Investigation of photocatalytic chlorpyrifos degradation by a new silica mesoporous material immobilized by WS2 and Fe3O4 nanoparticles: Application of response surface methodology

In the present research, Fe₃O₄ and WS₂ nanoparticles immobilized on or in KIT-6 (KIT: Korea Institute of Science and Technology) pores (KIT-6/WS₂-Fe₃O₄) were synthesized and studied as a photocatalyst for degradation of representative chlorpyrifos as an organophosphorus pesticide. In addition, the KIT-6/WS₂-Fe₃O₄ photocatalyst was characterized by different methods such as TEM, FESEM-EDS-Mapping, XRD, and N₂ adsorption/desorption surface area, in order to understand their morphology, structural, and physical properties. The photocatalytic performance of this photocatalyst was investigated for degradation of chlorpyrifos by visible light irritation. The effects of variables such as chlorpyrifos concentration, KIT-6/WS₂-Fe₃O₄ nanocatalyst amount, pH, and irradiation time on chlorpyrifos degradation efficiency was studied by central composite design with response surface methodology. The optimum conditions for CP degradation were obtained by 50 mg KIT-6/WS₂-Fe₃O₄ nanocatalyst, and 7.2 ppm chlorpyrifos solution with pH = 6, at 52 min. The pseudo-first-order model with rate constants equal to 0.069 min⁻¹ as best choice efficiency described the chlorpyrifos degradation process according to Langmuir-Hinshelwood kinetic.