Thermally treated fungal manganese oxides for bisphenol A degradation using sulfate radicals

Fungal manganese oxide (FMO) is ubiquitous in the environment and believed to be a promising material for catalysis due to its biological reactive mineral phases. In this study, layered FMO was produced by Mn (II)-oxidizing fungus. After thermal treatment at various temperatures, FMO was converted to manganese oxides (MnO2, Mn2O3 and Mn3O4) with different morphologies. The as-obtained manganese oxides were adopted as catalysts for peroxymonosulfate (PMS) activation to produce sulfate radicals, which were highly efficient for bisphenol A (BPA) degradation. Catalytic evaluation showed that FMO calcined at 400 degrees C performed well for BPA degradation. Complete BPA degradation and 97% TOC removal in solution could be achieved in 30 min. Effects of catalyst dosage, PMS loading, solution pH and reaction temperature on BPA degradation efficiencies were also investigated. In recycle study, remarkable decrease of BPA degradation efficiency was found, which was ascribed to the coverage of catalytic reaction intermediates on the surface of catalyst. Fortunately, heat treatment could recover the catalyst with a complete BPA degradation efficiency over regenerated catalyst. Furthermore, a BPA degradation pathway was proposed based on intermediates identification by GC-MS and LC-MS.