Removal effects and potential mechanisms of bisphenol A and 17α-ethynylestradiol by Biogenic Mn oxides generated by Bacillus sp. WH4.

Endocrine disrupting compounds (EDCs), such as bisphenol A (BPA) and 17α-ethynylestradiol (EE2), have increasingly negative effects on human and wildlife health. In this study, the biogenic Mn oxides (BMOs) generated by Bacillus sp. WH4 were characterized, and the removal effects and reaction kinetics of BPA and EE2 by BMOs under different pH values, initial organic concentrations, and dosages of BMOs were discussed. The results showed that the formation of BMOs was extracellular process, and Mn(II) was oxidized to Mn(III) and Mn(IV) with 23.56% and 76.44%, respectively. The degradation processes of BPA and EE2 by BMOs followed first-order reaction kinetics, and the removal effect decreased with increasing initial BPA/EE2 concentrations and increased with increasing dosages of BMOs. However, the removal effect of BPA by BMOs decreased and then increased with increasing pH, while the removal effect of EE2 by BMOs decreased with increasing pH. Under optimal conditions, the removal efficiency of BPA and EE2 exceeded 98.2% and 94.3%, respectively. Additionally, this study showed that BMOs degraded BPA by coupling, oxidative condensation, substitution, and elimination reactions to obtain sixteen intermediate products and EE2 by substitution and elimination reactions to obtain seven intermediate products.