Reviews - Multi-Compound - THMs - HAAs - HANs - HAMs - HNMs - HKs - Halobenzoquinones -

Aldehydes - Single DBP - Other

(See also: Indoor DBPs, Heating Studies)

 

Major Reports & Review Papers on DBP Degradation
Citation Notes Abstract
Hozalski, R.M., Arnold, W.A., Pearson, C.R. and Lee, J.-y. (2009) Abiotic Degradation of DBPs in Distribution Systems, Water Research Foundation, Denver CO.
report #2990
    

 

Multi-Compound Degradation Studies
Citation Notes Abstract
Chen, B. Y. (2011). "Hydrolytic Stabilities of Halogenated Disinfection Byproducts: Review and Rate Constant Quantitative Structure-Property Relationship Analysis." Environmental Engineering Science 28(6): 385-394. LFER analysis of literature data As toxicity studies of disinfection byproducts (DBPs) progress, enhanced knowledge of the stability of DBPs can help determine the likelihood of DBP occurrence in water and thus enable accurate exposure assessments. To elucidate the roles of functional group, halogen number, and halogen type on the hydrolytic stability of halogenated DBPs, this study reviewed the hydrolysis rate constants (k(H)) of six groups of DBPs, including haloacetic acids, trihalomethanes, haloacetaldehydes, haloketones, haloacetonitriles, and cyanogen halides. Quantitative structure-property relationship models were developed and validated via previously tested compounds, and by extrapolation, these models were projected to nontested chemicals of emerging health concern, especially iodinated DBPs. In general, the k(H) values follow the order haloketone > haloacetonitrile > haloacetaldehyde > haloacetic acid > trihalomethane for chlorinated and brominated species, increase with increasing number of halogen atoms within one DBP group, and increase as a function of increasing atomic weight of included halogens (i.e., F<Cl<Br<I). This is the first summary of both regulated and emerging DBPs that uses the novel approach of quantitative structure-property relationship to fit diverse sources of information. Predicted results may orient future studies of the fate and transport of persistent DBP species.

Hozalski, R.M., Arnold, W.A., Chun, C.L., LaPara, T.M., Lee, J.Y., Pearson, C.R. and Zhang, P. (2008) Degradation of Halogenated Disinfection Byproducts in Water Distribution Systems, In Disinfection by-Products in Drinking Water: Occurrence, Formation, Health Effects, and Control. Karanfil, T., Krasner, S.W. and Xie, Y. (eds), pp. 334-348.

   Water distribution systems are complex environments frequently containing corroded iron pipes and biofilms. To thoroughly understand the fate of halogenated disinfection byproducts (DBPs) in these systems, two degradation processes were investigated: abiotic degradation (i.e. hydrolysis and reductive dehalogenation) and biodegradation. DBPs were selected from 6 different compound classes representing both regulated DBPs (i.e. trihalomethanes or THMs, and haloacetic acids or HAAs) and non-regulated or "emerging" DBPs. Batch experiments were conducted to investigate the pathways and kinetics of DBP degradation. As expected, the relative importance of hydrolysis, abiotic reductive dehalogenation, and biodegradation depends on the DBP structure and on the environmental conditions (i.e. pH, temperature, dissolved oxygen, Fe minerals present, bacteria present, etc.). From our results, chloropicrin (i.e. trichloronitromethane) and most brominated DBPs are highly susceptible to abiotic reductive dehalogenation, trichloracetonitrile and trichloropropanone are the most susceptible to hydrolysis, and HAAs are readily biodegraded under aerobic conditions. Knowledge of DBP degradation mechanisms and rates in distribution systems is important for selecting DBP monitoring locations, modeling DBP fate, and for predicting exposure to these compounds. Such information could also be useful for developing treatment systems for DBP removal.
Chun, C.L., Hozalski, R.M. and Arnold, W.A. (2007) Degradation of disinfection byproducts by carbonate green rust. Environmental Science & Technology 41(5), 1615-1621.   Disinfection byproducts (DBPs) in drinking water flowing through corroded iron or steel pipes may encounter carbonate green rust (GR(CO32-)), a mixed Fe(II)/Fe(III) hydroxide mineral and potent reductant. This research was performed to investigate the kinetics and pathways of the degradation of selected halogenated DBPs in the presence of GR(CO32-). Trichloronitromethane was rapidly degraded to methylamine via sequential hydrogenolysis followed by nitro-reduction. Haloacetic acids reacted solely via sequential hydrogenolysis. Trichloroacetonitrile, 1,1,1-trichloropropanone, and trichloroacetaldehyde hydrate were transformed via hydrolysis and hydrogenolysis. Chloroform was unreactive over 300 h. The buffer identity affected reductive dehalogenation rates of DBPs, with faster rates in MOPS buffer than in carbonate buffer, the latter being representative of the buffer in drinking water systems. GR(CO32-) was unstable in both buffers and transformed to magnetite within 48 h. Thus, slower reacting compounds (half life > 3 hours) were transformed by a combination of minerals. Reductive dehalogenation kinetics were influenced by DBP chemical structure and correlated with one-electron reduction potential.

