Strong metal-support interaction between carbon nanotubes and Mn-Fe spinel oxide in boosting peroxymonosulfate activation: Underneath mechanisms and application

This study has revealed how the strong metal-support interaction (SMSI) between carbon nanotubes (CNTs) and Mn 0.65 Fe 2.35 O 4 (MnFeO) in boosting peroxymonosulfate (PMS) activation for rapid sulfamethoxazole (SMX) degradation. As synergized by CNTs, the PMS-activation efficiency of MnFeO could be enhanced by>24 times, but with the similar PMS-activation mechanism. It was explored that the SMSI-induced abundant surface hydroxyl groups, in cooperation with the highly hydrophobic CNTs, favored the rapid in situ interfacial degradation of SMX. This feature also endowed the MnFeO-CNTs catalyst resistance to high salinity waters containing inorganic anions (e.g., Cl - and NO 3 – ) of weak complexing abilities. Moreover, the SMSI allowed the greatly accelerated redox cycle rate of Mn species by electron-rich CNTs, resulting in efficient PMS activation. Furthermore, the application feasibility of the MnFeO-CNTs/PMS system was demonstrated for a SMX-spiked real reverse osmosis (RO) concentrate. It was found that higher concentration of PMS could realize the complete removal of SMX, despite the existence of electron-rich tyrosine-like substances would compete with the SMX degradation in the MnFeO-CNTs/PMS system. This study demonstrated that the SMSI could boost the PMS activation , and could serve as an effective material strategy for in situ interfacial organics degradation in the high salinity wastewater.