Document Detail

Assessment of degradation by-products and NDMA formation potential during UV and UV/H2O2 treatment of doxylamine in the presence of monochloramine.
MedLine Citation:
PMID:  23134233     Owner:  NLM     Status:  Publisher    
UV-C radiation is the US EPA recommended technology to remove N-nitrosodimethylamine (NDMA) during drinking and recycled water production. Frequently, H2O2 is added to the treatment to remove other recalcitrant compounds and to prevent NDMA reformation. However, the transformation of NDMA precursors during the UV and UV/H2O2 process and the consequences for NDMA formation potential are currently not well understood, in particular in the presence of monochloramine. In this study, doxylamine has been chosen as a model compound to elucidate its degradation by-products in the UV and UV/H2O2 process and correlate those with changes to the NDMA formation potential. This study shows that during UV treatment in the presence and absence of monochloramine NDMA formation potential can be halved. However, an increase of more than 30% was observed, when hydrogen peroxide was added. Ultra-fast liquid chromatography coupled to quadrupole-linear ion trap mass spectrometer was used for screening and structural elucidation of degradation by-products identifying twenty-one chemical structures from the original parent compound. This work shows that further oxidation of NDMA precursors does not necessarily lead to a decrease in NDMA formation potential. Degradation by-products with increased electron density in the vicinity of the dimethylamino moiety, for example induced by hydroxylation, may have a higher yield of nucleophilic substitution and subsequent NDMA formation compared to the parent compound during chloramination. This work demonstrates the need to consider the formation of oxidation by-products and associated implications for the control and management of NDMA formation in downstream processes and distribution, when integrating oxidative treatments into a treatment train generating either drinking water or recycled water for potable reuse.
Maria Jose Farre; Jelena Radjenovic; Wolfgang Gernjak
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-7
Journal Detail:
Title:  Environmental science & technology     Volume:  -     ISSN:  1520-5851     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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