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Reaction mechanism of hexavalent chromium with cellulose / Shan-Li Wang in Chemical engineering journal, Vol. 174 N° 1 (Octobre 2011) 

Public ISBD [article]  in Chemical engineering journal > Vol. 174 N° 1 (Octobre 2011) . - pp.289–295 Titre : Reaction mechanism of hexavalent chromium with cellulose Type de document : texte imprimé Auteurs : Shan-Li Wang, Auteur ; Jyh-Fu Lee, Auteur Année de publication : 2012 Article en page(s) : pp.289–295 Note générale : Génie chimique Langues : Anglais (eng) Mots-clés : Cellulose  Hexavalent  chromium  Reaction  mechanism  Water  treatment Résumé : It has been suggested that lignocellulosic materials are cost-effective materials for remediation of toxic Cr(VI) pollution; however, inconsistent interpretations of the reaction mechanism are frequently found in the literature. To clarify the reaction mechanism, the reaction of Cr(VI) with individual components of lignocellulosic materials must be better understood. Thus, the purpose of this work was to investigate the reaction mechanism of Cr(VI) with cellulose, which is one of the main components of lignocellulosic materials. The Cr(VI) reaction was evaluated at pH 2 and the results showed that Cr(VI) could be reduced to Cr(III) by cellulose. As indicated by the FT-IR spectra, the hydroxyl groups in cellulose were the reactive sites for Cr(VI) reduction, giving rise to the formation of carboxyl groups. The resultant Cr(III) was either bound to cellulose or released into solution. As revealed by the Cr K-edge EXAFS of cellulose after its reaction with Cr(VI), Cr(III) was bound to cellulose by forming bidentate–mononuclear complexes with carboxyl groups, which resulted from the oxidation of hydroxyl groups. The first-order rate constant of Cr(VI) reaction with cellulose was determined to be 3.84 × 10−7 s−1 at pH 2. The slow reduction of Cr(VI) by cellulose was attributed to the existence of H-bonding networks in cellulose, which restrict the accessibility of Cr(VI) to the hydroxyl groups in cellulose. ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science/article/pii/S1385894711010898 [article] Reaction mechanism of hexavalent chromium with cellulose [texte imprimé] / Shan-Li Wang, Auteur ; Jyh-Fu Lee, Auteur . - 2012 . - pp.289–295. Génie chimique Langues : Anglais (eng) in Chemical engineering journal > Vol. 174 N° 1 (Octobre 2011) . - pp.289–295 Mots-clés : Cellulose  Hexavalent  chromium  Reaction  mechanism  Water  treatment Résumé : It has been suggested that lignocellulosic materials are cost-effective materials for remediation of toxic Cr(VI) pollution; however, inconsistent interpretations of the reaction mechanism are frequently found in the literature. To clarify the reaction mechanism, the reaction of Cr(VI) with individual components of lignocellulosic materials must be better understood. Thus, the purpose of this work was to investigate the reaction mechanism of Cr(VI) with cellulose, which is one of the main components of lignocellulosic materials. The Cr(VI) reaction was evaluated at pH 2 and the results showed that Cr(VI) could be reduced to Cr(III) by cellulose. As indicated by the FT-IR spectra, the hydroxyl groups in cellulose were the reactive sites for Cr(VI) reduction, giving rise to the formation of carboxyl groups. The resultant Cr(III) was either bound to cellulose or released into solution. As revealed by the Cr K-edge EXAFS of cellulose after its reaction with Cr(VI), Cr(III) was bound to cellulose by forming bidentate–mononuclear complexes with carboxyl groups, which resulted from the oxidation of hydroxyl groups. The first-order rate constant of Cr(VI) reaction with cellulose was determined to be 3.84 × 10−7 s−1 at pH 2. The slow reduction of Cr(VI) by cellulose was attributed to the existence of H-bonding networks in cellulose, which restrict the accessibility of Cr(VI) to the hydroxyl groups in cellulose. ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science/article/pii/S1385894711010898