Photocatalytic mineralization of chlorpyrifos using CdS/MAX-phase nanocomposites and detailed investigation of the mechanism and degradation pathways†

Abstract

Due to the increased demand for food supplies, the agricultural sector has been enormously expanded and food production has been enhanced using various agrochemicals. Agrochemicals are known to have adverse effects on human health. Additionally, their extensive use has led to bioaccumulation affecting water quality and aquatic fauna. Taking the problem of bioaccumulation, the present study reports the use of CdS/MAX-phase for the photo mineralization of chlorpyrifos in an aqueous solution. CdS/MAX-phase nanocomposites with different loadings of CdS have been prepared via a simple one-pot thermal decomposition approach at 180 °C for 1 hour. The synthesized CdS/MAX-phase nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM) techniques. A maximum of 93% degradation of chlorpyrifos under visible light exposure using the nanocomposites was observed in 90 minutes with 3 major intermediates, chlorpyrifos-oxon, 3,5,6-trichloro 2-pyridinol, and pyridine. Studies on the effect of the parameters suggested that the best photocatalytic performance was achieved at pH 7.8 and a dosage of 1 mg mL⁻¹. A detailed investigation of the degradation pathways, mineralization studies, and a comprehensive mechanism supported by LC–MS and scavenger studies have been reported in the present study.