Red mud and fly ash supported Co catalysts for phenol oxidation

Industrial wastes, red mud (RM) and fly ash (FA), were employed as supports for synthesis of Co-oxide based catalysts. Co/RM and Co/FA were characterised by X-ray diffraction (XRD), scanning electron microscopy coupling with energy dispersive spectroscopy (SEM-EDS), elemental mapping, and UV–vis diffuse reflectance spectroscopy. Their catalytic activity in oxone activation for phenol degradation for wastewater treatment was tested. It was found that Co oxide on the catalysts was present in the Co3O4 phase and the oxide showed better dispersion on RM. Co/FA and Co/RM could degrade phenol with the presence of oxone and Co/RM exhibited much higher activity than Co/FA, due to high dispersion of Co oxide and surface basicity of RM. Higher oxone concentration in solution enhanced phenol degradation efficiency and reaction temperature also promoted phenol degradation. Kinetic studies showed that phenol degradation followed first order kinetics and the activation energies on Co/RM and Co/FA were found to be 66.3 and 47.0 kJ/mol, respectively.

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► Red mud (RM) and fly ash (FA) were used for synthesis of supported Co catalysts.
► Co/RM presented higher activity than Co/FA in oxidation of phenol.
► Phenol degradation on Co/RM and Co/FA followed first order kinetics.