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William A Mitch - One of the best experts on this subject based on the ideXlab platform.
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formation of n Nitrosamines during the analysis of municipal secondary biological nutrient removal process effluents by us epa method 521
Chemosphere, 2019Co-Authors: Yihsueh Chuang, Farzaneh Shabani, Joline Munoz, Roshanak Aflaki, Slavica Hammond, William A MitchAbstract:Abstract US EPA Method 521 employs activated carbon-based solid phase extraction (SPE) cartridges for analyzing N-Nitrosamines. The analysis of N-Nitrosamines and their chloramine-reactive and ozone-reactive precursors in nitrified municipal secondary effluent revealed the potential for NDMA to form as an artefact during the analysis. As samples passed through the SPE cartridge, the activated carbon mediated the reaction of nitrite with dimethylamine to form NDMA. The reaction was not significant with tertiary amines. Artefactual NDMA formation was important for nitrite concentrations >0.2 mg/L as N in the Biological Nitrogen Removal (BNR) process effluent. However, it is difficult to define a general threshold for nitrite concentrations, because the importance of the reaction also depends on secondary amine concentrations, which are usually poorly characterized. Pre-treatment of samples with sulfamic acid to destroy nitrite mitigated the artefact. This artefact did not affect NDMA analysis in a nitrified effluent from another facility, likely due to low dimethylamine concentrations. This artefact also did not affect the analysis of primary effluent, due to the lack of nitrite, or the analysis of other N-Nitrosamines, likely due to the lack of their secondary amine precursors. Because chloramination does not significantly degrade nitrite, this artefact could affect the analysis of chloramine-reactive N-Nitrosamine precursors. Because ozonation rapidly degrades nitrite, it should not affect the analysis of ozone-reactive precursors. However, ozonation at 0.8 mg ozone/mg dissolved organic carbon resulted in significant degradation of all N-Nitrosamines, even though simultaneous NDMA formation from ozone-reactive precursors resulted in a net increase in NDMA concentration.
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Nitrosamines and nitramines in amine based carbon dioxide capture systems fundamentals engineering implications and knowledge gaps
Environmental Science & Technology, 2017Co-Authors: Kun Yu, William A MitchAbstract:Amine-based absorption is the primary contender for postcombustion CO2 capture from fossil fuel-fired power plants. However, significant concerns have arisen regarding the formation and emission of toxic Nitrosamine and nitramine byproducts from amine-based systems. This paper reviews the current knowledge regarding these byproducts in CO2 capture systems. In the absorber, flue gas NOx drives Nitrosamine and nitramine formation after its dissolution into the amine solvent. The reaction mechanisms are reviewed based on CO2 capture literature as well as biological and atmospheric chemistry studies. In the desorber, Nitrosamines are formed under high temperatures by amines reacting with nitrite (a hydrolysis product of NOx), but they can also thermally decompose following pseudo-first order kinetics. The effects of amine structure, primarily amine order, on Nitrosamine formation and the corresponding mechanisms are discussed. Washwater units, although intended to control emissions from the absorber, can cont...
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oral intake of ranitidine increases urinary excretion of n nitrosodimethylamine
Carcinogenesis, 2016Co-Authors: Teng Zeng, William A MitchAbstract:The H2-receptor antagonist, ranitidine, is among the most widely used pharmaceuticals to treat gastroesophageal reflux disease and peptic ulcers. While previous studies have demonstrated that amines can form N-Nitrosamines when exposed to nitrite at stomach-relevant pH, N-Nitrosamine formation from ranitidine, an amine-based pharmaceutical, has not been demonstrated under these conditions. In this work, we confirmed the production of N-nitrosodimethylamine (NDMA), a potent carcinogen, by nitrosation of ranitidine under stomach-relevant pH conditions in vitro We also evaluated the urinary NDMA excretion attributable to ingestion of clinically used ranitidine doses. Urine samples collected from five female and five male, healthy adult volunteers over 24-h periods before and after consumption of 150mg ranitidine were analyzed for residual ranitidine, ranitidine metabolites, NDMA, total N-Nitrosamines and dimethylamine. Following ranitidine intake, the urinary NDMA excreted over 24h increased 400-folds from 110 to 47 600ng, while total N-Nitrosamines increased 5-folds. NDMA excretion rates after ranitidine intake equaled or exceeded those observed previously in patients with schistosomiasis, a disease wherein N-Nitrosamines are implicated as the etiological agents for bladder cancer. Due to metabolism within the body, urinary NDMA measurements represent a lower-bound estimate of systemic NDMA exposure. Our results suggest a need to evaluate the risks attributable to NDMA associated with chronic consumption of ranitidine, and to identify alternative treatments that minimize exposure to N-Nitrosamines.
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contribution of n Nitrosamines and their precursors to domestic sewage by greywaters and blackwaters
Environmental Science & Technology, 2015Co-Authors: Teng Zeng, William A MitchAbstract:N-Nitrosamines and their precursors are significant concerns for water utilities exploiting wastewater-impacted water supplies, particularly those practicing potable reuse of wastewater. Previous efforts to identify specific precursors in municipal wastewater accounting for N-Nitrosamine formation have met with limited success. As an alternative, we quantified the relative importance of greywater (i.e., shower, kitchen sink, bathroom washbasin, and laundry) and blackwater (i.e., urine and feces) streams in terms of their loadings of ambient specific and total N-Nitrosamines and chloramine-reactive and ozone-reactive N-Nitrosamine precursors to domestic sewage. Accounting for the volume fractions of individual greywater and blackwater streams, laundry water represented the most significant source of N-Nitrosamines and their precursors, followed by shower water and urine. Laundry water was particularly important for ozone-reactive N-Nitrosamine precursors, accounting for ∼99% of N-nitrosodimethylamine (NDMA...
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controlling Nitrosamines nitramines and amines in amine based co2 capture systems with continuous ultraviolet and ozone treatment of washwater
Environmental Science & Technology, 2015Co-Authors: William A MitchAbstract:Formation of Nitrosamines and nitramines from reactions between flue gas NOx and the amines used in CO2 capture units has arisen as a significant concern. Washwater scrubbers can capture Nitrosamines and nitramines. They can also capture amines, preventing formation of Nitrosamines and nitramines downwind by amine reactions with ambient NOx. The continuous application of UV alone, or a combination of UV and ozone to the return line of a washwater treatment unit was evaluated to control the accumulation of Nitrosamines, nitramines and amines in a laboratory-scale washwater unit. With model secondary amine solvents ranging from nonvolatile diethanolamine to volatile morpholine, application of 272–537 mJ/cm2 UV incident fluence alone reduced the accumulation of Nitrosamines and nitramines by approximately an order of magnitude. Modeling indicated that the gains achieved by UV treatment should increase over time, because UV treatment converts the time dependence of Nitrosamine accumulation from a quadratic to...
Jorg E Drewes - One of the best experts on this subject based on the ideXlab platform.
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n Nitrosamine rejection by nanofiltration and reverse osmosis membranes the importance of membrane characteristics
Desalination, 2013Co-Authors: Takahiro Fujioka, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E Drewes, Annalie Roux, Long Duc NghiemAbstract:Abstract The influence of membrane characteristics on the rejection of eight N-Nitrosamines was investigated using one nanofiltration (NF), one seawater reverse osmosis (SWRO) and six low pressure reverse osmosis (LPRO) membranes. The rejection of the two lowest molecular weight N-Nitrosamines, namely N-nitrosodimethylamine (NDMA) and N-nitrosomethylethylamine (NMEA), varied in the range from 8–82% to 23–94%, respectively. In general, the rejection of NDMA and NMEA increased with decreasing membrane permeability. The impact of membrane characteristics became less important for higher molecular weight N-Nitrosamines. Among the four LPRO membranes (i.e. ESPA2, LFC3, TFC-HR and 70LW) that are commonly used for water reclamation applications, similar rejections were obtained for NDMA (37–52%) and NMEA (69–82%). In addition, rejection values of NDMA and NMEA among two LPRO membranes (i.e. ESPA2 and 70LW) were almost identical when compared under variable permeate flux and feed temperature conditions. However, it is noteworthy that the ESPAB membrane could achieve very high rejection of NDMA (as high as 71%) despite having a similar permeability to the LPRO membranes. Results reported here suggest that membrane characteristics associated with permeability such as the pore size and thickness of the active skin layer can be a key factor determining N-Nitrosamine rejection.
