Trihaloacetic Acid Research Articles

Potential risks and approaches to reduce the toxicity of disinfection by-product – A review

Water contamination through anthropogenic and industrial activities has led to the emergence and necessity of disinfection methods. Chlorine and bromine gases, often used to disinfect water, resulted in the by-product formation by reacting with organic matter. The Disinfectant by-products (DBP) led to the formation of Trihaloaceticacid (TAA), Trihalomethane (THM), and other minor components. The release of chemicals has also led to the outbreak of diseases like infertility, asthma, stillbirth, and types of cancer. There are new approaches that are found to be useful to compensate for the generation of toxic by-products and involve membrane technologies, namely reverse osmosis, ultrafiltration, and nanofiltration. This review mainly focuses on the toxicology effects of DBPs and various approaches to mitigate the same. The health hazards caused by different DBPs and the various treatment techniques available for the removal are discussed. In addition, a critical comparison of the different removal techniques was discussed.

Seasonal Variation of Disinfection Byproduct Precursors in a Large Water Supply

Disinfection byproduct (DBP) precursors originate in large reservoirs from at least three types of sources: (1) watershed or allochthonous, (2) algal or autochthonous, and (3) bottom sediments or benthic. The properties of the bulk natural organic matter (NOM) and the DBP precursor content of that NOM are unique to each source. Knowledge about the relative importance of these three sources would be valuable in understanding the natural variability in DBP precursor occurrence and in managing source waters for the purpose of minimizing DBP precursors. In this study, we used temporal and spatial water quality data from a drinking water reservoir to shed light on autochthonous and benthic sources of NOM and DBP precursors. The Cannonsville Reservoir (New York) was chosen for this work because of its well‐documented water quality. To assist in the data analysis, we developed a series of two‐dimensional contour plots that bring clarity to benthic and near‐surface (algal) processes on water quality. Combining conventional water quality parameters with DBP precursor analysis can facilitate a more comprehensive understanding of limnological factors that define DBP precursor levels. These data were compared with known properties of NOM and related natural biochemical parameters. From this analysis, we conclude that algal‐dominated NOM contributes disproportionately to dihaloacetonitrile formation, whereas watershed‐dominated NOM is especially rich in trihaloacetic acid and trihalomethane precursors as well as ultraviolet‐absorbing substances. The sediment‐dominated precursor behaved like a mix of the other two but most resembled the watershed NOM.

Multicolor Emission in Chemically and Structurally Tunable Er:Yb:SrFX (X = Cl, Br) Upconverting Nanocrystals

The synthesis, structural analysis, and NIR-to-visible upconversion luminescence of color-tunable Er:Yb:SrFX (X = Cl, Br) nanocrystals are reported. Green, orange, and red-emitting upconverters were achieved by employing chemically and structurally tunable alkaline-earth fluorohalides as hosts for Er3+–Yb3+ activator–sensitizer pairs. Solution-phase thermolysis of metal trifluoroacetates and of the corresponding trihaloacetic acid was utilized to synthesize Er:Yb:SrFCl and Er:Yb:SrFBr nanocrystals with average sizes of ≈15 and 50 nm, respectively. X-ray total scattering and Sr K edge absorption spectroscopy showed that a bulk-type crystallographic model provided an adequate description of the average and local structures of Er:Yb:SrFBr but failed to describe the local structure of Er:Yb:SrFCl nanocrystals, as deviations from the model were observed in the second coordination shell of strontium. Steady-state and time-resolved spectrofluorometric analyses showed that the red-to-green ratio of the upconverted emission could be compositionally tuned between 1 (green emitter) and 50 (red emitter). Single-band, red-emitting Er:Yb:SrFCl nanocrystals with Er3+ excited state lifetimes in the 100–160 μs range were thus achieved.

A versatile quinoxaline derivative serves as a colorimetric sensor for strongly acidic pH.

