Artigo
Effect of the competition of Cu(II) and Ni(II) on the kinetic and thermodynamic stabilities of Cr(III)-organic ligand complexes using competitive ligand exchange (EDTA)
Registro en:
Journal Of Environmental Management. London: Academic Press Ltd- Elsevier Science Ltd, v. 154, p. 259-265, 2015.
0301-4797
10.1016/j.jenvman.2015.02.038
WOS:000352671500028
Autor
Cunha, Graziele da Costa
Goveia, Danielle [UNESP]
Cruz Romao, Luciane Pimenta
Oliveira, Luciana Camargo de
Resumen
The effect of competition of Cu(II) and Ni(II) on the kinetic stability of Cr(III) complexed with natural organic matter (NOM) was characterized using EDTA exchange with single-stage tangential-flow ultrafiltration. For a water sample from Serra de Itabaiana, 3% of spiked Cr(III) was exchanged, while for a sample from the Itapanhau River, 7, 10, 10, and 21% was exchanged in experiments using Cr(III) alone and in combination with Cu(ll), NOD, or Cu(II) + Ni(II), respectively. Times required to reach exchange equilibrium with EDTA were less than 360 min. The influence of competition from Ni(II) and Cu(II) on the availability of complexed Cr(III) was low, demonstrating preference of the ligand sites for Cr(III). This was correlated with sample humification, as confirmed by EPR and C-13 NMR analyses. Exchange efficiency was in the order Cu > Ni > Cr, and the process could be readily described by first order kinetics, with average rate constants of 0.35-0.37 11-1. (C) 2015 Elsevier Ltd. All rights reserved. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Univ Fed Sergipe, Dept Chem, BR-49100000 Sao Cristovao, SE, Brazil Sao Paulo State Univ UNESP, BR-18409010 Itapeva, SP, Brazil Fed Univ Sao Carlos UFSCar, Dept Phys Chem &Math, BR-18052780 Sorocaba, SP, Brazil Sao Paulo State Univ UNESP, BR-18409010 Itapeva, SP, Brazil CNPq: 307029/2013-1