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effects of membrane fouling on n Nitrosamine rejection by nanofiltration and reverse osmosis membranes
Journal of Membrane Science, 2013Co-Authors: Takahiro Fujioka, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E Drewes, Rita K Henderson, Long Duc NghiemAbstract:Abstract The impact of fouling on N-Nitrosamine rejection by nanofiltration (NF) and reverse osmosis (RO) membranes was investigated in this study. Membrane fouling was simulated using tertiary treated effluent and several model fouling solutions (that contained sodium alginate, bovine serum albumin, humic acid or colloidal silica) to elucidate the changes in rejection behaviour of N-Nitrosamines. In general, the rejection of N-Nitrosamines increased when the membranes were fouled by tertiary effluent. The rejection of small molecular weight N-Nitrosamines was most affected by membrane fouling. In particular, the rejection of N-nitrosodimethylamine (NDMA) by the ESPA2 membrane increased from 34% to 73% after membrane fouling caused by tertiary effluent. The results also indicate that the impact was less apparent for the lowest permeability membrane (i.e., ESPAB), and the rejection of N-Nitrosamines by the ESPAB membrane was over 82% regardless of membrane fouling. The effect of membrane fouling caused by model foulants on N-Nitrosamine rejection was considerably less than that caused by tertiary effluent. Size exclusion chromatography analyses revealed that the tertiary effluent contains a high fraction of low molecular weight (
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effects of feed solution characteristics on the rejection of n Nitrosamines by reverse osmosis membranes
Journal of Membrane Science, 2012Co-Authors: Takahiro Fujioka, Long Duc Nghiem, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E DrewesAbstract:Abstract The rejection of eight N-Nitrosamines was investigated in this laboratory-scale study, focusing on the influence of feed solution characteristics on their separation by low pressure reverse osmosis membranes. The rejection mechanisms of N-Nitrosamines were first examined using one nanofiltration (NF90) and two reverse osmosis (TFC-HR and SWC5) membranes. The TFC-HR membrane was used to investigate the effects of feed solution characteristics. The rejection of a particular N-Nitrosamine was generally membrane dependent and increased in the order of NF (NF90), low pressure RO (TFC-HR) and seawater RO (SWC5) membranes. In general, the rejection of N-Nitrosamines by a given membrane also increased in the order of increasing molecular weight. These results suggested that steric hindrance was a dominating rejection mechanism of N-Nitrosamines. Nevertheless, it was also observed from the result of N-nitrosomorpholine (NMOR) that the rejection of N-Nitrosamines may also depend on other physicochemical properties such as hydrophobicity. A decrease in the feed solution pH (from 9 to 3) resulted in a decrease in the rejection of the two smallest molecular weight N-Nitrosamines, namely N-nitrosodimethylamine (NDMA) and N-nitrosomethylethylamine (NMEA). Changes in the feed solution ionic strength (from 26 to 260 mM) caused a discernible decrease only in NDMA rejection, while no apparent impact on rejection was observed for an increase in the feed concentration. On the other hand, it is striking that an increase in the feed temperature led to a significant decrease in the rejection of all N-Nitrosamines and the impact was more pronounced for the small molecular weight N-Nitrosamines. For example, a significant drop in NDMA rejection (from 49 to 25%) was observed as the feed temperature increased from 20 to 30 °C. The results also indicate that pH, ionic strength, and temperature of the feed solution can exert some influence on the rejection of NDMA and in some cases other N-Nitrosamines. The combined effects of these feed solution characteristics, particularly feed temperature, may account for some of the variation of NDMA rejection by RO membranes previously reported in the literature.
