Heterogeneous Catalytic Oxidation of Aqueous Phenol on Red Mud-Supported Cobalt Catalysts

Red mud (RM), an industrial waste from the alumina refinery industry, was used as a support for preparation of Co-oxide-based catalysts (Co/RM). The samples were characterized by N 2 adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and UV–vis diffusive reflectance spectroscopy. The heterogeneous catalytic activity was evaluated in aqueous phenol degradation using peroxymonosulphate (PMS) as an oxidizing agent. It was found that Co 3 O 4 particles were highly dispersed on the RM surface and that pretreatment of the red mud (RM-T) would significantly influence catalytic activity. Co/RM-T catalysts exhibited high effectiveness in heterogeneous activation of PMS to produce sulfate radicals for phenol degradation compared with Co/RM-NT. Phenol degradation followed first-order kinetics, and activation energies on Co/RM-T and Co/RM-NT are 46.2 and 47.0 kJ/mol, respectively.