The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Naiyun Gao - One of the best experts on this subject based on the ideXlab platform.
-
evaluating Iopamidol degradation performance and potential dual wavelength synergy by uv led irradiation and uv led chlorine treatment
Chemical Engineering Journal, 2019Co-Authors: Zechen Gao, Yi-li Lin, Ying Xia, Tongcheng Cao, Xiangyun Zou, Naiyun GaoAbstract:Abstract This study revealed the Iopamidol degradation performance and the synergistic effect of dual-wavelength ultraviolet light-emitting diodes (UV-LEDs). It was found that the dual-wavelength irradiation (265 and 280 nm) can promote Iopamidol degradation during both UV-LED alone and UV-LED/chlorine processes (p
-
Chlor(am)ination of Iopamidol: Kinetics, pathways and disinfection by-products formation
Chemosphere, 2017Co-Authors: Fu-xiang Tian, Yi-li Lin, Tian-yang Zhang, Shengji Xia, Wenhai Chu, Naiyun GaoAbstract:Abstract The degradation kinetics, pathways and disinfection by-products (DBPs) formation of Iopamidol by chlorine and chloramines were investigated in this paper. The chlorination kinetics can be well described by a second-order model. The apparent second-order rate constants of Iopamidol chlorination significantly increased with solution pH. The rate constants of Iopamidol with HOCl and OCl − were calculated as (1.66 ± 0.09) × 10 −3 M −1 s −1 and (0.45± 0.02) M −1 s −1 , respectively. However, the chloramination of Iopamidol fitted well with third-order kinetics and the maximum of the apparent rate constant occurred at pH 7. It was inferred that the free chlorine (i.e., HOCl and OCl − ) can react with Iopamidol while the combined chlorine species (i.e., NH 2 Cl and NHCl 2 ) were not reactive with Iopamidol. The main intermediates during chlorination or chloramination of Iopamidol were identified using ultra performance liquid chromatography - electrospray ionization-mass spectrometry (UPLC-ESI-MS), and the destruction pathways including stepwise deiodination, hydroxylation as well as chlorination were then proposed. The regular and iodinated DBPs formed during chlorination and chloramination of Iopamidol were measured. It was found that iodine conversion from Iopamidol to toxic iodinated DBPs distinctly increased during chloramination. The results also indicated that although chloramines were much less reactive than chlorine toward Iopamidol, they led to the formation of much more toxic iodinated DBPs, especially CHI 3 .
-
photodegradation kinetics of Iopamidol by uv irradiation and enhanced formation of iodinated disinfection by products in sequential oxidation processes
Water Research, 2014Co-Authors: Fu-xiang Tian, Yi-li Lin, Tian-yang Zhang, Naiyun GaoAbstract:abstract The photochemical degradation of Iopamidol with low-pressure UV lamps and the for-mation of iodinated disinfection by-products (I-DBPs) during sequential oxidation pro-cesses including chlorine, monochloramine and chlorine dioxide were investigated in thisstudy. Iopamidol can be effectively decomposed by UV irradiation with pseudo-first orderreaction kinetics. The evaluated quantum yield was found to be 0.03318 mol einstein 1 .Results showed that Iopamidol degradation rate was significantly increased by higher UVintensity and lower initial Iopamidol concentration. However, the effect of solution pH wasnegligible. Degradation of Iopamidol by UV photolysis was subjected to deiodination andhydroxylation mechanisms. The main degradation products including eOH substitutesand iodide were identified by UPLC-ESI-MS and UPLC-UV, respectively. Increasing the in-tensity of UV irradiation promoted the release of iodide. Destruction pathways of iopa-midol photolysis were proposed. Enhanced formation of I-DBPs were observed afterIopamidol photolysis followed by disinfection processes including chlorine, monochlor-amine and chlorine dioxide. With the increase of UV fluence, I-DBPs formation weresignificantly promoted.a 2014 Elsevier Ltd. All rights reserved.* Corresponding author. Tel.: þ86 13918493316.E-mail addresses: tjwenwu@gmail.com, tjwenwu@tongji.edu.cn (B. Xu).
