Removal of bisphenol A via a hybrid process combining oxidation on β-MnO2 nanowires with microfiltration

A novel hybrid process combining β-MnO2 nanowires oxidation and microfiltration was adopted to remove bisphenol A (BPA), an endocrine disrupting chemical (EDC) in the aquatic environment. The β-MnO2 nanowires synthesized via a facile hydrothermal method were characterized by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscope, and nitrogen sorption. It was demonstrated that β-MnO2 nanowires can degrade BPA effectively. Investigation on operation parameters indicated that oxidation of BPA using β-MnO2 nanowires was evidently dependent on pH, while humic acid and coexisting metal ions such as Ca2+, Mg2+, and Mn2+ induced suppressive effects. After oxidation, a crossflow microfiltration process was conducted to efficiently separate and recover the β-MnO2 nanowires from treated water. Membrane fouling study showed that the as-synthesized β-MnO2 nanowires possess excellent mechanical stability and was able to retain the 1D structure with high aspect ratios after reaction, thus significantly reducing membrane pore blocking in the microfiltration process.