Takahiro Fujioka - One of the best experts on this subject based on the ideXlab platform.
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an inline ion exchange system in a chemiluminescence based analyzer for direct analysis of n Nitrosamines in treated wastewater
Journal of Chromatography A, 2018Co-Authors: Hitoshi Kodamatani, Shannon L Roback, Megan H Plumlee, Kenneth P Ishida, Hiroto Masunaga, Noboru Maruyama, Takahiro FujiokaAbstract:Abstract A newly developed, ion exchange-based inline pretreatment system was used to mitigate the effect of background constituents in natural water and treated wastewater to achieve rapid, reliable, and sensitive analysis of N-Nitrosamines. The pretreatment system (anion exchange module, AEM) was incorporated into a high-performance liquid chromatograph (HPLC) coupled with a photochemical reactor (PR) and chemiluminescence (CL) detector (HPLC-PR-CL), which can analyze four hydrophilic N-Nitrosamines at ng/L levels. This system requires no pre-concentration of the water sample nor the use of deuterated surrogates, unlike other conventional N-Nitrosamine analytical techniques. The AEM converted anions in the eluent to hydroxide ions after HPLC separation and increased eluent pH, allowing for the subsequent photochemical reactions, which are otherwise achieved by pH conditioning with an additional dosing pump of basic chemical. The AEM also removed anionic interfering compounds (e.g. nitrate) from the samples, allowing for improved N-Nitrosamine analysis in treated wastewater. The operating conditions of the AEM and PR were optimized to obtain sensitive and stable analytical performance. As a result, the lowest-concentration minimum reporting levels of N-nitrosodimethylamine, N-nitrosomorpholine, N-nitrosomethylethylamine, and N- nitrosopyrrolidine using the optimized system were 0.42, 0.54, 0.58, and 1.4 ng/L, respectively. The improved analytical method was validated by comparing the results with a conventional method based on gas chromatography coupled with a mass spectrometric ion trap detector. These results indicated that HPLC-PR-CL equipped with an inline AEM can be competitively applied as a rapid analytical technique for the determination of N-Nitrosamines in various water matrices.
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n Nitrosamine rejection by nanofiltration and reverse osmosis membranes the importance of membrane characteristics
Desalination, 2013Co-Authors: Takahiro Fujioka, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E Drewes, Annalie Roux, Long Duc NghiemAbstract:Abstract The influence of membrane characteristics on the rejection of eight N-Nitrosamines was investigated using one nanofiltration (NF), one seawater reverse osmosis (SWRO) and six low pressure reverse osmosis (LPRO) membranes. The rejection of the two lowest molecular weight N-Nitrosamines, namely N-nitrosodimethylamine (NDMA) and N-nitrosomethylethylamine (NMEA), varied in the range from 8–82% to 23–94%, respectively. In general, the rejection of NDMA and NMEA increased with decreasing membrane permeability. The impact of membrane characteristics became less important for higher molecular weight N-Nitrosamines. Among the four LPRO membranes (i.e. ESPA2, LFC3, TFC-HR and 70LW) that are commonly used for water reclamation applications, similar rejections were obtained for NDMA (37–52%) and NMEA (69–82%). In addition, rejection values of NDMA and NMEA among two LPRO membranes (i.e. ESPA2 and 70LW) were almost identical when compared under variable permeate flux and feed temperature conditions. However, it is noteworthy that the ESPAB membrane could achieve very high rejection of NDMA (as high as 71%) despite having a similar permeability to the LPRO membranes. Results reported here suggest that membrane characteristics associated with permeability such as the pore size and thickness of the active skin layer can be a key factor determining N-Nitrosamine rejection.
