Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/102054
Type: Artigo de periódico
Title: Humic Acid-divalent Cation Interactions
Author: Prado A.G.S.
Airoldi C.
Abstract: The adsorption behavior of divalent cations M2+ (Cu, Ni, Co and Zn) with commercial humic acid (HAAl) and also with an extracted fraction of peat soil (HAPs) was followed in aqueous solution. The series of adsorption isotherms were fitted to a modified Langmuir equation. The maximum number of moles adsorbed gave: 0.55 ± 0.02, 0.66 ± 0.02, 0.54 ± 0.02, 0.40 ± 0.02 mmol per gram for HAAl and 0.63 ± 0.03, 0.61 ± 0.06, 0.55 ± 0.02, 0.54 ± 0.03 mmol/g for solid HAPs, for copper, nickel, zinc and cobalt, respectively. The same interaction followed calorimetrically gave endothermic values: 2.4 ± 1.0, 8.4 ± 0.9, 18.3 ± 0.9, 10.6 ± 0.9 kJ mol-1 and 18.4 ± 1.2, 15.9 ± 1.4, 15.4 ± 1.2, 15.0 ± 1.2 kJ mol-1 for HAAl and HAPs, respectively, for the same sequence. Because all Gibbs free energies were negative. Complexation must be accompanied by an increase in entropy. © 2003 Elsevier B.V. All rights reserved.
Editor: 
Rights: fechado
Identifier DOI: 10.1016/S0040-6031(03)00196-5
Address: http://www.scopus.com/inward/record.url?eid=2-s2.0-0142182228&partnerID=40&md5=333375974a71a29f7f5151352335bc37
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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