-
A comparison of iodinated trihalomethane formation from iodide and Iopamidol in the presence of organic precursors during monochloramination
Chemical Engineering Journal, 2014Co-Authors: Zhen Wang, Fu-xiang Tian, Yi-li Lin, Tian-yang Zhang, Naiyun GaoAbstract:Abstract The formation of iodinated trihalomethanes (I-THMs) from iodide and Iopamidol, two major iodine sources to form iodinated disinfection by-products (I-DBPs) during monochloramination, was compared in the presence of different organic precursors including algae organic matter (AOM), Suwannee River humic acid (HA), fulvic acid (FA) and 2 raw waters. Effect of bromide, reaction time and pH on I-THM formation was also studied. The results showed that in the presence of HA and FA, monochloramination of iodide exhibited much higher I-THM formation than that of Iopamidol, while in the presence of AOM, monochloramination of Iopamidol formed more I-THMs than that of iodide. The presence of bromide increased I-THM formation from iodide with iodoform as the dominant species, while bromine-containing I-THM species increased significantly from Iopamidol with bromochloroiodomethane as the predominant species. The reaction between monochloramine and Iopamidol is relatively slow and long-lasting compared to that between monochloramine and iodide. I-THM formation from iodide in the presence of HA was maximum at pH 7 but significantly inhibited at pH higher than 7.5 from Iopamidol in the presence of AOM. The correlation between the ratio of I-THMs to dissolved organic carbon concentration and the specific ultraviolet absorbance value of raw waters was positive for iodide but negative for Iopamidol during monochloramination.
Phillip Zhe Sun - One of the best experts on this subject based on the ideXlab platform.
-
a generalized ratiometric chemical exchange saturation transfer cest mri approach for mapping renal ph using Iopamidol
Magnetic Resonance in Medicine, 2018Co-Authors: Iris Y Zhou, Dario Livio Longo, Takahiro Igarashi, Silvio Aime, Phillip Zhe SunAbstract:PURPOSE To extend the pH detection range of Iopamidol-based ratiometric chemical exchange saturation transfer (CEST) MRI at sub-high magnetic field and establish quantitative renal pH MRI. METHODS Chemical exchange saturation transfer imaging was performed on Iopamidol phantoms with pH of 5.5 to 8.0 and in vivo on rat kidneys (n = 5) during Iopamidol administration at a 4.7 T. Iopamidol CEST effects were described using a multipool Lorentzian model. A generalized ratiometric analysis was conducted by ratioing resolved Iopamidol CEST effects at 4.3 and 5.5 ppm obtained under 1.0 and 2.0 µT, respectively. The pH detection range was established for both the standard ratiometric analysis and the proposed resolved approach. Renal pH was mapped in vivo with regional pH assessed by one-way analysis of variance. RESULTS Good-fitting performance was observed in multipool Lorentzian resolving of CEST effects (R2 s > 0.99). The proposed approach extends the in vitro pH detection range to 5.5 to 7.5 at 4.7 T. In vivo renal pH was measured to be 7.0 ± 0.1, 6.8 ± 0.1, and 6.5 ± 0.2 for cortex, medulla and calyx, respectively (P < 0.05). CONCLUSIONS The proposed ratiometric approach extended the Iopamidol pH detection range, enabling the renal pH mapping in vivo, which is promising for pH imaging studies at sub-high or low fields with potential clinical applicability. Magn Reson Med 79:1553-1558, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
-
quantification of Iopamidol multi site chemical exchange properties for ratiometric chemical exchange saturation transfer cest imaging of ph
Physics in Medicine and Biology, 2014Co-Authors: Phillip Zhe Sun, Dario Livio Longo, Gang XiaoAbstract:pH-sensitive chemical exchange saturation transfer (CEST) MRI holds great promise for in vivo applications. However, the CEST effect depends on not only exchange rate and hence pH, but also on the contrast agent concentration, which must be determined independently for pH quantification. Ratiometric CEST MRI normalizes the concentration effect by comparing CEST measurements of multiple labile protons to simplify pH determination. Iopamidol, a commonly used x-ray contrast agent, has been explored as a ratiometric CEST agent for imaging pH. However, Iopamidol CEST properties have not been solved, determination of which is important for optimization and quantification of Iopamidol pH imaging. Our study numerically solved Iopamidol multi-site pH-dependent chemical exchange properties. We found that Iopamidol CEST MRI is suitable for measuring pH between 6 and 7.5 despite that T1 and T2 measurements varied substantially with pH and concentration. The pH MRI precision decreased with pH and concentration. The standard deviation of pH determined from MRI was 0.2 and 0.4 pH unit for 40 and 20?mM Iopamidol solution of pH 6, and it improved to be less than 0.1 unit for pH above 7. Moreover, we determined base-catalyzed chemical exchange for 2-hydrooxypropanamido (ksw = 1.2*10pH?4.1) and amide (ksw = 1.2*10pH?4.6) protons that are statistically different from each other (P?Iopamidol pH imaging.
