ORCID Profile
0000-0002-9226-6601
Current Organisation
University of Washington
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Chemical Engineering | Water Quality Engineering | Water Treatment Processes | Powder and Particle Technology | Environmental Technologies
ANZSRC Socio-Economic Objective (SEO)
Industrial chemicals and related products | Energy transformation | Renewable energy |
Related Links
Publications
Use of differential spectroscopy to evaluate the structure and reactivity of humics
Publisher: IWA Publishing
Date: 1999
Differentiation of Pathways of Nitrated Byproduct Formation from Ammonium and Nitrite During Sulfate Radical Oxidation
Publisher: American Chemical Society (ACS)
Date: 12-05-2022
Abstract: Recent studies found that both nitrite (NO
Rotating Ring-Disk Electrode Study of the Electrochemical Dehalogenation of Iodinated Contrast Media
Publisher: The Electrochemical Society
Date: 13-04-2018
DOI: 10.1149/MA2018-01/36/2134
Abstract: Iodinated contrast media (ICM) occur widely in the environment and are difficult to remove by conventional water treatment methods because of ICMs’ hydrophilicity and resistance to biodegradation. ICMs have also been shown to be precursors of toxic reaction products, notably iodine-containing trihalomethanes and haloacetic acids. This study examined the performance of an alternative method of ICM degradation, notably their electrochemical (EC) reduction. ICMs used in this study were exemplified by iopamidol and diatrizoate. The method of rotating ring-disc electrode (RRDE) was used to elucidate rates and mechanisms of the EC reactions of the selected ICMs. Experiments were carried at varying hydrodynamic conditions, concentrations of iopamidol, diatrizoate, natural organic matter (NOM) and model compounds (resorcinol, catechol, guaiacol) which were used to examine interactions between products of the EC reduction of ICMs and halogenation-active species. The data showed that iopamidol and diatrizoate were EC-reduced at potentials -0.45 V vs. s.c.e. In the range of potentials -0.65 to -0.85 V their reduction was mass transfer-controlled. The presence of NOM and model compounds did not affect the EC reduction of iopamidol and diatrizoate but active iodine species formed as a result of the EC-induced transformations of these ICMs reacted readily with NOM and model compounds. These data provide more insight into the nature of generation of iodine-containing by-products in the case of reductive degradation of ICMs.
Solid Phase Excitation-Emission Matrix Spectroscopy for In-Situ Chemical Analysis of Combustion Aerosols
Publisher: American Chemical Society (ACS)
Date: 22-04-2020
DOI: 10.26434/CHEMRXIV.12167865
Abstract: Exposure to combustion generated aerosols such as PM from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. It is important to assess the chemical composition of PM to examine personal exposure. Excitation-emission matrix (EEM) spectroscopy has been shown as a sensitive and cost-effective technique for evaluation of combustion PM composition and as a source apportionment tool. However, EEM measurements are hindered by a solvent extraction step and a need for benchtop instrumentation. Here, we present a methodology that eliminates this labor-intensive s le preparation and allows to automate and miniaturize the detection platform. A miniature electrostatic collector deposits PM s le onto transparent polydimethylsiloxane (PDMS) coated substrate, where PAH components are extracted into solid-phase (SP) solvent and analyzed using EEM spectroscopy in-situ. We evaluated external and internal excitation schemes to optimized signal to noise ratio. Analysis of woodsmoke and cigarette smoke s les showed good agreement with liquid extraction EEM spectra. Internal excitation is hindered by fluorescent interference from PDMS at λ nm. The external excitation EEM spectra are dependent on the incident angle ranges of 30-40⁰ and 55-65⁰ showed the best results. The proposed SP-EEM technique can be used for development of miniaturized sensors for chemical analysis of combustion generated PM.
Separation of cesium from high ionic strength solutions using a cobalt hexacyanoferrate-modified graphite electrode
Publisher: American Chemical Society (ACS)
Date: 24-06-1999
DOI: 10.1021/ES980983O
Investigation of Mechanisms of Oxidation of EDTA and NTA by Permanganate at High pH
Publisher: American Chemical Society (ACS)
Date: 13-07-2006
DOI: 10.1021/ES0605366
Abstract: Permanganate has been used for oxidation of nuclear wastes containing chelating agents such as ethylenediaminetetraacetic and nitrilotriacetic acids (EDTA and NTA) to improve separation of radionuclides and heavy metals from the wastes, butthe mechanisms of degradation of these and related organic ligands at high pHs have not been studied. EDTA, NTA, and the model compound ethylenediamine (EN) were found to be readily oxidized by permanganate at pH 12-14. The reduction of permangante was accompanied by formation of unstable manganate and dispersed MnO2 particles, which constituted the final product of permanganate reduction. The yields and speciation of EDTA, NTA, and EN breakdown products were affected by the pH and permanganate dose. Iminodiacetic acid (IDA), oxalate, formate, and ammonia were the predominant EDTA and NTA oxidation products. Mineralization of EDTA, NTA, and EN to CO2 was more significant at pH 12. At pH 14 formation of oxalate and deamination to NH3 were the most important reactions. IDA was released upon the oxidation of both EDTA and NTA, but EDTA oxidation yielded no ethylenediaminediacetic acid (EDDA). The speciation of the reaction products indicated that the ethylene group in EDTA was the preferred attack site in oxidations by alkaline permanganate.
Development of surrogate correlation models to predict trace organic contaminant oxidation and microbial inactivation during ozonation
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.WATRES.2012.08.037
Abstract: The performance of ozonation in wastewater depends on water quality and the ability to form hydroxyl radicals (·OH) to meet disinfection or contaminant transformation objectives. Since there are no on-line methods to assess ozone and ·OH exposure in wastewater, many agencies are now embracing indicator frameworks and surrogate monitoring for regulatory compliance. Two of the most promising surrogate parameters for ozone-based treatment of secondary and tertiary wastewater effluents are differential UV(254) absorbance (ΔUV(254)) and total fluorescence (ΔTF). In the current study, empirical correlations for ΔUV(254) and ΔTF were developed for the oxidation of 18 trace organic contaminants (TOrCs), including 1,4-dioxane, atenolol, atrazine, bisphenol A, carbamazepine, diclofenac, gemfibrozil, ibuprofen, meprobamate, naproxen, N,N-diethyl-meta-toluamide (DEET), para-chlorobenzoic acid (pCBA), phenytoin, primidone, sulfamethoxazole, triclosan, trimethoprim, and tris-(2-chloroethyl)-phosphate (TCEP) (R(2) = 0.50-0.83) and the inactivation of three microbial surrogates, including Escherichia coli, MS2, and Bacillus subtilis spores (R(2) = 0.46-0.78). Nine wastewaters were tested in laboratory systems, and eight wastewaters were evaluated at pilot- and full-scale. A predictive model for OH exposure based on ΔUV(254) or ΔTF was also proposed.
Insights into Molecules of Natural Organic Matter Binding with a Copper(II) Cation: Interpretation Based on FT-ICR-MS and Differential UV–Vis Absorbance Spectra
Publisher: American Chemical Society (ACS)
Date: 04-09-2023
Excitation-Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter
Publisher: American Chemical Society (ACS)
Date: 26-09-2019
DOI: 10.26434/CHEMRXIV.9702242.V2
Abstract: Analysis of particulate matter (PM) is critical for the assessment of human exposures to potentially harmful agents, notably combustion-generated PM specifically polycyclic aromatic hydrocarbons (PAHs) found in them and associated with carcinogenic and mutagenic effects. In this study, we quantify the presence and concentrations of PAHs with low molecular weight (LMW) and higher molecular weight (HMW) in combustion-generated PM using excitation-emission matrix (EEM) fluorescence spectroscopy. PM s les were generated in a laminar diffusion inverted gravity flame reactor (IGFR) operated on Ethylene and Ethane. Fuel dilution by Ar in 0% to 90% range controls the flame temperature, the maximum flame temperature decreases with fuel dilution. The colder flames result in lower PM yields however, the PM PAH content increases significantly. Temperature thresholds for PM transition from low to high organic carbon content were characterized based on the maximum flame temperature (1814K-1864K) and highest soot luminosity region temperature (1600K-1650K). Principal component regression (PCR) analysis of the EEM spectra correlates to GCMS data, R 2 values of 0.98 for LMW and 0.99 for HMW PAHs. The agreement demonstrates that EEM analysis can be used to determine relative concentrations of organic carbon and PAH fractions in combustion PM, and can be related to PM health effects and used in the environmental studies.
Study of iron and aluminum binding to Suwannee River fulvic acid using absorbance and fluorescence spectroscopy: Comparison of data interpretation based on NICA-Donnan and Stockholm humic models
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.WATRES.2013.06.022
Abstract: This study examined the evolution of absorbance and fluorescence spectra of standard Suwannee River fulvic acid (SRFA) induced by its interactions with iron and aluminum. The results show that changes of SRFA absorbance are associated with a consistent response of the carboxylic and phenolic functional groups to iron and aluminum forming bonds with these groups, and their deprotonation induced by such binding. The observed changes of SRFA absorbance were quantified via the use of DSlope325-375 parameter that determines the behavior of the slope of logarithms of SRFA absorbance in the range of wavelengths 325-375 nm in the presence of varying concentrations of iron or aluminum. DSlope325-375 values were correlated linearly with the concentration of SRFA-bound iron and aluminum determined using either NICA-Donnan or Stockholm Humic Model (SHM) but the correlation was stronger for the former model (R(2) > 0.98). The slopes of these correlations were similar for both iron and aluminum concentrations <10.0 μM and at a wide pH range. Fluorescence of SRFA was responsive to metal binding but it changed less consistently in the presence of the examined metals, especially in the case of aluminum. The combination of these techniques can help explore in more detail manifestations of DOM site specificity at realistically low concentrations of DOM and metal ions.
Excitation-Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter
Publisher: American Chemical Society (ACS)
Date: 22-08-2019
DOI: 10.26434/CHEMRXIV.9702242.V1
Abstract: Analysis of particulate matter (PM) is critical for the assessment of human exposures to potentially harmful agents, notably combustion-generated PM specifically polycyclic aromatic hydrocarbons (PAHs) found in them and associated with carcinogenic and mutagenic effects. In this study, we quantify the presence and concentrations of PAHs with low molecular weight (LMW) and higher molecular weight (HMW) in combustion-generated PM using excitation-emission matrix (EEM) fluorescence spectroscopy. PM s les were generated in a laminar diffusion inverted gravity flame reactor (IGFR) operated on Ethylene and Ethane. Fuel dilution by Ar in 0% to 90% range controls the flame temperature, the maximum flame temperature decreases with fuel dilution. The colder flames result in lower PM yields however, the PM PAH content increases significantly. Temperature thresholds for PM transition from low to high organic carbon content were characterized based on the maximum flame temperature (1814K-1864K) and highest soot luminosity region temperature (1600K-1650K). Principal component regression (PCR) analysis of the EEM spectra correlates to GCMS data, R 2 values of 0.98 for LMW and 0.99 for HMW PAHs. The agreement demonstrates that EEM analysis can be used to determine relative concentrations of organic carbon and PAH fractions in combustion PM, and can be related to PM health effects and used in the environmental studies.
The relationship between TOX formation and spectral changes accompanying chlorination of pre-concentrated or fractionated NOM
Publisher: Elsevier BV
Date: 07-2002
DOI: 10.1016/S0043-1354(02)00020-9
Abstract: The change in the absorbance upon chlorination (the differential absorbance, AA) of natural organic matter (NOM) that has been concentrated, isolated, and/or fractionated from five sources was explored as a possible indicator of the formation of total organic halogen (TOX) in the s les. The results demonstrate that concentration and isolation of NOM using techniques that are currently in widespread use does not significantly alter the TOX-deltaA272 relationship that applies to the unprocessed NOM. However, when such s les are fractionated, the TOX-deltaA272 relationships for the different fractions are not identical. In particular, when the hydrophobic and hydrophilic neutral fractions of NOM are chlorinated, the amount of TOX formed per unit of A272 destroyed is significantly larger than the corresponding value for other NOM fractions. This observation might reflect the relatively high content of proteins and other amino acid structures that can be disinfection by-product precursors but that absorb little or no light at 272 nm.
