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
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
Globally, there has been a decrease in dissolved oxygen in the oceans, that is more pronounced in coastal waters, resulting in more frequent hypoxia exposure for many marine animals. Managing hypoxia ...requires an understanding of the dynamics of dissolved oxygen (DO) where it occurs. The French coast facing the Bay of Biscay (N-E Atlantic Ocean) hosts at least a dozen tidal and turbid estuaries, but only the large estuaries of the Gironde and the Loire, are subject to a continuous monitoring. Here, we compared the DO dynamics in these two systems, in order to evaluate to what extent it is possible to predict the sensitivity to hypoxia of a tidal and turbid estuary based on its most common and easily accessible characteristics (the estuary surface area and length, liquid and solid discharge, suspended particulate load, water renewal time, presence of cities). Whereas the hyperturbid Gironde estuary is the longest (170 km), implying longer water and particle residence times, and is bordered by a large metropole (> 750 000 inhabitants), only episodic summer hypoxia events (DO < 2 mg L-1) were recorded in its urban Garonne subestuary. In contrast, the turbid Loire estuary, smaller in terms of surface area and length, experiences permanent summer hypoxia. This demonstrates the inability to evaluate the susceptibility of a tidal and turbid estuary to hypoxia only by considering its general characteristics. We urge that there is a need for a pertinent DO survey strategy based on an initial assessment of DO in a specific estuary based on longitudinal investigations, in particular during the warm season (as higher water temperatures decrease DO solubility), for detecting the potential zones of minimum DO.
•A detailed description of the LC/MS–MS analysis for the chlordecone in various matrices (surface water, wastewaters).•An extraction protocol for measuring the amount of chlordecone adsorbed onto ...activated sludge.•The kinetics and the equilibrium of biosorption of the chlordecone onto activated sludge.•Similar solid/liquid partition coefficient for the chlordecone sorbed onto activated sludge as values obtained in soils.
Chlordecone (also known as Kepone) was used extensively in the French West Indies until 1993. This persistent pollution raises the question of the faith of this pesticide through water treatment plants and its eventual release in the environment. To address this issue, a two-step methodology is herein proposed. First, a complete description of the analysis of CLD is given using liquid chromatography with mass spectrometry (LC/MS–MS). The reliability of this analytical methodology was demonstrated in ultrapure water as well as in the presence of organic and/or inorganic compounds (groundwater, river water and nutritive solutions). The limits of quantification were decreased to 1.5μgL−1. In a second part, the removal of CLD is considered via the sorption onto activated sludge. Kinetics and isotherms of sorption were determined. Very short times (less than 5min) were observed to reach the equilibrium. Moreover, a linear relationship was determined for the sorption equilibrium, which led to the conclusion that the solid/liquid partition coefficient was 7600Lkg−1, i.e. logKOC of 3.88, very close to the values encountered for the sorption of CLD in soils.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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