Unravelling the synergism of carbon nanotubes encapsulated CoFe2O4 for efficiently activating peroxymonosulfate to degrade sulfamethoxazole

Abstract

The efficiency of producing reactive species in advanced oxidation processes was one of the biggest challenges in increasing the performance of heterogeneous catalysts. The confined catalyst was synthesized by encapsulating CoFe2O4 spinel in carbon nanotube (CNT) towards the activation of peroxymonosulfate (PMS). This catalyst not only exhibited superior catalytic property for sulfamethoxazole degradation, but also rapidly degrade 91 % of sulfamethoxazole (SMX) within 10 min. CNT provided an ideal nanoconfined environment for the formation and growth of the CoFe2O4 nanoparticles. The confined effect of CoFe2O4@CNT towards PMS activation could be improved in two ways: (i) increasing the contact probability between SMX and PMS; (ii) enhancing the electron transfer process. The interactions of micropollutants, oxygenants and catalysts was strengthened in confined effects and 1O2 was triggered as the main reactive species for SMX degradation. Moreover, the confined environment of CNT encapsulated CoFe2O4 was improved, further influencing catalytic performance and stability. The recyclability of CoFe2O4@CNT denoted 87 % of SMX removal up to the 5th run of usage.