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Type: Artigo de periódico
Title: Chemisorption Of Divalent Cations Onn-(2-pyridyl)acetamide Immobilized On Silica Gel - A Thermodynamic Study
Author: Airoldi C.
Alcantara E.F.C.
Abstract: N-(2-Pyridyl)acetamide covalently immobilized on silica gel ("≡Si-pa") has a great ability to chemisorb cations from propanonic or ethanolic solutions through the amount of substance divided by mass 1.57.10-4mol·g-1of bidentate groups attached to this inorganic support. The chemisorption isotherms obtained with MCl2(M: Ni, Co, Cu, Zn, Cd, Hg) in each solvent are similar and adjustable to a modified Langmuir equation. The sequence of the maximum capacity is Cu > Co > Zn in propanone and Hg > Cd > Zn > Co > Cu > Ni in ethanol. The enthalpies of chemisorption of the cations by "≡Si-pa" atT= (298.15 ± 0.02) K showed larger values in ethanol. With the exception of cobalt {ΔHm= + (6.12 ± 0.01) kJ·mol-1} in propanone, all other cation-surface interactions are enthalpically favourable in both solvents. The enthalpic sequence is Cu > Zn > Co in each solvent and the complete series Cu > Cd > Hg > Ni > Zn > Co was found in ethanol. The standard molar Gibbs free energies are in agreement with the spontaneity of the proposed reactions between a cation and a basic centre, which has a favourable enthalpic contribution to these chelating processes. © 1995 Academic Press. All rights reserved.
Rights: fechado
Identifier DOI: 10.1006/jcht.1995.0064
Date Issue: 1995
Appears in Collections:Unicamp - Artigos e Outros Documentos

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