Activated carbon fiber cloths (ACFC) have shown promising results when applied to water treatment, especially for removing organic micropollutants such as pharmaceutical compounds. Nevertheless, ...further investigations are required, especially considering trace concentrations, which are found in current water treatment. Until now, most studies have been carried out at relatively high concentrations (mg L−1), since the experimental and analytical methodologies are more difficult and more expensive when dealing with lower concentrations (ng L−1). Therefore, the objective of this study was to validate an extrapolation procedure from high to low concentrations, for four compounds (Carbamazepine, Diclofenac, Caffeine and Acetaminophen). For this purpose, the reliability of the usual adsorption isotherm models, when extrapolated from high (mg L−1) to low concentrations (ng L−1), was assessed as well as the influence of numerous error functions. Some isotherm models (Freundlich, Toth) and error functions (RSS, ARE) show weaknesses to be used as an adsorption isotherms at low concentrations. However, from these results, the pairing of the Langmuir-Freundlich isotherm model with Marquardt's percent standard of deviation was evidenced as the best combination model, enabling the extrapolation of adsorption capacities by orders of magnitude.
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•Adsorption of pharmaceuticals onto ACFC was studied at trace concentration.•Both adsorption models and error functions were studied.•Adsorption capacities were extrapolated at trace concentrations using models.•The Langmuir-Freundlich model adjusted with a MPSD error was is the best choice.•The external mass transfer occurred outside the yarn of the ACFC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Knowing the concentration of hydrogen peroxide (H2O2) is crucial for the monitoring and optimizing the Fenton reaction in advanced oxidation processes. Several analytical methods exist to determine ...these concentrations, but their applications can be difficult because of low selectivity (interaction with other metals), the use of toxic compounds, or low concentrations (μmol LmmolL-1). To overcome these problems, we developed a differential pulse polarographic (DPP) method at the dropping mercury electrode (DME) with the following conditions: tg=1.0s, ΔE=−100mV and v=10mVs−1. Calibration curves had very high correlation coefficients (R2>0.999). The limits of detection and quantification were evaluated respectively at 13 and 21μmolL−1 with peak area measurements of hydrogen peroxide reduction (Ap). The DPP method was compared with other analytical methods (iodometric titration and spectrophotometry) for determining at low concentrations of H2O2 (in the order of mmolL−1 to μmol L−1) in Fenton and electro-Fenton processes. The method developed here allows measure low concentrations of hydrogen peroxide in Fenton and electro-Fenton processes in acidic solutions (∼3) and the presence of interfering species such as Fe3+ and dissolved oxygen.
•Quantification of residual H2O2 in Fenton and electro-Fenton processes•Calibration range of H2O2 between 0.02 and 1.00 mmol L−1•Limit of detection and quantification respectively 13 and 21μmolL−1•No interference from Fe3+ or dissolved O2•Overestimate of the measurement by the presence of Zn2+ in solution
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Disinfection by-products (DBPs) are formed in swimming pools by the reactions of bather inputs with the disinfectant. Although a wide range of molecules has been identified within DBPs, only few ...kinetic rates have been reported. This study investigates the kinetics of chlorine consumption, chloroform formation and dichloroacetonitrile formation caused by human releases. Since the flux and main components of human inputs have been determined and formalized through Body Fluid Analogs (BFAs), it is possible to model the DBPs formation kinetics by studying a limited number of precursor molecules. For each parameter the individual contributions of BFA components have been quantified and kinetic rates have been determined, based on reaction mechanisms proposed in the literature. With a molar consumption of 4 mol Cl2/mol, urea is confirmed as the major chlorine consumer in the BFA because of its high concentration in human releases. The higher reactivity of ammonia is however highlighted. Citric acid is responsible for most of the chloroform produced during BFA chlorination. Chloroform formation is relatively slow with a limiting rate constant determined at 5.50 × 10−3 L/mol/sec. L-histidine is the only precursor for dichloroacetonitrile in the BFA. This DBP is rapidly formed and its degradation by hydrolysis and by reaction with hypochlorite shortens its lifetime in the basin. Reaction rates of dichloroacetonitrile formation by L-histidine chlorination have been established based on the latest chlorination mechanisms proposed. Moreover, this study shows that the reactivity toward chlorine differs whether L-histidine is isolated or mixed with BFA components.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Rationale
Chlorine reacts in swimming pools with several compounds released by bathers to form disinfection by‐products (DBPs). Epidemiological studies have shown adverse effects on health associated ...with the exposure to DBPs present in indoor swimming pool atmosphere. DBPs analyses require the use of multiple techniques depending on the targeted molecules. The measurement process itself is challenging due to the low stability of several compounds and the lack of specificity of certain methods. The Membrane Introduction Mass Spectrometry (MIMS) technique provides a solution to these problems by specific and sensitive in situ measurement of DBPs. This study investigates the effect of analytical conditions on quantification of DBPs and assesses the relevance of using MIMS for reliable analysis under typical swimming pool operating conditions.
