Different Co-based MOFs templated synthesis of Co3O4 nanoparticles to degrade RhB by activation of oxone

Abstract

In this study, Co-based MOF with a 2D structure, 3D microrod structure and 3D nano-dodecahedral structure was synthesized by the coordination of cobalt ions and different organic ligands. Then, Co₃O₄, which was derived from these Co-based MOFs, was used to activate oxone for RhB degradation. It was found that the morphology and structure of the templates can significantly influence the formation of the nano Co₃O₄ products, which has an indirect effect on the catalytic ability of the resulting Co₃O₄ for oxone to degrade RhB. Among the products, nano-sphere Co₃O₄, which was derived from a template with a 3D nano-dodecahedral structure (ZIF-67) can effectively activate oxone to degrade RhB. Under neutral conditions, the rate constant of the degradation of RhB (0.1 mM) was 0.0509 min⁻¹ with 50 mg L⁻¹ catalyst and 1.0 mM oxone based on first-order kinetics. In addition, the influence of a series of parameter factors (pH, the dosage of catalyst and oxone) on the catalyst was also studied. Low cobalt ion dissolution (0.04 mg L⁻¹ at pH = 3, <0.01 mg L⁻¹ at pH = 7) and good recyclability (degradation rate of RhB after 5 cycles: close to 96%, 89% at pH = 7, pH = 3) further proved that the as-prepared Co₃O₄ can be used as a promising catalyst.