Oxidation of Sulfonamide Antibiotics of Six-Membered Heterocyclic Moiety by Ferrate(VI): Kinetics and Mechanistic Insight into SO 2 Extrusion

• Published in: Environmental science & technology Vol. 53; no. 5; pp. 2695 - 2704
• Main Authors: Feng, Mingbao, Baum, J Clayton, Nesnas, Nasri, Lee, Yunho, Huang, Ching-Hua, Sharma, Virender K
• Format: Journal Article
• Language: English
• Published: United States 05-03-2019
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.8b06535

This work presents ferrate(VI) (Fe
O
, Fe
) oxidation of a wide range of sulfonamide antibiotics (SAs) containing five- and six-membered heterocyclic moieties ( R) in their molecular structures. Kinetics measurements of the reactions between Fe
and SAs at different pH (6.5-10.0) give species-specific second-order rate constants, k
and k
of the reactions of protonated Fe
(HFeO
) and unprotonated Fe
(Fe
O
) with protonated SAs (HX), respectively. The values of k
varied from (1.2 ± 0.1) × 10
to (2.2 ± 0.2) × 10
M
s
, while the range of k
was from (1.1 ± 0.1) × 10
to (1.0 ± 0.1) × 10
M
s
for different SAs. The transformation products of reaction between Fe
and sulfadiazine (SDZ, contains a six-membered R) include SO
extrusion oxidized products (OPs) and aniline hydroxylated products. Comparatively, oxidation of sulfisoxazole (SIZ, a five-membered R) by Fe
has OPs that have no SO
extrusion in their structures. Density functional theory calculations are performed to demonstrate SO
extrusion in oxidation of SDZ by Fe
. The detailed mechanisms of oxidation are proposed to describe the differences in the oxidation of six- and five-membered heterocyclic moieties ( R) containing SAs (i.e., SDZ versus SIZ) by Fe
.