Formation of brominated by-products during the degradation of tetrabromobisphenol S by Co2+/peroxymonosulfate oxidation.

Tetrabromobisphenol S (TBBPS), an emerging brominated flame retardant, can cause neurotoxic and cytotoxic effects to human physiology. In this study, the degradation of TBBPS in Co2+ activated peroxymonosulfate (PMS) oxidation process was explored. In particular, brominated by-products formed during the degradation of the TBBPS were examined. It was found that TBBPS could be effectively removed in the Co2+/PMS oxidation process. The pseudo-first-order rate constants were 0.13 min-1 at 0.2 mM PMS and 0.5 µM Co2+ initially. It appeared that TBBPS degradation occurred via and HO attacks, but played a dominant role. The presence of natural organic matter (NOM) greatly inhibited the transformation of the TBBPS, which can be explained by the scavenging of the radical species. ß-Scission, debromination, and cross-coupling were identified as the main reaction pathways of TBBPS degradation in the Co2+/PMS system. Further oxidation and ring-opening of the intermediates generated brominated by-products including bromoform, monobromoacetic acid, and dibromoacetic acid. The formation of the brominated by-products increased gradually in approximately 48 h. But, the presence of NOM reduced the yields of the brominated -by-products. The findings of this study indicate that organic bromine contaminants can be effectively removed but lead to brominated by-products in the activated PMS oxidation process, which should be taken into consideration when -based oxidation technology is applied.

Identification of unknown disinfection byproducts in drinking water produced from Taihu Lake source water.

Although disinfection byproducts (DBPs) in drinking water have been suggested as a cancer causing factor, the causative compounds have not yet been clarified. In this study, we used liquid chromatography quadrupole-time-of-flight spectrometry (LC-QTOF MS) to identify the unknown disinfection byproducts (DBPs) in drinking water produced from Taihu Lake source water, which is known as a convergence point for the anthropogenic pollutants discharged from intensive industrial activities in the surrounding regions. In total, 91 formulas of DBPs were discovered through LC-QTOF MS nontarget screen, 81 of which have not yet been reported. Among the 91 molecules, 56 only contain bromine, 15 only contain chlorine and 20 DBPs have both bromine and chlorine atoms. Finally, five DBPs including 2,4,6-tribromophenol, 2,6-dibromo-4-chlorophenol, 2,6-dichloro-4-bromophenol, 4-bromo-2,6-di-tert-butylphenol and 3,6-dibromocarbazole were confirmed using standards. The former three compounds mainly formed in the predisinfection step (maximum concentration, 0.2-2.6 µg/L), while the latter two formed in the disinfection step (maximum concentration, 18.2-33.6 ng/L). In addition, 19 possible precursors of the discovered DBPs were detected, with the aromatic compounds being a major group. 2,6-di-tert-butylphenol as the precursor of 4-bromo-2,6-di-tert-butylphenol was confirmed with standard, with a concentration of 20.3 µg/L in raw water. The results of this study show that brominated DBPs which are possibly formed from industrial pollutants are relevant DBP species in drinking water produced form Taihu source water, suggesting protection of Taihu Lake source water is important to control the DBP risks.

Exposure to disinfection byproducts and risk of type 2 diabetes: a nested case-control study in the HUNT and Lifelines cohorts.

INTRODUCTION: Environmental chemicals acting as metabolic disruptors have been implicated with diabetogenesis, but evidence is weak among short-lived chemicals, such as disinfection byproducts (trihalomethanes, THM composed of chloroform, TCM and brominated trihalomethanes, BrTHM). OBJECTIVES: We assessed whether THM were associated with type 2 diabetes (T2D) and we explored alterations in metabolic profiles due to THM exposures or T2D status. METHODS: A prospective 1:1 matched case-control study (n = 430) and a cross-sectional 1:1 matched case-control study (n = 362) nested within the HUNT cohort (Norway) and the Lifelines cohort (Netherlands), respectively, were set up. Urinary biomarkers of THM exposure and mass spectrometry-based serum metabolomics were measured. Associations between THM, clinical markers, metabolites and disease status were evaluated using logistic regressions with Least Absolute Shrinkage and Selection Operator procedure. RESULTS: Low median THM exposures (ng/g, IQR) were measured in both cohorts (cases and controls of HUNT and Lifelines, respectively, 193 (76, 470), 208 (77, 502) and 292 (162, 595), 342 (180, 602). Neither BrTHM (OR = 0.87; 95% CI: 0.67, 1.11 | OR = 1.09; 95% CI: 0.73, 1.61), nor TCM (OR = 1.03; 95% CI: 0.88, 1.2 | OR = 1.03; 95% CI: 0.79, 1.35) were associated with incident or prevalent T2D, respectively. Metabolomics showed 48 metabolites associated with incident T2D after adjusting for sex, age and BMI, whereas a total of 244 metabolites were associated with prevalent T2D. A total of 34 metabolites were associated with the progression of T2D. In data driven logistic regression, novel biomarkers, such as cinnamoylglycine or 1-methylurate, being protective of T2D were identified. The incident T2D risk prediction model (HUNT) predicted well incident Lifelines cases (AUC = 0.845; 95% CI: 0.72, 0.97). CONCLUSION: Such exposome-based approaches in cohort-nested studies are warranted to better understand the environmental origins of diabetogenesis.

