Résultat de la recherche
3 résultat(s) recherche sur le tag 'réduction' 
Affiner la recherche Générer le flux rss de la recherche
Partager le résultat de cette recherche Interroger des sources externesEtude de l’elimination des ions Cr(VI) par des procédés physico-chimiques application aux eaux de chromage / Imene Chaabna
Titre : Etude de l’elimination des ions Cr(VI) par des procédés physico-chimiques application aux eaux de chromage Type de document : texte imprimé Auteurs : Imene Chaabna, Auteur ; Chahrazed Boukhalfa- Djebbar, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 172 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : Cr(VI) traitement des eaux adsorption échange d’ions réduction charbon actif ferrihydrite composite (charbon actif/fer) Amberlite A21 Amberlite IRN78 eaux de chromage water treatment ion exchange reduction activated carbon composite (activated carbon/iron) chrome plating water "?????? ??????? ?????? ?????? ???????? ??????? ??????? ??????? ??? ???? ???? (???- ???? ) Index. décimale : 540 Chimie et sciences connexes Résumé : The present work focuses on the development of effective, practical and inexpensive physico-chemical processes for the decontamination of water containing Cr (VI) ions.
Adsorption removal was carried out using commercial activated charcoal, prepared ferrihydrite and composites (activated carbon/iron) prepared by precipitation of Fe (III) ions in the presence of coal at mass ratios (1/10) and 1/5). These adsorbents are characterized by DRX, ATR-FTIR, BET analysis, thermal analysis and by physicochemical analysis. The ion exchange removal is carried out using the Amberlite A21 resin (weak base type) and the Amberlite IRN78 resin (strong base type). The removal efficiency of Cr (VI) ions by precipitation after reduction is evaluated using ascorbic acid and sodium sulfite as reducing agents and soda and lime as precipitants.
In synthetic solutions, macroscopic experiments of Cr (VI) ions removal are carried out in the absence and in the presence of competitives ions in batch and in column (according the case). kinetics, equilibrium and thermodynamics studies are carried out.
The binding of Cr (VI) ions by adsorption is also studied through spectroscopic analysis. In chrome-plating waters, removal of Cr (VI) ions by these methods is evaluated as a function of pH The synthesized composites are characterized by the predominance of mesopores. Their specific surfaces are similar to that of ferrihydrite. Increasing the amount of iron involves increasing the content of basic functions and the formation of hematite.
The results of macroscopic experiments show that whatever the method used, the maximum elimination of Cr (VI) ions is recorded at acidic pH. The effectiveness of sodium sulfite in reducing Cr (VI) ions decreases rapidly with increasing pH. The increase in temperature implies an increase in the elimination in the case of the resins
and a decrease in the case of the adsorbents. The presence of competitive ions implies a decrease in the optimum pH range of the removal and a slowing down of adsorption and exchange processes. The removal efficiency of Cr (VI) ions by ferrihydrite, composites and resins is strongly influenced by the presence of sulfate ions.
The spectroscopic analysis (ATR-FTIR) suggest that the mechanism of Cr (VI) uptake by ferrihydrite and composites depends on pH and the presence of competitive ions. At pH <6, Cr (VI) ions form inner-sphere surface complexes. Whatever the pH, the interaction of the Cr (VI) ions is essentially electrostatic in the presence of the
competitive ions.
In chrome-plating waters, the efficiencies of Cr (VI) removal by the used solids at pH: 3 follow the order: IRN78> CAC> CACFe (1/5)> Ferrihydrite.
Diplôme : Doctorat En ligne : ../theses/chimie/CHA7019.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10421 Etude de l’elimination des ions Cr(VI) par des procédés physico-chimiques application aux eaux de chromage [texte imprimé] / Imene Chaabna, Auteur ; Chahrazed Boukhalfa- Djebbar, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 172 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : Cr(VI) traitement des eaux adsorption échange d’ions réduction charbon actif ferrihydrite composite (charbon actif/fer) Amberlite A21 Amberlite IRN78 eaux de chromage water treatment ion exchange reduction activated carbon composite (activated carbon/iron) chrome plating water "?????? ??????? ?????? ?????? ???????? ??????? ??????? ??????? ??? ???? ???? (???- ???? ) Index. décimale : 540 Chimie et sciences connexes Résumé : The present work focuses on the development of effective, practical and inexpensive physico-chemical processes for the decontamination of water containing Cr (VI) ions.
