Fabrication of a Co3O4 monolithic membrane catalyst as an efficient PMS activator for the removal of methylene blue

Abstract

In this work, a Co₃O₄ monolithic membrane catalyst with a nanosheet-like morphology was successfully fabricated on a porous nickel foam (NF) substrate using a facile two-step approach. The catalytic behavior of this kind of Co₃O₄ monolithic membrane in activating peroxymonosulfate (PMS) was evaluated by employing methylene blue (MB) as the degradation model. The results showed that a MB degradation rate of 84.06% could be achieved within 40 min under the reaction conditions: two pieces of NF-based Co₃O₄ catalytic films (2 × 4 cm²), 0.6 mmol L⁻¹ of PMS, 10 mg L⁻¹ of MB with a volume of 500 mL, and a temperature of 25 °C. Moreover, ˙OH, SO₄˙⁻, ˙O₂⁻ and ¹O₂ were identified as the reactive oxygen species (ROS) responsible for MB degradation by an electron paramagnetic resonance (EPR) technique. Remarkably, the Co₃O₄ monolithic membrane catalyst presented a stable performance upon PMS activation. A MB degradation rate of more than 65% could be kept even after eleven consecutive cycling runs. These results revealed that the NF-based Co₃O₄ membrane was a promising candidate catalyst towards PMS activation for treating aquatic dye contaminants attributed to its excellent performance and easy recovery nature.