Insights into the carbon nanotubes-mediated activation of permanganate for decontamination under high salinity

Yang, Shuai; Wang, Jingquan; Chai, Zhizhuo; Guo, Hongguang

doi:10.1016/j.chemosphere.2023.139153

Cited by 1 publication

(1 citation statement)

References 42 publications

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“…Carbon nanotubes (CNTs), as an emerging carbon material, have recently received increasing attention for the abatement of aqueous pollutants. Several studies have shown that CNTs exhibit excellent activity toward various oxidants (e.g., permanganate, persulfate, peracetic acid). − Yun et al studied the activation of peroxydisulfate (PDS) by CNTs and found that CNTs could also activate PI . Despite some enlightening results on the system of PI activation by CNTs, the intrinsic nature of the oxidation process remains ambiguous.…”

Section: Introductionmentioning

confidence: 99%

Removal of Phenols by Highly Active Periodate on Carbon Nanotubes: A Mechanistic Investigation

Peng

Zhou

et al. 2023

Environ. Sci. Technol.

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Carbon nanotubes (CNTs) and their derivatives have been widely exploited to activate various oxidants for environmental remediation. However, the intrinsic mechanism of CNTs-driven periodate (PI) activation remains ambiguous, which significantly impedes their scientific progress toward practical application. Here, we found that CNTs can strongly boost PI activation for the oxidation of various phenols. Reactive oxygen species analysis, in situ Raman characterization, galvanic oxidation process experiments, and electrochemical tests revealed that CNTs could activate PI to form high-potential metastable intermediates (CNTs−PI*) rather than produce free radicals and 1 O 2 , thereby facilitating direct electron transfer from the pollutants to PI. Additionally, we analyzed quantitative structure− activity relationships between rate constants of phenols oxidation and double descriptors (e.g., Hammett constants and logarithm of the octanol−water partition coefficient). The adsorption of phenols on CNT surfaces and their electronic properties are critical factors affecting the oxidation process. Besides, in the CNTs/PI system, phenol adsorbed the CNT surfaces was oxidized by the CNTs−PI* complexes, and products were mainly generated via the coupling reaction of phenoxyl radical. Most of the products adsorbed and accumulated on the CNT surfaces realized phenol removal from the bulk solution. Such a unique non-mineralization removal process achieved an extremely high apparent electron utilization efficiency of 378%. The activity evaluation and theoretical calculations of CNT derivatives confirmed that the carbonyl/ketonic functional groups and double-vacancy defects of the CNTs were the primary active sites, where high-oxidation-potential CNTs−PI* were formed. Further, the PI species could achieve a stoichiometric decomposition into iodate, a safe sink of iodine species, without the generation of typical iodinated byproducts. Our discovery provides new mechanistic insight into CNTs-driven PI activation for the green future of environmental remediation.

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