 

THMs
Citation Notes Abstract

   

HAAs
Citation Notes Abstract
Peck & Reckhow, Haloacetic Acids, unpublished started 2011  
Lifongo, L.L., Bowden, D.J. and Brimblecombe, P. (2010) Thermal degradation of haloacetic acids in water. International Journal of the Physical Sciences 5(6), 738-747.   Haloacetic acids are commonly found in most natural waters. These are known as degradation products of some halogenated compounds such as C(2)-chlorocarbons and CFC replacement compounds: hydroflurocarbons (HFCs) and hydrochloroflurocarbons (HCFCs). While knowledge clarifying the particular sources of these compounds and precursor degradation mechanisms are progressing, there is less understanding of mechanisms for the environmental degradation resulting from haloacetic acids. In particular, increasing concentrations of trifluoroacetic acid (TFAA) and its stability to degradation have prompted concerns that it will accumulate in the environment. Here we present the results of experiments on the non-biological decomposition of aqueous haloacetic acids. The decarboxylation of trichloroacetic acid (TCAA) and tribromoacetic acid (TBAA) was investigated in the 1930's, so this process seemed a potentially important pathway for degradation of trihaloacetic acids (THAAs) in the environment. We have measured the rate of decarboxylation of TFAA, TCAA, and TBAA and also the hydrolysis rate constants for some mono-, di-, and mixed halogen haloacetic acids in water at temperatures above ambient. The results suggest long lifetimes in natural waters. Tri-substituted acids degrade through decarboxylation with half-lives (extrapolated) at 15 degrees C for 103 days, 46 years and 40,000 years for TBAA, TCAA and TFAA respectively. The mono and di-substituted haloacetic acids degrade via hydrolysis with half-lives (extrapolated) of 2, 12, 15, and 68 years at 15 degrees C for monobromo- (MBAA), dibromo- (DBAA), monochloro- (MCAA) and dichloro-(DCAA) acetic acids respectively. The mixed haloacetic acids, bromochloro- (BCAA) and chlorodifluoro- (CDFAA) degrade by hydrolysis with half-lives (extrapolated) of 6 and 83 years respectively at 15 C. The overall stability of nine haloacetic acids investigated in this study of thermal degradation regardless the process, is in the order: TFAA >> CDFAA > DCAA > DBAA > MCAA > BCAA > MBAA > TCAA > TBAA. We found no catalytic effect of iron, copper and manganese on the rate of decarboxylation in water.
Wang, W. and Zhu, L.Z. (2010) Effect of zinc on the transformation of haloacetic acids (HAAs) in drinking water. Journal of Hazardous Materials 174(1-3), 40-46.   Suspected carcinogen haloacetic acids (HAAs), as a major class of disinfection byproducts, are widespread in drinking water. Batch experiments were conducted to investigate the effect of zinc, a metal component of galvanized pipe in water distribution systems, on the fate of the HAAs. Results showed that zinc could induce sequential dehalogenation of HAAs. All brominated acetic acids were transformed to acetate ultimately, and chloroacetic acid (MCAA) was the final product for the dehalogenation of trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA). The concentrations of the parent compounds as a function of time were fitted pseudo-first-order kinetic model with R-2 > 0.904. Brominated acetic acids were more activated than chlorinated acetic acids in the reaction with zinc and the activity of HAAs decreased with the number of substituents reduced. While flowing through galvanized pipe, brominated and chlorinated acetic acids except MCAA would decrease to 1% of their initial concentrations in 2.11-6.34 h, and the rates would not be affected obviously by the hydrodynamic or duct conditions. The health risk due to TCAA, DCAA in drinking water tends to be magnified, and that due to TBAA, DBAA tends to be first increased and then decreased, also that due to MBAA tends to be decreased.
