Activation of peroxymonosulfate by a magnetic Co doped NiFe2O4 catalyst for efficient Bisphenol A degradation in water

Sulfate radicals-based advanced oxidation process (AOPs) were considered to be an effective process for treating organic wastewater. However, the difficult separation of catalysts and the toxicity of metal ions may cause secondary pollution. A new efficient and separable heterogeneous catalyst is desirable to be explored. Magnetic porous Co-doped NiFe2O4 (CoxNi1-xFe2O4, x = 0, 0.05, 0.2 and 0.5), prepared by a simple sol-gel method, were used as heterogeneous catalysts for the removal of Bisphenol A (BPA) in aqueous solution by the generation of strong oxidizing radicals and reactive oxygen species from activating peroxymonosulfate (PMS). Co addition increased the saturation magnetism of the catalyst and decreased the redox preparation temperature. Increasing the amount of Co-doping resulted in a pronounced enhancement of BPA removal, which the removal rate increased by 33.6% with Co-doping amount from 0 to 0.2. The hydroxyl groups on the catalyst surface plays a vital role in activating PMS, and the main reactive species for BPA degradation was determined as sulfate radical (SO4•-) and singlet oxygen (1O2) in Co0.2Ni0.8Fe2O4/PMS system. The conversion of Ni2+/Ni3+, Co2+/Co3+, and O2-/O2 for maintaining Co0.2Ni0.8Fe2O4 charge balance, PMS was activated simultaneously.