Characterization of proton and copper binding properties of natural organic matter from an Australian drinking water source by differential absorbance spectroscopy
Publisher: IWA Publishing
Date: 12-2008
DOI: 10.2166/WS.2008.140
Abstract: This study examined the effects of changes in pH and copper concentration on the absorbance spectra of natural organic matter (NOM) from a reservoir in Western Australia. Differential absorbance spectra generated for this NOM under changing pH and copper concentration conditions revealed features that could be correlated to the activity of distinct types of chromophores. A comparison of results with those generated for experiments with standard Suwannee River fulvic acid highlighted important differences in chemistry between the two s les.
New Insights into the Role of Nitrite in the Degradation of Tetrabromobisphenol S by Sulfate Radical Oxidation
Publisher: American Chemical Society (ACS)
Date: 12-2022
Abstract: Tetrabromobisphenol S (TBBPS) is a brominated flame retardant and a contaminant of emerging concern. Several studies found that sulfate radical (SO
PET/PP blending by using PP-g-MA synthesized by solid phase
Publisher: Wiley
Date: 27-03-2007
DOI: 10.1002/APP.26253
Measurement invariances of the PHQ‐9 across gender and age groups in Chinese adolescents
Publisher: Wiley
Date: 03-02-2020
DOI: 10.1111/APPY.12381
Excitation–Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter
Publisher: American Chemical Society (ACS)
Date: 06-2020
The impact of sunlight on fouling behaviors and microbial communities in membrane bioreactors
Publisher: Elsevier BV
Date: 04-2023
Influence of natural organic matter on the morphology of corroding lead surfaces and behavior of lead-containing particles
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.WATRES.2004.12.009
Abstract: Influence of natural organic matter (NOM) on the morphology of lead surfaces exposed to drinking water and on the properties of lead-containing colloidal particles was explored based on the data of scanning electron microscopy, sequential filtrations, measurements of particle size distributions and electrophoretic potential. It was demonstrated that NOM prevented the formation of cerussite and hindered the growth of hydrocerussite crystals. Measurements of zeta-potential showed that the surface activity was highest for unaltered NOM, while ozonation and chlorination decreased it. The concentrations of soluble lead and tin increased several fold in the presence of NOM, while large colloidal particles of lead and solder corrosion products tended to break down to form smaller fragments. It is suggested that these phenomena are important for understanding of lead release mechanisms in drinking water.
Changes of excitation/emission matrixes of wastewater caused by Fenton- and Fenton-like treatment and their associations with the generation of hydroxyl radicals, oxidation of effluent organic matter
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.JHAZMAT.2012.10.064
Abstract: Changes of fluorescence excitation emission matrixes (EEM) of wastewater caused by Fenton process (FP) and Fenton-like process (FLP) were quantified in this study. Their association with the generation of hydroxyl radicals, formation of oxidation products of effluent organic matter (EfOM) and degradation of pharmaceuticals and personal care products (PPCPs) were examined as well. Both FP and FLP caused a consistent decrease of EfOM fluorescence. This decrease was most prominent in the EEM region associated with soluble microbial products (SMPs). Measurements of the consumption of the radical probe pCBA and calculations of OH· radicals exposures showed that relative changes of EEM quantified using alternative parameters (such as humic region response or peak intensity relative change) were predictive of OH· exposures irrespective of whether the wastewater was treated with FP or FLP at any Fe doses and treatment times. The generation of EfOM oxidation products such as formate, oxalate and acetate was also correlated with EEM changes. Similar observations were obtained for PPCPs whose removal was interpreted based on first-order kinetics. Values of selected parameters representing correlations between PPCPs oxidation and EfOM fluorescence decreases were strongly correlated with the intrinsic rates of the oxidation of trace-level organic species by OH· radicals.
XANES Study of Cu2+-Binding Sites in Aquatic Humic Substances
Publisher: American Chemical Society (ACS)
Date: 14-04-2000
DOI: 10.1021/ES990561U
Formation of disinfection by-products and applicability of differential absorbance spectroscopy to monitor halogenation in chlorinated coastal and deep ocean seawater
Publisher: Elsevier BV
Date: 06-2005
Excitation-Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter
Publisher: American Chemical Society (ACS)
Date: 26-09-2019
DOI: 10.26434/CHEMRXIV.9702242
Abstract: Analysis of particulate matter (PM) is critical for the assessment of human exposures to potentially harmful agents, notably combustion-generated PM specifically polycyclic aromatic hydrocarbons (PAHs) found in them and associated with carcinogenic and mutagenic effects. In this study, we quantify the presence and concentrations of PAHs with low molecular weight (LMW) and higher molecular weight (HMW) in combustion-generated PM using excitation-emission matrix (EEM) fluorescence spectroscopy. PM s les were generated in a laminar diffusion inverted gravity flame reactor (IGFR) operated on Ethylene and Ethane. Fuel dilution by Ar in 0% to 90% range controls the flame temperature, the maximum flame temperature decreases with fuel dilution. The colder flames result in lower PM yields however, the PM PAH content increases significantly. Temperature thresholds for PM transition from low to high organic carbon content were characterized based on the maximum flame temperature (1814K-1864K) and highest soot luminosity region temperature (1600K-1650K). Principal component regression (PCR) analysis of the EEM spectra correlates to GCMS data, R sup /sup values of 0.98 for LMW and 0.99 for HMW PAHs. The agreement demonstrates that EEM analysis can be used to determine relative concentrations of organic carbon and PAH fractions in combustion PM, and can be related to PM health effects and used in the environmental studies.
Occurrence of trace inorganic contaminants in drinking water distribution systems
Publisher: Wiley
Date: 03-2012
Transient Changes of Corrosion Potentials and Their Correlations with Metal Release During Stagnation and Flow Episodes in Drinking Water Systems
Publisher: The Electrochemical Society
Date: 13-04-2018
DOI: 10.1149/MA2018-01/14/1063
Abstract: Corrosion and metal release in drinking water systems are affected by the chemistry of ambient water (e.g., pH, concentrations of carbonate and other ions), stagnation/flow transitions associated with diurnal and seasonal changes of water consumption as well as the introduction of alternative water sources, for instance desalinated water. Control of metal release in drinking water is mandated by the EPA within the Lead and Copper Rule (LCR). The current LCR paradigm of copper and lead monitoring is based on measurements of metal concentrations at the end of a predetermined stagnation time (e.g., 6 hours). While this approach is suitable for the general evaluation of LCR compliance, it does not provide any information concerning metal release in short-term stagnation episodes nor does it allow evaluating effects of short-term changes of water chemistry. The goal of this study was to address these deficiencies based on the quantitation of transient changes of open circuit corrosion potentials (E corr ) of metal surfaces during stagnation/flow episodes and examining relationships between such changes and attendant metal release at varying water chemistries. Experimental data demonstrate that E corr transients for copper, lead and iron are characterized by several consistently present features. Theoretical interpretation shows that the E corr transients are associated with the concurrent processes of release of metal solutes and consumption of oxidants (dissolved oxygen, chlorine species). The former process is dominant in the case of copper or lead while the latter effect is more significant for higher corrosion rates typical for iron. Further modeling shows the presence of the phase of rapid quasi-exponential consumption of the oxidants at the surface followed by a slower phase associated with the development of diffusion controlled fluxes. These results show that the monitoring of E corr transients allows quantitating corrosion and metal release rates in conditions characteristic for drinking water systems, notably when other methods either do not provide relevant data or cannot be deployed.
Distribution of Corrosion Potentials across Galvanically Coupled Interfaces Exposed in Drinking Water
Publisher: The Electrochemical Society
Date: 13-04-2018
DOI: 10.1149/MA2018-01/14/1064
Abstract: Control of lead release from lead-containing materials galvanically coupled with copper or bronze represent a challenge for corrosion engineers and water treatment practitioners. Currently available data show that in some situations galvanically coupled lead remains passivated and releases little metal while in other cases, for instance those associated with changes of ambient water chemistry, previously passive coupled lead becomes active with resultant episodes of elevated lead release. While this problem has been thoroughly investigated on a phenomenological level, current understanding of the electrochemistry of galvanic stimulation of lead corrosion and release in drinking water remains insufficient. The goal of this study was to quantify changes of the open circuit corrosion potential (E corr (x)) across lead/copper interfaces as a function of the distance from the galvanic juncture and concentrations of background salts such sodium chloride, carbonate and others. The theory developed by Song et al. 2010 provides a detailed mathematical description of the distribution of E corr across galvanic interfaces but this theory has been developed and rested for systems that are notably different from those typical for drinking water. Measurements of trans-galvanic interface E corr profiles performed in this study showed that E corr (x) profiles conformed to predictions made based on the existing theory and the effective length of the longitudinal penetration of ionic currents increased as a square root of solution conductivity. The effective length of the coupled ionic currents was notably different for copper and lead. The data demonstrate that short- and long-term changes of properties of ambient water can cause E corr (x) to undergo considerable changes. This can potentially induce shifts of the galvanically affected zone in which accelerated lead release takes place. Further studies are needed to examine actual effects of such E corr (x) shifts on spatially localized lead release from galvanically coupled lead-containing materials. Song, G. L. (2010). Potential and current distributions of one-dimensional galvanic corrosion systems. Corrosion Science, 52(2), 455-480
Monitoring the Behavior of Emerging Contaminants in Wastewater-Impacted Rivers Based on the Use of Fluorescence Excitation Emission Matrixes (EEM)
Publisher: American Chemical Society (ACS)
Date: 06-04-2017
Abstract: This study investigated the applicability of fluorescence indexes based on the interpretation of excitation emission matrices (EEMs) by PARAFAC analysis and by selecting fluorescence intensities at a priori defined excitation/emission pairs as surrogates for monitoring the behavior of emerging organic compounds (EOCs) in two catchment basins impacted by wastewater discharges. Relevant EOC and EEM data were obtained for a 90 km stretch of the Simeto River, the main river in Sicily, and the smaller San Leonardo River, which was investigated for a 17 km stretch. The use of fluorescence indexes developed by these two different approaches resulted in similar observations. Changes of the fluorescence indexes that correspond to a group of humic-like fluorescing species were determined to be highly correlated with the concentrations of recalcitrant contaminants such as sucralose, sulfamethoxazole and carbamazepine, which are typical wastewater markers in river water. Changes of the fluorescence indexes related to tyrosine-like substances were well correlated with the concentrations of ibuprofen and caffeine, anthropogenic indicators of untreated wastewater discharges. Chemical oxygen demand and dissolved organic carbon concentrations were correlated with humic-like fluorescence indexes. The observed correlations were site-specific and characterized by different regression parameters for every collection event. Caffeine and carbamazepine showed correlations with florescence indexes in the San Leonardo River and in the alluvial plain stretch of the Simeto River, whereas sucralose, sulfamethoxazole and ibuprofen have always been well correlated in all the investigated river stretches. However, when data of different collection events from river stretches where correlations were observed were combined, good linear correlations were obtained for data sets generated via the normalization of the measured concentrations by the average value for the corresponding collection event. These results show that fluorescence based indexes can be used to monitor the behavior of some trace organic contaminants in wastewater impacted rivers and to track wastewater discharges in streams and rivers.
