This study elucidates the mechanism behind persulfate activation by exploring the role of various oxyanions (e.g., peroxymonosulfate, periodate, and peracetate) in two activation systems utilizing iron nanoparticle (nFe0) as the reducing agent and single-wall carbon nanotubes (CNTs) as electron transfer mediators. Since the tested oxyanions serve as both electron acceptors and radical precursors in most cases, oxidative degradation of organics was achievable through one-electron reduction of oxyanions on nFe0 (leading to radical-induced oxidation) and electron transfer mediation from organics to oxyanions on CNTs (leading to oxidative decomposition involving no radical formation). A distinction between degradative reaction mechanisms of the nFe0/oxyanion and CNT/oxyanion systems was made in terms of the oxyanion consumption efficacy, radical scavenging effect, and EPR spectral analysis. Statistical study of substrate-specificity and product distribution implied that the reaction route induced on nFe0 varies depending on the oxyanion (i.e., oxyanion-derived radical), whereas the similar reaction pathway initiates organic oxidation in the CNT/oxyanion system irrespective of the oxyanion type. Chronoamperometric measurements further confirmed electron transfer from organics to oxyanions in the presence of CNTs, which was not observed when applying nFe0 instead.
Bibliographical noteFunding Information:
This study was supported by a National Research Foundation of Korea grant funded by the Korea Government (NRF-2017R1A2B4002235), a grant from the National Research Foundation of Korea, funded by the Ministry of Science, ICT, and Future Planning (No. 2016M3A7B4909318), Korea Ministry of Environment as "Advanced Industrial Technology Development Project" (2017000140005), and by Korea Ministry of Environment as “The GAIA Project” (2016000550007).
© 2017 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry