International audienc
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The relationships between polymer structure and water diffusivity have been investigated in four structural series: amine-epoxyde networks (A), aromatic polysulfones (B), styrene crosslinked polyesters or vinylesters (C) and polyethylenes... more
The relationships between polymer structure and water diffusivity have been investigated in four structural series: amine-epoxyde networks (A), aromatic polysulfones (B), styrene crosslinked polyesters or vinylesters (C) and polyethylenes containing polar groups (D). In each family, it appears water diffusivity is almost inversely proportional to equilibrium water concentration. This result indicates that water diffusion is considerably slowed down by its interactions with polar sites in the polymer.
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Abstract During disinfections, water ultrafiltration membranes are mechanically and chemically stressed. A previous study demonstrated (S. Rouaix, Characterisation and study of ageing of an ultrafiltration membrane, PhD thesis, Universite... more
Abstract During disinfections, water ultrafiltration membranes are mechanically and chemically stressed. A previous study demonstrated (S. Rouaix, Characterisation and study of ageing of an ultrafiltration membrane, PhD thesis, Universite Paul Sabatier, Toulouse, France, 2005) a drop of membranes mechanical properties in contact with bleach accompanied by a degradation of transport properties. It clearly appears fiber embrittlement is a determining criterium, specially for water treaters. It seems thus essential to study long term behavior of polysulfone membranes in focussing on chemical structure–mechanical properties relationships. In this article, polysulfone membranes were immersed in bleach solutions with various pH values. Their structural changes were monitored by mechanical testing, molar mass determination and spectrochemical measurements. The observed degradation, which generates an embrittlement of the fiber, occurs by chain scission (determined by Size Exclusion Chromatography) with the hydroxyl radical OH formed in the bleach solution. The lifetime of the fiber depends on the total chlorine concentration of the ageing solution but also on its pH which drives the formation of hypochlorous acid and hypochlorite ion in great proportion, essential condition for the formation of hydroxyl radicals.
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ABSTRACT In France, hot water quality control inside buildings is occasionally assured by disinfection treatments using sodium hypochlorite (between 0.5 and 1 ppm residual free chlorine). This disinfectant is a strong oxidizer and it... more
ABSTRACT In France, hot water quality control inside buildings is occasionally assured by disinfection treatments using sodium hypochlorite (between 0.5 and 1 ppm residual free chlorine). This disinfectant is a strong oxidizer and it could interact with metallic and polymer pipes used in hot water systems. To assess the long-term performance of these pipes, it is then necessary to study the impact of these treatments on the material behaviour, in particular for polymeric materials, even at relatively low disinfectant concentrations as used in potable water treatments. The objective of this work was to study the influence of sodium hypochlorite concentration on PERT/Al/PERT (PolyEthylene Raised Temperature) pipe degradation. Pipe samples were filled with chlorinated water solutions (concentrations ranging between 0 and 100 ppm) and maintained in static conditions during 270 days at 70 °C. The antioxidant depletion profile through a PERT wall was monitored using the oxidation induction time (OIT) method, which is a conventional technique of Differential Scanning Calorimetry. Chemical changes on the aged polymer were checked by Infrared Spectrometry. OIT change showed that the PERT stabilizing system was rapidly chemically consumed by the action of chlorinated water at 25 and 100 ppm concentrations. However, PERT degradation was strictly confined to the immediate inner wall. Only a 0.3 mm thick layer (inner part of the pipe) showed significant antioxidant depletion. An increase of the OH and C–O–C infrared bands was also observed on inner part of any samples during ageing which characterize the oxidation of the PERT on the inner wall.
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During disinfections, water ultrafiltration membranes are mechanically and chemically stressed. A previous study demonstrated (S. Rouaix, Characterisation and study of ageing of an ultrafiltration membrane, PhD thesis, Université Paul... more
During disinfections, water ultrafiltration membranes are mechanically and chemically stressed. A previous study demonstrated (S. Rouaix, Characterisation and study of ageing of an ultrafiltration membrane, PhD thesis, Université Paul Sabatier, Toulouse, France, 2005) a drop of membranes mechanical properties in contact with bleach accompanied by a degradation of transport properties. It clearly appears fiber embrittlement is a determining criterium, specially
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Afin de proposer une solution alternative aux branchements PEHD pour les reseaux exploites au dioxyde de chlore, Aliaxis R&D, Arkema et Veolia ont developpe un tube multicouche PEHD/PVDF. La durabilite de ce branchement a ete etudiee... more
Afin de proposer une solution alternative aux branchements PEHD pour les reseaux exploites au dioxyde de chlore, Aliaxis R&D, Arkema et Veolia ont developpe un tube multicouche PEHD/PVDF. La durabilite de ce branchement a ete etudiee de maniere exhaustive grâce a la mutualisation des moyens d’essai et de caracterisation des partenaires. Les resultats valident que la couche de PVDF protege efficacement le PEHD en maintenant l’integrite mecanique du tube en conditions de vieillissement accelerees. Ces elements suggerent donc que la duree de vie de ce tube multicouche serait significativement superieure a celle des tubes PEHD classiques.
