Activation of peroxydisulfate by carbon nanotube for the degradation of 2,4-dichlorophenol: Contributions of surface-bound radicals and direct electron transfer
Journal
Chemosphere
Journal Volume
283
Date Issued
2021
Author(s)
Abstract
Carbon materials have been used to activate peroxydisulfate (PDS) for the degradation of organic pollutants. The mechanism involved, especially whether radicals are formed in these processes, is still under debate. In this research, multi-walled carbon nanotube (MWCNT) was employed to activate PDS for the removal of 2,4-dichlorophenol (2,4-DCP). The effects of solution pH, PDS concentration, 2,4-DCP concentration, and MWCNT loading on the degradation of 2,4-DCP were investigated. The mechanism was explored via radical scavenging experiments, electron paramagnetic resonance (EPR) and MWCNT surface characterization. The results showed that the rate of 2,4-DCP degradation increased with the increasing solution pH, PDS concentration and MWCNT loading. The presence of OH[rad] and SO4[rad]? signals in EPR studies, no inhibitory effect in radical scavenging experiments, and the chlorination of MWCNT observed by X-ray photoelectron spectroscopy (XPS) suggested that surface reactions involving both surface-bound radicals and direct electron transfer were responsible for 2,4-DCP degradation. Reusability tests showed that the surface sites responsible for surface-bound radical formation were poisoned after PDS activation, while those responsible for direct electron transfer remained active after five cycles. This research provided the first in-depth insights for the dual roles of MWCNT in the PDS activation process. ? 2021 Elsevier Ltd
Subjects
Electron transfer
Hydroxyl radical
Multi-walled carbon nanotube
Persulfate
Sulfate radical
Chemical activation
Electron spin resonance spectroscopy
Free radical reactions
Multiwalled carbon nanotubes (MWCN)
Organic pollutants
Paramagnetic resonance
Reusability
Sulfur compounds
Surface reactions
X ray photoelectron spectroscopy
Yarn
Dichlorophenols
Direct electron transfer
Hydroxyl radicals
Multi-walled-carbon-nanotubes
Peroxydisulfate
Persulphate
Solution pH
Sulfate radicals
Surface bounds
Electron transitions
2,4 dichlorophenol
carbon nanotube
multi walled nanotube
peroxydisulfate
radical
sulfate
unclassified drug
2,4-dichlorophenol
chlorophenol
activation energy
chlorination
degradation
electron
free radical
adsorption
Article
chemical composition
controlled study
electron spin resonance
electron transport
pH
scanning electron microscopy
surface area
surface property
X ray photoemission spectroscopy
oxidation reduction reaction
Chlorophenols
Electrons
Nanotubes, Carbon
Oxidation-Reduction
SDGs
Type
journal article