Magnetic nano-sized cadmium ferrite as an efficient catalyst for the degradation of Congo red in the presence of microwave irradiation

Abstract

A highly active nano-sized CdFe₂O₄ catalyst was prepared by a hydrothermal process and characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), BET specific surface area method, and vibrating sample magnetometer (VSM) at room temperature. Application of the microwave-induced catalytic degradation method in the abatement of Congo red (CR) using the magnetic catalyst was studied. The degradation ratio of CR with CdFe₂O₄ reached 94.4% with 10 min microwave irradiation (MW), proving CdFe₂O₄ to be an excellent microwave catalyst. The intermediate products from CR degradation were investigated by UV-Vis, HPLC and ion chromatography. The reaction kinetics, effects of different ion species (SO₄²⁻, NO₃⁻, HCO₃⁻, and CH₃COO⁻), pH of the solution, dye initial concentration, dosage of catalyst, as well as degradation mechanism were comprehensively studied. Radical trapping studies and the fluorescence technique revealed the holes (h⁺) and hydroxyl radicals (˙OH) were involved as the main active species in the reaction. The band structure of CdFe₂O₄ was analyzed by UV-Vis diffuse reflectance spectroscopy and Mott–Schottky measurements. The mechanism of the degradation was discussed in detail. This work can provide an effective technology for dye wastewater treatment.