Transformation of bromide and formation of brominated disinfection byproducts in peracetic acid oxidation of phenol.

Peracetic acid (PAA) has attracted increasing attention in wastewater treatment as a disinfectant. However, the transformation of bromide (Br-) during PAA oxidation of bromide-containing wastewater has not been fully explored. This study showed that Br- could be oxidized by PAA to free bromine which reacted with phenol to form organic bromine. At pH 7.0, more than 35.2% inorganic Br- was converted to organic bromines in 4 h. At acidic conditions, the conversion ratio was even higher, reaching 69.9% at pH 2.8. Most of the organic bromines were presented as bromophenols (i.e., 2-bromophenol, 4-bromophenol, and 2,4-dibromophenol), while regulated brominated disinfection byproducts (Br-DBPs, i.e., bromoform and bromoacetic acids) only accounted for a tiny fraction of total organic bromine. Similar results were observed when PAA was applied to natural organic matter (NOM) or wastewater in presence of Br-. The organic bromine yield reached 56.6 µM in the solution containing 0.1 mM Br- and 2 mg/L NOM initially. Among them, only 1.00 µM bromoform and 0.16 µM dibromoacetic acid were found. Similarly, regulated Br-DBPs only accounted for 28.3% of the organic bromine in a real wastewater effluent treated with PAA. All these data show that monitoring regulated DBPs cannot fully indicate the potential environmental risk of the application of PAA to wastewater.

Toxicity of disinfection byproducts formed during the chlorination of sulfamethoxazole, norfloxacin, and 17ß-estradiol in the presence of bromide.

Brominated disinfection byproducts (Br-DBPs) are formed during the disinfection process of water containing bromine ions, such as marine aquaculture water. Little attention has been paid to Br-DBPs with anthropogenic chemicals as precursors. This study summarized the sodium hypochlorite (NaClO) oxidation of three frequently used pharmaceuticals, including two antibiotics, norfloxacin (NOR) and sulfamethoxazole (SMX), and the growth hormone estrogen 17ß-estradiol (E2). Transformations of the pharmaceuticals were found to be faster in marine aquaculture water than in distilled water. Several Br-DBPs and Cl-DBPs were identified for NOR, SMX, and E2. It was shown that the carboxyl group, piperazine ring, C3, and C8 atoms were the primary reaction sites on NOR. The aniline moiety and S-N bond were identified to be the reaction sites on SMX. The C2, C4, C9, and C16 atoms were the potential reaction centers on E2. Preliminary calculation by QSAR model indicated that the value of logKow significantly increased with an increase in the number of bromine atoms in the Br-DBPs. The results of the bioconcentration factors (BCF) analysis suggested that the bioaccumulation of Br-DBPs were greater than that chlorinated DBPs (Cl-DBPs) in distilled water.

Reduction of bromate by zero valent iron (ZVI) enhances formation of brominated disinfection by-products during chlorination.