A facile and reliable method to monitor strongly acidic pH was developed. The sensing mechanism was found to involve the protonation-deprotonation equilibrium of the synthesized probe HQphy (1) (N-phenyl-N'-quinoxalin-2-ylmethylene-hydrazine) within a working range of pH 0.7-2.7. The eventual sensing of Fe3+ was the outcome of acidity imparted by [Fe(H2O)6]3+ ions in solution during the formation of [Fe(H2O)5(OH)]2+. The protonation-deprotonation phenomenon of HQphy was investigated using 1H NMR and single crystal X-ray diffraction experiments. The protonated probe, H2Qphy+, was crystallized with FeCl4-/ClO4- counter anions as [H2Qphy][FeCl4]·H2O (2)/[H2Qphy][ClO4]·H2O (3). A further complex containing the [H2Qphy] cation (4) was also formed. The complexes were characterized by SC-XRD experiments. Moreover, single crystal to single crystal transformation is observed between 1 and 3. In order to understand the sensing mechanism, various analytical studies, such as UV-Vis titration, ESI-MS spectrometry analysis and 1H NMR, were carried out in detail. A theoretical study correlates well with the experimental data, where the π(L) → π*(L) transition of the ligand is red shifted by 100 nm due to protonation of the quinoxaline moiety. The probe enables discrimination of trihalo acetic acid from its mono- and di-analogues.

ChemInform Abstract: anti‐Dioxylation of Cyclohex‐4‐ene‐1,2‐diamine Derivatives: Asymmetric Routes to Hydroxy‐ and Amino‐Substituted Cyclohexane and 7‐Azanorbornane.

The highly diastereoselective anti-dioxylation of (1R,2R)-1,2-bis[(1S)-phenylethylamino]cyclohexene was accomplished through epoxidation of the double bond with m-chloroperbenzoic acid (mCPBA) in the presence of a sulfonic or trihaloacetic acid and ring opening of the epoxide in situ in the presence of sulfonate or carboxylate anions. The two procedures, after basic quenching and reductive removal of the N-substituents, provide stereoselective access to 2-exo-5-endo-5-amino-7-azabicyclo[2.2.1]heptan-2-ol and 4,5-diaminocyclohexane-1,2-diol, respectively. The different outcomes are explained by differing chair conformations of the protonated diamine-epoxide intermediates, which undergo ring opening through a preferred anti-diaxial mechanism.

Anti‐Dioxylation of Cyclohex‐4‐ene‐1,2‐diamine Derivatives: Asymmetric Routes to Hydroxy‐ and Amino‐Substituted Cyclohexane and 7‐Azanorbornane

AbstractThe highly diastereoselective anti‐dioxylation of (1R,2R)‐1,2‐bis[(1S)‐phenylethylamino]cyclohexene was accomplished through epoxidation of the double bond with m‐chloroperbenzoic acid (mCPBA) in the presence of a sulfonic or trihaloacetic acid and ring opening of the epoxide in situ in the presence of sulfonate or carboxylate anions. The two procedures, after basic quenching and reductive removal of the N‐substituents, provide stereoselective access to 2‐exo‐5‐endo‐5‐amino‐7‐azabicyclo[2.2.1]heptan‐2‐ol and 4,5‐diaminocyclohexane‐1,2‐diol, respectively. The different outcomes are explained by differing chair conformations of the protonated diamine‐epoxide intermediates, which undergo ring opening through a preferred anti‐diaxial mechanism.

Formation characteristics of haloacetic acids from phenols in drinking water chlorination

Haloacetic acids (HAAs) are typical chlorination disinfection by-products in drinking water. Apart from natural organic matter, synthetic organic compounds in raw water contribute to HAAs due to their high frequency of detection in raw water and high reactive activities with chlorine. Formation characteristics of HAAs from synthetic organic compounds were investigated using seven phenols as models in the chlorination process. Two HAAs, trihaloacetic acid (TCAA) and dihaloacetic acid (DCAA), were generated and TCAA was the main product. The molar yields of HAAs varied between 0.087 mol/(mol phenol) from resorcinol to 0.251 mol/(mol phenol) from 2,4,6-trichlorophenol at pH 7.0. Phenols having para- or ortho-substituent groups were found to have higher reactive activities than those having meta-substituent groups in forming HAAs. HAA formation potential (HAAFP) of raw water was significantly enhanced with spiked phenols. These results indicate that synthetic organic compounds in raw water have high activities in yielding HAAs, and more research should be focused on their behaviors in drinking water disinfection.

