Zif-67-Derived Dispersed Cobalt Embedded Carbon Nanotubes Efficiently Activate Peroxomonosulfate for Degradation of Organic Pollutants

Abstract

The aggregation of metal nanoparticles can be prevented and catalytic activity maintained by confining them within carbon nanotubes. However, the issue of secondary pollution arises due to metal leaching. Consequently, this study is based on porous morphology control of metal-organic frameworks (ZIF-67) and conductive carbon nanotubes (CNTs) carbon-based materials of different sizes. ZIF-67-derived cobalt was embedded into CNTs to synthesize a novel carbon nanotube-connected dispersed cobalt nanomaterial (Co@CNT-3), which was utilized to activate PMS for efficient degradation of organic pollutants. In this unique structure, exhibited excellent catalytic activity due to the synergistic interaction between ZIF-67-derived Co NPs and CNT-3. The removal of methylene blue (MB) reached more than 99% within 20 min after the addition of PMS and showed good catalytic activity in a wide pH range (3.0-11.0) and most anions, cations, and humic acids in the aqueous environment. The cobalt ion leaching rate of Co@CNT-3 in solution is only 0.01 mg/L. Through X-ray photoelectron spectroscopy (XPS), quenching and electron paramagnetic resonance (EPR) experiments, it was found that the redox electron transfer process of Co2+/Co3+ generated by the catalyst activated PMS and the non-radical pathway were involved in the degradation of MB. Finally, the possible degradation pathway of MB was proposed by intermediate analysis. This study provides a simple strategy for the synthesis of high-efficiency catalysts with low cobalt ion leaching.

Keywords: Peroxymonosulfate, Low leaching, Confinement, Organic pollutants