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Adsorption of divalent lead on a montmorillonite−illite type of clay / John U. Kennedy Oubagaranadin in Industrial & engineering chemistry research, Vol. 48 N° 23 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10627–10636 Titre : Adsorption of divalent lead on a montmorillonite−illite type of clay Type de document : texte imprimé Auteurs : John U. Kennedy Oubagaranadin, Auteur ; Z. V. P. Murthy, Auteur Année de publication : 2010 Article en page(s) : pp. 10627–10636 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Adsorption--Divalent  Lead--Montmorillonite−Illite--Clay Résumé : Lead(II) was removed from aqueous solution by adsorption on a montmorillonite−illite type of clay (MIC) collected from the Gulbarga district of Karnataka, India. The objectives of the current work were (i) to characterize the clay (adsorbent) and (ii) to perform equilibrium, kinetic, mass-transfer, and thermodynamic studies for the adsorption of Pb(II) on the clay. Batch adsorption equilibrium data were determined with different initial Pb(II) concentrations (100, 150, and 200 ppm) at pH 4 and 37 °C, and the data were tested with isotherm models. The three-parameter Freundlich−Langmuir model gave the best fit to the equilibrium data (R2 = 0.9979). However, as the initial Pb(II) concentration was increased (150 and 200 ppm), multilayer adsorption was observed. The maximum monolayer adsorption capacity of the clay was determined to be ∼52 mg/g. Kinetic studies indicated that the rate of adsorption of Pb(II) on the clay followed a second-order rate mechanism, with decreasing rate constant values of 0.1097, 0.0571, and 0.0022 g/(mg min) as the initial Pb(II) concentration was increased in the order of 100, 150, and 200 ppm, respectively. The value of the Freundlich constant (n) in the range of 2.5−4.6 indicated that MIC was a good adsorbent of divalent lead. At a higher initial Pb(II) concentration (200 ppm), the adsorption process was determined to be film-diffusion-controlled, with a rate of 0.051 min−1. The mean values of the thermodynamic parameters—the change in the free energy (ΔH°), the change in the entropy (ΔS°), and the change in the Gibbs free energy (ΔG°) showed that the adsorption process was endothermic, thermodynamically favorable, and spontaneous. A two-stage adsorber system that has been proposed reduced the clay dose by 8.5%, compared to that of a single-stage adsorption system. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005047 [article] Adsorption of divalent lead on a montmorillonite−illite type of clay [texte imprimé] / John U. Kennedy Oubagaranadin, Auteur ; Z. V. P. Murthy, Auteur . - 2010 . - pp. 10627–10636. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10627–10636 Mots-clés : Adsorption--Divalent  Lead--Montmorillonite−Illite--Clay Résumé : Lead(II) was removed from aqueous solution by adsorption on a montmorillonite−illite type of clay (MIC) collected from the Gulbarga district of Karnataka, India. The objectives of the current work were (i) to characterize the clay (adsorbent) and (ii) to perform equilibrium, kinetic, mass-transfer, and thermodynamic studies for the adsorption of Pb(II) on the clay. Batch adsorption equilibrium data were determined with different initial Pb(II) concentrations (100, 150, and 200 ppm) at pH 4 and 37 °C, and the data were tested with isotherm models. The three-parameter Freundlich−Langmuir model gave the best fit to the equilibrium data (R2 = 0.9979). However, as the initial Pb(II) concentration was increased (150 and 200 ppm), multilayer adsorption was observed. The maximum monolayer adsorption capacity of the clay was determined to be ∼52 mg/g. Kinetic studies indicated that the rate of adsorption of Pb(II) on the clay followed a second-order rate mechanism, with decreasing rate constant values of 0.1097, 0.0571, and 0.0022 g/(mg min) as the initial Pb(II) concentration was increased in the order of 100, 150, and 200 ppm, respectively. The value of the Freundlich constant (n) in the range of 2.5−4.6 indicated that MIC was a good adsorbent of divalent lead. At a higher initial Pb(II) concentration (200 ppm), the adsorption process was determined to be film-diffusion-controlled, with a rate of 0.051 min−1. The mean values of the thermodynamic parameters—the change in the free energy (ΔH°), the change in the entropy (ΔS°), and the change in the Gibbs free energy (ΔG°) showed that the adsorption process was endothermic, thermodynamically favorable, and spontaneous. A two-stage adsorber system that has been proposed reduced the clay dose by 8.5%, compared to that of a single-stage adsorption system. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005047

