Minerals and transitional metal oxides of earth-abundant elements are desirable catalysts for in situ chemical oxidation in environmental remediation. However, catalytic activation of peroxydisulfate (PDS) by manganese oxides was barely investigated. In this study, one-dimension manganese dioxides (α- and β-MnO2) were discovered as effective PDS activators among the diverse manganese oxides for selective degradation of organic contaminants. Compared with other chemical states and crystallographic structures of manganese oxide, β-MnO2 nanorods exhibited the highest phenol degradation rate (0.044 min-1, 180 min) by activating PDS. A comprehensive study was conducted utilizing electron paramagnetic resonance, chemical probes, radical scavengers, and different solvents to identity the reactive oxygen species (ROS). Singlet oxygen (1O2) was unveiled to be the primary ROS, which was generated by direct oxidation or recombination of superoxide ions and radicals from a metastable manganese intermediate at neutral pH. The study dedicates to the first mechanistic study into PDS activation over manganese oxides and provides a novel catalytic system for selective removal of organic contaminants in wastewater.

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Persulfate Activation on Crystallographic Manganese Oxides: Mechanism of Singlet Oxygen Evolution for Nonradical Selective Degradation of Aqueous Contaminants.

Iron-mediated activation of persulfate and peroxymonosulfate in both homogeneous and heterogeneous ways: A review

Persulfate-based advanced oxidation processes (AOPs) for organic-contaminated soil remediation: A review

Efficient removal of bisphenol A by superoxide radical and singlet oxygen generated from peroxymonosulfate activated with Fe0-montmorillonite

The mechanisms involved in the activation of persulfate by nanosized zero-valent iron (NZVI) were elucidated and the NZVI transformation products identified. Two distinct reaction stages, in terms of the kinetics and radical formation mechanism, were found when phenol was oxidized by the persulfate/NZVI system. In the initial stage, lasting 10 min, Fe0(s) was consumed rapidly and sulfate radicals were produced through activation by aqueous Fe2+. The second stage was governed by Fe catalyzed activation in the presence of aqueous Fe3+ and iron (oxyhydr)oxides in the NZVI shells. The second stage was 3 orders of magnitude slower than the initial stage. An electron balance showed that the sulfate radical yield per mole of persulfate was more than two times higher in the persulfate/NZVI system than in the persulfate/Fe2+ system. Radicals were believed to be produced more efficiently in the persulfate/NZVI system because aqueous Fe2+ was supplied slowly, preventing sulfate radicals being scavenged by excess aqu...

Cheolyong Kim

Papers

Activation of Persulfate by Nanosized Zero-Valent Iron (NZVI): Mechanisms and Transformation Products of NZVI.

Effect of anions and humic acid on the performance of nanoscale zero-valent iron particles coated with polyacrylic acid

Electrochemical degradation of ibuprofen using an activated-carbon-based continuous-flow three-dimensional electrode reactor (3DER).

Mechanisms of electro-assisted persulfate/nano-Fe0 oxidation process: Roles of redox mediation by dissolved Fe.

Effects of oxidants on in situ treatment of a DNAPL source by nanoscale zero-valent iron: A field study