Bromate (BrO3-) is a predominant undesired toxic disinfection by-product (DBP) during ozonation of bromide-containing waters. The reduction of BrO3- by zero valent iron (ZVI) and its effect on formation of organic halogenated DBPs during chlorination were investigated in this study. The presence of ZVI could reduce BrO3- to bromide (Br-), and Br- formed could be transformed to free bromine (HOBr/OBr-) during chlorination, further leading to organic brominated (Br-) DBPs formation. Formation of DBPs during chlorination, including trihalomethanes (THMs) and haloacetonitriles (HANs) was detected under different conditions. The results showed that when ZVI dosage increased from 0 to 1 g L-1, the formation of Br-DBPs (e.g., TBM and DBCM) was significantly improved, while the formation of Cl-DBPs (e.g., TCM, TCAN and DCAN) reduced. Higher ZVI dosage exhibited inhibitory effect on Br-DBPs formation due to the competition between ZVI and free chlorine (HOCl/OCl-). The bromine substitution factor (BSF) of THMs significantly decreased from 0.61 ± 0.06 to 0.22 ± 0.02, as the pH was raised from 5.0 to 9.0. Besides, the increase of initial BrO3- concentration significantly improved the formation of Br-DBPs and decreased the formation of Cl-DBPs, leading to an obvious rise on the BSF of THMs. As the initial concentration of HOCl increased, all THMs and HANs gradually increased. Moreover, the analysis based on the cytotoxicity index (CTI) of the determined DBPs showed that reduction of BrO3- by ZVI during chlorination had certain risks in real water sources, which should be paid attention to in the application.

Accelerated oxidation of the emerging brominated flame retardant tetrabromobisphenol S by unactivated peroxymonosulfate: The role of bromine catalysis and formation of disinfection byproducts.

Tetrabromobisphenol S (TBBPS) is an emerging brominated flame retardant (BFR) that can cause endocrinological abnormalities in aquatic species and is neurotoxic and cytotoxic to humans. Herein, we investigated the oxidation of TBBPS by unactivated peroxymonosulfate (PMS) in aqueous solution. Results show that PMS was capable of oxidizing TBBPS without activation, and the transformation of TBBPS was pH-dependent. Interestingly, the unactivated PMS oxidation of TBBPS exhibited an autocatalytic behavior. Radical quenching experiments and electron paramagnetic resonance (EPR) analyzes ruled out the involvement of hydroxyl radical (HO•) and sulfate radical (SO4•­) as reactive species. While the generation of singlet oxygen (1O2) was confirmed in PMS solution, it was also not responsible for TBBPS oxidation. The bromine substituents are believed to be responsible for the autocatalysis observed during PMS oxidation. We propose that the initial oxidation of TBBPS by PMS resulted in the release of bromide ions (Br-) via debromination, which could be rapidly oxidized to hypobromous acid (HOBr). 3,5-Dimethyl-1H-pyrazole (DMPZ) trapping coupled with liquid chromatography-mass spectrometry (LC-MS) analysis evidenced the formation of HOBr in PMS/TBBPS system. Therefore, the presence of Br-, albeit at trace level, could significantly accelerate the oxidation of TBBPS in PMS solution via HOBr formation. The intermediate products of TBBPS were identified by solid phase extraction (SPE) coupled with high resolution-mass spectrometry (HR-MS). The oxidation of TBBPS by unactivated PMS was likely initiated through a single electron transfer mechanism, and the transformation pathways included ß-scission, debromination, and cross-coupling reactions. Further oxidation and ring-opening of the intermediates yielded three brominated disinfection byproducts (Br-DBPs), including bromoform (CHBr3), mono-, and di-bromoacetic acids (MBAA and DBAA), as quantified by gas chromatography (GC). The presence of natural organic matter (NOM) inhibited the oxidation of TBBPS and reduced the yields of Br-DBPs. Our results indicate that unactivated PMS was efficient in the abatement of TBBPS in aqueous solution due to the accelerated oxidation by bromine catalysis; however, the formation of brominated intermediate products and Br-DBPs should be scrutinized due to their potential carcinogenicity and mutagenicity.

Characterization of brominated disinfection byproducts formed during chloramination of fulvic acid in the presence of bromide.

To date, study on the speciation of brominated disinfection byproducts (Br-DBPs), which have higher cytotoxicity and genotoxicity than their analogous chlorinated DBPs (Cl-DBPs), formed in chloramination is still limited. In this study, the previous unknown Br-DBPs formed during chloramination of artificial drinking water were explored with electrospray ionization ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). In total, 193 formulae of one bromine containing Br-DBPs and 5 formulae of two bromine containing Br-DBPs were detected in the chloraminated artificial drinking water sample. Compared to Br-DBPs formed in chlorination, Br-DBPs formed in chloramination have relatively high O/C ratio for the same nominal molecular mass. More than 63% of the Br-DBPs formed during chloramination can be classified as aromatic molecules or polycyclic aromatic molecules, according to their modified aromaticity index (AImod). Further investigation on the change of precursor SRFA molecules during chloramination showed that SRFA molecules with high O/C ratio and low H/C ratio were more reactive and decreased significantly in relative abundance during chloramination. Precursor SRFA molecules with high degree of oxidation and high unsaturation were preferred to form Br-DBPs during chloramination. The results reported in this study provide valuable information on Br-DBPs formed during chloramination and may help us in minimizing DBPs during chloramination.

