Photodegradation of aqueous 2,4-Dichlorophenol under visible light using Fe-ZnO catalysts prepared by impregnation method

Abstract

Fe-ZnO catalysts were synthesized by impregnation technique and used to test the photocatalytic degradation of 2,4-DCP under visible light. Catalyst characteristic mainly presented wurtzite structure of ZnO, with crystalline size of 35-40 nm and 5-10 m²g⁻¹ of specific surface area. Visible absorption of Fe-ZnO catalyst increased proportionally with Fe content. Oxidation state of Fe on ZnO surface was +3 and zero point charge was found at pH 9.5. Degradation experimental following Box-Behnken analysis provided an optimal condition of 2,4-DCP (initial concentration: 5.0 mg L⁻¹) degradation under visible light at 5.0 mol% Fe-ZnO calcined at 700, and catalyst loading of 1.5 g L⁻¹ (volume of synthetic waste water). Besides, the addition of 2 mM potassium persulfate (K₂S₂O₈) could increase the degradation efficiency and the reaction could be completed within 90 min. The degradation performance on Fe-ZnO combined with K₂S₂O₈ was 5 times higher than that using ZnO combined with K₂S₂O₈. Reaction kinetics was fitted very well with the Langmuir-Hinshelwood model