Facile preparation of porous Mn/Fe3O4 cubes as peroxymonosulfate activating catalyst for effective bisphenol A degradation

Metal oxides are potentially interesting catalysts for activating peroxymonosulfate (PMS) for the degradation of recalcitrant contaminants. This study presents a magnetic porous Mn-Fe binary oxide (p-Mn/Fe3O4) in micron-size with abundant micro- and meso- pores. This novel catalyst exhibited high efficacy and long-term stability in activating PMS for degradation of bisphenol A (BPA). Sulfate radicals and hydroxyl radicals were identified from catalytic PMS activation according to electron paramagnetic resonance (EPR) characterization. The effects of Fe/Mn ratio, catalyst dose, initial pH and temperature were investigated. Compared to monometallic oxides, p-Mn/Fe3O4 exhibited a better catalytic performance because of the significant synergy between Mn and Fe species. Several BPA intermediates were identified. On the basis of bio-toxicity assay and TOC measurements, BPA transformed to some toxic intermediates during the initial reaction stage, and then decomposed efficiently to low toxicity products and mineralized to carbon dioxide and water molecules. This study shows that p-Mn/Fe3O4 is an efficient and environmentally benign catalyst for PMS oxidation of organic pollutants.