Understanding the ozonated degradation of sulfadimethoxine, exploration of reaction site, and classification of degradation products. (December 2018)

• Record Type: Journal Article
• Authors: Shad, Asam; Li, Chenguang; Zuo, Jialiang; Liu, Jiaoqin; Dar, Afzal Ahmed; Wang, Zunyao
• Is Part Of: Chemosphere. Volume 212(2018)
• Page Start: 228
• Page End: 236
• Publication Date: 2018-12
• Subjects: Sulfadimethoxine -- Ozonation -- Product identification -- Reaction sites; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.08.050
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Ozonation has been demonstrated to be an efficient method of water treatment. In this study, the degradation of 20 mg/L of sulfadimethoxine (SDM) in different water matrices during ozonation was investigated. At pH 7.0, 100% removal of SDM was achieved by ozonation within 10 min. The degradation of SDM was more pronounced at acidic pH than under ambient environmental conditions, and was also dependent on different water matrices. Both direct and indirect oxidation of SDM by ozone were observed, and it was also shown that both ozone molecules and hydroxyl radicals were involved in the SDM degradation process, whereas it was found that the saturated ring of SDM made it O3 -recalcitrant. Seven transformation products (TPs) were identified during SDM ozonation, allowing three degradation pathways to be proposed. Additionally, the main reaction sites, including N (7) and C (2) on the aniline ring, and the __ S __ N __ bond, were confirmed both experimentally and theoretically. The toxicity evolution during the degradation process was investigated, and the results showed no toxic intermediate products obtained during ozonation. Graphical abstract: Highlights: 20 mg/L of SDM was completely degraded by ozonation in 10 min at pH 7.0. 7 products were determined by LC-Q-TOF-MS and FED calculations. Oxidation of NH2 group, hydroxylation and SN bond cleavage were observed. Toxicity predictions showed no toxic intermediate products were formed from ozonation.