Activity of the ZnO–Fe2O3 catalyst on the degradation of Dicamba and 2,4-D herbicides using simulated solar light

In this study, the solar photocatalytic activity of ZnO–Fe2O3 coupled oxide was investigated for the degradation of commercial Dicamba and 2,4-D herbicides. Both pesticides, which are extensively used in agriculture, are active ingredients in water-soluble commercial formulations called Fortune® (480 g/L 3,6-dichloro-2-methoxybenzoic acid, Dicamba) and Hierbamina® (479.5 g/L 2,4-dichlorophenoxyacetic acid, 2,4-D). The catalyst was synthesized via the sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), and Raman spectroscopy. UV-vis diffuse reflectance spectroscopy (DRS) was used to estimate the band gap energy (Eg) of the prepared material. Photocatalytic tests were conducted in a planar reactor operated in batch-mode using a solar light simulator. Complete degradation of both herbicides was attained for a 10 mg/L initial concentration after 300 min using 0.5 g/L of catalyst loading. Oxalic, formic, and acetic acids were the byproducts identified during the degradation of both herbicides. Dechlorination after photocatalytic decomposition was complete for Dicamba. However, only 70% dehalogenation was attained for 2,4-D under simulated solar light.