Peroxymonosulfate activation by carbon-encapsulated metal nanoparticles: Switching the primary reaction route and increasing chemical stability

• Published in: Applied catalysis. B, Environmental Environmental, 2020-12, Vol.279, p.119360, Article 119360
• Main Authors: Yun, Eun-Tae, Park, Sung-Woo, Shin, Hyun Jung, Lee, Hongshin, Kim, Dong-Wan, Lee, Jaesang
• Format: Article
• Language: English
• Subjects: Acceleration; Carbon; Carbon encapsulation; Catalysts; Chemical stability; Composite fabrication; Copper; Core-shell structure; Cores; Deactivation; Electric wire; Electrical conductivity; Electrical resistivity; Electron paramagnetic resonance; Electron spin resonance; Electron transfer; Encapsulation; Fabrication; Iron; Leaching; Mediated electron transfer; Metal ions; Metals; Nanoparticles; Nickel; Oxidation; Peroxymonosulfate activation; Primary degradative pathway transition; Reduction (metal working)
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119360

[Display omitted] •Carbon encapsulation of metal nanoparticles switches primary PMS activation route.•Metal cores increase the overall electric conductivity of metal-carbon composites.•Metal-carbon composites primarily activate PMS via mediated electron transfer.•Protective carbon shell imparts pH-independent activity and reduces metal leaching.•Carbon wrapping mitigates catalyst deactivation and allows facile regeneration. This study explores the technical merits of carbon encapsulation via an electrical wire explosion method to enhance the peroxymonosulfate activation performance of metals. Reflecting the nature of core-shell structures, the outer carbon layers hampered the reductive conversion of peroxymonosulfate to sulfate radicals by the inner metal cores, whereas the metal cores increased the overall electrical conductivity as a pivotal factor in non-radical activation. Hence, the impact of carbon wrapping hinged on the peroxymonosulfate reduction capability of the metals, i.e., kinetic retardation in organic degradation with reactive Cu, Fe, and Ni-Fe, but acceleration with unreactive Ni. Further, composite fabrication switched the major degradative pathway from radical-induced oxidation to mediated electron transfer, as determined from the effects of methanol and chloride, formaldehyde and bromate formation yields, reactivity toward multiple organics, and electron paramagnetic resonance spectral features. The protective carbon shells enabled pH-insensitive peroxymonosulfate activation, prevented metal ion leaching, and alleviated catalyst deactivation.