Stephen E. Duirk - One of the best experts on this subject based on the ideXlab platform.
-
Chloramination of Iopamidol- and bromide-spiked waters containing natural organic matter
Water Supply, 2020Co-Authors: Nana Osei B. Ackerson, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract Iopamidol (an iodinated X-ray contrast medium) and bromide are precursors in the formation of halogenated disinfection byproducts (DBPs). The interactions of these precursors are vital to elucidate the formation of halogenated DBPs during chloramination. This work investigated the formation of total organic halogen and select individual DBPs in two laboratory-chloraminated source waters containing Iopamidol and bromide. Experiments were carried out in batch reactors containing Barberton source water (BSW) and Cleveland BSW (CSW), spiked with Iopamidol (5 μM), bromide (15 μM), and 100 μM monochloramine. Total organic iodine concentrations were approximately equal regardless of source water since they are mostly unreacted Iopamidol and Iopamidol DBPs. Almost equal amounts of total organic chlorine (3–4 nM) were produced in the source waters, but higher quantities of total organic bromine were formed in BSW than CSW. Substantial quantities of regulated trihalomethanes (THMs) and haloacetic acids (HAAs) were formed in the source waters, along with appreciable concentrations of iodinated trihalomethanes (CHBrClI, CHCl2I, and CHBr2I). Low concentrations of iodo-HAAs were detected, especially at low pH. Overall, bromide concentrations appeared to suppress iodo-DBP formation during chloramination of Iopamidol in the presence of natural organic matter. A good correlation (R2 = 0.801) between the yields of regulated DBPs and iodo-DBPs was observed.
-
disinfection byproducts and halogen specific total organic halogen speciation in chlorinated source waters the impact of Iopamidol and bromide
Journal of Environmental Sciences-china, 2020Co-Authors: Nana Osei B. Ackerson, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract This study investigated the speciation of halogen-specific total organic halogen and disinfection byproducts (DBPs) upon chlorination of natural organic matter (NOM) in the presence of Iopamidol and bromide (Br−). Experiments were conducted with low bromide source waters with different NOM characteristics from Northeast Ohio, USA and varied spiked levels of bromide (2–30 μmol/L) and Iopamidol (1–5 μmol/L). Iopamidol was found to be a direct precursor to trihalomethane (THM) and haloacetic acid formation, and in the presence of Br− favored brominated analogs. The concentration and speciation of DBPs formed were impacted by Iopamidol and bromide concentrations, as well as the presence of NOM. As Iopamidol increased the concentration of iodinated DBPs (iodo-DBPs) and THMs increased. However, as Br− concentrations increased, the concentrations of non-brominated iodo- and chloro-DBPs decreased while brominated-DBPs increased. Regardless of the concentration of either Iopamidol or bromide, bromochloroiodomethane (CHBrClI) was the most predominant iodo-DBP formed except at the lowest bromide concentration studied. At relevant concentrations of Iopamidol (1 μmol/L) and bromide (2 μmol/L), significant quantities of highly toxic iodinated and brominated DBPs were formed. However, the rapid oxidation and incorporation of bromide appear to inhibit iodo-DBP formation under conditions relevant to drinking water treatment.
