Activation of Peroxymonosulfate by Fe0@Fe3O4 Core-Shell Nanowires for Sulfate Radical Generation: Electron Transfer and Transformation Products

Abstract

Nanoscale zero-valent iron (nZVI) is highly promising for oxidative removal of micropollutants by initiating advanced oxidation processes, but its vulnerability to deactivation due to the surface oxidation is challenging. In this study, we propose Fe0@Fe3O4 core–shell nanowires (CSNWs) as a novel activator to generate radicals for atrazine, a representative micropollutant, degradation via the activation of peroxymonosulfate (PMS). Fe0@Fe3O4 CSNWs with a shell thickness of around 5 nm were synthesized using a facile chemical reduction approach and were comprehensively characterized using a series of surface sensitive techniques. The results showed that the Fe0@Fe3O4 CSNW had great reactivity for atrazine degradation via the activation of PMS; near complete degradation of atrazine was achieved after reaction for only 2 min. Under identical conditions, the pseudo-first order rate constant with Fe0@Fe3O4 was more than 36 times greater than that with nano Fe3O4. The surface activation of PMS contributed only a small proportion to the overall degradation. Instead, the iron released from Fe0@Fe3O4 CSNWs primarily activated PMS to generate SO4∙- that degraded atrazine. The Fe0@Fe3O4 CSNWs were stable and no deactivation was observed after exposing Fe0@Fe3O4 CSNWs to air for 3 months. The results from this study demonstrate a stable nZVI for oxidative removal of organic contaminants. © 2020 Elsevier B.V.