Efficient removal of 17α-ethinylestradiol (EE2) from water using freshly formed Fe-Mn binary oxide

An in situ formed Fe-Mn binary oxide (FMBO) was successfully fabricated for efficient removal of 17 alpha-ethinylestradiol (EE2) from water. Moreover, manganese oxide (MnO2) and ferric oxide (FeOOH) were also studied for the comparison of EE2 removal efficiency and FMBO showed a better removal capacity towards EE2 than both MnO2 and FeOOH. Various removal conditions including contact time, pH and coexisting ions were investigated. The results showed that the best removal capacity was obtained at pH 6.0 and FMBO rapidly reached a removal efficiency of approximately 96% in 30 min at pH 6.0. The retarded first-order kinetic model was able to simulate the entire removal kinetics (R-2 = 0.96). Besides, it was found that the investigated coexisting ions (SO42-, Ca2+, Mg2+, Fe3+) did not have an obvious effect on EE2 removal, while phosphate, carbonate, and manganous ions reduced the removal efficiency, especially phosphate. Fourier transform infrared and X-ray photoelectron spectroscopy results were investigated and they revealed that EE2 was adsorbed through hydrogen bonding and then oxidized by MnO2 on FMBO, which contributed to further degradation of EE2. Besides, the intermediates during removal were studied by gas chromatography-mass spectroscopy, indicating that the products still kept the core ring structure of estrogenwhile lowering estrogen activity. Above all, FMBOcan be used as a promisingmaterial to remove EE2.