Adsorption removal was carried out using commercial activated charcoal, prepared ferrihydrite and composites (activated carbon/iron) prepared by precipitation of Fe (III) ions in the presence of coal at mass ratios (1/10) and 1/5). These adsorbents are characterized by DRX, ATR-FTIR, BET analysis, thermal analysis and by physicochemical analysis. The ion exchange removal is carried out using the Amberlite A21 resin (weak base type) and the Amberlite IRN78 resin (strong base type). The removal efficiency of Cr (VI) ions by precipitation after reduction is evaluated using ascorbic acid and sodium sulfite as reducing agents and soda and lime as precipitants.
In synthetic solutions, macroscopic experiments of Cr (VI) ions removal are carried out in the absence and in the presence of competitives ions in batch and in column (according the case). kinetics, equilibrium and thermodynamics studies are carried out.
The binding of Cr (VI) ions by adsorption is also studied through spectroscopic analysis. In chrome-plating waters, removal of Cr (VI) ions by these methods is evaluated as a function of pH The synthesized composites are characterized by the predominance of mesopores. Their specific surfaces are similar to that of ferrihydrite. Increasing the amount of iron involves increasing the content of basic functions and the formation of hematite.
The results of macroscopic experiments show that whatever the method used, the maximum elimination of Cr (VI) ions is recorded at acidic pH. The effectiveness of sodium sulfite in reducing Cr (VI) ions decreases rapidly with increasing pH. The increase in temperature implies an increase in the elimination in the case of the resins
and a decrease in the case of the adsorbents. The presence of competitive ions implies a decrease in the optimum pH range of the removal and a slowing down of adsorption and exchange processes. The removal efficiency of Cr (VI) ions by ferrihydrite, composites and resins is strongly influenced by the presence of sulfate ions.
The spectroscopic analysis (ATR-FTIR) suggest that the mechanism of Cr (VI) uptake by ferrihydrite and composites depends on pH and the presence of competitive ions. At pH <6, Cr (VI) ions form inner-sphere surface complexes. Whatever the pH, the interaction of the Cr (VI) ions is essentially electrostatic in the presence of the
competitive ions.
In chrome-plating waters, the efficiencies of Cr (VI) removal by the used solids at pH: 3 follow the order: IRN78> CAC> CACFe (1/5)> Ferrihydrite.
Diplôme : Doctorat En ligne : ../theses/chimie/CHA7019.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10421 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Isolation of Shewanella sp. from Algeria and characterization of a system involved in detoxification of chromate Type de document : texte imprimé Auteurs : Hiba Baaziz, Auteur ; Radia Alatou, Directeur de thèse ; Michel Fons, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2018 Importance : 144 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Anglais (eng) Tags : Shewanella sp. chromate resistance reduction bioremediation Index. décimale : 570 Sciences de la vie. Biologie Résumé : The widespread use of the toxic heavy metal chromium (Cr) in industrial applications resulted in large quantities of Cr being discharged into the environment, causing severe contamination of global soil and water systems. Cr primarily exists in two stable forms, Cr(III) and Cr(VI). The latter is highly toxic due to its strong oxidizing nature and its high solubility. The model organism for bioremediation Shewanella oneidensis MR1 has evolved diverse resistance mechanisms to cope with chromate toxicity. The first aim of the present thesis was to study the chromate resistance and reduction mechanisms of this bacterium under semi-aerobic conditions. We showed that chrASO gene is induced by chromate and its deletion impairs the chromate resistance and reduction capacity of MR-1 strain, we confirmed that its product functions as an efflux pump to extrude chromate ions from the cytoplasm protecting cells from chromate toxicity. With cymAdeletion mutants, we revealed the involvement of the c-type cytochrome CymA in chromate resistance and reduction. We also identified a potential chromate reductase DmsA2, as well as two other proteins Fdh and DmsA1 that are potentially involved in chromate resistance and reduction in MR-1 strain. In the second part of this work, we isolated, identified and characterized two novel Mediterranean Shewanella sp. strains, S. fidelis H76 and S. algidipiscicola H111. Both strains are characterized by their great chromate resistance and their ability to reduce it efficiently even at high concentrations. Although the small size of its genome and the absence of several genes encoding enzymes known to play a role in chromate resistance and reduction, the H111 strain is the best chromate resistant strain. Interestingly, the air liquid interface biofilm (Pellicles) of both strains reduce more efficiently chromate than their freeswimming cells. Moreover, they can accumulate a significant amount of its reduced forms. These characteristics make those strains, in particular H111 strain, suitable candidates for chromate bioremediation.
