Acid-catalyzed esteriﬁcation of free fatty acids with ethanol: an assessment of acid oil pretreatment, kinetic modeling and simulation Paula C. Murad 1 • Fabiane Hamerski 1 • Marcos L. Corazza 1 • Luiz F. L. Luz Jr. 1 • Fernando A. P. Voll 1 Received: 25 September 2017 / Accepted: 17 December 2017 Ó Akade ´miai Kiado ´, Budapest, Hungary 2017 Abstract This work reports experimental data and kinetic modeling of the esteri- ﬁcation of different free fatty acids (lauric, stearic, oleic, and also an industrial mixture of fatty acids) with ethanol catalyzed by sulfuric acid. In addition, the esteriﬁcation of acid oil was also studied. The effects of temperature (40, 50, 60, 70 °C), amount of catalyst (0.330, 0.425 and 0.66 wt% of H 2 SO 4 related to the mass of substrate, which includes ethanol and free fatty acid) and initial molar ratio of ethanol to fatty acid (1:1, 6:1, 9:1, 12:1) were evaluated. The kinetics was modeled using an elementary mechanism approach considering a homogeneous system. The model parameters were estimated by ﬁtting the kinetic model to the experimental data of lauric acid esteriﬁcation, and, therefore, the model was used to predict the esteriﬁcation of different feedstocks. The predictions were in a good agreement with the experimental data obtained, which means that the parameters adjusted for lauric acid esteriﬁcation can be used for simulations involving acid oils and different types of free fatty acids. Keywords Esteriﬁcation  Sulfuric acid  Acid oil  Lauric acid Introduction Biodiesel is deﬁned by the American Society for Testing and Materials (ASTM) as monoalkyl esters of long chain fatty acids derived from renewable lipid feedstock, which can be vegetable oils or animal fats. Some advantages of biodiesel are its & Fernando A. P. Voll fernando_voll@ufpr.br 1 Department of Chemical Engineering, Parana ´ Federal University (UFPR), Polytechnic Center (DTQ/ST/UFPR), Jardim das Ame ´ricas, Curitiba, PR 82530-990, Brazil 123 Reac Kinet Mech Cat https://doi.org/10.1007/s11144-017-1335-3