Oxidation Kinetics of Bromophenols by Nonradical Activation of Peroxydisulfate in the Presence of Carbon Nanotube and Formation of Brominated Polymeric Products

Abstract

This work demonstrated that bromophenols (BrPs) could be readily oxidized by peroxydisulfate (PDS) activated by a commercial carbon nanotube (CNT), while furfuryl alcohol (a chemical probe for singlet oxygen (O)) was quite refractory. Results obtained by radical quenching experiments, electron paramagnetic resonance spectroscopy, and Fourier transform infrared spectroscopy further confirmed the involvement of nonradical PDS-CNT complexes rather than O. Bicarbonate and chloride ion exhibited negligible impacts on BrPs degradation by the PDS/CNT system, while a significant inhibitory effect was observed for natural organic matter. The oxidation of BrPs was influenced by solution pH with maximum rates occurring at neutral pH. Linear free energy relationships (LFERs) were established between the observed pseudo-first-order oxidation rates of various substituted phenols and the classical descriptor variables (i.e., Hammett constant σ, and half-wave oxidation potential E). Products analyses by liquid chromatography tandem mass spectrometry clearly showed the formation of hydroxylated polybrominated diphenyl ethers and hydroxylated polybrominated biphenyls on CNT surface. Their formation pathway possibly involved the generation of bromophenoxyl radicals from BrPs one-electron oxidation and their subsequent coupling reactions. These results suggest that the novel nonradical PDS/CNT oxidation technology is a good alternative for selectively eliminating BrPs with alleviating toxic byproducts in treated water effluent.

Tuning of Persulfate Activation from a Free Radical to a Nonradical Pathway through the Incorporation of Non-Redox Magnesium Oxide

“…The calculated k obs in CuOMgO/Fe 3 O 4 +PMS system were then compared with literature values obtained for similar reactions in aqueous solution (Table S6). [60][61][62] Among the studied substituted phenols, 4-MeCONH exhibited the maximum degradation rate with k obs (0.168 min −1 ), while 4-NO 2 phenol demonstrated the slowest oxidation with k obs (0.037 min −1 ). To describe the quantitative effect of substitution on the degradation rate of these phenols, the obtained k obs values were changed to relative rates (k rel ) using 4-CP as the reference compound, as described in Eq 11. logk rel = log (11)…”

“…σ, σ + and σ − ) were mostly used to quantitatively correlate the electron donating (large negative value) or electron withdrawing (large positive value) properties of substituents. [61][62][63] Of the three Hammett constants (i.e. σ, σ + and σ − ), σ + give relatively good correlation (Figure 4 A and Figure S50 A,B) with linear regression as expressed in Eq.…”

Multiple Metabolic Pathways of 2,4,6-Tribromophenol in Rice Plants

“…Apart from natural and anthropogenic sources, OH-PBDEs and PBDD/Fs are known to be produced as unintended transformation products by coupling of bromophenols in biocatalysis and photocatalysis processes. 13–18 Remarkably, the bromophenols, including 2,4,6-tribromophenol and its debromination and hydroxylation metabolites (TP 250 and TP 266 , respectively), comprised the biotic coupling reactions forming OH-PBDEs and PBDD/Fs. Compared to 2,4,6-tribromophenol, OH-PBDEs are more potent in endocrine disruption and neurotransmitter release.…”

Microplastics and suspended particles in a strongly impacted coastal environment: Composition, abundance, surface texture, and interaction with metal ions

“…XPS is usually employed to identify the specific electron binding energies (B.E.) of the surface particles in marine sediments or soils (Gerin et al, 2003;Arnarson and Keil, 2007;Kim et al, 2014;Guan et al, 2017). Figures 4a and 4b show the survey spectra of the untreated samples and those treated with H 2 O 2 , respectively.…”