Cobalt oxide functionalized ceramic membrane for 4-hydroxybenzoic acid degradation via peroxymonosulfate activation

Membrane separation and sulfate radicals-based advanced oxidation processes (SR-AOPs) can be combined as an efficient technique for the elimination of organic pollutants. The immobilization of metal oxide catalysts on ceramic membranes can enrich the membrane separation technology with catalytic oxidation avoiding recovering suspended catalysts. Herein, nanostructured Co₃O₄ ceramic catalytic membranes with different Co loadings were fabricated via a simple ball-milling and calcination process. Uniform distribution of Co₃O₄ nanoparticles in the membrane provided sufficient active sites for catalytic oxidation of 4-hydroxybenzoic acid (HBA). Mechanistic studies were conducted to determine the reactive radicals and showed that both SO₄^•- and ^•OH were present in the catalytic process while SO₄^•- plays the dominant role. The anti-fouling performance of the composite Co@Al₂O₃ membranes was also evaluated, showing that a great flux recovery was achieved with the addition of PMS for the fouling caused by humic acid (HA).