Aqueous chlorination of sulfamethazine and sulfamethoxypyridazine: Kinetics and transformation products identification

Abstract

Sulfonamides (SNs) are synthetic antimicrobial agents. These substances are continually introduced into the environment, and they may spread and maintain bacterial resistance in the different compartments. The chlorination of 2 SNs, namely, sulfamethazine (SMT) and sulfamethoxypyridazine (SMP), was investigated to study their reactivity with chlorine at typical concentrations for water treatment conditions. Experiments conducted in purified water show an acceleration of SMT and SMP degradation of a factor 1.5 by comparison to drinking water matrix. This difference is due to pH variation and competitive reactions between SNs and mineral and organic compounds, with chlorine in drinking water. In the presence of an excess of chlorine (6.7 μmol·L ) in ultrapure water at pH 7.2, second-order degradation rate constants were equal to 4.5 × 10 M ·s and 5.2 × 10 M ·s for SMT and SMP, respectively. The structures of transformation products were investigated by liquid chromatography tandem mass spectrometry analyses with equimolar concentrations between chlorine and SNs. SO elimination, cyclization, and electrophilic substitutions were the main pathways of by-products formation. Moreover, the toxicity of the proposed structures was predicted by using toxicity estimation software tool program. The results indicated that most by-products may present developmental toxicity.

A Review of the Distribution of Antibiotics in Water in Different Regions of China and Current Antibiotic Degradation Pathways

“…Ji et al (2015), Yan et al (2015) used thermal activation of peroxynitrite to produce sulfate radicals to effectively degrade sulfonamide antibiotics, but the effect is not very stable. Gaffney et al (2015), Nassar et al (2018) found that chlorination and oxidation selectively removed sulfonamide antibiotics from water, but the degradation effect was greatly influenced by the concentration of the antibiotics and pH.…”

Insights into antimicrobial agent sulfacetamide transformation during chlorination disinfection process in aquaculture water

“…S8 †). 40 20,[41][42][43][44] the degradation route of SFA and potential formation pathway of HAAs were proposed in Fig. 7.…”

“…The transformation process of SFA in NaClO disinfection system can be divided into three steps: (1) with the oxidation of [Cl 2 ], the C-S bond between sulfonyl group and benzene ring and S-N bond between sulfonyl and acylamino groups of SFA were scissored, and then the intermediate sulfonyl group formed p1(chloromethanesulfonyl chloride), and the rest intermediate aminobenzene were oxidized to produce p2 (4hydroxyaniline), p3 (4-chlorophenol) and p4 (2-hydroxyaniline). 20,43 (2) Due to the chlorination mechanism in NaClO system, the intermediate products p2 and p4 were substituted by chlorine to produce p5 (4-chloroaniline), p6 (2,4-dichloroaniline) and p7 (2-amino-4-chlorophenol). The intermediate product p3 was substituted by chlorine to form polychlorophenols (p8-p10).…”

On the Biophysical Investigation of Sulfamethazine‐Hemoglobin Binding and the Resulting Adverse Effects of Antibiotics

“…Like some other antibiotics, Sulfamethazine is a well-known pollutant and several reports are available on its transformation, degradation, harmfulness in aqueous media. [26][27][28] It can be potentially toxic to body proteins as well. However, the molecular mechanism and energetics of SMZ binding with the most important heme protein, Hb, is not yet known in details.…”

“…Like some other antibiotics, Sulfamethazine is a well‐known pollutant and several reports are available on its transformation, degradation, harmfulness in aqueous media [26–28] . It can be potentially toxic to body proteins as well.…”