Multi-wavelength spectroscopic and chromatography study on the photocatalytic oxidation of natural organic matter
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.WATRES.2010.01.036
Abstract: The effect of TiO2 photocatalytic oxidation on the natural organic matter (NOM) properties of two Australian surface waters were quantified using UV-vis spectroscopy, high performance size exclusion chromatography (HPSEC) with a multi-wavelength UV detector, liquid chromatography with organic carbon detector (LC-OCD), and trihalomethane formation potential (THMFP) analyses. Both the UV absorbance at wavelengths greater than 250 nm and dissolved organic carbon (DOC) content decreased significantly with treatment, although complete mineralization of NOM could not be achieved. Multi-wavelength UV detection of HPSEC analysis was shown to be useful to display further changes to NOM composition and molecular weight profiles because the organic molecules was transformed into compounds that absorb weakly at the typical detection wavelength of 250-260 nm. The multi-wavelength HPSEC results also revealed that photocatalytic oxidation yields by-products with a low aromaticity and low molecular weight. The LC-OCD chromatograms indicated that low molecular acids and neutral compounds remained after photocatalytic oxidation. Those groups of compounds did not seem to contribute significantly to the formation of trihalomethanes.
Electrochemical reduction of haloacetic acids and exploration of their removal by electrochemical treatment
Publisher: Elsevier BV
Date: 12-2001
Effect of chlorination on the characteristics of effluent organic matter and the phototransformation of sulfamethoxazole in secondary wastewater
Publisher: Elsevier BV
Date: 05-2022
DOI: 10.1016/J.CHEMOSPHERE.2021.133193
Abstract: Chlorination is the most common disinfection technology used to treat wastewater effluent discharged into receiving aquatic environments. Effluent organic matter (EfOM) abundant in wastewater is a well-known photosensitizer and it greatly affects phototransformation of antibiotics in water. However, effects of chlorination on the characteristics and photochemical properties of EfOM have not been studied in sufficient detail. This paper investigated effects of chlorination on the characteristics of EfOM, and its impact on the phototransformation of sulfamethoxazole (SMX). Correlations between the EfOM characteristics and steady-state concentrations of reactive intermediates (RI) formed in the system were established. Chlorination was shown to preferentially remove the aromatic protein-like substances in EfOM, and the incorporation of chlorine into followed by the cleavage of the aromatic rings in EfOM molecules led to the formation of low molecular aliphatic organic matter. Both unaltered and chlorinated EfOM promoted the photodegradation of SMX whose rate constant in the wastewater was 1.32-1.65 times higher than that in pH 8 phosphate buffer. However, the rate of SMX photodegradation decreased at higher chlorination concentrations. The photodegradation of SMX was found to proceed through direct photolysis and oxidation by the RIs generated from EfOM and the self-sensitization of SMX. The steady-state concentrations of ·OH,
Influence of Chlorination on Chromophores and Fluorophores in Humic Substances
Publisher: American Chemical Society (ACS)
Date: 04-03-1999
DOI: 10.1021/ES980787H
EXAFS Study of the Inner Shell Structure in Copper(II) Complexes with Humic Substances
Publisher: American Chemical Society (ACS)
Date: 08-1998
DOI: 10.1021/ES980016D
Examination ofin situGeneration of Hydroxyl Radicals and Ozone in a Flow-through Electrochemical Reactor
Publisher: Informa UK Limited
Date: 04-2008
Active-chlorine-mediated oxidation of 5-fluorouracil on a hierarchically ordered macroporous RuO2 electrode
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.CHEMOSPHERE.2022.134728
Abstract: A hierarchically ordered macroporous RuO
Modelling disinfection by-products formation in bromide-containing waters
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.JHAZMAT.2009.02.078
Abstract: A kinetic model capable of simulating by-products formation in bromide-containing waters during disinfection processes is presented in this paper. The model is based on two parallel sequences of incorporation and oxidation reactions induced by bromine or chlorine reacting with natural organic matter (NOM). Each sequence starts from a different type of NOM functionality that has its own set of specific reaction rate. Decay reactions of NOM and halogenated intermediates are assumed to follow a first order kinetic, while disinfection by-product (DBP) generation reactions are simulated introducing so-called splitting coefficients. This approach allows obtaining explicit expressions for DBP species. Model's results are compared with experimental data obtained for seawater s les. Comparison of the data confirms the model's ability to predict DBPs formation with high precision.
Changes in NOM Fluorescence Caused by Chlorination and their Associations with Disinfection by-Products Formation
Publisher: American Chemical Society (ACS)
Date: 05-01-2009
DOI: 10.1021/ES801939F
Abstract: Relationships between the formation of disinfection byproduct (DBPs) and changes of the fluorescence of natural organic matter (NOM) in chlorinated water were quantified using two fluorescence indexes. They were defined as the change of the wavelength that corresponds to 50% of the maximum intensity of fluorescence (Deltalambdaem0.5) and the differential ratio of fluorescence intensities measured at 500 and 450 nm (Delta(I500/I450)). Although variations of chlorine doses, reaction times and temperatures affected the kinetics of chlorine consumption and DBPs release, correlations between chlorine consumption, concentrations, and speciation of trihalomethanes, haloacetonitriles, haloacetic acids and, on the other hand, Delta(I500/I450) and Deltalambdaem0.5 values remained unaffected by chlorination conditions and, to some extent, NOM properties. These results allow developing a fluorescence-based approach to monitor DBPs formation in drinking water.
Electrochemical and XAFS Studies of Effects of Carbonate on the Oxidation of Arsenite
Publisher: American Chemical Society (ACS)
Date: 30-11-2005
DOI: 10.1021/ES0516817
Abstract: Measurements of electrochemical (EC) arsenite oxidation demonstrated thatthe arsenite oxidation current increased in the presence of carbonate while the potential of the onset of EC arsenite oxidation exhibited a strong shift toward less positive values. Examination of pH and total carbonate concentration effects on the EC arsenite oxidation parameters showed that they were affected solely by the concentration of carbonate ion CO3(2-), which appeared to form relatively weak mono- and dicarbonate complexes with arsenite. The EC activity of these complexes was determined to be almost an order of magnitude higher than that of free arsenite. However, X-ray absorption fine-structure (XAFS) measurements did not show any changes in the properties of the As(III) inner complexation shell associated with the presence of the bound carbonate ions. It was accordingly concluded that the strength of bonds between the bound carbonate and As(III) is close to that for As(III)-OH- interactions. The acceleration of the oxidation of carbonate-As(III) complexes was hypothesized to be associated with an additional pathway of the formation of As(IV) intermediates, in which the carbonate group present in the As(III) inner shell provides an electron to form a bound carbonate radical and also a good leaving group for facile cleavage from the transient As(IV) species.
Interpretation of the formation of unstable halogen-containing disinfection by-products based on the differential absorbance spectroscopy approach
Publisher: Elsevier BV
Date: 04-2021
Excitation Emission Matrix Fluorescence Spectroscopy for Combustion Generated Particulate Matter Source Identification
Publisher: American Chemical Society (ACS)
Date: 21-08-2019
DOI: 10.26434/CHEMRXIV.9177146.V1
Abstract: The inhalation of particulate matter (PM) is a significant health risk associated with reduced life expectancy due to increased cardio-pulmonary disease and exacerbation of respiratory diseases such as asthma and pneumonia. PM originates from natural and anthropogenic sources including combustion engines, cigarettes, agricultural burning, and forest fires. Identifying the source of PM can inform effective mitigation strategies and policies, but this is difficult to do using current techniques. Here we present a method for identifying PM source using excitation emission matrix (EEM) fluorescence spectroscopy and a machine learning algorithm. We collected combustion generated PM2.5 from wood burning, diesel exhaust, and cigarettes using filters. Filters were weighted to determine mass concentration followed by extraction into cyclohexane and analysis by EEM fluorescence spectroscopy. Spectra obtained from each source were used as machine learning training data for source identification in mixed s les. This method can predict the presence or absence of the three laboratory sources with an overall accuracy of 89% when the threshold for classifying a source as present is 1.1 µg/m3 in air over a 24-hour s ling time. We apply this method to a small set of field s les to evaluate its effectiveness.
Effects of NOM properties on copper release from model solid phases
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.WATRES.2013.04.055
Abstract: This study examined impacts of concentrations and properties of natural organic matter (NOM) on copper release from characteristic copper solid model phases such as tenorite CuO and malachite Cu2(OH)2CO3. Unaltered Aldrich humic acid (AHA) and standard Suwannee River fulvic acid (SRFA) strongly increased copper release from the model phases but NOM alteration by chlorination or ozonation gradually suppressed or, at higher oxidant doses, eliminated these effects. The nature of NOM changes induced by chlorination and ozonation was examined using differential absorbance spectroscopy (DAS) and high-performance size-exclusion chromatography (HPSEC). The data of these methods show that NOM molecules with higher apparent molecular weight (AMW), higher aromaticities and contributions of protonation-active phenolic and carboxylic groups play a key role in adsorption and colloidal dispersion of the model solids. The data also show that metal release from model phases was well correlated with a number of spectroscopic parameters characterizing NOM properties, notably SUVA254, spectral slopes of NOM absorbance, and differential absorbance at wavelength of 280 nm and 350 nm that is indicative of the contributions of carboxylic and phenolic functional groups. Changes of ζ-potential of the model solid phases were the strongest predictor of the enhancement of copper release especially in the system controlled by malachite. While effects of NOM on the ζ-potential of tenorite and malachite were prominent for unaltered NOM, its oxidation by chlorine and ozone was accompanied by a gradual decrease and ultimately disappearance of its surface activity.
Quantifying metal ions binding onto dissolved organic matter using log-transformed absorbance spectra
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.WATRES.2013.02.044
Abstract: This study introduces the concept of consistent examination of changes of log-transformed absorbance spectra of dissolved organic matter (DOM) at incrementally increasing concentrations of heavy metal cations such as copper, cadmium, and aluminum at environmentally relevant concentrations. The approach is designed to highlight contributions of low-intensity absorbance features that appear to be especially sensitive to DOM reactions. In accord with this approach, log-transformed absorbance spectra of fractions of DOM from the Suwannee River were acquired at varying pHs and concentrations of copper, cadmium, and aluminum. These log-transformed spectra were processed using the differential approach and used to examine the nature of the observed changes of DOM absorbance and correlate them with the extent of Me-DOM complexation. Two alternative parameters, namely the change of the spectral slope in the range of wavelengths 325-375 nm (DSlope325-375) and differential logarithm of DOM absorbance at 350 nm (DLnA350) were introduced to quantify Cu(II), Cd(II), and Al(III) binding onto DOMs. DLnA350 and DSlope325-375 datasets were compared with the amount of DOM-bound Cu(II), Cd(II), and Al(III) estimated based on NICA-Donnan model calculations. This examination showed that the DLnA350 and DSlope325-375 acquired at various pH values, metal ions concentrations, and DOM types were strongly and unambiguously correlated with the concentration of DOM-bound metal ions. The obtained experimental results and their interpretation indicate that the introduced DSlope325-375 and DLnA35 parameters are predictive of and can be used to quantify in situ metal ions interactions with DOMs. The presented approach can be used to gain more information about DOM-metal interactions and for further optimization of existing formal models of metal-DOM complexation.
Investigation of the kinetics and mechanisms of the oxidation of cerussite and hydrocerussite by chlorine
Publisher: American Chemical Society (ACS)
Date: 20-03-2008
DOI: 10.1021/ES7024406
Abstract: Reactions of representative lead (II) solid phases (hydrocerussite, cerussite) with chlorine were examined in this study. Chlorine consumption profiles for these solids exhibited a lag phase, during which little consumption of chlorine occurred, and an ensuing rapid reaction phase. The durations of these phases were affected by the pH, carbonate, and chlorine concentrations. SEM and XRD data showed that hydrocerussite started to be transformed into cerussite during the lag phase. Kinetic analysis indicated that only the protonated form of HClO drives the autocatalytic oxidation step, which is mediated by dispersed PbO2 crystals. The rate of the noncatalytic oxidation decreased with the increase of carbonate due to the formation of unreactive surface carbonate Pb(II) complexes.
