is a low cost raw material considered an excellent alternative to reduce the cost of biodiesel production. The aim of this study was to optimize the esterification process of DRBO. In the first stage, using 100 % of ethanol, nontoxic alcohol obtained from renewable source and ferric sulphate (Fe 2 (SO 4 ) 3 ) as environmentally friendly catalyst adjusting DRBO for the transesterification process in the second step. The raw material had free fatty acids (FFAs) content reduced from 21.8 to 3.0 %, by ethanol esterification reaching 85.8 % conversion of FFA to fatty acid ethyl esters (FAEE), when the molar ratio ethanol:DRBO was 8:1, 3 % of Fe 2 (SO 4 ) 3 by weight and 3 h of reaction time at the reflux temperature of ethanol. In the second step of the reaction by transesterification, potassium hydroxide (KOH) was used as catalyst in a range from 1.0 to 1.75 % by weight of the esterified oil, the molar ratio methanol:oil (6:1), magnetic stirring of 450 rpm and temperature of 60 °C in 1 h of reaction time. After the two steps reaction, the maximum conversion achieved was 96.6 % of the mixture of FAEE and fatty acid methyl esters.