Photocatalytic degradation of boscalid in aqueous titanium dioxide suspension: Identification of intermediates and degradation pathways

The photocatalytic degradation of boscalid in aqueous suspensions was investigated by using titanium dioxide (TiO2) as a photocatalyst. Accordingly, a complete degradation of fungicide was achieved by applying the optimal operational conditions of 2.5 g L−1 of catalyst, natural pH of 6.0 and the temperature at 20 ± 1 °C after 90 min irradiation. Photodegradation of boscalid exhibited pseudo-first-order reaction kinetics. The rate of photodecomposition of boscalid was measured using high performance liquid chromatography-diode array detector (HPLC-DAD) while its mineralization was followed using total organic carbon (TOC) analysis. The influence of physicochemical parameters such as photonic flux, presence of inorganic cations and anions, pH and oxygen concentration on the kinetic process was studied. The identification of reaction intermediate products was carried out using coupled techniques HPLC–MS/MS after a SPE pre-concentration step and a degradation pathway was proposed. By this technique, 17 degradation products were identified.