CONICET | Buscador de Institutos y Recursos Humanos

Epoxidized soybean oils (SO) and its fatty acid methyl esters (FAME) are extremely valuable because of the many reactions they undergo. They have many commercial applications, e.g., specially as additive for PVC. Epoxidation reactions are generally performed in a two-phase system using organic peracids generated in-situ. An oxidant -H2O2- reacts with a carboxylic acid (AA) -an oxygen carrier- in the aqueous phase, to give a peracid (PAA). The PAA attacks the double bonds of the unsaturated SO or FAME in the organic phase to form the oxirane ring giving AA as the co-product, which returns to the aqueous phase to close the sequence. This work forms part of a research program that analysis the liquid-liquid reacting epoxidation process, taking into account each of the transport and intrinsic kinetic steps in both phases, that will allow us to establish well-founded criteria for reactor design and to determine whether obtaining intrinsic kinetic data under process conditions is feasible. In particular in this paper we determined the partition coefficient (K) of AA between aqueous and oil phases that is needed to be able to model the two-phase system. The experiments were conducted by equilibrating the systems, SO-H2O-AA and FAME-H20-AA, at 40 ºC. AOCS norms were employed in the characterization of SO and FAME. The carboxylic acids were measured in both phases and the water content in the organic phase was determined by Karl Fischer. The partition coefficients were also estimated by applying the activity coefficients of the carboxylic acid in the two phases using a predictive group contribution method, the UNIFAC equation. The K values estimated with UNIFAC were of the same order of magnitude than the experimental values. Then, this calculation method could be used as a predictive tool for process optimisation or design.