Fluidized-bed Fenton treatment of imidacloprid: Optimization and degradation pathway

Abstract

Environmental impact of pesticides is one of the great concerns being addressed by water-food nexus research. Imidacloprid is one of the most used insecticides as an alternative for carcinogenic organochloride insecticides. Even though Imidacloprid has lower toxicity for mammals, its fate and incomplete degradation by conventional wastewater treatment technologies are worrisome when considering continuous environmental exposure. Application of fluidized-bed Fenton process is proposed as an alternative treatment to mitigate the impact of imidacloprid in water. The consequence of different experimental parameter variations such as Fe2+ catalyst concentration, H2O2 concentration and propylene glycol (a common excipient in commercial pesticides) was evaluated. Experimental results under optimized conditions demonstrate almost complete removal of imidacloprid and abatement of chemical oxygen demand and total organic carbon. The intermediates of oxidized imidacloprid yield during fluidized-bed Fenton treatment were identified using GC–MS and a reaction sequence for imidacloprid degradation was proposed. Keywords: Fluidized-bed Fenton, Wastewater treatment technologies, Contaminants of emerging concern, Advanced oxidation processes, Pesticides