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In water treatment by microfiltration and ultrafiltration, a major concern is the integrity loss or failure of membrane induced by onsite operations, potentially leading to permeate water contamination. This study aims to provide a better... more
In water treatment by microfiltration and ultrafiltration, a major concern is the integrity loss or failure of membrane induced by onsite operations, potentially leading to permeate water contamination. This study aims to provide a better understanding of the phenomena responsible for membrane damage by analyzing its causes and effects. The role of sodium hypochlorite exposure conditions and the impact of mechanical stress on membrane characteristics were investigated. Monitoring of hydraulic response, mechanical properties and the evolution of the chemical structure showed, on multiple scales, strong indications of membrane chemical degradation, involving radical mechanisms, accelerated by tensile stress application.
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Dans un souci d’ameliorer la qualite de ses services, Veolia Eau souhaite valider une methode de qualification des revetements protecteurs pour la rehabilitation des reseaux d’eau potable. Dans cette perspective, les etapes majeures de la... more
Dans un souci d’ameliorer la qualite de ses services, Veolia Eau souhaite valider une methode de qualification des revetements protecteurs pour la rehabilitation des reseaux d’eau potable. Dans cette perspective, les etapes majeures de la validation d’un revetement protecteur sont l’evaluation : des performances techniques sur site (enduction), de la fonctionnalite (effet barriere a la corrosion) et de l’impact du revetement apres enduction sur la qualite d’eau delivree. Grâce a trois chantiers (prototype et pilote), VERI et Setha ont montre que la qualite d’enduction (integrite du revetement final) et la qualite physico-chimique et microbiologique de l’eau apres enduction sont des criteres determinants pour valider tout nouveau revetement destine a proteger la canalisation. Les donnees de terrain associees aux analyses de laboratoire permettront au groupe de valider techniquement tout nouveau revetement pour la rehabilitation des conduites d’eau potable.
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... Auteur de correspondance : emmanuelle.gaudichet@veolia ... de branchements polyéthylène vieillis prélevés sur site et sur pilote mettent en évidence les éléments suivants : L'identification de sous-produits d'oxydation... more
... Auteur de correspondance : emmanuelle.gaudichet@veolia ... de branchements polyéthylène vieillis prélevés sur site et sur pilote mettent en évidence les éléments suivants : L'identification de sous-produits d'oxydation iden-tiques (Rozental-Evesque et al., 2006; Fayolle et al ...
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During disinfections, water ultrafiltration membranes are mechanically and chemically stressed. These stresses lead to an early membrane ageing implying a drop of the quality of ultrafiltrated water. The aim of this study is to examine... more
During disinfections, water ultrafiltration membranes are mechanically and chemically stressed. These stresses lead to an early membrane ageing implying a drop of the quality of ultrafiltrated water. The aim of this study is to examine the long term behaviour of an ultrafiltration polysulfone hollow fibre in contact with bleach. After the initial characterisation of the fibre and its main component (polysulfone), we broached watermembrane physical interaction. The sorption behaviour of this asymmetric membrane could be interpreted within a dual mechanism constituted of two simultaneous phenomena: pore filling and water absorptiondiffusion in the pore walls. As chemical ageing could induce large modifications on membranes interaction and transport properties, we studied these phenomena via structure-properties relationships. The bleach-membrane chemical interaction shows a degradation of the polysulfone, in spite its well-known chemical stability. The degradation, which generates an ...
... oai:hal-ensmp.archives-ouvertes.fr:hal-00659435. Contributeur : Odile Adam <>. Soumis le :Jeudi 12 Janvier 2012, 17:26:46. Dernière modification le : Jeudi 12 Janvier 2012, 17:26:46. tous les articles de la base du CCSd... tous... more
... oai:hal-ensmp.archives-ouvertes.fr:hal-00659435. Contributeur : Odile Adam <>. Soumis le :Jeudi 12 Janvier 2012, 17:26:46. Dernière modification le : Jeudi 12 Janvier 2012, 17:26:46. tous les articles de la base du CCSd... tous les articles de la base du CCSd... ...
... oai:hal-ensmp.archives-ouvertes.fr:hal-00659435. Contributeur : Odile Adam <>. Soumis le :Jeudi 12 Janvier 2012, 17:26:46. Dernière modification le : Jeudi 12 Janvier 2012, 17:26:46. tous les articles de la base du CCSd... tous... more
... oai:hal-ensmp.archives-ouvertes.fr:hal-00659435. Contributeur : Odile Adam <>. Soumis le :Jeudi 12 Janvier 2012, 17:26:46. Dernière modification le : Jeudi 12 Janvier 2012, 17:26:46. tous les articles de la base du CCSd... tous les articles de la base du CCSd... ...