Haloacetic acids chlorination

Removal of Refractory Organics. Ozone reacts slowly or insignificantly with certain micropoUutants in some source waters such as carbon tetrachloride, trichlorethylene (TCE), and perchlorethylene (PCE), as well as in chlorinated waters, ie, ttihalomethanes, THMs (eg, chloroform and bromoform), and haloacetic acids (HAAs) (eg, trichloroacetic acid). Some removal of these compounds occurs in the ozone contactor as a result of volatilization (115). Air-stripping in a packed column is effective for removing some THMs, but not CHBr. THMs can be adsorbed on granular activated carbon (GAG) but the adsorption efficiency is low. 

Ells B, Barnett DA, Purves RW, Guevremont R (2000) Detection of nine chlorinated and brominated haloacetic acids at part-per-trillion levels using ESI-FAIMS-MS. Anal Chem 72 (19) 4555 559... 

Dickenson ERV, Summers RS, Croue J-P, Gallard H (2008) Haloacetic Acid and Trihalo-methane Formation from the Chlorination and Bromination of Aliphatic (3-Dicarbonyl Acid Model Compounds. Environ Sci Technol 42 3226... 

Irradiation was also successful in the decomposition of THMs to chloride and bromide ions (Cooper et al., 1993b). Toxic organic by-products such as haloacetic acid, aldehyde, ketones, or halogenated organic compounds were formed after irradiation. It has also been proven effective in the destruction of halogenated ethenes such as TCE and PCE. Removal rates decreased 20-fold in the presence of methanol as opposed to its absence. Aldehydes and formic acid were found when low solute concentrations of TCE and PCE were irradiated however, at high concentrations no more than 5% formic acid was found. Complete conversion of organic chlorine to chloride ion can be achieved. 

Haloacetic acids (HAAs), monochloroacetate, dichloroacetate and trichloroacetate, can also be formed as the result of reaction of chlorine with organic matter contained in raw water. Some countries monitor HAAs as well as THMs, but HAAs are much more difficult and expensive to analyse than THMs. 

Disinfectants are usually only monitored to ensure that disinfection has taken place. Certain disinfectants, such as chlorine, are sometimes monitored at the tap or in the distribution system, as a measure of the quality in distribution. A wide range of potential by-products of disinfection may be formed in treatment, particularly if natural organic matter is present at high concentrations. The most commonly monitored by-products are the trihalomethanes (THMs) formed through chlorination THMs are normally considered to be an adequate marker of the total disinfection by-products from chlorination. Some countries also monitor haloacetic acids, but these are difficult and expensive to analyse because of their high polarity. Bromate is sometimes measured when ozone is used, but its formation relates to bromide concentrations in the raw water and the conditions of ozonation. Analysis can be extremely difficult and monitoring is not usually considered except where standards have been set or on an infrequent basis. 

As a result of the disinfection of drinking water by means of ozone, chlorine dioxide, chloramine, and chlorine, a variety of disinfection byproducts may occur in drinking water, including oxyhalides, haloacetic acids, and halogenated AEO and APEO metabolites (Ch. 8.4.2). The LC-MS analysis of disinfection byproducts in drinking water was recently reviewed by Zwiener and Richardson [65]. 

Chlorine is applied as chlorine gas, powdered calcium hypochlorite (Ca(OCl)2), or liquid sodium hypochlorite (NaOCl bleach). Chlorine reacts with the organic (natural organic matter, NOM) or inorganic (bromide ion, Br ) precursors in the water to form chlorine disinfection by-products (CBPs), including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), haloketones, chloral hydrate, and chloropicrin. Humic and fulvic acids are the predominant NOMs. When bromine exists, the chlorine oxidizes it to hypobromous acid/ hypobromite ion (HOBr/OBr ) to form bromo THMs (bromodichloromethane, BDCM, and di-bromochloromethane, DBCM), HAAs, and HANs. 

It is common for water suppliers to use disinfectants such as chlorine, chloramines and chlorine dioxide to kill microorganisms such as giardia and E coli. Levels of disinfectants used may be higher after rainstorms in summer months. By-products include trihalomethanes, haloacetic acids, bro-mate, and chlorite. Levels of disinfection products and by-products are regulated. 

