Kinetic analysis for oxidation of oleic acid

Oleic acid oxidation experiments were conducted under various temperature conditions, and the time courses of the concentrations of oleic acid, hydroperoxide and dissolved oxygen (DO) were measured. A novel kinetic model was constructed on the basis of an autocatalytic free-radical chain reaction mechanism, in which two kinds of initiation reactions due to hydroperoxide decomposition, the reaction to generate a secondary product, and the consecutive reaction of the secondary product with oxygen were involved. There were seven unknown constants, two constants for gas-liquid mass transfer, and five constants for chemical reaction in the model. In order to estimate the constants for the gas-liquid mass transfer, gas absorption experiments were conducted using oleic acid with antioxidant. The chemical kinetic constants were estimated by fitting the model equations with the results for the concentrations of the oleic acid, the hydroperoxide and the dissolved oxygen obtained experimentally. The fitted results were in good agreement with the experimental data over a wide range of temperatures. The validity of activation energies in the kinetic constants was verified by comparison with the previously reported literature values. Furthermore, the variation of the oxidized oleic acid composition was simulated by the model.