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effects of membrane fouling on n Nitrosamine rejection by nanofiltration and reverse osmosis membranes
Journal of Membrane Science, 2013Co-Authors: Takahiro Fujioka, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E Drewes, Rita K Henderson, Long Duc NghiemAbstract:Abstract The impact of fouling on N-Nitrosamine rejection by nanofiltration (NF) and reverse osmosis (RO) membranes was investigated in this study. Membrane fouling was simulated using tertiary treated effluent and several model fouling solutions (that contained sodium alginate, bovine serum albumin, humic acid or colloidal silica) to elucidate the changes in rejection behaviour of N-Nitrosamines. In general, the rejection of N-Nitrosamines increased when the membranes were fouled by tertiary effluent. The rejection of small molecular weight N-Nitrosamines was most affected by membrane fouling. In particular, the rejection of N-nitrosodimethylamine (NDMA) by the ESPA2 membrane increased from 34% to 73% after membrane fouling caused by tertiary effluent. The results also indicate that the impact was less apparent for the lowest permeability membrane (i.e., ESPAB), and the rejection of N-Nitrosamines by the ESPAB membrane was over 82% regardless of membrane fouling. The effect of membrane fouling caused by model foulants on N-Nitrosamine rejection was considerably less than that caused by tertiary effluent. Size exclusion chromatography analyses revealed that the tertiary effluent contains a high fraction of low molecular weight (
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effects of feed solution characteristics on the rejection of n Nitrosamines by reverse osmosis membranes
Journal of Membrane Science, 2012Co-Authors: Takahiro Fujioka, Long Duc Nghiem, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E DrewesAbstract:Abstract The rejection of eight N-Nitrosamines was investigated in this laboratory-scale study, focusing on the influence of feed solution characteristics on their separation by low pressure reverse osmosis membranes. The rejection mechanisms of N-Nitrosamines were first examined using one nanofiltration (NF90) and two reverse osmosis (TFC-HR and SWC5) membranes. The TFC-HR membrane was used to investigate the effects of feed solution characteristics. The rejection of a particular N-Nitrosamine was generally membrane dependent and increased in the order of NF (NF90), low pressure RO (TFC-HR) and seawater RO (SWC5) membranes. In general, the rejection of N-Nitrosamines by a given membrane also increased in the order of increasing molecular weight. These results suggested that steric hindrance was a dominating rejection mechanism of N-Nitrosamines. Nevertheless, it was also observed from the result of N-nitrosomorpholine (NMOR) that the rejection of N-Nitrosamines may also depend on other physicochemical properties such as hydrophobicity. A decrease in the feed solution pH (from 9 to 3) resulted in a decrease in the rejection of the two smallest molecular weight N-Nitrosamines, namely N-nitrosodimethylamine (NDMA) and N-nitrosomethylethylamine (NMEA). Changes in the feed solution ionic strength (from 26 to 260 mM) caused a discernible decrease only in NDMA rejection, while no apparent impact on rejection was observed for an increase in the feed concentration. On the other hand, it is striking that an increase in the feed temperature led to a significant decrease in the rejection of all N-Nitrosamines and the impact was more pronounced for the small molecular weight N-Nitrosamines. For example, a significant drop in NDMA rejection (from 49 to 25%) was observed as the feed temperature increased from 20 to 30 °C. The results also indicate that pH, ionic strength, and temperature of the feed solution can exert some influence on the rejection of NDMA and in some cases other N-Nitrosamines. The combined effects of these feed solution characteristics, particularly feed temperature, may account for some of the variation of NDMA rejection by RO membranes previously reported in the literature.
Long Duc Nghiem - One of the best experts on this subject based on the ideXlab platform.