Investigation of the reduction of lead dioxide by natural organic matter
Publisher: American Chemical Society (ACS)
Date: 30-06-2007
DOI: 10.1021/ES070596R
Abstract: Experiments with immobilized lead dioxide showed that this solid was reduced by natural organic matter (NOM) isolated from Potomac River water. Kinetically, the process was slow and occurred throughout many weeks of exposure. The amount of mobilized lead was affected by the concentration of NOM and exposure time but not significantly influenced by the type of NOM used in the experiments. The interactions of NOM with PbO2 were quantified using differential absorbance spectroscopy. It showed that the oxidation of chromophoric groups in NOM was strongly correlated with lead release. Because lead release yields were higher thatthose predicted based on the depletion of the aromatic groups, it is hypothesized that NOM moieties otherthan aromatic functionalities are engaged in the reduction of PbO2 by NOM and/or lead mobilization involves the formation of mixed Pb(II)/Pb(IV) soluble and colloidal species.
Correlations between differential absorbance and the formation of individual DBPs
Publisher: Elsevier BV
Date: 07-2002
DOI: 10.1016/S0043-1354(02)00042-8
Abstract: This study examined correlations between the differential absorbance at 272nm (deltaA272) and the formation of disinfection by-products (DBPs) in chlorinated water from the Tolt River, a water source for Seattle, WA. The DBPs investigated included chloroform (CHCl3), dichlorobromomethane (CHCl2Br), mono-, di- and trichloroacetic acids (MCAA, DCAA, and TCAA, respectively), chloral hydrate (CH), dichloroacetonitrile (DCAN) and 1,1,1-trichloropropanone (TCP). Whereas the kinetics of DBP formation are complex and are non-linear, the same DBP data represented as a function of deltaA272 are quite simple. Absorbance decreases when the water is chlorinated, i.e., deltaA272 is always negative. The DBP vs. -deltaA272 correlations can almost always be quantified by linear equations, at least above some threshold value of -deltaA272, with R2 values > 0.95. The only DBP that did not follow this trend was CH, for which an exponential relationship better described the data. TCP and DCAN were unstable at pH 7 and 8, but at pH 6 linear correlations between their concentrations and -deltaA272 were as strong as those for the more stable DBPs. The threshold -deltaA272 value is approximately the same for many of the DBPs studied, supporting the hypothesis that in idual DBPs are released following the formation of a common intermediate, or at least a small group of similar intermediates. The DBP vs. -deltaA272 correlations may have practical value since they provide an alternative approach for monitoring the formation of in idual DBP species on-line, but the generality of the relationships needs to be further examined.
Quantum-chemical simulations of the hydration of Pb(II) ion: structure, hydration energies, and pKa1 value
Publisher: Springer Science and Business Media LLC
Date: 04-07-2018
DOI: 10.1007/S00894-018-3726-4
Abstract: Thermodynamic and structural aspects of the hydration of Pb(II) ions were explored based on DFT calculations combined with the supermolecular/continuum solvent model. Hydration of Pb(II) was considered as the formation of Pb(H
Aging of Iron (Hydr)oxides by Heat Treatment and Effects on Heavy Metal Binding
Publisher: American Chemical Society (ACS)
Date: 18-08-2000
DOI: 10.1021/ES9914543
In situ study of binding of copper by fulvic acid: Comparison of differential absorbance data and model predictions
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.WATRES.2012.10.020
Abstract: This study examined the binding of copper(II) by Suwannee River fulvic acid (SRFA) using the method of differential absorbance that was used at environmentally-relevant concentrations of copper and SRFA. The pH- and metal-differential spectra were processed via numeric deconvolution to establish commonalities seen in the changes of absorbance caused by deprotonation of SRFA and its interactions with copper(II) ions. Six Gaussian bands were determined to be present in both the pH- and Cu-differential spectra. Their maxima were located, in the order of increasing wavelengths at 208 nm, 242 nm, 276 nm, 314 nm, 378 nm and 551 nm. The bands with these maxima were denoted as A0, A1, A2, A3, A4 and A5, respectively. Properties of these bands were compared with those existing in the spectra of model compounds such as sulfosalicylic acid (SSA), tannic acid (TA), and polystyrenesulfonic acid-co-maleic acid (PSMA). While none of the features observed in differential spectra of the model compound were identical to those present in the case of SRFA, Gaussian bands A1, A3 and possibly A2 were concluded to be largely attributable to a combination of responses of salicylic- and polyhydroxyphenolic groups. In contrast, bands A4 and A5 were detected in the differential spectra of SRFA only. Their nature remains to be elucidated. To examine correlations between the amount of copper(II) bound by SRFA and changes of its absorbance, differential absorbances measured at indicative wavelengths 250 nm and 400 nm were compared with the total amount of SRFA-bound copper estimated based on Visual MINTEQ calculations. This examination showed that the differential absorbances of SRFA in a wide range of pH values and copper concentrations were strongly correlated with the concentration of SRFA-bound copper. The approach presented in this study can be used to generate in situ information concerning the nature of functional groups in humic substances engaged in interactions with metals ions. This information can be useful for further elaboration and development of detailed theoretic models that describe the complexation of metals in the environment.
Use of log-transformed absorbance spectra for online monitoring of the reactivity of natural organic matter
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.WATRES.2015.07.029
Abstract: This study examined the significance of water quality monitoring parameters obtained via logarithmic transformation of the absorbance spectra of raw and treated drinking water. The data were generated using s les of the influent, settled and filtered water acquired weekly over a six months period at two full scale treatment plants. Examination of the weekly plant s les combined with the data of laboratory fractionation and chlorination experiments showed that the slopes of the log-transformed spectra are correlated with typically reported water quality parameters (e.g., its specific absorbance at 254 nm, SUVA254) yet the determination of spectral slopes is considerably simpler and potentially information-rich. The spectral slopes determined for the range of wavelength 280-350 nm were shown to be correlated with the yields of trihalomethanes (THMs) and haloacetic acids (HAAs). These results support the notion that multi-wavelength monitoring of the absorbance spectra of drinking water and their interpretation via logarithmic transformation constitutes a promising practically implementable approach for online water quality monitoring.
Effect of changing water quality on galvanic coupling
Publisher: Wiley
Date: 03-2012
Effects of pH on the speciation coefficients in models of bromide influence on the formation of trihalomethanes and haloacetic acids
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.WATRES.2014.05.024
Abstract: This study investigated effects of pH, bromide and natural organic matter (NOM) level on yields and speciation of trihalomethanes (THMs) and haloacetic acids (HAAs) in chlorinated water. Experimental data were obtained using two water sources, one with a medium (DOC = 1.4 mg/L and SUVA = 2.60 L mg(-1) m(-1)) and the other with higher (DOC = 7.7 mg/L and SUVA = 4.26 L mg(-1) m(-1)) organic carbon level. The experiments employed the simulated distribution system (SDS) procedure at varying bromide concentrations and pH values of 7.0, 8.5 and 10. The speciation of THMs and dihalogenated HAAs (DHAAs) was interpreted based on the modelling of mixed halogenation yields via dimensionless ratios of bromination/chlorination reaction rates at each halogen incorporation node. The approach allowed precise modelling of the speciation of THMs and DHAAs at all examined pHs. In the case of DHAA, the dimensionless ratios of the bromination/chlorination reaction rates were not consistently affected by pH variations. For THMs, increase of pH caused the values of the dimensionless bromination/chlorination reaction rates to decrease in the case of halogenation of the initial reaction sites indicating a decreasing preference toward bromination at this reaction node. A similar trend was observed for the reactivity of dichlorinated reaction intermediate denoted as SCl2 whose formation precedes the release of CHCl3 and CHBrCl2. A similar but less consistent trend was observed for intermediate SBrCl whose halogenation yields both CHBrCl2 and CHBr2Cl. An opposite trend of increasing preference towards bromination at higher pHs was observed monobrominated intermediate SBr and in some extent dibrominated intermediate SBr2. These results help develop detailed DBP speciation models which needed to better understand the generation and potential health effects of THMs and HAAs at varying operating conditions and ultimately to adopt measure to minimize their levels in drinking water systems.
Effects of blending of desalinated water with treated surface drinking water on copper and lead release
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.WATRES.2010.05.014
Abstract: This study examined effects of desalinated water on the corrosion of and metal release from copper and lead-containing materials. A jar test protocol was employed to examine metal release from copper and lead-tin coupons exposed to water chemistries with varying blending ratios of desalinated water, alkalinities, pHs and orthophosphate levels. Increasing fractions of desalinated water in the blends resulted in non-monotonic changes of copper and lead release, with generally lower metal concentrations in the presence of desalinated water, especially when its contribution increased from 80% to 100%. SEM examination showed that the increased fractions of desalinated water were associated with pronounced changes of the morphology of the corrosion scales, likely due to the influence of natural organic matter. This hypothesis was corroborated by the existence of correlations between changes of the zeta-potential of representative minerals (malachite and hydrocerussite) and metal release. For practical applications, maintaining pH at 7.8 and adding 1 mg/L orthophosphate as PO(4) were concluded to be adequate to decrease copper and lead release. Lower alkalinity of desalinated water was beneficial for blends containing 50% or more desalinated water.
A density functional study of dissociative electron transfer reactions with participation of halogenated methanes
Publisher: Elsevier BV
Date: 12-2004
Spectroscopic study of the degradation of antibiotics and the generation of representative EfOM oxidation products in ozonated wastewater
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.CHEMOSPHERE.2011.11.003
Abstract: This study examined effects of ozonation on thirteen fluoroquinolone, macrolide and lincosamide antibiotics present in municipal wastewater. Transformations of effluent organic matter (EfOM) caused by ozonation were characterized using absorbance/fluorescence spectroscopy and high performance size exclusion chromatography (HPSEC). Concentrations of aldehydes and carboxylic acids generated via the oxidation of EfOM were also determined. The absorbance and fluorescence of ozonated wastewater decreased with increasing ozone dose or treatment time. HPSEC data showed that these phenomena corresponded to the oxidation of all EfOM fractions, with some preference towards the degradation of the EfOM molecules with high apparent molecular weight. The removal of antibiotics and production of aldehydes and carboxylic acids were strongly correlated with the changes in both EfOM absorbance and fluorescence. Applications of a model describing the concurrent degradation of trace level contaminants and relative changes of EfOM emission allowed achieving a good fitting between the experimental and modeled ΔC/C(0) vs. ΔA/A(0) and ΔC/C(0) vs. ΔF/F(0) data.