Characterization of trihalomethane, haloacetic acid, and haloacetonitrile precursors in a seawater reverse osmosis system.

Seawater reverse osmosis (SWRO) has been extensively applied to replenish the limited freshwater resources. One concern of such technology is the formation of disinfection by-products (DBPs) during the pre-chlorination process. For the SWRO tested in this study, the concentrations of trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs) increased by 35.1, 23.7 and 4.9µg/L, respectively, after a seawater sample (with UV254/DOC of 3.7L/mg·m and Br- of 50.9mg/L) was pre-chlorinated (1-2mg-Cl2/L). The dissolved organic matter (DOM) with molecular weight (MW) <1kDa dominated the formation of total THMs, HAAs and HANs. To further investigate DBPs precursors in the seawater, the DOM with MW<1kDa was fractionated to hydrophobic acids (HOA), hydrophobic bases (HOB), hydrophobic neutrals (HON), and hydrophilic substances (HIS). The excitation emission matrix fluorescence spectra analysis showed that most aromatic protein and fulvic acid of the DOM with MW<1kDa were present in the HON and HIS fractions. The HON fraction was the dominant precursor to form THMs and HAAs, while HIS controlled the formation of HANs. Furthermore, bromo - DBPs dominated the total DBPs yields after the chlorination of HIS fraction.

[Formation of Brominated Disinfection By-products in Low Temperature Multi-effect Distillation (LT-MED) Process for Seawater Desalination].

Changes in water quality and brominated disinfection by-products (Br-DBPs) during a low temperature multi-effect distillation (LT-MED) process for seawater desalination were investigated. The concentrations of bromide ion and specific ultraviolet absorbance (SUVA) in the seawater (i.e. the influent of LT-MED) were 54.6 mg·L-1 and 1.7 L·(mg·m)-1, respectively. The tryptophan-like aromatic protein, fulvic acid-like and soluble microbial by-product-like organics dominated the fluorescent dissolved organic matter (DOM) in the seawater. After the NaClO pre-chlorination in the LT-MED process, the concentrations of DBPs in the seawater were significantly increased, especially Br-DBPs, and Bromoform(CHBr3) accounted for 100% of total trihalomethanes (THMs), Bromoacetic acid (C2H3BrO2) and dibromoacetic acid (C2H2Br2O2) accounted for 31.9% and 68.1%, respectively of total haloacetic acids (HAAs), while 4-Bromophenol (C6H5BrO) accounted for 100% of total halogenated phenols (HPs). The formation of THMs, HAAs and HPs was not detected in the finishing water produced by the LT-MED desalination process, but these substances were retained in the concentrated brine, of which THMs, HAAs and HPs were 56.9, 35.0 and 0.1 µg·L-1.

Cobalt catalyzed peroxymonosulfate oxidation of tetrabromobisphenol A: Kinetics, reaction pathways, and formation of brominated by-products.

Degradation of tetrabromobisphenol A (TBBPA), a flame retardant widely spread in the environment, in Co(II) catalyzed peroxymonosulfate (PMS) oxidation process was systematically explored. The second-order-rate constant for reaction of sulfate radical (SO4(-)) with TBBPA was determined to be 5.27×10(10)M(-1)s(-1). Apparently, degradation of TBBPA showed first-order kinetics to the concentrations of both Co(II) and PMS. The presence of humic acid (HA) and bicarbonate inhibited TBBPA degradation, most likely due to their competition for SO4(-). Degradation of TBBPA was initiated by an electron abstraction from one of the phenolic rings. Detailed transformation pathways were proposed, including ß-scission of isopropyl bridge, phenolic ring oxidation, debromination and coupling reactions. Further oxidative degradation of intermediates in Co(II)/PMS process yielded brominated disinfection by-products (Br-DBPs) such as bromoform and brominated acetic acids. Evolution profile of Br-DBPs showed an initially increasing and then decreasing pattern with maximum concentrations occurring around 6-10h. The presence of HA enhanced the formation of Br-DBPs significantly. These findings reveal potentially important, but previously unrecognized, formation of Br-DBPs during sulfate radical-based oxidation of bromide-containing organic compounds that may pose toxicological risks to human health.

Enhanced formation of bromate and brominated disinfection byproducts during chlorination of bromide-containing waters under catalysis of copper corrosion products.

