Photometabolic pathways of chlorantraniliprole in aqueous slurries containing binary and ternary oxides of Zn and Ti

•The photocatalytic oxidation of chlorantraniliprole (CL) in water was studied.•ZnO, TiO2 and Zn2TiO4 were used as photocatalyst under artificial irradiation.•The addition of Na2S2O8 enhanced the photodegradation rate of CL in all cases.•The efficiency in the photodegradation of CL was in the order: ZnO > TiO2 ≫ Zn2TiO4.•The photodegradation pathways proceed mostly via hydroxylation.

The photocatalytic degradation of a new insecticide, chlorantraniliprole (CL) was studied in aqueous suspensions of binary (ZnO and TiO2) and ternary (Zn2TiO4) oxides of Zn and Ti under artificial light irradiation (300–460 nm). Photocatalytic experiments showed that the addition of semiconductors, paired with Na2S2O8 as electron acceptor, greatly improved the elimination of CL in aqueous slurries compared with ZnO and TiO2 alone, and photolytic tests. The reaction rates significantly increased, especially for ZnO/Na2S2O8 and TiO2/Na2S2O8 systems with half-lives of 53 and 71 min, respectively. Zn2TiO4/Na2S2O8 appears to be less effective than ZnO/Na2S2O8 and TiO2/Na2S2O8, although it can be used as photocatalyst for CL oxidation (t1/2 = 462 min). Seven phototransformation products were identified by liquid chromatography tandem mass spectrometry (LC–MS2) and liquid chromatography time of flight mass spectrometry (LC–TOF/MS) techniques while its mineralization was followed using dissolved organic carbon (DOC) analysis. The probable photooxidation pathways are proposed and discussed, being hydroxylation and N-demethylation the major routes of phototransformation observed.

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