-
Formation of DBPs and halogen-specific TOX in the presence of Iopamidol and chlorinated oxidants
Chemosphere, 2018Co-Authors: Nana Osei B. Ackerson, Edward J. Machek, Alexis H. Killinger, Elizabeth A. Crafton, Pushpita Kumkum, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract Iopamidol is a known direct precursor to iodinated and chlorinated DBP formation; however, the influence of Iopamidol on both iodo/chloro-DBP formation has yet to be fully investigated. This study investigated the effect of Iopamidol on the formation and speciation of halogen-specific total organic halogen (TOX), as well as iodo/chloro-DBPs, in the presence of 3 source waters (SWs) from Northeast Ohio and chlorinated oxidants. Chlorination and chloramination of SWs were carried out at pH 6.5–9.0 and, different Iopamidol and dissolved organic carbon (DOC) concentrations. Total organic iodine (TOI) loss was approximately equal (22–35%) regardless of SW. Total organic chlorine (TOCl) increased in all SWs and was substantially higher in the higher SUVA254 SWs. Iopamidol was a direct precursor to chloroform (CHCl3), trichloroacetic acid (TCAA), and dichloroiodomethane (CHCl2I) formation. While CHCl3 and TCAA exhibited different formation trends with varying Iopamidol concentrations, CHCl2I increased with increasing Iopamidol and DOC concentrations. Low concentrations of iodo-acids were detected without discernible trends. Total trihalomethanes (THMs), total haloacetic acids (HAAs), TOCl, and unknown TOCl (UTOCl) were correlated with fluorescence regional volumes and SUVA254. The yields of all these species showed a strong positive correlation with fulvic, humic, and combined humic and fulvic regions, as well as SUVA254. Iopamidol was then compared to the 3 SWs with respect to DBP yield. Although the SUVA254 of Iopamidol was relatively high, it did not produce high yields of THMs and HAAs compared to the 3 SWs. However, chlorination of Iopamidol did result in high yields of TOCl and UTOCl.
-
Comparative Toxicity of High-Molecular Weight Iopamidol Disinfection Byproducts
Environmental Science & Technology Letters, 2016Co-Authors: Friedrich M. Wendel, Susan D. Richardson, Thomas A. Ternes, Stephen E. Duirk, Justin A. Pals, Elizabeth D. Wagner, Michael Jacob PlewaAbstract:When the X-ray contrast pharmaceutical Iopamidol was chlorinated in natural source water, a toxic mixture of many disinfection byproducts (DBPs) was formed. We isolated and identified five high-molecular weight Iopamidol chlorination DBPs and analyzed their cytotoxicity and genotoxicity using mammalian cells. Of the five DBPs, four exhibited low levels of cytotoxicity, while none of the Iopamidol DBPs was genotoxic. These data support the hypothesis that these high-molecular weight DBPs were not the forcing agents that induced the cytotoxicity and genotoxicity observed after Iopamidol was disinfected in natural source waters.
-
Comparative Toxicity of High-Molecular Weight Iopamidol Disinfection Byproducts
2016Co-Authors: Friedrich M. Wendel, Susan D. Richardson, Thomas A. Ternes, Stephen E. Duirk, Justin A. Pals, Elizabeth D. Wagner, Michael J. PlewaAbstract:When the X-ray contrast pharmaceutical Iopamidol was chlorinated in natural source water, a toxic mixture of many disinfection byproducts (DBPs) was formed. We isolated and identified five high-molecular weight Iopamidol chlorination DBPs and analyzed their cytotoxicity and genotoxicity using mammalian cells. Of the five DBPs, four exhibited low levels of cytotoxicity, while none of the Iopamidol DBPs was genotoxic. These data support the hypothesis that these high-molecular weight DBPs were not the forcing agents that induced the cytotoxicity and genotoxicity observed after Iopamidol was disinfected in natural source waters
Thomas A. Ternes - One of the best experts on this subject based on the ideXlab platform.
-
Chloramination of Iopamidol- and bromide-spiked waters containing natural organic matter
Water Supply, 2020Co-Authors: Nana Osei B. Ackerson, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract Iopamidol (an iodinated X-ray contrast medium) and bromide are precursors in the formation of halogenated disinfection byproducts (DBPs). The interactions of these precursors are vital to elucidate the formation of halogenated DBPs during chloramination. This work investigated the formation of total organic halogen and select individual DBPs in two laboratory-chloraminated source waters containing Iopamidol and bromide. Experiments were carried out in batch reactors containing Barberton source water (BSW) and Cleveland BSW (CSW), spiked with Iopamidol (5 μM), bromide (15 μM), and 100 μM monochloramine. Total organic iodine concentrations were approximately equal regardless of source water since they are mostly unreacted Iopamidol and Iopamidol DBPs. Almost equal amounts of total organic chlorine (3–4 nM) were produced in the source waters, but higher quantities of total organic bromine were formed in BSW than CSW. Substantial quantities of regulated trihalomethanes (THMs) and haloacetic acids (HAAs) were formed in the source waters, along with appreciable concentrations of iodinated trihalomethanes (CHBrClI, CHCl2I, and CHBr2I). Low concentrations of iodo-HAAs were detected, especially at low pH. Overall, bromide concentrations appeared to suppress iodo-DBP formation during chloramination of Iopamidol in the presence of natural organic matter. A good correlation (R2 = 0.801) between the yields of regulated DBPs and iodo-DBPs was observed.