Methods
MIMS is based on the simultaneous permeation of the selected compounds from the air or water samples through a polydimethylsiloxane (PDMS) membrane. DBPs are identified and quantified with a quadrupole analyzer after electron ionization. Limits of quantification (LOQs) of five DBPs are determined to assess the sensitivity of the system. Moreover, signal changes are monitored while varying physicochemical parameters such as temperature, pH and ionic strength.
Results
The mass spectra obtained for individual molecules show that the simultaneous measurement of trihalomethanes (THMs) and chloramines requires the monitoring of several ions and mathematical corrections of the signal. The pH and ionic strength of the solution do not significantly influence the determination of THMs. On the contrary, the temperature and hydraulics at the membrane interface must be controlled for accurate determination of DBPs.
Conclusions
Results confirm that MIMS is a promising technology for the simultaneous quantification of volatile DBPs in both water and air of swimming pools. However, operating conditions such as membrane temperature should be treated with great care in order to avoid interferences.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The presence of pesticides (alachlor, metolachlor and atrazine) is a major concern for the production of drinking water. However, their main metabolites, namely oxanilic acid (OA) and ethanesulfonic ...acid (ESA) for alachlor and metolachlor, and desethyl- and deisopropyl-atrazine for atrazine, are also encountered in natural waters. The adsorption of these micropollutants onto two types of granular activated carbons under dynamic (fixed bed) conditions was studied. The performance of the adsorbers was evaluated under operating conditions comparable to those found for the production of drinkable water, i.e. inlet concentrations of 1.0 μg L−1 for each pesticide and metabolite added to groundwater containing 1.5 mCL−1 of natural organic matter. Regardless of the location in the column or the duration of the treatment, humic acids were preferentially removed compared to fulvic acids. As for micropollutants, a pseudo-steady state was reached after filtration of approximately 2.0 m3 of water (6000 equivalent bed volumes). The retention of micropollutants onto granular activated carbons is driven by their adsorption kinetics. Moreover, in the case of alachlor and metolachlor, but not atrazine, different adsorption profiles were observed between the parent pesticide and its metabolites. Desethyl- and deisopropyl-atrazine, were adsorbed quickly; the mass transfer zone was narrow (approximately 60 cm) with a superficial velocity of the liquid phase equal to 10 m h−1. By contrast, the OA and ESA metabolites reached breakthrough when the mass transfer zones were larger than the height of the columns. The Amundson model was used to determine the adsorption rate and adsorption capacity each pollutant.
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•Fate of the transformation by-products of pesticides in adsorbers.•Leakage of the ESA and OA metabolites of metolachlor and alachlor.•A pseudo-steady state reached after 6000 bed volumes.•Natural organic matters partially removed regardless of their nature.•Predominant impact of the kinetics of adsorption and of mass transfer limitations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The presence of pharmaceutical residues in water resources is a critical issue for the production of drinking water, even though trace concentrations are mostly encountered. The adsorption of eight ...micropollutants, in mixture, onto a microporous activated carbon fibre cloth was investigated. For each compound, the kinetics and isotherms of adsorption were studied in batch reactors with ultrapure water, groundwater and half-diluted groundwater. Experimental data were generated and compared to values calculated by the association of Ideal Adsorbed Solution Theory (IAST) model and the Homogeneous Surface Diffusion Model (HSDM). The impact of the nature and the content of Natural Organic Matter (NOM) was modelled considering an Equivalent Background Compound (EBC). The presence of NOM in the groundwater is largely detrimental for the adsorption of trace micropollutants.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
This study assessed the environmental footprint of emerging micropollutants in Cambodia and France. The aim was to develop and apply an analytical method to detect micropollutants in diverse water ...sources and climatic regions. Consequently, an analytical method, using online solid-phase extraction coupled with an ultra-performance liquid chromatography-tandem mass spectrometer (online-SPE-UPLC-MS/MS), was successfully developed and validated. This method permits the accurate and rapid multi-residual determination of 15 emerging micropollutants in water at low detection and quantification limits, around 10 ng.L−1 and 30 ng.L−1, respectively, within a total analytical run of seven minutes, including the equilibrium step. The findings revealed that no water body was free of micropollutants in any case of its sources (effluent wastewater, surface water, and even tap water). In surface water, 13 and 11 of the 15 target micropollutants were detected at least once in the Couesnon River (France) and Upper Mekong River (Cambodia), respectively. The concentration of micropollutant detected in Couesnon River ranged from 6–975.5 ng.L−1, with tramadol having the highest concentration. In the Upper Mekong River, the concentration detected ranged from 5–240 ng.L−1, with ketoprofen having the highest concentration. Caffeine was found in the highest concentration in the treated effluent of a Cambodian wastewater treatment plant (WWTP).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of the present study was to provide an integrated view of algal removal of diclofenac (DCF). Two isolated microalgal strains Picocystis sp. and Graesiella sp. were cultivated under different ...DCF concentrations and their growth, photosynthetic activity and diclofenac removal efficiency were monitored.
