(2021) Separation and Purification Technology_Investigating crystal plane effect of Co3O4 with various morphologies on catalytic activation of monopersulfate for degradation of phenol in water

Liu W.-J., Wang H., Lee J., Kwon E., Thanh B.X., You S., Park Y.-K., Tong S., Lin K.-Y.A.

(Elsevier B.V.) Separation and Purification Technology ISSN: 13835866 Vol.276 Issue. Article No.119368 DOI: 10.1016/j.seppur.2021.119368

As phenol represents as the most typical persistent organic pollutants in wastewater, SO₄^•−-involved chemical oxidation techniques using monopersulfate (MPS) have been regarded as a promising method to eliminate phenol. Since Co3O4 is the benchmark heterogeneous catalyst for activating MPS, it is highly critical to investigate shape-varied Co₃O₄ catalysts with well-defined crystal planes for activating MPS to degrade phenol. Thus, the aim of this study is to elucidate how different Co3O4 catalysts with various well-defined planes would influence catalytic activities for MPS activation. Specifically, three Co₃O₄ nanocrystals are fabricated: nanoplate (NP), nanobundle (NB), and nanocube (NC) with different dominant exposed facets of {1 1 2}, {1 1 0}, and {1 0 0}, respectively. As the facets of {1 1 2} and {1 1 0} consist of more abundant Co²⁺/Co³⁺, Co₃O₄-NP and Co₃O₄-NB exhibit noticeably higher catalytic activities then Co₃O₄-NC for activating MPS to degrade phenol. Nevertheless, since Co₃O₄-NP shows a much higher surface area than Co₃O₄-NB, Co₃O₄-NP could exhibit a relatively high catalytic activity in comparison to Co₃O₄-NB. In addition, Co3O4-NP also exhibits much faster degradation kinetics with a rate constant of 0.061 min⁻¹ at 30 °C, and more resistance towards pH variation, with much stable reaction stoichiometric efficiencies (RSE) ranging from 0.034 to 0.039 at pH = 3 ~ 9, than the other two Co3O4 nanocrystals, making Co₃O₄-NP with the {1 1 2} facet a more outstanding Co₃O₄ for activating MPS to degrade phenol. © 2021