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n Nitrosamine rejection by nanofiltration and reverse osmosis membranes the importance of membrane characteristics
Desalination, 2013Co-Authors: Takahiro Fujioka, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E Drewes, Annalie Roux, Long Duc NghiemAbstract:Abstract The influence of membrane characteristics on the rejection of eight N-Nitrosamines was investigated using one nanofiltration (NF), one seawater reverse osmosis (SWRO) and six low pressure reverse osmosis (LPRO) membranes. The rejection of the two lowest molecular weight N-Nitrosamines, namely N-nitrosodimethylamine (NDMA) and N-nitrosomethylethylamine (NMEA), varied in the range from 8–82% to 23–94%, respectively. In general, the rejection of NDMA and NMEA increased with decreasing membrane permeability. The impact of membrane characteristics became less important for higher molecular weight N-Nitrosamines. Among the four LPRO membranes (i.e. ESPA2, LFC3, TFC-HR and 70LW) that are commonly used for water reclamation applications, similar rejections were obtained for NDMA (37–52%) and NMEA (69–82%). In addition, rejection values of NDMA and NMEA among two LPRO membranes (i.e. ESPA2 and 70LW) were almost identical when compared under variable permeate flux and feed temperature conditions. However, it is noteworthy that the ESPAB membrane could achieve very high rejection of NDMA (as high as 71%) despite having a similar permeability to the LPRO membranes. Results reported here suggest that membrane characteristics associated with permeability such as the pore size and thickness of the active skin layer can be a key factor determining N-Nitrosamine rejection.
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effects of membrane fouling on n Nitrosamine rejection by nanofiltration and reverse osmosis membranes
Journal of Membrane Science, 2013Co-Authors: Takahiro Fujioka, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E Drewes, Rita K Henderson, Long Duc NghiemAbstract:Abstract The impact of fouling on N-Nitrosamine rejection by nanofiltration (NF) and reverse osmosis (RO) membranes was investigated in this study. Membrane fouling was simulated using tertiary treated effluent and several model fouling solutions (that contained sodium alginate, bovine serum albumin, humic acid or colloidal silica) to elucidate the changes in rejection behaviour of N-Nitrosamines. In general, the rejection of N-Nitrosamines increased when the membranes were fouled by tertiary effluent. The rejection of small molecular weight N-Nitrosamines was most affected by membrane fouling. In particular, the rejection of N-nitrosodimethylamine (NDMA) by the ESPA2 membrane increased from 34% to 73% after membrane fouling caused by tertiary effluent. The results also indicate that the impact was less apparent for the lowest permeability membrane (i.e., ESPAB), and the rejection of N-Nitrosamines by the ESPAB membrane was over 82% regardless of membrane fouling. The effect of membrane fouling caused by model foulants on N-Nitrosamine rejection was considerably less than that caused by tertiary effluent. Size exclusion chromatography analyses revealed that the tertiary effluent contains a high fraction of low molecular weight (
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effects of feed solution characteristics on the rejection of n Nitrosamines by reverse osmosis membranes
Journal of Membrane Science, 2012Co-Authors: Takahiro Fujioka, Long Duc Nghiem, Yvan Poussade, James A Mcdonald, Stuart J. Khan, Jorg E DrewesAbstract:Abstract The rejection of eight N-Nitrosamines was investigated in this laboratory-scale study, focusing on the influence of feed solution characteristics on their separation by low pressure reverse osmosis membranes. The rejection mechanisms of N-Nitrosamines were first examined using one nanofiltration (NF90) and two reverse osmosis (TFC-HR and SWC5) membranes. The TFC-HR membrane was used to investigate the effects of feed solution characteristics. The rejection of a particular N-Nitrosamine was generally membrane dependent and increased in the order of NF (NF90), low pressure RO (TFC-HR) and seawater RO (SWC5) membranes. In general, the rejection of N-Nitrosamines by a given membrane also increased in the order of increasing molecular weight. These results suggested that steric hindrance was a dominating rejection mechanism of N-Nitrosamines. Nevertheless, it was also observed from the result of N-nitrosomorpholine (NMOR) that the rejection of N-Nitrosamines may also depend on other physicochemical properties such as hydrophobicity. A decrease in the feed solution pH (from 9 to 3) resulted in a decrease in the rejection of the two smallest molecular weight N-Nitrosamines, namely N-nitrosodimethylamine (NDMA) and N-nitrosomethylethylamine (NMEA). Changes in the feed solution ionic strength (from 26 to 260 mM) caused a discernible decrease only in NDMA rejection, while no apparent impact on rejection was observed for an increase in the feed concentration. On the other hand, it is striking that an increase in the feed temperature led to a significant decrease in the rejection of all N-Nitrosamines and the impact was more pronounced for the small molecular weight N-Nitrosamines. For example, a significant drop in NDMA rejection (from 49 to 25%) was observed as the feed temperature increased from 20 to 30 °C. The results also indicate that pH, ionic strength, and temperature of the feed solution can exert some influence on the rejection of NDMA and in some cases other N-Nitrosamines. The combined effects of these feed solution characteristics, particularly feed temperature, may account for some of the variation of NDMA rejection by RO membranes previously reported in the literature.
