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Triethanolamine as an efficient cosolvent for biodiesel production by CaO-catalyzed sunflower oil ethanolysis: An optimization study

Đokić-Stojanović Dušica R. (Zdravlje Actavis, Leskovac, Serbia)
Todorović Zoran B. (Faculty of Technology, University of Niš, Leskovac, Serbia)
Troter Dragan Z. (Faculty of Technology, University of Niš, Leskovac, Serbia)
Stamenković Olivera S. (Faculty of Technology, University of Niš, Leskovac, Serbia)
Veselinović Ljiljana M. (Institute of Technical Sciences of the Serbian Academy of Sciences and Arts, Belgrade, Serbia)
Zdujić Miodrag V. (Institute of Technical Sciences of the Serbian Academy of Sciences and Arts, Belgrade, Serbia)
Manojlović Dragan D. (Faculty of Chemistry, University of Belgrade, Belgrade, Serbia)
Veljković Vlada B. (Faculty of Technology, University of Niš, Leskovac, Serbia + Serbian Academy of Sciences and Arts, Belgrade, Serbia)

Triethanolamine was applied as an efficient „green“ cosolvent for biodiesel production by CaO-catalyzed ethanolysis of sunflower oil. The reaction was conducted in a batch stirred reactor and optimized with respect to the reaction temperature (61.6-78.4°C), the ethanol-to-oil molar ratio (7:1-17:1) and the cosolvent loading (3-36 % of the oil weight) by using a rotatable central composite design (RCCD) combined with the response surface methodology (RSM). The optimal reaction conditions were found to be: the ethanol-to-oil molar ratio of 9:1, the reaction temperature of 75°C and the cosolvent loading of 30 % to oil weight, which resulted in the predicted and actual fatty acid ethyl ester (FAEE) contents of 98.8 % and 97.9±1.3 %, respectively, achieved within only 20 min of the reaction. Also, high FAEE contents were obtained with expired sunflower oil, hempseed oil and waste lard. X-ray diffraction analysis (XRD) was used to understand the changes in the CaO phase. The CaO catalyst can be used without any treatment in two consecutive cycles. Due to the calcium leaching into the product, an additional purification stage must be included in the overall process.

Keywords: biodiesel, heterogeneous catalysis, transesterification, XRD

Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45001