Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9674324 | Journal of Hazardous Materials | 2005 | 5 Pages |
Abstract
Humic acid immobilized onto silica gel surface was studied by the calorimetric titration of divalent cations in aqueous solution. The adsorption isotherms were obtained by the batchwise method and were fitted to a modified Langmuir equation. The maximum number of moles per gram of the material gave: 10.42 ± 0.75, 13.16 ± 0.58, 7.87 ± 0.58 for copper, nickel and zinc, respectively. Gibbs free energies were negative for all systems and the adsorption interactions calorimetrically followed presented endothermic enthalpic values: 6.24 ± 0.47, 6.75 ± 0.74, 6.97 ± 0.58 kJ molâ1 for the same sequence of divalent cations. All liquid/solid interface adsorptions were entropically driven.
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Authors
Alexandre G.S. Prado, Bárbara S. Miranda, Luiz F. Zara,