Zhang, L., Arnold, W.A. and Hozalski, R.M. (2004) Kinetics of haloacetic acid reactions with Fe(0). Environmental Science & Technology 38(24), 6881-6889.   Detailed kinetic studies of the reactions of haloacetic acids (HAAS) with Fe(O) were performed in longitudinally mixed batch reactors. The reactions of tribromoacetic acid (TBAA), bromodichloroacetic acid, and chlorodibromoacetic acid were mass transfer limited, with corrected mass transfer coefficients of 3.7-3.9 x 10(-4) m/s. The reactions of trichloroacetic acid (TCAA), dichloroacetic acid (DCAA), chloroacetic acid (CAA), and bromoacetic acid (BAA) were reaction limited. Bromochloroacetic acid (BCAA) and dibromoacetic acid (DBAA) were partially reaction limited. For the reaction limited species and partially reaction limited species, intra- and interspecies competition effects were observed. A Langmuir-Hinshelwood-Hougen-Watson kinetic model incorporating a mass transfer term was adopted to account for these effects. The lumped kinetic parameters for the HAAS ranged from 0.04 to 248 muM min(-1) for an iron loading of 0.3 g of Fe/125 mL and followed the trend DBAA > BCAA > TCAA > BAA > DCAA. The adsorption parameters ranged from 0.0007 to 0.0065 muM(-1). The effect of dissolved oxygen (DO) on the reaction of TBAA or BAA with Fe(O) was also investigated. No significant effect of DO on the reaction rate of TBAA, which is a mass transfer limited species, was observed. A lag phase, however, was observed for the reaction of BAA, which is a reaction limited species, until the DO was depleted. Simulations were performed to investigate the potential significance of the reactions of HAAs with Fe(O) in water distribution systems.
Zhang, X.R. and Minear, R.A. (2002) Decomposition of Trihaloacetic Acids and Formation of the Corresponding Trihalomethanes in Drinking Water. Water Research 36(14), 3665-3673. pH-dependent decarboxylation The decomposition of trihaloacetic acids [bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), tribromoacetic acid (TBAA)], and the formation of the corresponding trihalomethanes [bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM)] were studied. Like TBAA, the two mixed chlorobromo-species, BDCAA and DBCAA, were found to decompose to form BDCM and DBCM, respectively, via a decarboxylation pathway. The decomposition of BDCAA, DBCAA and TBAA in water at neutral pH follows a first order reaction, with rate constants of 0.0011, 0.0062 and 0.040 day(-1) at 23degreesC, respectively; and 0.000028, 0.00014 and 0.0016 day(-1) at 4degreesC, respectively. The activation energies for the decomposition reaction of BDCAA, DBCAA and TBAA in water at neutral pH were found to be 35.0, 34.5 and 29.2 kcal/mol, respectively. The effect of pH in the range of 6-9 and the effect of a drinking water matrix on the decomposition of BDCAA, DBCAA, and TBAA in water were found to be insignificant. Measurement and health implications due to decomposition of trihaloacetic acids and formation of the corresponding trihalomethanes were discussed. By applying the technique of quantitative structure-activity relationships (QSAR), the decomposition rate constants of six iodinated trihaloacetic acids were estimated.
Urbansky, E.T. (2001) The Fate of the Haloacetates in Drinking Water - Chemical Kinetics in Aqueous Solution. Chemical Reviews 101(11), 3233-3243. extensive review as of 2001; great starting point  

