Superior photo-Fenton degradation of acetamiprid by α-Fe2O3-pillared bentonite/L-cysteine complex: Synergy of L-cysteine and visible light

Acetamiprid is a potential threat to human health, aquatic life, soil microorganisms and beneficial insects as a recalcitrant pollutant in wastewater treatment plant effluents. In this work, the synthesized & alpha;-Fe2O3-pillared bentonite (FPB) was used to degrade acetamiprid in the photo-Fenton process with the assistance of L-cysteine (L-cys) existing in natural aquatic environment. The kinetic constant k of acetamiprid degradation by FPB/L-cys in the photo-Fenton process was far more than that in the Fenton process of FPB/L-cys lacking light and the photo-Fenton process of FPB without L-cys. The positive linear correlation between k and & EQUIV;Fe(II) content indicated the synergy of L-cys and visible light accelerated the cycle of Fe(III) to Fe(II) in FPB/L-cys during the degradation of acetamiprid by elevating the visible light response of FPB, and promoting the interfacial electron transfer from the active sites of FPB to hydrogen peroxide and photo-generated electron transfer from conduction band of & alpha;-Fe2O3 to the active sites of FPB. The boosting & BULL;OH and 1O2 were predominantly responsible for acetamiprid degradation. Acetamiprid could be efficiently degraded into less toxic small molecules in the photoFenton process via C-N bond breaking, hydroxylation, demethylation, ketonization, dechlorination, and ring cleavage.

Automated summary

Acetamiprid, a recalcitrant pollutant in wastewater treatment plant effluents, poses a potential threat to human health, aquatic life, soil microorganisms, and beneficial insects. In this study, α-Fe2O3-pillared bentonite (FPB) was synthesized and used in the photo-Fenton process, with the assistance of L-cysteine (L-cys) present in natural aquatic environments, for the degradation of acetamiprid. The degradation rate constant (k) of acetamiprid by FPB/L-cys in the photo-Fenton process was significantly higher than that in the Fenton process of FPB/L-cys without light and the photo-Fenton process of FPB without L-cys. The synergistic effect of L-cys and visible light was found to accelerate the cycle of Fe(III) to Fe(II) in FPB/L-cys, enhancing the visible light response of FPB and promoting interfacial and photo-generated electron transfer for acetamiprid degradation.