Electrified Nitrogen-Doped MXene Membrane Electrode for Micropollutants Decontamination via Peroxymonosulfate Activation
Wenxiang Li, Limin Jin, Shengtao Jiang, Yanbiao Liu
Abstract
Advanced oxidation processes based on peroxymonosulfate (PMS) activation have attracted tremendous attention as a promising approach for removing micropollutants. Herein, we designed a nitrogen-doped Ti 3 C 2 T x MXene (N-Ti 3 C 2 T x ) electrocatalytic filtration system for the activation of PMS to efficiently and selectively degrade micropollutants. The system was configured for flow-through operation, which led to significant improvements in performance compared with a conventional batch reactor system because of the enhanced convective mass transfer. Specifically, a 90.8% removal of 0.04 mmol L –1 sulfamethoxazole (SMX) solution could be achieved in flow-through mode ( k = 0.0173 ± 0.0003 min –1 ) within 120 min under optimal conditions. This value was 4.7-fold higher than the conventional batch mode ( k = 0.0037 ± 0.0001 min –1 ). Radical quenching tests, electron paramagnetic resonance measurements, and electrochemical tests verified that SMX was degraded in the N-Ti 3 C 2 T x /PMS filtration system primarily via nonradical pathways. Density functional theory calculations demonstrated that doping of N changed the PMS activation pathway and enhanced the ability of the N-Ti 3 C 2 T x membrane electrode to transfer electrons. In the presence of inorganic anions or humic acids (15.0 mmol L –1 ), the SMX removal efficiency remained above 81.1%, illustrating that naturally occurring substances in water did not interfere with the system. This work demonstrates the capabilities of the N-Ti 3 C 2 T x membrane electrode, which should provide beneficial improvements in systems targeting the serious issue of micropollutants in water.