-
disinfection byproducts and halogen specific total organic halogen speciation in chlorinated source waters the impact of Iopamidol and bromide
Journal of Environmental Sciences-china, 2020Co-Authors: Nana Osei B. Ackerson, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract This study investigated the speciation of halogen-specific total organic halogen and disinfection byproducts (DBPs) upon chlorination of natural organic matter (NOM) in the presence of Iopamidol and bromide (Br−). Experiments were conducted with low bromide source waters with different NOM characteristics from Northeast Ohio, USA and varied spiked levels of bromide (2–30 μmol/L) and Iopamidol (1–5 μmol/L). Iopamidol was found to be a direct precursor to trihalomethane (THM) and haloacetic acid formation, and in the presence of Br− favored brominated analogs. The concentration and speciation of DBPs formed were impacted by Iopamidol and bromide concentrations, as well as the presence of NOM. As Iopamidol increased the concentration of iodinated DBPs (iodo-DBPs) and THMs increased. However, as Br− concentrations increased, the concentrations of non-brominated iodo- and chloro-DBPs decreased while brominated-DBPs increased. Regardless of the concentration of either Iopamidol or bromide, bromochloroiodomethane (CHBrClI) was the most predominant iodo-DBP formed except at the lowest bromide concentration studied. At relevant concentrations of Iopamidol (1 μmol/L) and bromide (2 μmol/L), significant quantities of highly toxic iodinated and brominated DBPs were formed. However, the rapid oxidation and incorporation of bromide appear to inhibit iodo-DBP formation under conditions relevant to drinking water treatment.
-
Formation of DBPs and halogen-specific TOX in the presence of Iopamidol and chlorinated oxidants
Chemosphere, 2018Co-Authors: Nana Osei B. Ackerson, Edward J. Machek, Alexis H. Killinger, Elizabeth A. Crafton, Pushpita Kumkum, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract Iopamidol is a known direct precursor to iodinated and chlorinated DBP formation; however, the influence of Iopamidol on both iodo/chloro-DBP formation has yet to be fully investigated. This study investigated the effect of Iopamidol on the formation and speciation of halogen-specific total organic halogen (TOX), as well as iodo/chloro-DBPs, in the presence of 3 source waters (SWs) from Northeast Ohio and chlorinated oxidants. Chlorination and chloramination of SWs were carried out at pH 6.5–9.0 and, different Iopamidol and dissolved organic carbon (DOC) concentrations. Total organic iodine (TOI) loss was approximately equal (22–35%) regardless of SW. Total organic chlorine (TOCl) increased in all SWs and was substantially higher in the higher SUVA254 SWs. Iopamidol was a direct precursor to chloroform (CHCl3), trichloroacetic acid (TCAA), and dichloroiodomethane (CHCl2I) formation. While CHCl3 and TCAA exhibited different formation trends with varying Iopamidol concentrations, CHCl2I increased with increasing Iopamidol and DOC concentrations. Low concentrations of iodo-acids were detected without discernible trends. Total trihalomethanes (THMs), total haloacetic acids (HAAs), TOCl, and unknown TOCl (UTOCl) were correlated with fluorescence regional volumes and SUVA254. The yields of all these species showed a strong positive correlation with fulvic, humic, and combined humic and fulvic regions, as well as SUVA254. Iopamidol was then compared to the 3 SWs with respect to DBP yield. Although the SUVA254 of Iopamidol was relatively high, it did not produce high yields of THMs and HAAs compared to the 3 SWs. However, chlorination of Iopamidol did result in high yields of TOCl and UTOCl.
-
Comparative Toxicity of High-Molecular Weight Iopamidol Disinfection Byproducts
Environmental Science & Technology Letters, 2016Co-Authors: Friedrich M. Wendel, Susan D. Richardson, Thomas A. Ternes, Stephen E. Duirk, Justin A. Pals, Elizabeth D. Wagner, Michael Jacob PlewaAbstract:When the X-ray contrast pharmaceutical Iopamidol was chlorinated in natural source water, a toxic mixture of many disinfection byproducts (DBPs) was formed. We isolated and identified five high-molecular weight Iopamidol chlorination DBPs and analyzed their cytotoxicity and genotoxicity using mammalian cells. Of the five DBPs, four exhibited low levels of cytotoxicity, while none of the Iopamidol DBPs was genotoxic. These data support the hypothesis that these high-molecular weight DBPs were not the forcing agents that induced the cytotoxicity and genotoxicity observed after Iopamidol was disinfected in natural source waters.
