Peroxymonosulfate activation by Fe3O4-MnO2/CNT nanohybrid electroactive filter towards ultrafast micropollutants decontamination: Performance and mechanism

Electrocatalytic peroxymonosulfate (PMS) activation is a promising advanced oxidation process for the degradation of micropollutants. Herein, we developed an electroactive carbon nanotube (CNT) filter functionalized with Fe3O4-MnO2 hybrid (Fe3O4-MnO2/CNT) to activate PMS towards ultrafast degradation of sulfamethoxazole (SMX). SMX was completely degraded via a single-pass through the nanohybrid filter (τ < 2 s). The ultrafast degradation kinetics were maintained across a wide pH range (from 3.0 to 8.0), in complicated matrices (e.g., tap water, lake water, WWTP effluent and pharmaceutical wastewater), and for the degradation of various persistent micropollutants. Compared with a conventional batch reactor, the flow-through operation provides an 9.2-fold higher SMX degradation kinetics by virtue of the convection-enhanced mass transport (1.47 vs. 0.16 min-1). The efficient redox cycle of Fe2+/Fe3+ and Mn2+/Mn4+ facilitate the PMS activation to generate SO4•- under electric field. Meanwhile, the ketonic groups on the CNT provide active sites for the generation of 1O2. Both experimental and theoretical results revealed the superior activity of nanohybrid filter associated with the synergistic effects among Fe, Mn, CNT and electric field. Therefore, the electrocatalytic filter based PMS activation system provides a green strategy for the remediation of micropollutants in a sustainable manner.