Α-Mno2 Nanofiber Membrane for Continuous Degradation of Flow-Through Carbamazepine Via Peroxymonosulfate Activation: The Dominant Role of Mn3+ and Singlet Oxygen

Persulfate-based advanced oxidation process (PS-AOP) has been increasingly concerned in the removal of pharmaceutical and personal care products (PPCPs) from aqueous solutions. However, the application of PS-AOP is hindered by these shortages including the recycling difficulty of a powdered catalyst and the secondary pollution (such as metal ion leaching). Herein, α-MnO2 nanofibers are prepared by hydrothermal method and further assembled into nanofiber membrane (NFM) by filtration. The catalytic activity of NFM catalysts in PMS activation is evaluated by the continuous degradation of flow-through carbamazepine (CBZ). The results show that the membrane catalyst of NFM-140 prepared at the hydrothermal temperature of 140 °C can deliver the optimized catalytic activity due to its high SBET, Mn3+ concentration and Ov content, as well as low Rct, which are conducive to PMS activation for the removal of CBZ. The Mn3+ on the surface of the α-MnO2 nanofibers is the dominant active sites for PMS activation. The electrochemical experiments and quenching results elucidate the electron transfer process among NFM/PMS/CBZ and confirm that ROS is the sole driving force for removing CBZ. Combining with the DFT calculation results indicate that the ROS, primarily [[EQUATION]], preferentially attacks the active atoms (C, N) and bonds (C-N) in CBZ, leading to its open-loop degradation. The low metal leaching and biotoxicity further demonstrate the potential of NFM membrane catalysts in the practical application for the removal of PPCPs from aqueous solutions.