-
Comparative Toxicity of High-Molecular Weight Iopamidol Disinfection Byproducts
2016Co-Authors: Friedrich M. Wendel, Susan D. Richardson, Thomas A. Ternes, Stephen E. Duirk, Justin A. Pals, Elizabeth D. Wagner, Michael J. PlewaAbstract:When the X-ray contrast pharmaceutical Iopamidol was chlorinated in natural source water, a toxic mixture of many disinfection byproducts (DBPs) was formed. We isolated and identified five high-molecular weight Iopamidol chlorination DBPs and analyzed their cytotoxicity and genotoxicity using mammalian cells. Of the five DBPs, four exhibited low levels of cytotoxicity, while none of the Iopamidol DBPs was genotoxic. These data support the hypothesis that these high-molecular weight DBPs were not the forcing agents that induced the cytotoxicity and genotoxicity observed after Iopamidol was disinfected in natural source waters
Michael J. Plewa - One of the best experts on this subject based on the ideXlab platform.
-
Chloramination of Iopamidol- and bromide-spiked waters containing natural organic matter
Water Supply, 2020Co-Authors: Nana Osei B. Ackerson, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract Iopamidol (an iodinated X-ray contrast medium) and bromide are precursors in the formation of halogenated disinfection byproducts (DBPs). The interactions of these precursors are vital to elucidate the formation of halogenated DBPs during chloramination. This work investigated the formation of total organic halogen and select individual DBPs in two laboratory-chloraminated source waters containing Iopamidol and bromide. Experiments were carried out in batch reactors containing Barberton source water (BSW) and Cleveland BSW (CSW), spiked with Iopamidol (5 μM), bromide (15 μM), and 100 μM monochloramine. Total organic iodine concentrations were approximately equal regardless of source water since they are mostly unreacted Iopamidol and Iopamidol DBPs. Almost equal amounts of total organic chlorine (3–4 nM) were produced in the source waters, but higher quantities of total organic bromine were formed in BSW than CSW. Substantial quantities of regulated trihalomethanes (THMs) and haloacetic acids (HAAs) were formed in the source waters, along with appreciable concentrations of iodinated trihalomethanes (CHBrClI, CHCl2I, and CHBr2I). Low concentrations of iodo-HAAs were detected, especially at low pH. Overall, bromide concentrations appeared to suppress iodo-DBP formation during chloramination of Iopamidol in the presence of natural organic matter. A good correlation (R2 = 0.801) between the yields of regulated DBPs and iodo-DBPs was observed.
-
disinfection byproducts and halogen specific total organic halogen speciation in chlorinated source waters the impact of Iopamidol and bromide
Journal of Environmental Sciences-china, 2020Co-Authors: Nana Osei B. Ackerson, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract This study investigated the speciation of halogen-specific total organic halogen and disinfection byproducts (DBPs) upon chlorination of natural organic matter (NOM) in the presence of Iopamidol and bromide (Br−). Experiments were conducted with low bromide source waters with different NOM characteristics from Northeast Ohio, USA and varied spiked levels of bromide (2–30 μmol/L) and Iopamidol (1–5 μmol/L). Iopamidol was found to be a direct precursor to trihalomethane (THM) and haloacetic acid formation, and in the presence of Br− favored brominated analogs. The concentration and speciation of DBPs formed were impacted by Iopamidol and bromide concentrations, as well as the presence of NOM. As Iopamidol increased the concentration of iodinated DBPs (iodo-DBPs) and THMs increased. However, as Br− concentrations increased, the concentrations of non-brominated iodo- and chloro-DBPs decreased while brominated-DBPs increased. Regardless of the concentration of either Iopamidol or bromide, bromochloroiodomethane (CHBrClI) was the most predominant iodo-DBP formed except at the lowest bromide concentration studied. At relevant concentrations of Iopamidol (1 μmol/L) and bromide (2 μmol/L), significant quantities of highly toxic iodinated and brominated DBPs were formed. However, the rapid oxidation and incorporation of bromide appear to inhibit iodo-DBP formation under conditions relevant to drinking water treatment.