Comparison of the formation of aldehydes and carboxylic acids in ozonated and electrochemically treated surface water
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.CHEMOSPHERE.2022.135664
Abstract: This study compared effects of conventional ozonation and electrochemical oxidation (EO) on the formation of aldehydes and aliphatic carboxylic acids produced via the oxidation of natural organic matter (NOM) present in a low-mineralized surface water with a relatively low NOM concentration. Conventional ozonation and EO were effective in degrading the aromatic moiety of NOM characterized by the absorbance at 254 nm. Yields of aliphatic carboxylic acids in the ozone treated water were dominated by formate, acetate and oxalate, while no acetate was observed in the case of EO treatment. The speciation of aldehydes was similar in the case of ozonation and EO treatment, but the aldehydes yields were notably higher for ozonation. The presence of the elevated carbonate concentration moderated the changes in disinfection by-products (DBPs) concentration in the EO treated water due to the interception of ∙OH by HCO
Interactions of Pb(II)/Pb(IV) Solid Phases with Chlorine and Their Effects on Lead Release
Publisher: American Chemical Society (ACS)
Date: 25-03-2009
DOI: 10.1021/ES803179B
Abstract: This study examined changes of colloidal properties and lead release from representative solid phases of lead (IV) (PbO2) and lead (II) (hydrocerussite, cerussite) and during the oxidation of the lead (II) solids by chlorine. Chlorine is determined to cause the zeta-potential of lead (II) solids to undergo significant changes apparently associated with the generation of Pb(lll) intermediates that are formed before the PbO2 phase becomes abundant enough to be morphologically distinct. Simultaneouslywith the changes of the zeta-potential, a pronounced decrease of lead release from hydrocerussite takes place. In contrast with that, lead release from cerussite undergoes a transient increase during the oxidation of that solid by chlorine. The existence of differences in processes governing lead release from these Pb(ll) solids is supported by SEM data showing different patterns of morphological changes of the cerussite and hydrocerussite crystal surfaces.
Differential absorbance study of effects of temperature on chlorine consumption and formation of disinfection by-products in chlorinated water
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.WATRES.2007.11.013
Abstract: Effects of chlorine dose, reaction time and temperature on the formation of disinfection by-products (DBPs) and corresponding changes in the absorbance of natural organic matter (NOM) in chlorinated water were examined in this study. Although variations of chlorination parameters, notably those of temperature that was varied from 3 to 35 degrees C, influenced the kinetics of chlorine consumption and DBP release, correlations between chlorine consumption, concentrations of trihalomethanes (THMs), haloacetonitriles (HANs), other DBP species and, on the other hand, intensity of differential absorbance at 272nm remained unaffected. THM and HAN speciation was correlated with the differential absorbance, indicating preferential incorporation of bromine at the initial phases of halogenation that correspond to low DeltaA(272) values. Because the DeltaA(272) parameter is a strong indicator of the formation of DBP species and chlorine decay, optimization of chlorination operations and DBPs control based on this parameter can be beneficial for many water utilities, especially those with pronounced variability of water temperature and residence times.
Comparison of the yields of mono-, Di- and tri-chlorinated HAAs and THMs in chlorination and chloramination based on experimental and quantum-chemical data
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.WATRES.2019.115100
Abstract: Thermodynamic and kinetic aspects of the formation of trihalomethanes and haloacetic acids determined based on the quantum chemical (QC) simulations were compared in this study with the experimental data generated using the differential spectroscopy approach in chlorination and chloramination. The ratios of the slopes of the correlations between -DlnA
Interactions between natural organic matter (NOM) and the cationic dye toluidine blue at varying pHs and ionic strengths: Effects of NOM charges and Donnan gel potentials
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.CHEMOSPHERE.2019.07.003
Abstract: This study examined effects of charges of molecules of natural organic matter (NOM) on its interactions with organic cations represented by toluidine blue (TB). NOM was exemplified in this study by Suwannee River (SR) and South Platte (SP) NOM. TB/NOM interactions were probed in the range of pH 3 to 11, DOC concentrations 0-10.6 mg L
The decrease of UV absorbance as an indicator of TOX formation
Publisher: Elsevier BV
Date: 04-1997
Using Spectrophotometric Titrations To Characterize Humic Acid Reactivity at Environmental Concentrations
Publisher: American Chemical Society (ACS)
Date: 10-08-2010
DOI: 10.1021/ES1012142
Abstract: Potentiometric titration is a common method to characterize dissolved organic matter (DOM) reactivity. Because of the sensitivity of pH electrodes, it is necessary to work with very high DOM (>1 g/L) concentrations that are unrealistic compared to those found in natural waters (0.1 to 100 mg/L). To obtain proton binding data for concentrations closer to environmental values, spectroscopic titration methodology is a viable alternative to traditional potentiometric titrations. Spectrophotometric titrations and UV-visible spectra of a diluted solution of purified Aldrich humic acid (5 mgDOC/L) are used to estimate changes in proton binding moieties as function of pH and ionic strength after calculation of differential absorbance spectra variations. After electrostatic correction of spectrophotometric data, there is a linear operational correlation between spectrophotometric and potentiometric data which can be used as a transfer function between the two properties. Spectrophotometric titrations are then used to determine the changes of humic acid protonation after adsorption onto alpha-alumina.
Use of iron oxide-coated sand to remove strontium from simulated Hanford tank wastes
Publisher: American Chemical Society (ACS)
Date: 03-11-2001
DOI: 10.1021/ES0108990
Abstract: The ability of iron oxide-coated sand (IOCS) to adsorb strontium from synthetic wastes simulating the tank wastes at the Hanford Nuclear Reservation was examined in this study. These wastes have high pH and high ionic strength, containing up to 5.5 M Na+, 3.7 M NO3-, and 1.2 M OH-. The use of IOCS in such applications may be advantageous because it is inexpensive, is nontoxic, and can be prepared from readily available materials. IOCS can selectively remove strontium from solutions, even when they contain overwhelmingly higher concentrations of potentially competing cations such as Ca2+, Al3+, and Cr3+. Sr-EDTA chelates do not adsorb to IOCS. However, the interference caused by EDTA can be substantially overcome by the addition of excess Ca to the solution since Ca displaces Sr from EDTA. The adsorbed Sr can be released, and the IOCS can be regenerated by exposure to dilute acid (pH approximately 3) for short periods. The physical and adsorptive properties of the IOCS remain essentially unaltered over at least several dozens of regeneration cycles, corresponding to treatment of at least 20000 bed volumes of influent. The only byproduct of the regeneration process is a small volume of residual waste containing essentially only strontium and dilute acid.
Absorbance spectroscopy-based examination of effects of coagulation on the reactivity of fractions of natural organic matter with varying apparent molecular weights
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.WATRES.2008.12.041
Abstract: Absorbance spectra of fractions of natural organic matter (NOM) with varying apparent molecular weights (AMWs) were examined in this study. Size exclusion chromatography (SEC) was employed to obtain AMW distributions for three Australian water sources which represented low- and high-dissolved organic carbon (DOC) surface waters and a source with highly degraded NOM. These waters were coagulated with alum and other coagulants. Effects of coagulation on AMW distributions were quantified based on an absorbance slope index (ASI) calculated using NOM absorbance measured at 220, 230, 254 and 272 nm. This index can be calculated for any AMW fraction of NOM. Similarly to SUVA(254), ASI values decrease consistently in coagulated waters and are correlated with trihalomethane yields. Comparison of ASI indexes in different water sources indicates the presence of both common trends and differences indicative of NOM site-specificity.
Development and validation of online surrogate parameters for water quality monitoring at a conventional water treatment plant using a UV absorbance spectrolyser
Publisher: IEEE
Date: 12-2011
Examination of NOM Chlorination Reactions by Conventional and Stop-Flow Differential Absorbance Spectroscopy
Publisher: American Chemical Society (ACS)
Date: 17-03-2007
DOI: 10.1021/ES062268H
Abstract: Mechanisms of chlorination of natural organic matter (NOM) in surface water (Lake Washington) were explored via differential spectroscopy. Two types of differential spectra (overall and incremental) were generated for this water chlorinated at pH 7 using varying chlorine doses and reaction times. The differential spectra contain two kinetically and spectroscopically distinct components. One of these components is attributable to functional groups that react rapidly with chlorine, while the other reflects transformations of slowly reacting chromophores that arise following the depletion of the fast chromophores. Small concentrations of disinfection byproducts (DBPs), exemplified in this study by dichloroacetic acid and chloral hydrate, were produced during the initial phase of chlorination, when the fast-reacting chromophores were being consumed. Rather, the release of those DBPs was correlated with the breakdown of the slowly reacting chromophores.
Excitation Emission Matrix Fluorescence Spectroscopy for Combustion Generated Particulate Matter Source Identification
Publisher: American Chemical Society (ACS)
Date: 21-08-2019
DOI: 10.26434/CHEMRXIV.9177146
Abstract: The inhalation of particulate matter (PM) is a significant health risk associated with reduced life expectancy due to increased cardio-pulmonary disease and exacerbation of respiratory diseases such as asthma and pneumonia. PM originates from natural and anthropogenic sources including combustion engines, cigarettes, agricultural burning, and forest fires. Identifying the source of PM can inform effective mitigation strategies and policies, but this is difficult to do using current techniques. Here we present a method for identifying PM source using excitation emission matrix (EEM) fluorescence spectroscopy and a machine learning algorithm. We collected combustion generated PM2.5 from wood burning, diesel exhaust, and cigarettes using filters. Filters were weighted to determine mass concentration followed by extraction into cyclohexane and analysis by EEM fluorescence spectroscopy. Spectra obtained from each source were used as machine learning training data for source identification in mixed s les. This method can predict the presence or absence of the three laboratory sources with an overall accuracy of 89% when the threshold for classifying a source as present is 1.1 µg/m3 in air over a 24-hour s ling time. We apply this method to a small set of field s les to evaluate its effectiveness. br
In situ examination of the protonation behavior of fulvic acids using differential absorbance spectroscopy
Publisher: American Chemical Society (ACS)
Date: 05-08-2008
DOI: 10.1021/ES800741U
Abstract: The effects of pH changes on the absorbance spectra of fulvic acids, which constitute a major part of natural organic matter (NOM) were examined based primarily on the ex le of standard Suwannee River fulvic acid (SRFA). Differential absorbance spectra of SRFA generated at varying pH values were determined to be rich in features that are absent in the conventional spectra. Analysis of the differential absorbance revealed the existence of two predominant types of pH-active chromophores which produced features that emerged in the pH ranges associated with carboxylic and phenolic functional groups of fulvic acids. Comparison of the differential absorbance spectra of SRFA and those of the fraction of hydrophobic acids of South Platte River fulvic acid show the existence of differences indicative of fulvic acids's site-specificity. The evolution of the pH-differential spectra of fulvic acids was in accord with predictions made based on the NICA-Donnan theory. These results show that pH-differential absorbance spectroscopy can be used to quantify in situ the protonation and site-specificity of fulvic acids.
Studies of metal-binding sites in natural organic matter and their role in the generation of disinfection by-products using lanthanide ion probes
Publisher: Elsevier BV
Date: 11-2002
DOI: 10.1016/S0045-6535(02)00353-3
Abstract: In this study, the complexation of Tb3+ with natural organic matter (NOM) was studied by the method of time-resolved fluorescence spectroscopy. In the presence of NOM, the excitation of Tb3+ was observed in a wide range of wavelengths, for which virtually no excitation of free Tb3+ took place. The pseudo-quantum yield spectra (excitation intensity normalized by corresponding light absorbance values) had a maximum at 282 nm. This indicated that the excitation of NOM-bound Tb3+ proceeds through energy transfer from aromatic groups in NOM. The concentration of the metal-binding sites (C(L)) was determined by titration with Tb3+ and was found to range from 0.21% to 0.83% of total moles of organic carbon. The actual number of the carbon atoms that comprise these functionalities was hypothesized to be at least seven times higher. The C(L) values were well correlated with the reactivity of NOM with chlorine quantified by total organic halogen formation potential and with the contribution of polyhydroxyaromatic moieties determined by pyrolysis-GC/MS method. The correlation of C(L) with the contributions of aromatic and carboxylic moieties in NOM determined by 13C NMR was poor. Based on the data, it was concluded that the metal binding functionalities in NOM are closely associated with halogen attack sites.
