Potassium ferrate enhanced active manganese oxide filter material to remove BPA: Influence of NH4+、Mn2+

Abstract

Active manganese oxide (MnOx) filter media can remove NH4+ and Mn2+ with high efficiency, but the removal of Bisphenol A (BPA) in water has the problem of poor stability, and the interaction between BPA and other inorganic pollutants in water is not clear. In order to improve the ability of continuous removal of BPA, this study used potassium ferrate (PF) to strengthen MnOx filter media to remove BPA from water, and investigated the effects of NH4+ and Mn2+ on the removal of BPA. The results showed that the removal efficiency of BPA increased from 73 % to 100 % by adding 0.1 mol/L PF, and the removal efficiency increased with the increase of PF concentration. A certain concentration of NH4+ and Mn2+ increased the removal efficiency of BPA by reacting with high-valent Fe to produce more active substances. The continuous removal of bisphenol A showed that the MnOx filter media had good stability, but the removal efficiency was only 48 % after 11 consecutive BPA removal tests, and the removal efficiency could be maintained above 70 % after adding PF. Combined with the results of free radical quenching, electron paramagnetic resonance (EPR) and methylphenyl sulfoxide (PMSO) experiments, it was confirmed that the active substances in the system included ·OH, 1O2, and high-valent Fe and Mn, but the main contribution to the BPA removal was Mn(Ⅲ). The results of X-ray photoelectron spectroscopy (XPS) also demonstrated that the addition of PF generated new active substances on the surface of the filter media, which increased the removal rate of BPA.