Formation of ruthenium nanoparticles by the mixing of two reactive microemulsions / Sachin U. Nandanwar in Industrial & engineering chemistry research, Vol. 50 N° 19 (Octobre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11445-11451 Titre : Formation of ruthenium nanoparticles by the mixing of two reactive microemulsions Type de document : texte imprimé Auteurs : Sachin U. Nandanwar, Auteur ; Mousumi Chakraborty, Auteur ; Z. V. P. Murthy, Auteur Année de publication : 2011 Article en page(s) : pp. 11445-11451 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Microemulsion  Mixing  Nanoparticle Résumé : In this study, two reactants (ruthenium chloride and sodium borohydrate) were premicellized in two separate microemulsions and brought into contact through intermicellar exchange to conduct the reaction. As a result, ruthenium nanoparticles were formed. The overall reaction rate was governed by the intermicellar exchange rate. Particle size was controlled by varying surfactant concentration, water-to-surfactant molar ratio (ω), precursor (ruthenium chloride) concentration, and molar ratio of reducing agent-to-reagent (R). Dynamic light scattering and transmission electron microscopy were used to determine the size, size distribution, and structure of the synthesized ruthenium nanoparticles. The molar ratio ω was varied from 3 to 7; sizes of the particles were found to be in the range of 17.08―25.09 nm. The precursor (ruthenium chloride) concentration was varied in the range of 0.1―0.3 M; particle size was observed to decrease up to 0.2 M then increase due to particle agglomeration at higher precursor concentrations. Smaller nanoparticles were obtained at higher R values due to faster intramicellar nucleation and growth rate. Dispersion destabilization of colloidal ruthenium nanoparticles was detected by Turbiscan. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573341 [article] Formation of ruthenium nanoparticles by the mixing of two reactive microemulsions [texte imprimé] / Sachin U. Nandanwar, Auteur ; Mousumi Chakraborty, Auteur ; Z. V. P. Murthy, Auteur . - 2011 . - pp. 11445-11451. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11445-11451 Mots-clés : Microemulsion  Mixing  Nanoparticle Résumé : In this study, two reactants (ruthenium chloride and sodium borohydrate) were premicellized in two separate microemulsions and brought into contact through intermicellar exchange to conduct the reaction. As a result, ruthenium nanoparticles were formed. The overall reaction rate was governed by the intermicellar exchange rate. Particle size was controlled by varying surfactant concentration, water-to-surfactant molar ratio (ω), precursor (ruthenium chloride) concentration, and molar ratio of reducing agent-to-reagent (R). Dynamic light scattering and transmission electron microscopy were used to determine the size, size distribution, and structure of the synthesized ruthenium nanoparticles. The molar ratio ω was varied from 3 to 7; sizes of the particles were found to be in the range of 17.08―25.09 nm. The precursor (ruthenium chloride) concentration was varied in the range of 0.1―0.3 M; particle size was observed to decrease up to 0.2 M then increase due to particle agglomeration at higher precursor concentrations. Smaller nanoparticles were obtained at higher R values due to faster intramicellar nucleation and growth rate. Dispersion destabilization of colloidal ruthenium nanoparticles was detected by Turbiscan. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573341

Removal of cu(II) and ni(II) from industrial effluents by brown seaweed, cystoseira indica / Shaik Basha in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009)

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 961–975 Titre : Removal of cu(II) and ni(II) from industrial effluents by brown seaweed, cystoseira indica Type de document : texte imprimé Auteurs : Shaik Basha, Auteur ; Z. V. P. Murthy, Auteur ; B. Jha, Auteur Année de publication : 2009 Article en page(s) : p. 961–975 Note générale : chemical engineering Langues : Anglais (eng) Mots-clés : Cystoseira  --  biomass Résumé : The biomass of Cystoseira indica (RB) was chemically modified by cross-linking it with epichlorohydrin (CB1, CB2), and the same was oxidized by potassium permanganate (CB3) which was later employed for the treatment of Cu(II) and Ni(II) from effluents. The results indicated that biosorption equilibriums were rapidly established in about 30 and 75 min for Cu(II) and Ni(II), respectively. The metal biosorption was strictly pH dependent, and maximum removal of metals was observed at pH 6.0. The biosorption data dovetail the Langmuir isotherm, and the process obeyed pseudo-second-order kinetics. An intraparticle diffusion based Weber−Morris model was applied to evaluate rate-limiting steps, and the results suggested that film diffusion controlled the overall biosorption process. Fourier transform infrared analysis revealed that amino, hydroxyl, carboxyl, ether, and hydroxyl functional groups were involved in the metal binding and the sorption process was dominated by complexation as well as ion exchange. The loaded biosorbent was regenerated using HCl and used repeatedly over five cycles with little loss of uptake capacity beyond the second cycle. [article] Removal of cu(II) and ni(II) from industrial effluents by brown seaweed, cystoseira indica [texte imprimé] / Shaik Basha, Auteur ; Z. V. P. Murthy, Auteur ; B. Jha, Auteur . - 2009 . - p. 961–975. chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 961–975 Mots-clés : Cystoseira  --  biomass Résumé : The biomass of Cystoseira indica (RB) was chemically modified by cross-linking it with epichlorohydrin (CB1, CB2), and the same was oxidized by potassium permanganate (CB3) which was later employed for the treatment of Cu(II) and Ni(II) from effluents. The results indicated that biosorption equilibriums were rapidly established in about 30 and 75 min for Cu(II) and Ni(II), respectively. The metal biosorption was strictly pH dependent, and maximum removal of metals was observed at pH 6.0. The biosorption data dovetail the Langmuir isotherm, and the process obeyed pseudo-second-order kinetics. An intraparticle diffusion based Weber−Morris model was applied to evaluate rate-limiting steps, and the results suggested that film diffusion controlled the overall biosorption process. Fourier transform infrared analysis revealed that amino, hydroxyl, carboxyl, ether, and hydroxyl functional groups were involved in the metal binding and the sorption process was dominated by complexation as well as ion exchange. The loaded biosorbent was regenerated using HCl and used repeatedly over five cycles with little loss of uptake capacity beyond the second cycle.