Preparation, performance and mechanism of metal oxide modified catalytic ceramic membranes for wastewater treatment

Abstract

Catalytic ceramic membranes (CMs) integrated with different metal oxides were designed and fabricated by an impregnation-sintering method. The characterization results indicated that the metal oxides (Co₃O₄, MnO₂, Fe₂O₃ and CuO) were uniformly anchored around the Al₂O₃ particles of the membrane basal materials, which could provide a large number of active sites throughout the membrane for the activation of peroxymonosulfate (PMS). The performance of the CMs/PMS system was evaluated by filtrating a phenol solution under different operating conditions. All the four catalytic CMs showed desirable phenol removal efficiency and the performance was in order of CoCM, MnCM, FeCM and CuCM. Moreover, the low metal ion leaching and high catalytic activity even after the 6th run revealed the good stability and reusability of the catalytic CMs. Quenching experiments and electron paramagnetic resonance (EPR) measurements were conducted to discuss the mechanism of PMS activation in the CMs/PMS system. The reactive oxygen species (ROS) were supposed to be SO₄˙⁻ and ¹O₂ in the CoCM/PMS system, ¹O₂ and O₂˙⁻ in the MnCM/PMS system, SO₄˙⁻ and ·OH in the FeCM/PMS system, and SO₄˙⁻ in the CuCM/PMS system, respectively. The comparative study on the performance and mechanism of the four CMs provides a better understanding of the integrated PMS-CMs behaviors.