 

 

Haloacetonitiles
Citation Notes Abstract
Yang & Reckhow, Dihaloacetonitrile manuscript, unpublished started 2011 .
Peck & Reckhow, Trihaloacetonitrile manuscript, unpublished started 2011  
Reckhow, D.A., Platt, T.L., MacNeill, A.L. and McClellan, J.N. (2001) Formation and Degradation of Dichloroacetonitrile in Drinking Waters. Journal of Water Supply Research and Technology-Aqua 50(1), 1-13.   Dichloroacetonitrile (DCAN) is an important example of a reactive disinfection by-product for which a large body of occurrence data exists. Although it is known to undergo base-catalysed hydrolysis, DCAN's peculiar dependence on reaction time, chlorine dose and pH has never been fully reconciled with expectations based on its presumed precursor (i.e. amino acid residues). The purpose of this research was to improve existing models for DCAN degradation and to use this information for interpretation of DCAN concentration profiles. Laboratory studies were performed using buffered solutions of DCAN, natural organic matter (NOM) and treated drinking waters, both with and without free residual chlorine. DCAN concentrations were measured as a function of reaction time. Results indicate a decomposition scheme encompassing three pathways of hydrolysis: attack by hydroxide, hypochlorite and water. Any one of the three pathways may predominate in drinking water systems, depending on the pH John Fl. McClellan and chlorine residual. The resulting chemical kinetic model was used to show that the DCAN formed (and subsequently decomposed) was often many times the actual measured DCAN concentration. DCAN formation was found to agree with expectations based on the underlying chemistry of chlorine attack on proteinaceous material.
Glezer, V., Harris, B., Tal, N., Iosefzon, B. and Lev, O. (1999) Hydrolysis of Haloacetonitriles: Linear Free Energy Relationship, Kinetics and Products. Water Research 33(8), 1938-1948.   The hydrolysis rates of mono-, di- and trihaloacetonitriles were studied in aqueous buffer solutions at different pH. The stability of haloacetonitriles decreases and the hydrolysis rate increases with increasing pH and number of halogen atoms in the molecule: The monochloroacetonitriles are the most stable and are also less affected by pH-changes, while the trihaloacetonitriles are the least stable and most sensitive to pH changes. The stability of haloacetonitriles also increases by substitution of chlorine atoms with bromine atoms. The hydrolysis rates in different buffer solutions follow first order kinetics with a minimum hydrolysis rate at intermediate pH. Thus, haloacetonitriles have to be preserved in weakly acid solutions between sampling and analysis. The corresponding haloacetamides are formed during hydrolysis and in basic solutions they can hydrolyze further to give haloacetic acids. Linear free energy relationship can be used for prediction of degradation of haloacetonitriles during hydrolysis in water solutions.

 

 

