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Os(VIII) as an efficient homogeneous catalyst for the oxidative decolorization of methylene blue dye with alkaline chloramine-T: / K. N. Vinod in Industrial & engineering chemistry research, Vol. 49 N° 7 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3137–3145 Titre : Os(VIII) as an efficient homogeneous catalyst for the oxidative decolorization of methylene blue dye with alkaline chloramine-T: : kinetic, mechanistic, and platinum metal ions reactivity studies Type de document : texte imprimé Auteurs : K. N. Vinod, Auteur ; Puttaswamy, Auteur ; K. N. Ninge Gowda, Auteur Année de publication : 2010 Article en page(s) : pp. 3137–3145 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Os  Oxidative  Oxecolorization  Methylene  Blue  Alkaline  Chloramine  Kinetic,  Mechanistic  Platinum  Metal  Ions  Reactivity Résumé : One of the most important thiazine dyes is methylene blue (MB), which is extensively used in the dyeing industry. It also facilitates a number of biological applications. Methylene blue dye is not significantly hazardous, but it can lead to various harmful effects. Among the physicochemical processes developed to remove this dye from wastewater textile and dyestuff manufacturing industries, the oxidative decolorization method alone seems to ensure the advantage of a low cost, simple, and efficient process. So we investigated a detailed oxidative decolorization kinetic study of MB by sodium-N-chloro-p-toluenesulfonamide (chloramine-T or CAT) in alkaline medium catalyzed by Os(VIII) spectrophotometrically at 664 nm (λmax of the dye). The reaction rate showed a first-order dependence each on [CAT]o and [MB]o, a fractional-order dependence on [Os(VIII)], and an inverse-fractional-order dependence on [NaOH]. A decrease of the dielectric constant of the medium by the addition of methanol decreased the rate. The solvent isotope effect k′ (H2O)/k′ (D2O) was equal to 1.37. Activation parameters were computed. The kinetics of oxidation of MB by CAT was also studied with other platinum metal ions. The relative reactivity of these catalysts are in the order Os(VIII) > Ru(III) > Ir(III) ≥ Rh(III) ≥ Pt(IV) > Pd(II). This trend may be attributed to the different d-electronic configurations of the metal ions. It was found that the catalyzed reactions are about 3-fold to 10-fold faster than the uncatalyzed reactions. The mechanism proposed and the derived rate law are consistent with the observed kinetics. This simple and economic redox system can also be adopted for removing the MB dye present in industrial wastewater. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900628r [article] Os(VIII) as an efficient homogeneous catalyst for the oxidative decolorization of methylene blue dye with alkaline chloramine-T: : kinetic, mechanistic, and platinum metal ions reactivity studies [texte imprimé] / K. N. Vinod, Auteur ; Puttaswamy, Auteur ; K. N. Ninge Gowda, Auteur . - 2010 . - pp. 3137–3145. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3137–3145 Mots-clés : Os  Oxidative  Oxecolorization  Methylene  Blue  Alkaline  Chloramine  Kinetic,  Mechanistic  Platinum  Metal  Ions  Reactivity Résumé : One of the most important thiazine dyes is methylene blue (MB), which is extensively used in the dyeing industry. It also facilitates a number of biological applications. Methylene blue dye is not significantly hazardous, but it can lead to various harmful effects. Among the physicochemical processes developed to remove this dye from wastewater textile and dyestuff manufacturing industries, the oxidative decolorization method alone seems to ensure the advantage of a low cost, simple, and efficient process. So we investigated a detailed oxidative decolorization kinetic study of MB by sodium-N-chloro-p-toluenesulfonamide (chloramine-T or CAT) in alkaline medium catalyzed by Os(VIII) spectrophotometrically at 664 nm (λmax of the dye). The reaction rate showed a first-order dependence each on [CAT]o and [MB]o, a fractional-order dependence on [Os(VIII)], and an inverse-fractional-order dependence on [NaOH]. A decrease of the dielectric constant of the medium by the addition of methanol decreased the rate. The solvent isotope effect k′ (H2O)/k′ (D2O) was equal to 1.37. Activation parameters were computed. The kinetics of oxidation of MB by CAT was also studied with other platinum metal ions. The relative reactivity of these catalysts are in the order Os(VIII) > Ru(III) > Ir(III) ≥ Rh(III) ≥ Pt(IV) > Pd(II). This trend may be attributed to the different d-electronic configurations of the metal ions. It was found that the catalyzed reactions are about 3-fold to 10-fold faster than the uncatalyzed reactions. The mechanism proposed and the derived rate law are consistent with the observed kinetics. This simple and economic redox system can also be adopted for removing the MB dye present in industrial wastewater. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900628r