Evolution of Absorbance Spectra of Ozonated Wastewater and Its Relationship with the Degradation of Trace-Level Organic Species
Publisher: American Chemical Society (ACS)
Date: 15-07-2010
DOI: 10.1021/ES1005175
Abstract: This study examined the evolution of absorbance spectra of wastewater ozonated using varying initial ozone concentrations or treatment times concomitant changes of concentrations of trace-level pharmaceuticals were also quantified. The absorbance of ozonated wastewater decreased due to the degradation of chromophores in effluent organic matter (EfOM). The relative decrease of absorbance (DeltaA/A(0)) ranged from < 30% for lambda 80% for lambda > 320 nm. The removal of atenolol, carbamazepine, DEET, diclofenac, gemfibrozil, ibuprofen, iopromide, naproxen, propranolol, sulfamethoxazole, trimethoprim, and p-chlorobenzoic acid was strongly correlated with DeltaA/A(0) values. The observed features were hypothesized to correspond to the engagement of kinetically distinct groups of EfOM chromophores. Modeling of the evolution of EfOM absorbance and concurrent degradation of trace-level organic species based on this hypothesis confirmed its applicability and utility for practical applications and theoretical exploration.
Bromide Catalyzes the Transformation of Nitrite by Sulfate Radical Oxidation
Publisher: American Chemical Society (ACS)
Date: 17-08-2023
Formation of Pb(III) Intermediates in the Electrochemically Controlled Pb(II)/PbO2 System
Publisher: American Chemical Society (ACS)
Date: 20-01-2012
DOI: 10.1021/ES203084N
Abstract: The formation of lead dioxide PbO(2), an important corrosion product in drinking water distribution systems with lead-bearing plumbing materials, has been hypothesized to involve Pb(III) intermediates, but their nature and formation mechanisms remain unexplored. This study employed the electrochemical (EC) method of rotating ring disk electrode (RRDE) and quantum chemical (QC) simulations to examine the generation of intermediates produced during the oxidation of Pb(II) to PbO(2). RRDE data demonstrate that PbO(2) deposition and reduction involves at least two intermediates. One of them is a soluble Pb(III) species that undergoes further transformations to yield immobilized PbO(2) nanoparticles. The formation of this intermediate in EC system is mediated by hydroxyl radicals (OH(•)), as was evidenced by the suppression of intermediates formation in the presence of the OH(•) scavenger para-chlorobenzoic acid. QC simulations confirmed that the oxidation of Pb(II) by OH(•) proceeds via Pb(III) species. These results show that Pb(III) intermediates play an important role in the reactions determining transitions between Pb(II) and Pb(IV) species and could impact lead release in drinking water.
Characterizing property and treatability of dissolved effluent organic matter using size exclusion chromatography with an array of absorbance, fluorescence, organic nitrogen and organic carbon detecto
Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.CHEMOSPHERE.2019.125321
Abstract: In this study, size exclusion chromatography with an array of absorbance, fluorescence, organic nitrogen and organic carbon detectors was used for characterizing property and treatability of effluent organic matter (EfOM) from 12 wastewater treatment plants. According to their apparent molecular weight (AMW), EfOM fractions were assigned to biopolymers (>20 kDa), humic substances that comprise sub-fractions of humic-like acids (HA-I & HA-II, 2.3-7.0 kDa) and fulvic-like acids (FA, 1.5-2.3 kDa), building blocks (0.55-1.5 kDa) and low molecular weight neutral substances ( HA subfraction > FA subfraction > building blocks, while little removal of protein-like fluorescence in HA-II and FA subfractions was detected. Anion exchange treatment could effectively reduce DOC and DON concentrations the sequence of the treatment efficiency was humic substances > biopolymers > building blocks. Increasing O
Changes of dissolved organic matter fractions and formation of oxidation byproducts during electrochemical treatment of landfill leachates: Development of spectroscopic indicators for process optimiza
Publisher: Elsevier BV
Date: 04-2023
Application of UV absorbance and fluorescence indicators to assess the formation of biodegradable dissolved organic carbon and bromate during ozonation
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.WATRES.2017.01.009
Abstract: This study examined the significance of changes of UV absorbance and fluorescence of dissolved organic matter (DOM) as surrogate indicators for assessing the formation of bromate and biodegradable dissolved organic carbon (BDOC) during the ozonation of surface water and wastewater effluent. Spectroscopic monitoring was carried out using benchtop UV/Vis and fluorescence spectrophotometers and a newly developed miniature LED UV/fluorescence sensor capable of rapidly measuring UVA280 and protein-like and humic-like fluorescence. With the increase of O
Comparative study of reactions of endocrine disruptors bisphenol A and diethylstilbestrol in electrochemical treatment and chlorination
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.WATRES.2006.01.003
Abstract: Transformations of diethylstilbestrol (DES) and bisphenol A (BPA) in conventional chlorination and electrochemically (EC) treated solutions were examined using spectrophotometry and chromatographic analyses. EC treatment was carried out using an un ided EC cell with a PbO2 anode and a stainless steel cathode. EC-treatment and conventional chlorination caused DES and BPA to undergo a rapid degradation accompanied by the generation of low molecular weight chlorinated organic species indicative of the breakdown of DES and BPA. The identified compounds were predominated by chloroacetic acids (HAAs), but approximately 80% of the total organic halogen (TOX) was comprised by unidentified species. For EC treatment, the HAA yields were lower and HAAs were predominated by monochloroacetic acid (MCAA), while in the case of conventional chlorination, trichloroacetic acid (TCAA) was predominant and MCAA was virtually absent. The changes in the HAA speciation and yields were concluded to be caused by the EC-driven reductive dehalogenation which, however, did not affect the unidentified fraction of TOX. This indicated that the unidentified part of TOX was comprised by aromatic chlorinated forms of BPA and DES. Their resistance to degradation in EC reactors indicates that these compounds may be stable in conditions typical for drinking water treatment and distribution.
A spectroscopic study of the bromination of the endocrine disruptor ethynylestradiol
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.CHEMOSPHERE.2008.02.055
Abstract: Bromination of ethynylestradiol (EE2) was studied using fluorescence and conventional and stopped-flow absorbance spectroscopy. EE2 transformations in the presence of bromine were determined to proceed through sequential reactions. The first step is very rapid and results in the formation of a brominated cyclohexadienone that is susceptible to reduction but in oxidative conditions it undergoes a transformation into monobromo-EE2 in a first-order OH- -accelerated reaction. The transformation from monobromo-EE2 to dibromo-EE2 follows a similar mechanism. The rates of reactions of bromine-substituted EE2 species are orders of magnitude lower than that of the parent compound indicating that these species can persist in conditions typical for water treatment operations.
Characterization of elemental and structural composition of corrosion scales and deposits formed in drinking water distribution systems
Publisher: Elsevier BV
Date: 08-2010
DOI: 10.1016/J.WATRES.2010.05.043
Abstract: Corrosion scales and deposits formed within drinking water distribution systems (DWDSs) have the potential to retain inorganic contaminants. The objective of this study was to characterize the elemental and structural composition of extracted pipe solids and hydraulically-mobile deposits originating from representative DWDSs. Goethite (alpha-FeOOH), magnetite (Fe(3)O(4)) and siderite (FeCO(3)) were the primary crystalline phases identified in most of the selected s les. Among the major constituent elements of the deposits, iron was most prevalent followed, in the order of decreasing prevalence, by sulfur, organic carbon, calcium, inorganic carbon, phosphorus, manganese, magnesium, aluminum and zinc. The cumulative occurrence profiles of iron, sulfur, calcium and phosphorus for pipe specimens and flushed solids were similar. Comparison of relative occurrences of these elements indicates that hydraulic disturbances may have relatively less impact on the release of manganese, aluminum and zinc, but more impact on the release of organic carbon, inorganic carbon, and magnesium.
Adsorption of natural organic matter (NOM) on iron oxide: Effects on NOM composition and formation of organo-halide compounds during chlorination
Publisher: Elsevier BV
Date: 07-1997
Characterization of NOM and its adsorption by iron oxide coated sand (IOCS) using UV and fluorescence spectroscopy
Publisher: Thomas Telford Ltd.
Date: 11-2006
DOI: 10.1139/S06-012
Abstract: The removal of natural organic matter (NOM) by adsorption onto iron oxide coated sand (IOCS) can be interpreted based on analysis of the absorbance and fluorescence spectra of the water before and after treatment. The useful spectral parameters include SUVA 254 , the widths of the benzenoid and electron transfer absorbance bands (W Bz , and W ET , respectively), the ratio of the absorbance intensities of these two bands (A ET /A Bz ), and the wavelength of the emission maximum (λ max em ). These parameters appear to reflect both the activated aromatic content in the s le and its average molecular weight, and are good indicators of the adsorbability of NOM onto IOCS. A multi-parametric spectroscopic approach for online monitoring of NOM and its reactions can be valuable for both practical treatment studies and for fundamental explorations of NOM reactivity. Key words: natural organic matter, UV absorbance, adsorption, activated aromatics.
Effects of thermal treatment on halogenated disinfection by-products in drinking water
Publisher: Elsevier BV
Date: 10-2001
DOI: 10.1016/S0043-1354(01)00080-X
Abstract: The influence of heating or boiling on the formation and behavior of disinfection by-products (DBPs) was investigated in DBP-spiked reagent water, municipal tap water, and synthetic water containing chlorinated aquatic humic substances. Thermal cleavage of larger halogenated species leads to both formation of smaller chlorinated molecules (including THMs and HAAs) and dechlorination of organics. In parallel with their formation from larger molecules, THMs can be volatilized, and this latter process dominates the change in their concentration when water is boiled. HAAs are not volatile, but they can be destroyed by chemical reactions at elevated temperatures, with the net effect being loss of trihalogenated HAAs and either formation or loss of less chlorinated HAAs. Although other identifiable DBPs can be generated at slightly elevated temperatures, in most cases their concentrations decline dramatically when the solution is heated.
Self-forming Dynamic Membranes for Wastewater Treatment
Publisher: Informa UK Limited
Date: 21-03-2021
Interpreting pH-Dependent Differential UV/VIS Absorbance Spectra to Characterize Carboxylic and Phenolic Chromophores in Natural Organic Matter
Publisher: Elsevier BV
Date: 10-2023
Use of fluorescence EEM to monitor the removal of emerging contaminants in full scale wastewater treatment plants
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.JHAZMAT.2016.05.035
Abstract: This study investigated the applicability of different techniques for fluorescence excitation/emission matrices data interpretations, including peak-picking method, fluorescence regional integration and PARAFAC modelling, to act as surrogates in predicting emerging trace organic compounds (ETOrCs) removal during conventional wastewater treatments that usually comprise primary and secondary treatments. Results showed that fluorescence indexes developed using alternative methodologies but indicative of a same dissolved organic matter component resulted in similar predictions of the removal of the target compounds. The peak index defined by the excitation/emission wavelength positions (λ
Developing surrogate indicators for predicting suppression of halophenols formation potential and abatement of estrogenic activity during ozonation of water and wastewater
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.WATRES.2019.05.092
Abstract: This study focused on developing surrogate indicators for predicting oxidation of phenolic groups in dissolved organic matter (DOM), suppression of halophenols' formation potential and abatement of estrogenic activity during ozonation of water and wastewater. The evolution of pH-dependent differential absorbance spectra suggests that O
Influence of natural organic matter on the corrosion of leaded brass in potable water
Publisher: Elsevier BV
Date: 2000
Modeling bromide effects on yields and speciation of dihaloacetonitriles formed in chlorinated drinking water
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.WATRES.2013.07.018
Abstract: This study examined effects of bromide on yields and speciation of dihaloacetonitrile (DHAN) species that included dichloro-, bromochloro- and dibromoacetonitriles generated in chlorinated water. Experimental data obtained using two water sources, varying concentrations and characters of Natural Organic Matter (NOM), bromide concentrations, reaction times, chlorine doses, temperatures and pHs were interpreted using a semi-phenomenological model that assumed the presence of three kinetically distinct sites in NOM (denoted as sites S1, S2 and S3) and the occurrence of sequential incorporation of bromine and chlorine into them. One site was found to react very fast with the chlorine and bromine but its contribution in the DHAN generation was very low. The site with the highest contribution to the yield of DHAN (>70%) has the lowest reaction rates. The model introduced dimensionless coefficients (denoted as φ1(DHAN), φ2(DHAN) and φ3(DHAN)) applicable to the initial DHAN generation sites and their monochlorinated and monobrominated products, respectively. These parameters were used to quantify the kinetic preference to bromine incorporation over that of chlorine. Values of these coefficients optimized for DHAN formation were indicative of the strongly preferential incorporation of bromine into the engaged NOM sites. The same set of φ(i)(DHAN) coefficients could be used to model the speciation of DHAN released from their kinetically different precursors. The dimensionless speciation coefficients φ(i)(DHAN) were determined to be site specific and dependent on the NOM content and character as well as pH. The presented model of DHAN formation and speciation can help quantify in more detail the generation of DHAN and provide more insight necessary for further assessment of their potential health effects.