Haloacetamides
(related info may be found in: DBP Analysis and Non-regulated DBP pages)
Citation Notes Abstract
Rapp & Reckhow, Dichloroacetamide manuscript, unpublished started ~2001  
Chu, W.H., Gao, N.Y. and Deng, Y. (2009) Stability of Newfound Nitrogenous Disinfection By-products Haloacetamides in Drinking Water. Chinese Journal of Organic Chemistry 29(10), 1569-1574.
   The conversion of drinking water disinfection process from free chlorine to mono-chloramine reduces the formation of trihalomethanes (THM), but increases the concentration of nitrogenous disinfection by-products (N-DBP), especially five new haloacetamides (HAcAm) including monochloroacetamide (MCAcAm), dichloroacetamide (DCAcAm), trichloroacetamide (TCAcAm), monobromoacetamide (MBAcAm) and dibromoacetamide (DBAcAm). Among these HAcAms, DCAcAm and TCAcAm are normally present in drinking water at a higher concentration. The hydrolysis characteristics with different pH values and chlorination characteristics under different chlorine dosages of HAcAm were studied by combination with linear free-energy relationship (LFER). Based on the hydrolysis and chlorination characteristics of HAcAm, the reaction pathways of hydrolysis and chlorination for HAcAm were also investigated by detection of final product haloacetic acids (HAA). The results indicated that DCAcAm reacted slowly with water in highly acidic condition (pH=4) but was stable at pH 5 within 7 d reaction time. Acid environment can not cause TCAcAm hydrolysis reaction. Obvious hydrolysis reactions of DCAcAm and TCAcAm were discovered in alkaline conditions, which followed the first order reaction. The water sample containing DCAcAm and TCAcAm could be preserved by adjusting pH to 5. The use of chlorine disinfection and increment of chlorine dosage caused the amount of THM and HAA to go up in drinking water, however, it maybe resulted in the decrease of N-DBP Such as HAcAm. Trichloroacetic acid (TCAA) was produced rapidly by TCAcAm hydrolysis at pH 10. For chlorination of TCAcAm, relatively stable Cl-N-TCAcAm was produced from a reaction between TCAcAm and HOCl, then continued to generate TCAA and NHCl(2) at a higher concentration of HOCl.

 

Halonitromethanes
Citation Notes Abstract
Lee, J.Y., Pearson, C.R., Hozalski, R.M. and Arnold, W.A. (2008) Degradation of trichloronitromethane by iron water main corrosion products. Water Research 42(8-9), 2043-2050.   Halogenated disinfection byproducts (DBPs) may undergo reduction reactions at the corroded pipe wall in drinking water distribution systems consisting of cast or ductile iron pipe. Iron pipe corrosion products were obtained from several locations within two drinking water distribution systems. Crystalline-phase composition of freeze-dried corrosion solids was analyzed using X-ray diffraction, and ferrous and ferric iron contents were determined via multiple extraction methods. Batch experiments demonstrated that trichloronitromethane (TCNM), a non-regulated DBP, is rapidly reduced in the presence of pipe corrosion solids and that dissolved oxygen (DO) slows the reaction. The water-soluble iron content of the pipe solids is the best predictor of TCNM reaction rate constant. These results indicate that highly reactive DBPs that are able to compete with oxygen and residual disinfectant for ferrous iron may be attenuated via abiotic reduction in drinking water distribution systems.

 

Haloketones
Citation Notes Abstract
Guthrie, J. P. and J. Cossar (1986). "The Chlorination of Acetone - A Complete Kinetic Analysis." Canadian Journal of Chemistry-Revue Canadienne De Chimie 64(6): 1250-1266. (correction) careful & detailed kinetic laboratory study  

Halobenzoquinones
(most HBQ references are in: Non-Regulated DBPs, see also: DBP Methods, DBP Occurrence and DBP Health)
Citation Notes Abstract
Qin, F., Zhao, Y.Y., Zhao, Y.L., Boyd, J.M., Zhou, W.J. and Li, X.F. (2010) A Toxic Disinfection By-product, 2,6-Dichloro-1,4-benzoquinone, Identified in Drinking Water. Angewandte Chemie-International Edition 49(4), 790-792. Supporting Info
    

 

Aldehydes
Citation Notes Abstract
McKnight, A. "Reactions of Ozonation Byproducts with Chlorine and Chloramines," MS Thesis, September, 1992.
 Chlorination and chloramination  
McKnight, A.P. and Reckhow, D.A. (1992) Reactions of Ozonation Byproducts With Chlorine and Chloramines, pp. 399-409, AWWA Proc, Vancouver. [CN32] Chlorination of Acetaldehyde (from thesis)  
McKnight, A.P. and Reckhow, D.A. (1992) Chlorine Reactions of Ozonation Byproducts: Model Compounds Studies, pp. 722-725, ACS Proc., Chicago. [CN64] Chlorination of Methyl Glyoxal (from thesis)  

 

Single Studies in VariousTreatment Scenarios
Citation Notes Abstract

   

Large DBP Studies with some Degradation Data
Citation Notes Abstract