Electrochemical monitoring of the photocatalytic degradation of the insecticide emamectin benzoate using TiO₂ and ZnO materials

Photocatalysis is a rapidly expanding technology where a diverse range of toxic chemicals can be completely degraded in water. In this study, an efficient photocatalytic method for the degradation of the aquatic pollutant, emamectin benzoate, coupled with a novel electrochemical monitoring method is reported for the first time. Photocatalytic reactions were performed in a slurry-based reactor containing either a ZnO or TiO₂ photocatalyst irradiated with 365 nm UV-LEDs. Electrochemical monitoring was accomplished using Square Wave Voltammetry using a cathodically pre-treated boron doped diamond indicator electrode. Parameters such as initial pollutant concentration, solution pH and photocatalyst dosage, were investigated to optimise the process. While ZnO provided a higher initial rate of degradation than TiO₂ at all concentrations investigated, the overall degradation profiles were similar. This novel technique allowed a large range of parameters to be rapidly and effectively scrutinised using electrochemical monitoring of the degradation.