Synthesis, physical and electrochemical properties of CoMn2O4: application to photocatalytic Ni2+ reduction

Nickel is a hazardous metal with a harmful effect on the health and environment. In this work, the photocatalytic reduction of Ni2+ was examined onto the hetero-system CoMn2O4/TiO2 under visible light irradiation. The spinel CoMn2O4 is prepared by co-precipitation and characterized in detail to correlate its structural, textural, morphological, compositional, optical and photoelectrochemical features. The effects of pH, catalyst dose and Ni2+ concentration were optimized. The Ni2+ reduction increased with decreasing both the catalyst dose and pH. The highest performance was obtained at pH 7.4, a catalyst dose of 1 g/L and Ni2+ concentration of 10 mg L-1 with a removal abatement of 88% after 180 min irradiation. The data were suitably fitted by the pseudo-first-order kinetic reaction with an apparent constant of 0.027 min(-1). Besides, the durability and the stability of the hetero-system CoMn2O4/TiO2 were evaluated by four consecutive catalytic cycles.

Automated summary

This study explores the photocatalytic reduction of Ni2+ using the hetero-system CoMn2O4/TiO2 under visible light irradiation. It was found that the optimal conditions were a pH of 7.4, catalyst dose of 1 g/L, and Ni2+ concentration of 10 mg/L, resulting in an 88% removal rate after 180 minutes of irradiation. The data was fitted with a pseudo-first-order kinetic reaction with an apparent constant of 0.027 min(-1), and the durability and stability of the CoMn2O4/TiO2 hetero-system were evaluated over four consecutive catalytic cycles.