Abstract
? 2022 Elsevier B.V.The rational design and development of a highly efficient and sustainable heterogeneous catalyst has become a limiting factor for the practical application of persulfate-based advanced oxidation processes in organic dye degradation. Herein, a nitrogen-doped porous carbon-coated CoFe2O4 core–shell composite (CoFe2O4 @NPC) was synthesized by in-situ growth of cobalt/iron bimetallic zeolitic imidazolate framework-9 (Co/Fe-ZIF-9) on graphene oxide (GO) nanosheets followed by one-step calcination of the bimetallic ZIF-GO composite in nitrogen. The textural, chemical, and magnetic properties of the composites were comprehensively characterized using various analytical techniques. The catalytic performances of the as-prepared CoFe2O4 @NPC in activating PMS to decompose Rhodamine B (RhB) were then systematically evaluated. The composite calcined at 600 °C exhibited the highest catalytic activity. The maximum RhB degradation efficiency of 99.05% and pseudo-second-order kinetic constant of 0.0766 L/(mg·min) were achieved after 20 min at 25 °C. Moreover, CoFe2O4 @NPC displayed excellent recyclability and stability with negligible leaching of Co and Fe ions into the solution. Subsequently, electron spin resonance, reactive oxygen species quenching, and X-ray photoelectron spectroscopy were conducted to clarify the PMS activation mechanisms. Results suggested that SO4?? and ?OH were generated during PMS activation and that SO4?? was the predominant radical involved in RhB degradation. In addition, Co(II), Fe(III), and structured nitrogen, especially pyridinic and graphitic N groups, participated in the PMS activation. Some insights into possible mechanisms of RhB degradation were also attained from spectral analyses. All these results suggested that CoFe2O4 @NPC had excellent potential as a PMS activator for application in dye-contaminated wastewater treatment.
NSTL
Elsevier