Removal of imidacloprid insecticide in the photocatalytic activation of proxymonosulfate with modified magnesium oxide as catalyst using ultraviolet A

Background and Objective: Imidacloprid, a neonicotinide plant toxin, is used as an insecticide in agriculture. Due to its high degradation resistance and water solubility it is of highly concerns. Therefore, the aim of this study was to investigate the degradation of imidacloprid by modified magnesium oxide catalyst under irradiation of light and peroxymonosulfate. Materials and Methods: In this study, modification of magnesium oxide with nitrogen was made by sol-gel method and then iron oxide nanoparticles was used as a magnetic source. Operational parameters were catalyst loading, peroxymonosulfate concentration, reaction time and common anions (nitrate, bicarbonate and chloride). Residual concentration of contaminant was measured by high performance liquid chromatography (HPLC) and mineralization rate was evaluated by measuring TOC. Results: The results of the study showed that the photocatalytic degradation of the pollutant in the optimal condition was as following: catalyst concentration= 150 mg/L, peroxymonosulfate = 75 mg/L and reaction time= 60 min was 88%. Moreover, at optimum condition, the rate of mineralization was obtained 52%. Results comparison for prepared catalyst under light and dark condition indicated that the as-made catalyst is photocatalytic. Conclusion: The as-prepared catalyst can be activated as a photocatalyst under LED light and proxymonosulfate for removal of organic pollutants.