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  4. Kinetics and Mechanisms of N-Nitrosodimethylamine Formation upon Ozonation of N,N-Dimethylsulfamide-Containing Waters: Bromide Catalysis
 
research article

Kinetics and Mechanisms of N-Nitrosodimethylamine Formation upon Ozonation of N,N-Dimethylsulfamide-Containing Waters: Bromide Catalysis

Von Gunten, Urs  
•
Salhi, Elisabeth
•
Schmidt, Carsten K.
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2010
Environmental Science & Technology

N,N-Dimethylsulfamide (DMS), a newly identified, ubiquitous degradation product of the fungicide tolylfluanide, has been shown to be a N-nitrosodimethylamine (NDMA) precursor during zonation. In this study, batch ozonation experiments in ultrapure buffered water, surface water, and tap water were performed to determine the kinetics and elucidate the mechanism of NDMA formation from DMS. It was found that at circumneutral pH, DMS reacts slowly with ozone (k approximate to 20 M-1 s(-1)) and moderately with hydroxyl radicals (k = 1.5 x 10(9) M(-1)s(-1)). The reaction of DMS with these oxidants does not lead to NDMA. NDMA was only formed if bromide was present during zonation of DMS-containing waters. Bromide is oxidized to hypobromous acid (HOBr) by ozone which then reacts with the primary amine of DMS to form a Br-DMS species. The rate limiting step of the formation of Br-DMS is the formation of HOBr. The reaction to form Br-DMS has an apparent second order rate constant at pH 8 of >3 x 10(4) M(-1)s(-1). The Br-DMS is transformed by ozone to NDMA and nitrate (k >= 5000 M-1 s(-1)), with yields of 54% and 39%, respectively, based on the primary amine nitrogen of DMS. These reactions release bromide, making bromide a catalyst NDMA is also formed during zonation of DMS in the presence of hypochlorous acid (20-30% yield). The last step of NDMA formation is an intramolecular rearrangement with sulfur dioxide extrusion. On the basis of the mechanistic and kinetic information, it was possible to model NDMA formation in DMS-containing Lake Zurich water.

  • Details
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Type
research article
DOI
10.1021/es1011862
Web of Science ID

WOS:000280367200018

Author(s)
Von Gunten, Urs  
Salhi, Elisabeth
Schmidt, Carsten K.
Arnold, William A.
Date Issued

2010

Published in
Environmental Science & Technology
Volume

44

Start page

5762

End page

5768

Subjects

Center-Dot Generation

•

Drinking-Water

•

Ndma Formation

•

Advanced Oxidation

•

Aqueous-Solution

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Waste-Water

•

Reaction-Products

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Hypobromous Acid

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Natural-Waters

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Sulfamic Acid

Editorial or Peer reviewed

REVIEWED

Written at

OTHER

EPFL units
LTQE  
Available on Infoscience
July 1, 2011
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/69155
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