-
Formation of DBPs and halogen-specific TOX in the presence of Iopamidol and chlorinated oxidants
Chemosphere, 2018Co-Authors: Nana Osei B. Ackerson, Edward J. Machek, Alexis H. Killinger, Elizabeth A. Crafton, Pushpita Kumkum, Hannah K. Liberatore, Michael J. Plewa, Susan D. Richardson, Thomas A. Ternes, Stephen E. DuirkAbstract:Abstract Iopamidol is a known direct precursor to iodinated and chlorinated DBP formation; however, the influence of Iopamidol on both iodo/chloro-DBP formation has yet to be fully investigated. This study investigated the effect of Iopamidol on the formation and speciation of halogen-specific total organic halogen (TOX), as well as iodo/chloro-DBPs, in the presence of 3 source waters (SWs) from Northeast Ohio and chlorinated oxidants. Chlorination and chloramination of SWs were carried out at pH 6.5–9.0 and, different Iopamidol and dissolved organic carbon (DOC) concentrations. Total organic iodine (TOI) loss was approximately equal (22–35%) regardless of SW. Total organic chlorine (TOCl) increased in all SWs and was substantially higher in the higher SUVA254 SWs. Iopamidol was a direct precursor to chloroform (CHCl3), trichloroacetic acid (TCAA), and dichloroiodomethane (CHCl2I) formation. While CHCl3 and TCAA exhibited different formation trends with varying Iopamidol concentrations, CHCl2I increased with increasing Iopamidol and DOC concentrations. Low concentrations of iodo-acids were detected without discernible trends. Total trihalomethanes (THMs), total haloacetic acids (HAAs), TOCl, and unknown TOCl (UTOCl) were correlated with fluorescence regional volumes and SUVA254. The yields of all these species showed a strong positive correlation with fulvic, humic, and combined humic and fulvic regions, as well as SUVA254. Iopamidol was then compared to the 3 SWs with respect to DBP yield. Although the SUVA254 of Iopamidol was relatively high, it did not produce high yields of THMs and HAAs compared to the 3 SWs. However, chlorination of Iopamidol did result in high yields of TOCl and UTOCl.
-
Comparative Toxicity of High-Molecular Weight Iopamidol Disinfection Byproducts
2016Co-Authors: Friedrich M. Wendel, Susan D. Richardson, Thomas A. Ternes, Stephen E. Duirk, Justin A. Pals, Elizabeth D. Wagner, Michael J. PlewaAbstract:When the X-ray contrast pharmaceutical Iopamidol was chlorinated in natural source water, a toxic mixture of many disinfection byproducts (DBPs) was formed. We isolated and identified five high-molecular weight Iopamidol chlorination DBPs and analyzed their cytotoxicity and genotoxicity using mammalian cells. Of the five DBPs, four exhibited low levels of cytotoxicity, while none of the Iopamidol DBPs was genotoxic. These data support the hypothesis that these high-molecular weight DBPs were not the forcing agents that induced the cytotoxicity and genotoxicity observed after Iopamidol was disinfected in natural source waters
-
Transformation of Iopamidol during Chlorination
2014Co-Authors: Friedrich M. Wendel, Edward J. Machek, Michael J. Plewa, Susan D. Richardson, Stephen E. Duirk, Christian Lütke Eversloh, Thomas A. TernesAbstract:The transformation of the iodinated X-ray contrast media (ICM) Iopamidol, iopromide, iohexol, iomeprol, and diatrizoate was examined in purified water over the pH range from 6.5 to 8.5 in the presence of sodium hypochlorite, monochloramine, and chlorine dioxide. In the presence of aqueous chlorine, only Iopamidol was transformed. All other ICM did not show significant reactivity, regardless of the oxidant used. Chlorination of Iopamidol followed a second order reaction, with an observed rate constant of up to 0.87 M–1 s–1 (±0.021 M–1 s–1) at pH 8.5. The hypochlorite anion was identified to be the reactive chlorine species. Iodine was released during the transformation of Iopamidol, and was mainly oxidized to iodate. Only a small percentage (less than 2% after 24 h) was transformed to known organic iodinated disinfection byproducts (DBPs) of low molecular weight. Some of the iodine was still present in high-molecular weight DBPs. The chemical structures of these DBPs were elucidated via MSn fragmentation and NMR. Side chain cleavage was observed as well as the exchange of iodine by chlorine. An overall transformation pathway was proposed for the degradation of Iopamidol. CHO cell chronic cytotoxicity tests indicate that chlorination of Iopamidol generates a toxic mixture of high molecular weight DBPs (LC50 332 ng/μL)
