Biodiesel production from rafination by-products of olive oil in supercritical media

The production of biodiesel derived from olive acid oil, which is obtained by acidification of soapstock during the refinery process of olive oil, in supercritical ethanol was investigated by using a tubular reactor of 45 ml in a bench-scale. The initial free fatty acid content of the feedstock is 85%. Experiments were performed based on experimental design, and operating conditions such as temperature (280-360°C), pressure (100-180 bar), volumetric ratio of ethanol to olive acid oil (1:1-2:1), and flow rate of the reactants mixture (0.3-0.9 mL/min) were selected as parameters to evaluate their effects on conversion. After the reaction ended and the excess of ethanol was removed by vacuum distillation, crude biodiesel samples were dried with anhydrous sodium sulfate in order to remove probable water they might contain. The conversion extent of free fatty acids to ethyl esters was optimized using a Response Surface Methodology. The most important parameters on the conversion were found as temperature and flow rate. Higher ester contents up to 99% were observed at the lower ratios of ethanol to olive acid oil and lower flow rates.