Multivariate distributions of disinfection by-products in chlorinated drinking water

Drinking water disinfection by-product (DBP) occurrence research is important in supporting risk assessment and regulatory performance assessment. Recent DBP occurrence surveys have expanded their scope to include non-regulated priority DBPs as well as regulated DBPs. This study applies a Box–Cox transformed multivariate normal model and data augmentation methods for left-censored and missing observations to US EPA Information Collection Rule (ICR) drinking water data to describe the variability in the trihalomethane (THM4), trihaloacetic acid (THAA), dihaloacetic acid (DHAA), and dihaloacetonitrile (DHAN) DBP classes, the relationship between class-sum and the occurrence of individual DBPs within these classes. Inferences about bromine incorporation in these classes are then compared to those made by Obolensky and Singer (2005). Results reported herein show that class-based and individual DBP concentrations are strongly related to bromine substitution, and that speciation and bromine substitution patterns are consistent across DBP classes. In addition, the multiple imputation approach employed reveals that uncertainties related to missing and left-censored DBPs have important implications for understanding bromine substitution in the THAA class. These concerns should be considered through alternative approaches to DBP regulation in subsequent Stage II D/DBP assessment and revisions, where appropriate.

Formation of HAAs and THMs in the Water Treatment and Distribution System of Macau

This study investigated the formation behavior of two CDBPs, namely THMs and HAAs, in a treatment plant and the distribution network of Macau. Concentrations of the four species of THMs and the six species of HAAs were monitored at different stages of the treatment process and at two separate points in the distribution network during February 2006 to January 2007. The results show that the mass concentration of THMs was generally higher than that of HAAs in treated water with a ratio ranging from around 1:1 to 2:1. The results suggested that two steps, pre-chlorination and coagulation, performed in the treatment process influenced the formation of CDBPs in the plant. The CDBPs formation was found to continue in the distribution system with the concentration of THMs increasing faster. The effect of temperature on the formation of HAAs was found to be more significant than on that of THMs. In an alkaline condition, both THMs and dihaloacetic acids were easier to form but the concentration of some trihaloacetic acid decreased.

Development and Interpretation of Disinfection Byproduct Formation Models Using the Information Collection Rule Database

Multiple linear regression models were used to examine relationships between water quality, treatment, and disinfection byproduct (DBP) formation in Information Collection Rule field data. Finished water models were specified using a cross-validation approach based on data for 225 free chlorine treatment plants. Turbidity, bromide, temperature, alkalinity, total organic carbon, ultraviolet absorbance at 254 nm, pH, chlorine residual, chlorine consumed, and chlorine contact time were employed as independent variables. Important trends within the trihalomethane, dihaloacetic acid, and trihaloacetic acid classes were observed. Bromide was a significant predictor for all DBP species and its influence changed in sign and magnitude with the extent of bromine substitution. A similar pattern followed by alkalinity suggested it plays an important role as an indicator of natural organic matter hydrophobicity and reactivity. Chlorine consumed and organic precursor variables were significant predictors in almost all DBP species models, exhibiting trends opposite to those for alkalinity and bromide. Temperature was the most significant variable in chloroform and chloral hydrate models and its significance declined with increasing bromine substitution within the trihalomethane class. pH had a strong positive influence on chloroform formation, a negative influence on trihaloacetic acid formation, and no influence on dihaloacetic acid formation.

Controlling oriented aggregation using increasing reagent concentrations and trihalo acetic acid surfactants

Zinc oxide particle growth from homogenous solutions prepared with isopropyl alcohol was monitored using in situ UV–vis spectroscopy, and results show that the rate of ZnO particle growth and the final ZnO nanoparticle size depend strongly upon the concentrations of precursors and the identity of surfactants used. In addition, particle size versus time data was fit using the coarsening model and the simultaneous oriented aggregation and coarsening model in order to evaluate the effect of changing synthetic variables on the mechanism of nanoparticle growth. In general, an increase in growth by oriented aggregation with increasing precursor concentrations was observed, a result that was consistent with results from high-resolution transmission electron microscopy (HRTEM) characterization. The increase in precursor concentrations resulted in an increase in the number concentration of ZnO nanoparticles, which resulted in a higher probability of particle–particle interactions and hence increased growth by oriented aggregation. Additionally, particle growth in solutions of trifluoro-, trichloro-, and tribromoacetate surfactants was studied, and growth by oriented aggregation followed the trend expected based on the number concentration of zinc oxide particles. Growth with trifluoroacetate was an exception, with growth by oriented aggregation substantially suppressed.

