Haloacetic acid and trihalomethane formation from the chlorination and bromination of aliphatic beta-dicarbonyl acid model compounds.
While it is known that resorcinol- and phenol-type aromatic structures within natural organic matter (NOM) react during drinking water chlorination to form trihalomethanes (THMs), limited studies have examined aliphatic-type structures as THM and haloacetic acid (HAA) precursors. A suite of aliphatic acid model compounds were chlorinated and brominated separately in controlled laboratory-scale batch experiments. Four and two beta-dicarbonyl acid compounds were found to be important precursors for the formation of THMs (chloroform and bromoform (71-91% mol/mol)), and dihaloacetic acids (DXAAs) (dichloroacetic acid and dibromoacetic acid (5-68% mol/mol)), respectively, after 24 h at pH 8. Based upon adsorbable organic halide formation, THMs and DXAAs, and to a lesser extent mono and trihaloacetic acids, were the majority (> 80%) of the byproducts produced for most of the aliphatic beta-dicarbonyl acid compounds. Aliphatic beta-diketone-acid-type and beta-keto-acid-type structures could be possible fast- and slow-reacting THM precursors, respectively, and aliphatic beta-keto-acid-type structures are possible slow-reacting DXAA precursors. Aliphatic beta-dicarbonyl acid moieties in natural organic matter, particularly in the hydrophilic fraction, could contribute to the significant formation of THMs and DXAAs observed after chlorination of natural waters.
Dickenson
Eric R V
ER
Civil, Environmental and Architectural Engineering Department, University of Colorado, 428 UCB, Boulder, Colorado 80309, USA. edickens@mines.edu
Summers
R Scott
RS
Croué
Jean-Philippe
JP
Gallard
Hervé
H
D000085:Acetates / Q000032:analysis* / Q000737:chemistry; D001966:Bromine / Q000737:chemistry*; D002625:Chemistry, Organic / Q000379:methods; D002713:Chlorine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D009930:Organic Chemicals; D013997:Time Factors; D022882:Trihalomethanes / Q000032:analysis*; D014867:Water / Q000737:chemistry; D018508:Water Purification
D000085:Acetates; D009930:Organic Chemicals; D022882:Trihalomethanes; D014867:Water; D002713:Chlorine; C006972:chloroacetic acid; C016274:bromoacetate; C088674:dibromoacetic acid; D001966:Bromine