Urs Von Gunten - One of the best experts on this subject based on the ideXlab platform.
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Quantification of Total N‑Nitrosamine Concentrations in Aqueous Samples via UV-Photolysis and Chemiluminescence Detection of Nitric Oxide
2016Co-Authors: Florian Breider, Urs Von GuntenAbstract:N-Nitrosamines are potent mutagens and carcinogens that can be formed during oxidative water treatment. This study describes a novel method for the determination of total N-Nitrosamines by UV-photolysis and subsequent chemiluminescence detection of nitric oxide. Denitrosation of N-Nitrosamines was accomplished with a microphotochemical reactor consisting of a knitted reaction coil and a low-pressure mercury lamp. The detection limits for differing N-Nitrosamines ranged between 0.07 μM (14 pmol injected) and 0.13 μM (26 pmol injected). The nitric oxide formation from selected N-Nitrosamines was linear (R2 = 0.98–0.99) from 0.1 to 10 μM. The small cross-section and volume of the microphotochemical reactor used in this study was optimal to reach a sensitivity level comparable to chemical denitrosation-based methods. In addition, this method had several advantages over other similar methods: (i) compared to chemical denitrosation with copper monochloride or triiodide, the UV-photolysis does not require chemicals and is not affected by interferences of byproducts (e.g., formation of NOI), (ii) the reproducibility of replicates was enhanced compared to the triiodide-based method, and (iii) a commercially available photoreactor and NO analyzer were used. The application of this method for the determination of the N-Nitrosamine formation potential of personal care products demonstrates its utility for assessing whether N-nitrosodimethylamine (NDMA) or other specific Nitrosamines of current interest are dominant or minor components, respectively, of the total N-Nitrosamine pool in technical aquatic systems or biological samples
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enhanced n Nitrosamine formation in pool water by uv irradiation of chlorinated secondary amines in the presence of monochloramine
Water Research, 2013Co-Authors: Urs Von Gunten, Fabian Soltermann, Minju Lee, Silvio CanonicaAbstract:N-Nitrosamines, in particular N-nitrosodimethylamine (NDMA), are carcinogens, which occur as chlorine disinfection by-products (DBPs) in swimming pools and hot tubs. UV treatment is a commonly used technique in swimming pools for disinfection and DBP attenuation. UV irradiation is known to efficiently degrade N-Nitrosamines. However, UV irradiation (at lambda = 254 nm) of chlorinated dimethylamine (CDMA) and monochloramine, two NDMA precursors present in swimming pool water, resulted in a substantial UV-induced NDMA formation (similar to 1-2% molar yield based on initial CDMA concentration) simultaneously to NDMA photolysis. Maximum NDMA concentrations were found at UV doses in the range used for advanced oxidation (350-850 mJ cm(-2)). Very similar behaviour was found for other chlorinated secondary amines, namely diethylamine and morpholine. Effectiveness of UV irradiation for N-Nitrosamine abatement depends on initial N-Nitrosamine and precursor concentrations and the applied UV dose. N-Nitrosamine formation is hypothesized to occur via the reaction of nitric oxide or peroxynitrite with the secondary aminyl radical, which are products from the photolysis of monochloramine and chlorinated secondary amines, respectively. Experiments with pool water showed that similar trends were observed under pool water conditions. UV treatment (UV dose: similar to 360 mJ cm(-2)) slightly increased NDMA concentration in pool water instead of the anticipated 50% abatement in the absence of NDMA precursors. (C) 2012 Elsevier Ltd. All rights reserved.
