Studies on Thermal, Oxidative and Cold Flow Properties of Ethyl Esters prepared from High FFA Karanja Oil

Abstract

Transesterification of high FFAs karanja oil was carried out with ethanol in presence of KOH as a catalyst. Two-step process was used to produce biodiesel from karanja oil. Initially pre-treatment i.e. acid –catalyzed esterification process was carried out to reduce FFAs content. The maximum decrease in the FFAs of karanja oil was found to be 2% at 55^oC, ethanol to oil molar ratio, 6:1; catalyst loading, 1 wt% (H₂SO₄) and reaction time, 75 min. In the second step, pretreated oil was transesterified using alkali (KOH) catalysts. Effect of different process parameters such as temperature, KOH loading, ethanol to molar oil ratio on the yield of ethyl esters was investigated. The maximum yield of ethyl esters was found to be 96-97%. Important fuel properties of karanja ethyl ester were estimated and compared with ASTM standard specifications. The study showed that low viscosity of ethyl ester increases the susceptibility of esters to oxidation and hence enhances the auto oxidation process and gives lower thermal and oxidative stability than the original oil. The cold flow property i.e. pour point of the prepared ethyl esters estimated using differential scanning calorimetry (DSC) technique was found to be -2^oC.