Photodegradation kinetics of organophosphorous with hydroxyl radicals: Experimental and theoretical study

Abstract

The presence of organophosphorus compounds (OPs) in the environmental counterparts has been an important problem because of their toxicity. In this study, the photocatalytic degradation reactions of the three OPs with hydroxyl radical were investigated by both experimental and quantum chemical methods. Photocatalytic degradation kinetics of organophosphorus compounds were investigated under UV-A irradiation using TiO2 as the photocatalyst. The effects of the initial concentrations on the degradation rate have been examined. There was an observable loss of OPs in the presence of TiO2 photocatalyst under UV-A at 0.2 g TiO2 per 100 mL. The quantum chemical calculations have been carried out by the Density Functional Theory (DFT) at B3LYP/6-31g(d) level. Reaction pathways were modeled to find the most probable mechanism for OPs with the OH radical and to determine the primary intermediates. The rate constants of the eight reaction paths were calculated by the Transition State Theory. CPCM (Conductor-like Polarizable Continuum Model) was used as the solvation model with the intention of understanding the water effect. Theoretical results were in agreement with experimental ones.