The inhibitory effect of natural organic matters and ions on 17ɑ-ethinylestradiol removal over new TiO2(B)/Bi5O7I and mesoporous carbon/TiO2(B)/BiOI composites: The role of mesoporous carbon

Abstract

The natural organic matters (NOMs) and ions prevalent in water matrixes always inhibits photocatalytic degradation of pollutants by TiO2. Herein, we prepared TiO2(B)/Bi5O7I and mesoporous carbon/TiO2(B)/BiOI composites to investigate the inhibitory effect of NOMs and ions on photocatalytic degradation of 17ɑ-ethinylestradiol (EE2). The results show that Bi5O7I or BiOI is tightly anchored onto the large surface of TiO2(B) nanobelt to form heterojunction, and metallic Bi forms on the surface of TiO2(B) in MC/TiO2(B)/BiOI composite. This intimate contact is beneficial for the separation of hole-electron pairs and stability. More importantly, the introduction of mesoporous carbon (MC) not only improve the EE2 removal but also eliminate obvious inhibitory effect of NOMs and inorganic ions. The main cause is that MC component in MC/TiO2(B)/BiOI composite can preferentially adsorb EE2 molecules from water via π-π and hydrophobic interaction forces between EE2 and MC. Quenching experiments and electron paramagnetic resonance confirm that •O2- and h+ are main reactive species for EE2 degradation over both TiO2(B)/Bi5O7I and MC/TiO2(B)/BiOI composites. Besides, the degradation mechanism was investigated, and degradation pathways are proposed based on intermediates identification. The MCF-7 cell test shows that the estrogenic activity of the treated solution can be rapidly eliminated. More importantly, MC/TiO2(B)/BiOI has excellent anti-interference capacity for the EE2 removal in real complex water matrixes.