Quantifying the formation of nitrogen-containing disinfection by-products in chlorinated water using absorbance and fluorescence indexes
Publisher: IWA Publishing
Date: 2011
DOI: 10.2166/WST.2011.006
Abstract: Among known but unregulated disinfection by-products (DBPs), several nitrogenous species (N-DBPs) have been found in drinking waters. While concentrations of N-DBP are much lower than those of trihalomethanes (THMs) and haloacetic acids (HAAs), their potential toxicity is higher. In this study the relationships between the formation of N-DBPs and the changes in NOM caused by the chlorination of raw Ancipa water quantified by the use of differential absorbance and fluorescence indexes were investigated. Very strong relationships were found between selected N-DBPs (i.e. trichloronitromethane and dichloroacetonitrile) and the proposed spectroscopic indexes that were previously developed to quantify the changes in natural organic matter (NOM) during chlorination at varying reaction conditions (chlorine dose, reaction time and temperature) and the generation of DBPs. Obtained results clearly indicate that the changes in NOM absorbance and fluorescence are fundamental descriptors of the formation of both commonly controlled halogenated DBPs and N-DBPs. This approach may be suitable for real time monitoring of emerging N-DBPs and for studying their formation pathways.
Reactions of the Flavonoid Hesperetin with Chlorine: A Spectroscopic Study of the Reaction Pathways
Publisher: American Chemical Society (ACS)
Date: 04-08-2004
DOI: 10.1021/ES049575C
Abstract: The flavonoid hesperetin (Hsp) contains aromatic rings substituted with hydroxyl and methoxyl groups, which activate it toward electrophilic attack and hence make it a potential surrogate for natural organic matter with respect to reactions with chlorine. This paper describes the chlorination pathway of Hsp, based on a combination of electrospray tandem mass spectrometry (MS/MS) and absorbance spectroscopy. When a solution containing Hsp is dosed with NaOCl at pH 7, chlorine substitution into Hsp occurs exclusively into the meta-dihydroxy substituted ring. The first two Cl atoms to enter the ring do so at the highly activated carbons that are each ortho to two oxygenated carbon atoms. These substitutions make the molecule more acidic, but do not change its primary structure or aromaticity. The third Cl atom that substitutes into the molecule does so at one of the previously chlorinated sites, destroying the aromaticity of the ring and altering the molecular properties more dramatically than do the first two. The absorbance spectra of Hsp and mono- and di-chlorinated Hsp are all very similar and are very distinct from that of trichlorinated Hsp. In particular, the latter is the only one of those species that absorbs visible light (in a characteristic band centered at approximately 422nm). Di- and trichloroHsp form even at low molar Cl/Hsp ratios, and can coexist with Hsp and monochloroHsp in neutral, aqueous solutions for at least 24 h in the absence of free chlorine. If free chlorine is present, the less-chlorinated species continue to acquire Cl, and trichloroHsp undergoes further reaction, until either the free chlorine or the trichloroHsp is fully depleted. The appearance of di- and trichloroHsp while substantial amounts of Hsp remain unreacted indicates that substitution of one or two Cl atoms into the ring facilitates the incorporation of yet more Cl into the ring. This autoacceleration of the chlorination process is hypothesized to be induced by the increase in acidity that accompanies Cl incorporation. Specifically, the increase in the acidity of the phenolic groups shifts the equilibrium toward the enolate anion, which is considered to be much more amenable to electrophilic attack than the enol.
Comparison of the effects of chloramine and chlorine on the aromaticity of dissolved organic matter and yields of disinfection by-products
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.CHEMOSPHERE.2017.10.063
Abstract: This study compared effects of chlorination and chloramination on the chromophores of dissolved organic matter (DOM) and attendant formation of disinfection by-products (DBPs) in raw and treated surface waters. Comparison of the differential absorbance spectra of chloraminated and chlorinated waters shows that interactions of chloramine with DOM chromophores result in changes that are in many respects similar to those observed for chlorine although the extent of degradation of DOM chromophores and the attendant decrease of DOM aromaticity by chloramine are less pronounced than that caused by free chlorine. The degradation of DOM chromophores caused by the examined disinfectants indicated that in both cases a gradual decrease of DOM took place. Decreases of DOM aromaticity estimated based on the changes of DOM absorbance at 254 or 280 nm were correlated with chlorine consumption in a similar way for both examined disinfectants. Correlations between changes of DOM absorbance and yields of dihaloacetic acids (DHAA) were also similar for chlorination and chloramination. This was interpreted to indicate that the generation of DHAA proceeds via the degradation of the reactive sites associated with DOM chromophores irrespective of whether these sites are engaged by chlorine or chloramine. Correlations between the decrease of DOM aromaticity and formation of other DBP (e.g. trihalomethanes - THM, trihaloacetic acids - THAA and dihaloacetonitriles - DHAN) for chloramine and chlorine were also observed but, as opposed to the observations for DHAA, the correlations between degradation of DOM aromaticity and yields of THM, THAA or DHAN were different for chlorination and chloramination.
Interpretation of the differential UV–visible absorbance spectra of metal-NOM complexes based on the quantum chemical simulations for the model compound esculetin
Publisher: Elsevier BV
Date: 08-2021
Advanced wastewater treatment and membrane fouling control by electro-encapsulated self-forming dynamic membrane bioreactor
Publisher: Springer Science and Business Media LLC
Date: 25-08-2022
DOI: 10.1038/S41545-022-00184-Z
Abstract: An advanced concept of aerobic membrane bioreactors (MBRs) for highly efficient wastewater treatment has been disclosed by introduction of an electro and encapsulated self-forming dynamic biomembrane (e-ESFDM). The biological filtering membrane is intercalated between two woven polyester fabrics as supports that assist the formation and protect the biomembrane. The innovative architecture of the e-ESFDM in combination with electrocoagulation processes resulted in efficient and cost-effective wastewater treatment and control of the membrane fouling. The performance of the e-ESFDMBR was compared to a yet highly efficient ESFDMBR, where the electric field was not present. The ESFDM-based reactors both showed comparable results in the removal of organic matter, in terms of COD and DOC. On the other hand, e-ESFDMBR exceeded the performance of the ESFDMBR in the reduction of nitrogen- and phosphorous-containing pollutants, responsible for eutrophication processes in the environment, and recalcitrant molecules, such as humic-like substances. In addition, an extremely low fouling rate was observed for the e-ESFDM bioreactor. Insights on the biological processes involved in the developed MBR were provided by investigations on the microbiological ersity found in reactor mixed liquor, ESFDM layer and treated wastewater.
Effects of Fenton treatment on the properties of effluent organic matter and their relationships with the degradation of pharmaceuticals and personal care products
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.WATRES.2011.11.002
Abstract: This study examined effects of Fenton oxidation on trace level pharmaceuticals and personal care products (PPCPs) commonly occurring in wastewater. The tested PPCPs included acetaminophen, atenolol, atrazine, carbamazepine, metoprolol, dilantin, DEET, diclofenac, pentoxifylline, oxybenzone, caffeine, fluoxetine, gemfibrozil, ibuprofen, iopromide, naproxen, propranolol, sulfamethoxazole, bisphenol-A and trimethoprim. Transformations of effluent organic matter (EfOM) caused by Fenton oxidation were also quantified. All tested PPCPs, except atrazine and iopromide, were completely removed by Fenton treatment carried out using a 20mg/L Fe (II) concentration and a 2.5 H(2)O(2)/Fe (II) molar ratio. Up to 30% on the total carbon concentration was removed during Fenton treatment which was accompanied by the oxidation of EfOM molecules and formation of oxidation products such as oxalic, formic and acetic acids and, less prominently, formaldehyde, acetaldehyde, propionaldehyde and glycolaldehyde. The absorbance of EfOM treated with Fenton reagent at varying Fe (II) concentration and contact time underwent a consistent decrease. The relative decrease of EfOM absorbance was strongly and unambiguously correlated with the removal of all tested PPCPs.
Sewage Sludge-Derived Biochar for Micropollutant Removal: A Brief Overview with Emphasis on European Water Policy
Publisher: MDPI
Date: 08-11-2022
Adsorption of Uranyl on Gibbsite: A Time-Resolved Laser-Induced Fluorescence Spectroscopy Study
Publisher: American Chemical Society (ACS)
Date: 14-01-2006
DOI: 10.1021/ES051714I
Abstract: Uranyl adsorbed on gibbsite at pH 4.0-8.0 and ionic strengths (ISs) 0.001-0.4 M (NaClO4) in the absence of carbonate was studied using time-resolved laser-induced fluorescence spectroscopy (TRLIFS) under cryogenic conditions. TRLIFS data showed the presence of several distinct emission components. Their contributions were determined using the evolving factor analysis approach. Four components denoted as species A, B, C, and D were discerned. Each of them was characterized by a characteristic response to pH and IS changes and also by a unique combination of the values of the fundamental transition energy E0,0, vibronic spacing deltaE, and half-width of the vibronic lines deltaW. Species A and B were major contributors to the overall emission. They were mainly affected by the pH and predominated below and above pH 5.0, respectively. In contrast with that, the contribution of species C was noticeable only at IS = 0.001 M, while it was suppressed or absent at high IS values. It was concluded that species A and B are likely to correspond to inner-sphere surface aluminol complexes =AlO-(UO2)+ and =AlO-(UO2)OH degrees, while species C was hypothesized to correspond to electrostatically bound uranyl complexes (predominantly [UO2(OH)3]-).
Characterization of dissolved organic matter using high-performance liquid chromatography (HPLC)–size exclusion chromatography (SEC) with a multiple wavelength absorbance detector
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.CHEMOSPHERE.2012.01.029
Abstract: High-performance liquid chromatography-size exclusion chromatography (HPLC-SEC) coupled with a multiple wavelength absorbance detector (200-445 nm) was used in this study to investigate the apparent molecular weight (AMW) distributions of dissolved organic matter (DOM). Standard DOM, namely humic acid, fulvic acid and hydrophilic acid, from the Suwannee River were tested to ascertain the performance and sensitivity of the method. In addition to four compounds groups: humic substances (Peak 1, AMW 16 kD), fulvic acids (Peak 2, AMW 11 kD), low AMW acids (Peak 3, AMW 5 kD), and low AMW neutral and hiphilic molecules, proteins and their amino acid building blocks (Peak 4, AMW 3 kD), an new group that appears to include low AMW, 6-10 kD, humic substances was found based on investigating the spectra at various elution times. The spectroscopic parameter S(>365) (slope at wavelengths >365 nm) was determined to be a good predictor of the AMW of the DOM. The detector wavelength played an important role in evaluating the AMW distribution. For some fractions, such as the humic and low AMW non-aromatic substances, the error in measurement was ± 30% as determined by two-dimensional chromatograms detected at an artificially selected wavelength. HPLC-SEC with multiple wavelength absorbance detection was found to be a useful technique for DOM characterization. It characterized the AMW distributions of DOM more accurately and provided additional, potentially important information concerning the properties of DOM with varying AMWs.