Copper corrosion products (CCPs) in water distribution pipes may catalyze the reactions among disinfectant, natural organic matter (NOM), and bromide (Br(-)). This study investigated the simultaneous formation of bromate (BrO3(-)) and brominated disinfection byproducts (Br-DBPs) during chlorination of Br(-)-containing waters in the presence of three CCPs (i.e., CuO, Cu2O, and Cu(2+)). In a synthetic water, both oxidant decay and BrO3(-) formation were enhanced by CCPs, whereas the presence of humic acid (HA) significantly inhibited BrO3(-) formation due to its competition for HOBr to form Br-DBPs. In the HOClBr(-)CuO system, the BrO3(-) yield increased obviously with increasing CuO dose and initial Br(-) concentration, while the catalytic formation of Br-DBPs was rather limited. A molar conversion (Br(-) to BrO3(-)) of 22.1% was observed under CuO catalysis, compared with little conversion in the absence of CuO. In the HOClBr(-)Cu2O/Cu(2+) systems, Cu2O or Cu(2+) mainly enhanced the formation of Br-DBPs, with enhancement ratios of 69.9% and 50.1%, respectively. The degree of enhancement on Br-DBPs formation became more apparent with increasing pH, while that on BrO3(-) formation reached maximal at pH 7.6. The catalytic formation of Br-DBPs and BrO3(-) by CCPs was also verified in three filtered real waters, although to a lesser extent because of the water matrix effect. In mechanism, the CCPs promoted the formation of BrO3(-) and Br-DBPs through catalyzing the HOBr disproportionation pathway and the reaction of HOBr toward HA, respectively.

Formation of brominated disinfection by-products and bromate in cobalt catalyzed peroxymonosulfate oxidation of phenol.

Formation of halogenated disinfection by-products (DBPs) in sulfate radical [Formula: see text] based oxidation processes attracted considerable attention recently. However, the underlying reaction pathways have not been well explored. This study focused on the transformation of Br(-) in cobalt activated peroxymonosulfate (Co(2+)/PMS) oxidation process. Phenol was added as a model compound to mimic the reactivity of natural organic matter (NOM). It was revealed that Br(-) was efficiently transformed to reactive bromine species (RBS) including free bromine and bromine radicals (Br, [Formula: see text] , etc.) in Co(2+)/PMS system. [Formula: see text] played a principal role during this process. RBS thus generated resulted in the bromination of phenol and formation brominated DBPs (Br-DBPs) including bromoform and bromoacetic acids, during which brominated phenols were detected as the intermediates. Br-DBPs were further degraded by excessive [Formula: see text] and transformed to bromate ultimately. Free bromine was also formed in the absence of Co(2+), suggesting Br(-) could be oxidized by PMS per se. Free bromine was incorporated to phenol sequentially leading to Br-DBPs as well. However, Br-DBPs could not be further transformed in the absence of [Formula: see text] . This is the first study that elucidated the comprehensive transformation map of Br(-) in PMS oxidation systems, which should be taken into consideration when PMS was applied to eliminate contamination in real practice.

Transformation of bromide in thermo activated persulfate oxidation processes.

Sulfate radicals ( [Formula: see text] ) are applied to degrade various organic pollutants. Due to its high oxidative potential, [Formula: see text] is presumed to be able to transform bromide to reactive bromine species that can react with natural organic matter subsequently to form brominated products including brominated disinfection by-products (Br-DBPs). This research was designed to investigate the transformation of bromide in thermo activated persulfate oxidation process in the presence of humic acid (HA). Significant formation of bromoform and bromoacetic acids was verified. Their formation was attributed to the reactions of HA and reactive bromine species including Br·, [Formula: see text] HOBr(-), and free bromine resulted from the oxidation of bromide by [Formula: see text] . Yields of Br-DBPs increased monotonically at persulfate concentration of 1.0 mM and working temperature of 70 °C. However, the time-depended formation exhibited an increasing and the decreasing profile when persulfate was 5.0 mM, suggesting further degradation of organic bromine. HPLC/ICP-MS analysis demonstrated that the organic bromine was eventually transformed to bromate at this condition. Thus, a transformation scheme was proposed in which the bromine could be recycled multiple times between inorganic bromide and organic bromine before being finally transformed to bromate. This is the first study that reveals the comprehensive transformation map of bromine in [Formula: see text] based reaction systems, which should be taken into consideration when such technologies are used to eliminate contamination in real practice.