Enhanced Reactivity and Stability of Natural Hematite Supported Cobalt for the Catalytic Oxidation of Congo Red Dye

Abstract

Natural hematite supported cobalt (Co/Nat-Hem), a new heterogeneous catalyst, was successfully prepared by a simple impregnation technique. Textural, structural, functional groups and morphological aspects of the prepared catalyst were analyzed by BET, XRD, FT-IR, XRF, pH_pzc, SEM-EDX methods. BET analysis shows that the Co/Nat-Hem catalyst has a specific surface area of ​​13.44 m²/g and a pore volume of 0.062 cm³/g. The SEM-EDX method showed that 7.19 wt% of the cobalt species were dispersed on the surface of the prepared catalyst. The catalytic activity of Co/Nat-Hem was evaluated by photo-Fenton oxidation of the dye Cong red (CR). The effect of reaction parameters on CR oxidation efficiency was investigated. Under optimal reaction conditions (1 g/L catalyst concentration, 0.2 mol/L H₂O₂ initial concentration and pH 3), the percentage of CR discoloration reaches 97% after 30 min. The Co/Nat-Hem catalyst achieved a synergistic ratio of 28.5%, which was added to the oxidation rate of the Nat-Hem catalyst. The stability of the Co/Nat-Hem catalyst was demonstrated by the limited activity of leachates in the homogeneous Fenton oxidation of CR. The phytotoxicity of the CR dye was tested during the irrigation of the bean (Vicia faba L.).