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.
Civil, Environmental and Architectural Engineering Department, University of Colorado, 428 UCB, Boulder, Colorado 80309, USA. edickens@mines.edu
Eric R V
ER
Dickenson
R Scott
RS
Summers
Jean-Philippe
JP
Croué
Hervé
H
Gallard
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