Magnetic CoFe alloy@N-CNTs as fenton-like activator for the efficient abatement of imidacloprid: Kinetics, transformation mechanisms, and toxicity assessment

Abstract

A magnetic bimetal-carbon nanohybrid, CoFe alloy@N-CNTs was designed to activate peroxydisulfate (PDS) for the degradation of imidacloprid (IMI). Under optimal conditions, 5 mg/L of IMI were completely removed within 6 h with a mineralization degree of 42.9 %. Moreover, a high rate of IMI removal was observed over a wide pH range and in the presence of different anions and humic acids. Stability tests conducted over five cycles and material characterizations confirmed the stability of CoFe alloy@N-CNTs. Furthermore, radical and non-radical oxidation contributed to the degradation process based on the results of quenching experiments, electron paramagnetic resonance (EPR), radical quantification and X-ray photoelectron spectroscopy (XPS). Hydroxylation was identified as the main degradation pathway through mass spectrometry observation, frontier electron densities (FEDs) theory calculations, fluorescence intensities and mineralization degree. Additionally, the predicted ecotoxicity of IMI and its intermediates towards three aquatic organisms using ECOSAR software was not harmful or low toxic, verifying the potential application of this technique from an ecological risk perspective. This study provides valuable insights for designing metal–carbon nanohybrids as efficient Fenton-like catalyst in water treatment.