It was discovered in the 1970s that chlorination of raw water high in organic content and/or infused with seawater results not only in the disinfection of water, but also in the formation of disinfection by-products (DBPs). These include trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs) J55-56 These chemicals are individually toxic at high concentrations and can cause cancer, liver disease, kidney disease, birth defects, and reproductive failuresJ57 59 ... 

As seen from the data, water disinfected with chlorine can have a complex mixture of lipophiles and hydrophiles. The lipophilic THMs can facilitate the absorption of the hydrophilic haloacetic acids, haloace-tonitriles and haloketones. An analogy between the reproductive toxicity and carcinogenicity of DBPs can be drawn. Though no single chlorinated byproduct studied appears to be carcinogenic, there is evidence from animal studies that DBP mixtures are carcinogenicJ4°l... 

Haloacetic acids are derivatives of acetic acid in which one or more hydrogen atoms on the alpha carbon are replaced by halogens (fluorine, chlorine, bromine or iodine) (Figure 12.1). The haloacetic acid most commonly used in peels is trichloroacetic acid, and we will therefore look at the chlorine derivatives of acetic acid. 

Municipal or other public water systems typically have contaminants of two types those that pass through the municipal purification system and those that are residues from the treatment process itself. Bacteria and turbidity are examples of the former. The latter may include materials such as alkalinity, alum, buffers, bromate, chlorine, chlorite, copper, haloacetic acids and trihalomethanes. 

Suedee, R., Intakong, W. and Dickert, E.L. (2006) Molecularly imprinted polymer-modified electrode for on-line conductometric monitoring of haloacetic acids in chlorinated water. Anal Chim Acta, 569 (1-2), 66-75. 

Disinfection by-products (DBFs) include trihalomethanes, haloketones, haloacetonitriles, haloacetic acids, and other chlorinated compounds. If ozone pretreatment is applied, ozonation by-products can be formed, one of them being bromate (Tal and Amy (1991)). 

Low-level chlorination of 0.5-1.5 mg/1, resulting in a chlorine residual of 0.1 -0.2 mg/1, is used to reduce the degree of biofouling. In sea-water, chlorine oxidizes bromide, present at about 65 mg/1, to bromine, which also contributes to the generation of halogenated by-products [176]. The by-products include hypobromous acid, hypobromite, chloramines, bromamines, trihalomethanes, haloacetonitriles,haloacetic acids, and small amounts of halophenols. However, some haloforms and bromophenols as well as other organobromine compounds are also produced naturally in coastal waters [ 181,182]. Empirical equations for the disappearance of chlorine/bromine derived oxidants from brackish water have been published [183]. 

In the disinfection process of drinking water, besides other chlorinated compounds, halogenated carboxylic acids arise. For quality control of drinking water the determination of these contaminants was established using LC-MS with a preference for ESI (cf 15.3.3.2 ESI, haloacetic acids). An application of APCI-MS for haloacetic acid analysis was reported after CE separation in a non-aqueous medium [303]. 

Perhaps the most spectacular of the early results that demonstrated the potential of FAIMS as a mobility filter for MS was in the detection of nine chlorinated and brominated haloacetic acids at the part-per-triUion levels in drinking water. - The selectivity and efficiency of ion transmission through the FAIMS into the MS improved the detection limits of these compounds by three to four orders of magnitude over conventional ESI-MS methods. 

In water, GC-MS is coupled to purge and trap or headspace sample preparation for the analysis of VOCs like BTEX and MTBE. Another important group of volatile analytes in water are DBFs. Attention has been directed to volatile chlorinated compounds such as trihalomethanes (THMs), as well as other semivolatile compounds such as haloacetic acids (HAAs), haloacetonitriles, haloketones, and ha-loaldehydes. The methods used to determine these compounds include GC-EI-LRMS, where a after derivatization step is necessary due to the low volatility and high polarity of these analytes. Using this technique, limits of detection were in the microgram per liter range. 

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