Integration of membrane filtration and peroxymonosulfate activation on CNT@nitrogen doped carbon/Al2O3 membrane for enhanced water treatment: Insight into the synergistic mechanism

Abstract

The performance of membrane filtration is always restricted by the contradiction between selectivity and permeability as well as themembrane fouling problem. Herein, a carbon nanotube@nitrogen doped carbon/Al2O3 (CNT@NC/Al2O3) membrane was designedandfabricated through coating the CNT wrapped by NC, which displays unique peroxymonosulfate (PMS) activation function, onto the Al2O3 membrane support. Upon PMS addition, the reactive oxygen species (e.g., sulfate radial) with strong oxidative capability could be generated from CNT@NC layer, thus assisting membrane filtration for enhanced pollutants removal. Within an extremely short reaction time of 0.44 s, the membrane filtration integrated with PMS activation (MFPA) displayed synergistic effect for enhanced removal of sulfamethoxazole unavailable by size-exclusion, whose removal efficiency was 3.3 or 2.8 times higher than that of filtration or PMS activation alone. CNT@NC/Al2O3 MFPA process also displayed good anti-fouling capability, whose permeate flux during treatment of humic acid was 2.1 times higher than that of filtration alone. The experiments and calculations substantiated the synergistic mechanism between membrane filtration and PMS activation in MFPA process: the membrane filtration facilitated the mass transfer for enhanced PMS activation on catalytic layer, while the PMS activation triggered radical (SO4−) and non-radical (1O2 and electron-transfer) processes for improved membrane performance.