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

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.