Results showed that DCF had slight inhibitory effects on the microalgal growth which did not exceed 21% for Picocystis and 36% for Graesiella after 5 days. Both species showed different patterns in terms of removal efficiency. In presence of Picocystis sp., the amounts of removed DCF were up to 73%, 43% and 25% of 25, 50 and 100 mg L−1 respectively; whereas only 52%, 28% and 24% were removed in the presence of Graesiella at same DCF tested concentrations. DCF removal was insured mainly by biodegradation. To better reveal the mechanism involved, metabolites analyses were performed. Two DCF biodegradation/biotransformation products were detected in presence of Picocystis.
This study indicated that Picocystis performed a satisfactory growth capacity and DCF removal efficiency and thus could be used for treatment of DCF contaminated aqueous systems.
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•The inhibitory growth effect of Diclofenac on Picocystis and Graesiella did not exceed 40% even at 200 mg L−1 DCF exposure.•Picocystis and Graesiella removed 73 and 52%, respectively, of 25 mg L−1 initial DCF concentration.•DCF biodegradation by Picocystis and Graesiella reached 69 and 44%, respectively, of 25 mg L−1 initial DCF concentration.•In Picocystis cultures two diclofenac metabolites are identified: hydroxy diclofenac and a mono-aromatic derivative.•The studied species, mainly Picocystis, are a good prospect for bioremediation of diclofenac-contaminated waters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A scale-up procedure was assessed in this study to predict the fixed bed adsorption behaviors with aging granular activated carbon (GAC) for various micropollutants (pesticides, pharmaceuticals). Two ...assumptions of this upscaling methodology (i.e., involving equal adsorption capacities and surface diffusivities between the batch test and the fixed bed) were studied for the first time to investigate the aging effect on the adsorption capacity and kinetics of carbon at full scale. This study was conducted in natural waters (the Seine River) treated by Veolia Eau d’Ile de France in Choisy-Le-Roi, a division of Syndicat des Eaux d’Ile de France, aiming to monitor real industrial conditions. The isotherms showed that the adsorption capacity for most compounds was significantly affected by aging. For the mass transfer coefficients (i.e., as determined by the homogeneous surface diffusion model (HSDM)), different patterns of adsorbate/adsorbent behaviors were observed, suggesting different competition mechanisms. The model predictions (i.e., HSDM) performed with all parameters obtained during the batch tests tended to overestimate the full-scale pilot adsorption performance. This overestimation could be compensated for by applying a scaling factor. Finally, an empirical pseudo-first order function was used to model the impact of the GAC service time on the characteristic adsorption parameters. Thus, our scale-up procedure may enable the prediction of long-term fixed bed adsorption behaviors and increase the model efficiency for practical implementation.
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•Adsorption capacities of the GAC reduced seriously after the 6 months of use.•Ds reached maximum after several months of use followed by a decrease.•An SF was required to predict the adsorption behaviors of the fixed bed.•A new pseudo-first order function was employed to model the impact of GAC aging on the adsorption parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The addition of powdered activated carbon (PAC) and a coagulant during the coagulation-flocculation process is an easy and common option for tackling pollution peaks from organic micropollutants ...(OMPs) in the production of drinking water. However, the adsorption-desorption mechanisms during this process have not been thoroughly explored. Thus, this research aims to study the mechanisms involved and the impact of the operating conditions when PAC and coagulant are simultaneous used. A commercial PAC with a BET-specific surface area of 961 m2/g, and ferric chloride (FeCl3) were added simultaneously to three different waters spiked with 15 OMPs (pesticides and pharmaceuticals). Different parameters such as PAC and coagulant dosage, pH, contact time and the nature/content of the natural organic matter (NOM) were examined. Results showed that using coagulant + PAC reduced OMP adsorption efficiency, whereas increasing PAC dosage and extending contact time enhanced OMP removal efficiency. Furthermore, a high concentration of NOM affected micropollutant adsorption by competing for adsorption sites. This study highlights for the first time an unexpected phenomenon that significantly affects overall efficiency: i.e. OMPs adsorbed during the slow mixing step that desorbed during the sedimentation step. Desorption sometimes reduced by >30 % the overall efficiency of OMP removal. The parameters that affected efficiency loss were pH, contact time, NOM concentration, and PAC and FeCl3 dosage. Some operational adaptations could be considered regarding these parameters to avoid or reduce desorption, making the process more cost-effective.
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•Adding PAC during coagulation improves micropollutant and NOM removal efficiency.•After adsorption during slow mixing, re-adsorption of micropollutants may occur during sedimentation.•Extended slow mixing time could prevent micropollutant desorption during an ongoing process.•The combination of NOM, FeCl3 and PAC leads to efficiency loss during sedimentation.•Contact time and PAC dosage have significant effects on removal performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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