Dependence of Oleic Acid Ozonolysis Rate on Film Thickness From Surface to Bulk Phases: Experimental and Modeling Approaches

Abstract

The surface and bulk reactions involved in alkene ozonolysis were investigated via reaction-system modeling using oleic acid (OA) as the representative alkene. Fourier transform infrared spectroscopy (FITR) confirmed the production of several products, including ketones and esters, as reported previously. Kinetic analysis of the experimental results indicated that the ozonolysis rate-constant was 14.6 times higher on the OA surface than in the liquid-bulk phase. Reaction-diffusion equation modeling of the surface/bulk kinetics of OA ozonolysis indicated that approximately 80% of the ozonolysis occurred on the surface of the OA thin films, over different thickness ranges, with the same result observed for all thicknesses examined (0.5–10 µm). The rate constants of the surface and bulk phase kinetics and the diffusivity of the reaction system do not affect the heterogeneousness of OA ozonolysis, indicating that the constant kinetics of surface/bulk reactions could be applied to the various size of particulate matter evaluated by air quality modeling.