In situ growth of CuFeS2/CuS bridged heterojunction catalyst with mixed redox-couple cations for excellent photocatalytic degradation of organophosphate insecticide: CFD and DFT modeling

Abstract

The coupling of interfacial electron transfer engineering and mass transfer booster photoreactors has merged as a promising strategy for facilitating photogenerated charge carriers' consumption capability and maximizing photocatalytic efficiency. Herein, a type II visible-light-driven CuFeS2/CuS (CFC) p-n heterojunction was synthesized for photocatalytic degradation of the Malathion (MA) in a compact static mixer photoreactor (SMPR). Physicochemical, photoelectrochemical and density functional theory (DFT) analyses verify the characteristics of type II p-n homojunction and interfacial charge transfer that exists between the interlayer in n-type CuFeS2 and p-type CuS and create an ultrahigh electron transfer tunnel. This system accelerates the separation of photoinduced electrons as well as increases the yields of reactive species (•O2−, h+ and •OH). The CuFeS2/CuS heterojunction revealed high photocatalytic activity, which can completely degrade malathion (25 mg/L) in an aqueous solution within 80 min. Additionally, the computational fluid dynamics (CFD) technique was applied to study the hydrodynamics studies of the photoreactor. The magnitude of solution velocity, photocatalyst particles’ trajectory, and malathion concentration profile was analyzed according to the CFD results and further validated based on the experimental data. The total degradation efficiency of malathion was achieved at 80 min. This study enables deep insights into the risk assessment of intermediates and their toxicity as well as promotes new avenues in the photocatalytic process for the effective degradation of organic pollutants in wastewater.