Characterization of Disinfection Byproduct Precursors Based on Hydrophobicity and Molecular Size

Natural organic matter (NOM) from five water sources was fractionated using XAD resins and ultrafiltration membranes into different groups based on hydrophobicity and molecular weight (MW), respectively. The disinfection byproduct formation from each fraction during chlorination and chloramination was studied. In tests using chlorination, hydrophobic and high MW (e.g., >0.5 kDa) precursors produced more unknown total organic halogen (UTOX) than corresponding hydrophilic and low MW (e.g., <0.5 kDa) precursors. Trihaloacetic acid (THAA) precursors were more hydrophobic than trihalomethane (THM) precursors. The formation of THM and THAA was similar among different fractions for a water with low humic content. Hydrophilic and low MW (<0.5 kDa) NOM fractions gave the highest dihaloacetic acid (DHAA) yields. No significant difference was found for DHAA formation among different NOM fractions during chloramination. Increasing pH from 6 to 9 led to lower TOX formation for hydrophobic and high MW NOM fractions but had little impact on TOX yields from hydrophilic and low MW fractions. Bromine and iodine were more reactive with hydrophilic and low MW precursors as measured by THM or HAA formation than their corresponding hydrophobic and high MW precursors. However, hydrophobic and high MW precursors produced more UTOX when reacting with bromine and iodine.

Coagulation of natural organic material: effects on speciation of halogenated disinfection by-products

A recent paper by Liang and Singer showed that haloacetic acid (HAA) precursors were removed by coagulation to a greater degree than trihalomethane (THM) precursors. Furthermore, they showed that coagulation generally removed more trihaloacetic acid precursors than THM precursors but removed dihaloacetic acid precursors and THM precursors to a similar degree. The objectives of this current study were to compare the findings by Liang and Singer to those of three other investigations conducted in the senior author's laboratory to demonstrate the extent to which coagulation removes THM and HAA precursors, and to contrast the removal of dihaloacetic acid and trihaloacetic precursors by coagulation. These other studies were conducted on seventeen other waters from across the US.

Factors influencing the formation and relative distribution of haloacetic acids and trihalomethanes in drinking water.

Various water quality and treatment characteristics were evaluated under controlled chlorination conditions to determine their influences on the formation and distribution of nine haloacetic acids and four trihalomethanes in drinking water. Raw waters were sampled from five water utilities and were coagulated with alum and fractionated with XAD-8 resin. The resulting four fractions--raw and coagulated water and the hydrophobic and hydrophilic extracts--were then chlorinated at pH 6 and 8 and held at 20 degrees C for various contact times. The results show that increasing pH from 6 to 8 increased trihalomethane formation but decreased trihaloacetic acid formation, with little effect on dihaloacetic acid formation. More trihalomethanes were formed than haloacetic acids at pH 8, while the reverse was true at pH 6. Hydrophobic fractions always gave higher haloacetic acid and trihalomethane formation potentials than their corresponding hydrophilic fractions, but hydrophilic carbon also played an important role in disinfection byproduct formation for waters with low humic content. The bromine-containing species comprised a higher molar proportion of the trihalomethanes than of the haloacetic acids. The hydrophilic fractions were more reactive with bromine than their corresponding hydrophobic fractions. Coagulation generally removed more haloacetic acid precursors than trihalomethane precursors. Waters with higher specific ultraviolet absorbance values were more amenable to removal of organic material by coagulation than waters with low specific ultraviolet absorbance values. Experimental evidence suggests that haloacetic acid precursors have a higher aromatic content than trihalomethane precursors.

Reduction of haloacetic acids by Fe0: implications for treatment and fate.

To predict the fate of haloacetic acids (HAAs) in natural or engineered systems, information is needed concerning the types of reactions that these compounds undergo, the rates of those reactions, and the products that are formed. Given that many drinking water distribution systems consist of unlined cast iron pipe, reactions of HAAs with elemental iron (Fe0) may play a role in determining the fate of HAAs in these systems. In addition, zerovalent iron may prove to be an effective treatment technology for the removal of HAAs from chlorinated drinking water and wastewater. Thus, batch experiments were used to investigate reactions of four trihaloacetic acids, trichloroacetic acid (TCAA), tribromoacetic acid (TBAA), chlorodibromoacetic acid (CDBAA), and bromodichloroacetic acid (BDCAA), with Fe0. All compounds readily reacted with Fe0, and investigation of product formation and subsequent disappearance revealed that the reactions proceeded via sequential hydrogenolysis. Bromine was preferentially removed over chlorine, and TBAA was the only compound completely dehalogenated to acetic acid. In compounds containing chlorine, the final product of reactions with Fe0 was monochloroacetic acid. Halogen mass balances were 95-112%, and carbon mass balances were 62.6-112%. The pseudo-first-order rate constants for trihaloacetic acid degradation were as follows: BDCAA (10.6 +/- 3.1 h-1) > CDBAA (1.43 +/- 0.32 h-1) approximately TBAA (1.41 +/- 0.28 h-1) >> TCAA (0.08 +/- 0.02 h-1).