Diplôme : Doctorat En ligne : ../theses/biologie/BAA7327.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10977 Isolation of Shewanella sp. from Algeria and characterization of a system involved in detoxification of chromate [texte imprimé] / Hiba Baaziz, Auteur ; Radia Alatou, Directeur de thèse ; Michel Fons, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2018 . - 144 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Anglais (eng)
Tags : Shewanella sp. chromate resistance reduction bioremediation Index. décimale : 570 Sciences de la vie. Biologie Résumé : The widespread use of the toxic heavy metal chromium (Cr) in industrial applications resulted in large quantities of Cr being discharged into the environment, causing severe contamination of global soil and water systems. Cr primarily exists in two stable forms, Cr(III) and Cr(VI). The latter is highly toxic due to its strong oxidizing nature and its high solubility. The model organism for bioremediation Shewanella oneidensis MR1 has evolved diverse resistance mechanisms to cope with chromate toxicity. The first aim of the present thesis was to study the chromate resistance and reduction mechanisms of this bacterium under semi-aerobic conditions. We showed that chrASO gene is induced by chromate and its deletion impairs the chromate resistance and reduction capacity of MR-1 strain, we confirmed that its product functions as an efflux pump to extrude chromate ions from the cytoplasm protecting cells from chromate toxicity. With cymAdeletion mutants, we revealed the involvement of the c-type cytochrome CymA in chromate resistance and reduction. We also identified a potential chromate reductase DmsA2, as well as two other proteins Fdh and DmsA1 that are potentially involved in chromate resistance and reduction in MR-1 strain. In the second part of this work, we isolated, identified and characterized two novel Mediterranean Shewanella sp. strains, S. fidelis H76 and S. algidipiscicola H111. Both strains are characterized by their great chromate resistance and their ability to reduce it efficiently even at high concentrations. Although the small size of its genome and the absence of several genes encoding enzymes known to play a role in chromate resistance and reduction, the H111 strain is the best chromate resistant strain. Interestingly, the air liquid interface biofilm (Pellicles) of both strains reduce more efficiently chromate than their freeswimming cells. Moreover, they can accumulate a significant amount of its reduced forms. These characteristics make those strains, in particular H111 strain, suitable candidates for chromate bioremediation.
Diplôme : Doctorat En ligne : ../theses/biologie/BAA7327.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10977 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
Titre : Préparation des aminés par électroréduction des aldhydes et cétones Type de document : texte imprimé Auteurs : Thauraya Hammoud (Née Benmechri) ; Université Mentouri, Editeur scientifique ; Aissa Chibani, Directeur de thèse Année de publication : 2008 Importance : 90 f. Note générale : 01 Disponible à la salle de recherche 02 Disponibles au magazin de la B.U.C. 01 CD Langues : Français (fre) Tags : Polarographie Base de Schiff Electrolyse à potentiel contr?lé Amines primaires aromatiques Réduction Index. décimale : 540 Chimie et sciences connexes En ligne : ../theses/chimie/HAM5259.pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=3683 Préparation des aminés par électroréduction des aldhydes et cétones [texte imprimé] / Thauraya Hammoud (Née Benmechri) ; Université Mentouri, Editeur scientifique ; Aissa Chibani, Directeur de thèse . - 2008 . - 90 f.
01 Disponible à la salle de recherche 02 Disponibles au magazin de la B.U.C. 01 CD
Langues : Français (fre)
Tags : Polarographie Base de Schiff Electrolyse à potentiel contr?lé Amines primaires aromatiques Réduction Index. décimale : 540 Chimie et sciences connexes En ligne : ../theses/chimie/HAM5259.pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=3683 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire
