Disinfection byproducts (DBPs) discharged from wastewater treatment plants may impair aquatic ecosystems and downstream drinking-water quality. Sunlight photolysis, as one process by which DBPs may ...dissipate in the receiving surface water, was investigated. Outdoor natural sunlight experiments were conducted in water for a series of carbonaceous DBPs (trihalomethanes, haloacetic acids, halopropanones, and haloacetaldehydes) and nitrogenous DBPs (nitrosamines, halonitromethanes, and haloacetonitriles). Their pseudo-first-order rate constants for photolytic degradation were then used to calibrate quantitative structure–activity relationship (QSAR) parameters, which, in return, predicted the photolysis potentials of other DBPs or related compounds. Nitrogenous DBPs were found to be more susceptible to solar irradiation than carbonaceous DBPs, with general rankings for the functional groups as follows: N-nitroso (N-NO)
>
nitro (NO
2)
>
nitrile (C
N)
>
carbonyl (C
O)
>
carboxyl (COOH). Compounds containing a high degree of halogenation (e.g., three halogens) were usually less stable than less halogenated species (e.g., those with two halogens). Bromine- or iodine-substituted species were more photosensitive than chlorinated analogs. While most bromine- and chlorine-containing trihalomethanes and haloacetic acids persisted over the 6-h test, nearly complete removal (>99%) of nitrosamines occurred within 1 h of sunlight exposure. Indoor laboratory experiments using simulated sunlight demonstrated that the degradation of nitrosamines was ∼50% slower when organic matter was present, and ∼11% slower in non-filtered water than in filtered water.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The growing usage of nanomaterials is causing emerging concern regarding their environmental behavior in aquatic environments. A major need is the capability to detect and quantify nanomaterials in ...complex water matrices. Carbon60 fullerene is of special interest because of the widespread application of nanocarbon technology. The present study focuses on how to separate and concentrate fullerenes from water containing salts and organic matter and then quantify their concentrations using liquid chromatography coupled with mass spectrometry (LC/MS). The stable aqueous C60 aggregates (nC60) prepared in the present study were approximately 60 to 70 nm in diameter and had an ultraviolet (UV) extinction coefficient of 0.0263 L/mg-cm at 347 nm, which equated to a UV detection limit of 0.4 mg/L based upon an absorbance of 0.01 cm-1. Ultraviolet analysis is not applicable to use in waters containing salts or organics (e.g., tap water) because of their interferences and potential to aggregate nC60. The LS/MS analysis detected C60 as single fullerene rather than aggregates. Three techniques were developed to separate and concentrate nC60 from ultrapure and tap water into toluene to facilitate LC/MS determination: Evaporation of sample to dryness; extraction using 20% NaCl into toluene; and solid-phase extraction. The first two methods had limitations for use in complex water matrices, but aqueous nC60 concentration as low as 300 ng/L in water were quantified using solid-phase extraction (SPE) separation method. This is the first publication on the application of extraction methods for nC60 from ultrapure and tap waters and determination of detection limits by LC/MS.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
With the recent emergence of endocrine disrupting compounds, pharmaceuticals, and personal care products (EDC/PPCPs) as an important potable drinking water and reclaimed wastewater quality issue, our ...study has investigated the removal of EDC/PPCPs of 27 compounds by nanofiltration (NF) and ultrafiltration (UF) membranes from various drinking water sources using a dead-end stirred-cell filtration system. Experiments were performed at environmentally relevant initial EDC/PPCP concentrations ranging typically from 2 to <150 ng/L. EDC/PPCP retention was quantified by liquid chromatography with mass spectroscopy-mass spectroscopy. We have observed a general separation trend due to hydrophobic adsorption as a function of octanol–water partition coefficient between the hydrophobic compounds and porous hydrophobic membrane during the membrane filtration. The results have showed that both hydrophobic adsorption and size exclusion mechanisms are dominant to retain EDC/PPCP for the NF membrane, while the UF membrane retained typically hydrophobic EDC/PPCPs due mainly to hydrophobic adsorption.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Characteristics, including fluorescence intensity and specific UV absorbance (SUVA), of 16 organic matter (OM) fractions isolated from four OM samples plus a standard were analyzed and correlated ...with their specific disinfection by-product (DBP) and total organic halogen (TOX) formation after chloramination. These isolates were obtained from various water sources by using XAD-8/4 resins. Chloramination was achieved by adding 20
mg/L monochloramine to a solution containing one OM isolate at 5
mg/L DOC and buffered at pH 7.5 for 7 days. The fluorescence regional integration (FRI) method was used to analyze the fluorescence intensity data obtained from excitation–emission matrix (EEM) fluorescence spectroscopy, in which the EEM figure was divided into five regions and a normalized fluorescence volume was calculated. The cumulative normalized EEM volumes at regions II and IV (
Φ
II+IV,
n
) showed linear relationships with the yields of dichloroacetic acid (DCAA) (
R
2=0.60), chloroform (
R
2=0.42), dichloroacetonitrile (DCAN) (
R
2=0.53), and TOX (
R
2=0.63). The SUVA values were found to have linear relationships with the yields of DCAA (
R
2=0.82), chloroform (
R
2=0.73), DCAN (
R
2=0.88) and TOX (
R
2=0.80), but not with the yields of cyanogen chloride (CNCl) and chloropicrin (CP). A modified model is proposed to simplify the reactions involving chloramination of OM fractions. FTIR spectra of OM before and after chloramination partially confirmed that ketone groups were reactive with monochloramine.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Green manufacturing of catalysts enables sustainable advanced oxidation processes and water treatment processes for removing trace contaminants such as pesticides. An environmentally friendly ...biosynthesis process produced high-surface-area CuO and NiO nanocatalysts using phytochemicals in the Capparis decidua leaf extract, which served as a reductant and influenced catalyst shape. Capparis decidua is a bushy shrub, widely distributed in dry and arid regions of Africa, Pakistan, India, Egypt, Jordan, Sudan, Saudi Arabia. The synthesized CuO and NiO nanoparticles were characterized by UV-vis spectroscopy (UV-vis), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) and thermo-gravimetric analysis/differential thermal analysis (TGA/DTA). The produced nanoparticles were spherical and flower-like in shape and have a characteristic face-centered cubic structure of CuO and NiO. Biosynthesized catalysts were photoactive and degraded recalcitrant pesticide Lambda-cyhalothrin (L-CHT). Photocatalytic degradation of L-CHT was affected by the initial L-CHT concentration, solution pH levels between 5 and 9, and photocatalyst concentration. The L-CHT removal percentage attained by CuO photocatalyst (~99%) was higher than for NiO photocatalyst (~89%). The degradation of L-CHT follows a pseudo-first-order kinetic model, and the apparent rate constant (kapp) decreased from 0.033 min−1 for CuO to 0.0084 min−1 for NiO photocatalyst. The novel flower-shaped nanoparticles demonstrated high stability in water and recyclability for removing L-CHT pesticide contamination in water.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Membrane fouling is a major challenge in water and wastewater treatment. Recent observations that ozone mitigates membrane fouling during filtration of secondary effluent prompted this study into the ...impact of preozonation on membrane fouling caused by biogenic colloids. The focus of this study was on liposomes, synthetic vesicles composed of (phospho)lipid bilayers, which are representative of the diverse cellular vesicles present in all biologically impacted waters. The overarching hypothesis was that these biologically produced, nonrigid or “soft” colloids (e.g., vesicles) present in wastewater give rise to unique fouling behavior that can be mitigated by preozonation. Using dead-end ultrafiltration (UF) and batch ozonation tests, the key findings of this study were (1) liposomes fouled UF membranes faster (4–13 times membrane cake resistance (R C) per mgC filtered) than polysaccharides, fatty acids, and NOM on a DOC-normalized basis; (2) based on the estimated carbon distribution of secondary effluent, liposome-like biogenic nanomaterials could be responsible for 20–60% of fouling during UF; and (3) preozonation reduces liposomal fouling during UF, likely due to the disruption of the liposome structure through cleavage of the fatty acid tails at carbon–carbon double bonds.