Solid Phase Excitation-Emission Matrix Spectroscopy for In-Situ Chemical Analysis of Combustion Aerosols
Publisher: American Chemical Society (ACS)
Date: 22-04-2020
DOI: 10.26434/CHEMRXIV.12167865.V1
Abstract: Exposure to combustion generated aerosols such as PM from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. It is important to assess the chemical composition of PM to examine personal exposure. Excitation-emission matrix (EEM) spectroscopy has been shown as a sensitive and cost-effective technique for evaluation of combustion PM composition and as a source apportionment tool. However, EEM measurements are hindered by a solvent extraction step and a need for benchtop instrumentation. Here, we present a methodology that eliminates this labor-intensive s le preparation and allows to automate and miniaturize the detection platform. A miniature electrostatic collector deposits PM s le onto transparent polydimethylsiloxane (PDMS) coated substrate, where PAH components are extracted into solid-phase (SP) solvent and analyzed using EEM spectroscopy in-situ. We evaluated external and internal excitation schemes to optimized signal to noise ratio. Analysis of woodsmoke and cigarette smoke s les showed good agreement with liquid extraction EEM spectra. Internal excitation is hindered by fluorescent interference from PDMS at λ nm. The external excitation EEM spectra are dependent on the incident angle ranges of 30-40⁰ and 55-65⁰ showed the best results. The proposed SP-EEM technique can be used for development of miniaturized sensors for chemical analysis of combustion generated PM.
Structural Study of the Incorporation of Heavy Metals into Solid Phase Formed during the Oxidation of EDTA by Permanganate at High pH
Publisher: American Chemical Society (ACS)
Date: 23-02-2007
DOI: 10.1021/ES062554T
Abstract: Properties of solid phases formed during the oxidation of EDTA by permanganate in a high-pH, high-ionic strength solution, and the retention of Cu2+, Ni2+, and Zn2+ by them were examined. Morphologically, the solids were agglomerates of particles with sizes 12. XAS showed that Cu2+ binding sites were located within MnO6 octahedra-comprised sheets that constitute birnessite while Zn2+ was positioned between them.
Speciation of trace inorganic contaminants in corrosion scales and deposits formed in drinking water distribution systems
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.WATRES.2011.08.017
Abstract: Sequential extractions utilizing the modified Tessier scheme (Krishnamurti et al., 1995) and measurements of soluble and particulate metal released from suspended solids were used in this study to determine the speciation and mobility of inorganic contaminants (As, Cr, V, U, Cd, Ni, and Mn) found in corrosion scales and particles mobilized during hydraulic flushing events. Arsenic, chromium and vanadium are primarily associated with the mobilization-resistant fraction that is resistant to all eluents used in this study and also bound in highly stable crystalline iron oxides. Very low concentrations of these elements were released in resuspension experiments. X-ray absorbance measurements demonstrated that arsenic in the s le with the highest As concentration was dominated by As(V) bound by iron oxides. Significant fractions of uranium and cadmium were associated with carbonate solids. Nickel and manganese were determined to be more mobile and significantly associated with organic fractions. This may indicate that biofilms and natural organic matter in the drinking water distributions systems play an important role in the accumulation and release of these inorganic contaminants.
Effects of chloride, sulfate and natural organic matter (NOM) on the accumulation and release of trace-level inorganic contaminants from corroding iron
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.WATRES.2013.06.004
Abstract: This study examined effects of varying levels of anions (chloride and sulfate) and natural organic matter (NOM) on iron release from and accumulation of inorganic contaminants in corrosion scales formed on iron coupons exposed to drinking water. Changes of concentrations of sulfate and chloride were observed to affect iron release and, in lesser extent, the retention of representative inorganic contaminants (vanadium, chromium, nickel, copper, zinc, arsenic, cadmium, lead and uranium) but, effects of NOM were more pronounced. DOC concentration of 1 mg/L caused iron release to increase, with average soluble and total iron concentrations being four and two times, respectively, higher than those in the absence of NOM. In the presence of NOM, the retention of inorganic contaminants by corrosion scales was reduced. This was especially prominent for lead, vanadium, chromium and copper whose retention by the scales decreased from >80% in the absence of NOM to <30% in its presence. Some of the contaminants, notably copper, chromium, zinc and nickel retained on the surface of iron coupons in the presence of DOC largely retained their mobility and were released readily when ambient water chemistry changed. Vanadium, arsenic, cadmium, lead and uranium retained by the scales were largely unsusceptible to changes of NOM and chloride levels. Modeling indicated that the observed effects were associated with the formation of metal-NOM complexes and effects of NOM on the sorption of the inorganic contaminants on solid phases that are typical for iron corrosion in drinking water.
Differential ATR FTIR spectroscopy of membrane fouling: Contributions of the substrate/fouling films and correlations with transmembrane pressure
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.WATRES.2019.05.086
Abstract: This study examined the formation of fouling films deposited on the surface of a polyethersulfone (PES) membrane during the filtration of alginate solutions with various ionic strengths. Membrane fouling was characterized by changes of the transmembrane pressure (TMP) and ex situ measured attenuated total reflectance (ATR) Fourier-transform IR (FTIR) spectra at varying stages of filtration runs. The ATR spectra that comprise the vibration bands characteristic of the PES substrate and the deposited film were processed taking into the gradual weakening of the PES substrate-specific bands, whose intensity was shown to depend on the wavenumber of IR radiation and the thickness of the deposited layer. Strongly linear correlations between ratios of first derivatives intensity and wavenumbers of the PES reference lines were established. Calculations of the PES bands' attenuation coefficients allowed determining the apparent thickness and ATR FTIR vibrations of the fouling films per se. Strong correlations between TMP development and ATR-determined apparent thickness of the fouling layers were observed. The intensity of ATR absorbance at 3200 cm
Insights into the mechanism of nonradical reactions of persulfate activated by carbon nanotubes: Activation performance and structure-function relationship
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.WATRES.2019.03.096
Abstract: This study aimed to elucidate the intrinsic mechanisms of PS activation by carbon nanotubes (CNTs). Singlet oxygen generation (
Use of UV Spectroscopy To Characterize the Reaction between NOM and Free Chlorine
Publisher: American Chemical Society (ACS)
Date: 12-05-2000
DOI: 10.1021/ES990899O
Effects of blending of desalinated and conventionally treated surface water on iron corrosion and its release from corroding surfaces and pre-existing scales
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.WATRES.2013.03.052
Abstract: This study examined effects of blending desalinated water with conventionally treated surface water on iron corrosion and release from corroding metal surfaces and pre-existing scales exposed to waters having varying fractions of desalinated water, alkalinities, pH values and orthophosphate levels. The presence of desalinated water resulted in markedly decreased 0.45 μm-filtered soluble iron concentrations. However, higher fractions of desalinated water in the blends were also associated with more fragile corroding surfaces, lower retention of iron oxidation products and release of larger iron particles in the bulk water. SEM, XRD and XANES data showed that in surface water, a dense layer of amorphous ferrihydrite phase predominated in the corrosion products. More crystalline surface phases developed in the presence of desalinated water. These solid phases transformed from goethite to lepidocrocite with increased fraction of desalinated water. These effects are likely to result from a combination of chemical parameters, notably variations of the concentrations of natural organic matter, calcium, chloride and sulfate when desalinated and conventionally treated waters are blended.
Comparative study of electrochemical degradation and ozonation of nonylphenol
Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.WATRES.2005.04.070
Abstract: Treatment of solutions of nonylphenol (NP), Triton X-100 (TrX) and phenol in a flow-through un ided EC reactor equipped with a Co(2+)-promoted PbO(2) anode and a stainless steel cathode was accompanied by consistent changes of absorbance, fluorescence and mass spectra of the effluents, and formation of aldehydes ranging from formaldehyde to decyl aldehyde. Deconvolution of the absorbance spectra of EC-treated NP, TrX and phenol and examination of their fluorescence indicated that the compounds are rapidly degraded in the reactor. For NP, the degradation of the target proceeded via the generation (at current densities 10mA/cm(2) was accompanied by the release of aldehydes that were predominated by acetaldehyde and formaldehyde. The total yield of aldehydes increased with the current density, but their speciation showed little sensitivity to it. Deconvolution of the absorbance spectra of NP solutions subjected to ozonation, and analysis for reaction by-products formed in these conditions showed the reaction pathway in the latter case was likely to be similar to that observed for the EC treatment.
Spectroscopic study of degradation products of ciprofloxacin, norfloxacin and lomefloxacin formed in ozonated wastewater
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.WATRES.2012.07.005
Abstract: This study addressed the formation and properties of degradation products of ciprofloxacin, norfloxacin and lomefloxacin formed during ozonation of secondary wastewater effluent containing these fluoroquinolone antibiotics. The generation of the degradation products was interpreted in the context of transformations of effluent organic matter (EfOM) tracked via absorbance measurements. The structures of 20 degradation products were elucidated for ciprofloxacin and norfloxacin, respectively. 27 degradation products were identified for lomefloxacin. The prevalent oxidation pathways were suggested based on the structures of the identified products formed in the absence and presence of the hydroxyl radical scavenger t-butanol. These pathways were largely similar for all studied fluoroquinolones and involved attacks on the piperazine ring and the quinolone structure. The quinolone ring remained intact in the presence of t-butanol thus indicating that this functional group could only be oxidized by OH radicals while the piperazine ring was readily oxidized by molecular ozone. The cleavage of the quinolone moiety that resulted in several identified degradation products occurred via the attack by hydroxyl radicals on the carbon-carbon double bond adjacent to the carboxylic acid group. Lomefloxacin had more erse oxidation products due to the presence of a methyl group on its piperazinyl ring. The concentrations of the identified degradation products behaved non-monotonically as a function of ozone dose or treatment time, yet exhibited interpretable correlations versus changes of EfOM absorbance. Examination of these correlations allowed developing a novel approach for elucidating the transformations of fluoroquinolone antibiotics during ozonation.
Monitoring the properties of natural organic matter through UV spectroscopy: A consistent theory
Publisher: Elsevier BV
Date: 07-1997
Comparison of the properties of standard soil and aquatic fulvic and humic acids based on the data of differential absorbance and fluorescence spectroscopy
Publisher: Elsevier BV
Date: 12-2020
A Novel Method to Dynamically Observe the Three-dimensional Global Oceanic Dissolved Organic Carbon Reservoir
Publisher: Research Square Platform LLC
Date: 02-02-2023
DOI: 10.21203/RS.3.RS-2357170/V1
Abstract: The current ex situ analytical methods to determine concentrations of dissolved organic carbon (DOC) are largely inadequate to form a dynamic understanding of the global carbon cycling, especially given the urgent need to understand how the oceans are responding to increasing concentrations of atmospheric CO2 and climate change. Here we establish a DOC algorithm, referred to as DOCUVFW, that is based on absorption characteristics of dissolved organic matter in the wavelength range of 275-443 nm. The algorithm performs uniformly for coastal and pelagic waters, as well as inland waters with DOC concentrations varying by several orders of magnitude. By applying the DOCUVFW algorithm, the three-dimensional distribution of oceanic DOC could be quantified via ocean color observed complementarily using field-observation spectral data and satellite remote-sensing images.
Related Organisations
Agenzia Nazionale Di Valutazione Del Sistema Universitario E Della Ricerca
Location: Italy
Related Funding Activities
Linkage Projects - Grant ID: LP100100481
Start Date: 02-2011
End Date: 12-2015
Amount: $557,000.00
Funder: Australian Research Council
View Funded Activity