The Jatropha oil used had an initial acid value of 6.2 mg KOH/g corresponding to a free fatty acid (FFA) level of 3.1%, which is above the 1% limit for a satisfactory transesterification reaction using an alkaline catalyst [16]. Therefore, FFAs were first converted to esters in a pretreatment process with methanol (molar ratio methanol/oil = 6.5:1) using H2SO4 as catalyst (0.3%) in 90 min reaction time at 60 °C [