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IJS, KILJ, NUK, PNG, UL, UM
Oxo-anions occur in drinking waters, pose potential health risks, and should be controlled. It may be possible to incorporate zero-valent iron (Fe0) into water treatment processes to remove ...oxo-anions. Under near neutral pH (∼7) and aerobic conditions, the three oxo-anions studied (NO3-, BrO3-, ClO3-) were electrochemically reduced by Fe0 in batch and continuous-flow packed column experiments. Mass balances provided strong evidence that ammonia is the primary reduction by-product from nitrate, chloride from chlorate, and bromide from bromate. Protons were consumed during the reaction, resulting in an increase in pH (i.e., production of hydroxide). Oxo-anion removal rates decreased as follows: BrO3->ClO3->NO3-. Differing rates of oxo-anion removal between batch and continuous flow column tests suggested that higher solid (Fe0) to liquid ratios increase oxo-anion electrochemical reduction, and scaling up of batch kinetic data to larger scale must consider the solid-liquid ratios. The atomic structure (atomic radii, electron orbital configuration, electron affinity) of nitrogen, chlorine, and bromine elements of the oxo-anions, and the bond dissociation energy between these elements and oxygen, were good indicators for the relative rates of reduction by Fe0.
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DOBA, FGGLJ, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We have built a highly sensitive surface plasmon resonance (SPR) sensor to detect arsenic (As) in groundwater. Using several thiol-containing organic compounds as sensor probes, we have been able to ...discriminate arsenic levels below and above the US EPA maximum containment level (0.010
mg/L
=10
ppb, according to 2006 regulation), in drinking water. The SPR sensor is simple comparing to conventional spectroscopic techniques currently employed for As detection, and can be potentially used for As level screening in groundwater.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The impact of treated wastewater discharges on downstream water quality was evaluated in an effluent-dominated stream in the Southwest USA. The fate and transport of effluent organic matter (EfOM) ...and disinfection by-product (DBP) precursors was studied. Nitrification and biodegradation were important mechanisms. Changes in DBP formation potential along the river appeared to correlate with dissolved organic carbon (DOC) and organic nitrogen concentrations and specific ultraviolet absorbance. The mean oxidation state of carbon (MOC) decreased in value along the river. MOC decreases paralleled decreases in the biodegradability of residual DOC (i.e., lower biodegradable DOC/DOC ratio). The EfOM was biodegradable by up to 40 percent, both in the stream and in a laboratory reactor, and many DBP precursors (e.g., haloacetonitriles, certain nitrosamines) decreased in concentration. Alternatively, the DBP yields for trihalomethanes or haloacetic acids either remained the same or increased slightly, suggesting that these precursors were part of the recalcitrant organic matter (OM).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
There is a need for new methodologies to quickly assess the presence and reactivity of nanoparticles (NPs) in commercial, environmental, and biological samples since current detection techniques ...require expensive and complex analytical instrumentation. Here, we investigate a simple and portable colorimetric detection assay that assesses the surface reactivity of NPs, which can be used to detect the presence of NPs, in complex matrices (e.g., environmental waters, serum, urine, and in dissolved organic matter) at as low as part per billion (ppb) or ng/mL concentration levels. Surface redox reactivity is a key emerging property related to potential toxicity of NPs with living cells, and is used in our assays as a key surrogate for the presence of NPs and a first tier analytical strategy toward assessing NP exposures. We detect a wide range of metal (e.g., Ag and Au) and oxide (e.g., CeO2, SiO2, VO2) NPs with a diameter range of 5 to 400 nm and multiple capping agents (tannic acid (TA), polyvinylpyrrolidone (PVP), branched polyethylenimine (BPEI), polyethylene glycol (PEG)). This method is sufficiently sensitive (ppb levels) to measure concentrations typically used in toxicological studies, and uses inexpensive, commercially available reagents.
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IJS, KILJ, NUK, PNG, UL, UM
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