Infrared study of α-haloacetic acids in solution

Rotation of the XCH 2 , X 2 CH, or X 3 C group about the carbonyl group for haloacetic acids causes erratic ν(CO) and ν op (CO) 2 frequency behavior that appears to offset the inductive effect. The inductive effect causes both ν(CO) and ν op (CO) 2 to either increase or decrease in frequency, depending upon whether sigma electrons of the group joined to the carbonyl group withdraw or donate sigma electrons to the carbonyl group, respectively. The X atoms of halogenated acetic acid in certain rotational configurations shield the carbonyl group from the reaction field of the solvent, and this factor is what we believe the one that offsets the inductive effect. Shielding of the carbonyl group by the halogen atoms in haloacetic acids from the reaction field of the solvent decreases in the order of I, Br, Cl and F. This is in the order of the decreasing atomic radius of the halogen atoms. The absorbance ratio A[ν (CO) ] A[ν op ( CO) 2 ] increases as the mole% CHCl 3 /CCl 4 is increased. It also increases in the monohaloacetic acid series, I through F, in the dihaloacetic acid series, Br 2 through F 2 , and in the trihaloacetic acid series, Br 3 through F 3 . Thus, as the mole% CHCl 3 /CCl 4 is increased, the concentration of acetic acid dimer decreases with an increase in the concentration of “monomeric” acetic acid. The ratio of “monomer” to “dimer” concentration with change in the mole% CHCl 3 / CCl 4 also increases as the pK a of the haloacetic acid is increased. This can be explained on the basis that as the acid proton becomes more acidic it forms a stronger intermolecular complex with chloroform. For example, which is in equilibrium with the intermolecularly hydrogen bonded carboxylic acid dimer. Support for this argument is that the acid ν(OH) frequency occurs at lower frequency in CHCl 3 solution than in CCl 4 solution even though the Cl atoms in CHCl 3 are less basic than the Cl atoms in CCl 4 .

Radical copolymerization of 3‐tri‐n‐butylstannylstyrene with several vinyl monomers

AbstractThe free radical homopolymerization and copolymerization of 3‐tri‐n‐butylstannylstyrene (3‐BTS) with styrene (ST), ethyl acrylate (EA), methyl methacrylate (MMA), vinyl acetate (VA), and acrylonitrile (AN) were carried out using 2,2′‐azobisisobutyronitrile (AIBN) at 60°C. It was found that the yield of conversion to poly(3‐BTS) increased with the molar ratio of initiator to monomer as well as with polymerization time. The conversion at equilibrium after 50 h was about 40%. The compositions of copolymer samples were determined from elemental analyses. Monomer reactivity ratio and Q‐e values were calculated. The copolymers of 3‐BTS‐MMA and 3‐BTS‐AN were found to be alternating. The copolymers of 3‐BTS with MMA, EA and AN were not soluble in any of a large number of organic solvents tested. The insolubility is believed to be due to formation of intermolecular coordination among the tributylstannyl moiety and the carbonyl or cyano groups of the polymer. These copolymers, however, were “soluble” in trihaloacetic acid, but this solubility was due to a cleavage of the trialkyltin moiety from the phenyl groups. The glass temperatures, Tg, and melting temperatures Tm, of the various polymers were also studied.

ChemInform Abstract: Homoazulene: Electrophilic Aromatic Substitution Reactions. Parallels to the Chemistry of Azulene.

AbstractHomoazulene (I) is acylated with the trihaloacetic acid anhydrides (II) in the presence of triethylamine to give the monosubstituted derivatives (III).

Separation of hydrophilic thiols using reversed-phase chromatography with trihaloacetate buffers

The reversed-phase retention behavior of several neutral and cationic hydrophilic thiols using trihaloacetic acid pairing agents is studied. Retention of cationic compounds increases with the size of the halogen substituent in the order: trifluoro- < trichloro- < tribromoacetic acid. The effect of pH, ionic strength, pairing ion and counter ion concentration on retention of cysteine and other thiols is measured. The formation of mobile phase ionic interactions is proposed as the mechanism of retention enhancement.