No abstract

Environmental concerns are driving industry to develop viable alternative fuels from renewable resources. On the other hand, to reduce food surplus, the Agricultural Policy of the European Union (EU) obliges the European farmers to leave a percentage of the arable land as set-aside, where can be grown, as an exception, vegetables for nonfood purposes, i.e., energetic ones. Currently, fossil fuels are used in diesel engines and are essential in industrialized places. In addition, petroleum-based diesel increases environmental pollution. To solve these problems, transesterified vegetable oil that has been grown in set-aside lands can be considered to be a renewable energy resource. In this sense, this work describes the optimization of the parameters involved in the transesterification process of Brassica carinata oil. Gas chromatography was used to determine the fatty acid composition of Brassica carinata oil and its esters. Results revealed that the free fatty acid content is a notorious parameter to determine the viability of the vegetable oil transesterification process. In this sense, it was not possible to perform a basic transesterification using Brassica carinata oil with a high erucic acid content. The transesterification process of Brassica carinata without erucic acid required 1.4% KOH and 16% methanol, in the range of 20-45°C, after 30 min of stirring. Our results suggest that the greater the presence of KOH, the lesser the methanol requirements. However, this is valid only under certain limits. Also, if the presence of KOH or methanol is lower or higher than the optimal values, the reaction either does not fully occur or leads to soap production, respectively. Based on this field trial, biodiesel from Brassica carinata oil could be recommended as a diesel fuel candidate if long-term engine performance tests provide satisfactory results.

In this study, chemical parameters involved in waste olive oil transesterification were investigated and optimized. Better results were obtained using KOH and methanol instead of NaOH and ethanol, which decreases transesterification rates. The presence of KOH and methanol above or below the optimum quantity decreases the ester yield because of the presence of soaps or unreacted glycerides, respectively. Settling at ambient temperature under 25°C increases the difficulty of ester and glycerol separation because of a conflict between glycerol solubility and low temperatures. This could be solved by increasing the settling temperature or the time for settling. In summary, the reaction was optimized at ambient temperature using 1.26% KOH, 12% methanol, 1 min of stirring, with 90 min of pour-off time, 11.38% distilled water by volume at 25°C to purify the ester, and drying over 0.5% Na 2 SO 4 . Losses of esters during the washing process were less than 4%. The ester yield of the reaction was 94%. The small presence of unreacted glycerides did not drop the engine performance. Fuel specifications were close to those of diesel fuel, thus indicating that methyl esters from used olive oil can be considered as a fuel candidate.