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https://locus.ufv.br//handle/123456789/13185
Tipo: | Artigo |
Título: | PEO-[M(CN) 5 NO] x- (M ) Fe, Mn, or Cr) Interaction as a driving force in the partitioning of the Pentacyanonitrosylmetallate anion in ATPS: strong effect of the central atom |
Autor(es): | Silva, Luis Henrique M. da Silva, Maria C. Hespanhol da Francisco, Kelly R. Cardoso, Marcus V. C. Minim, Luis A. Coimbra, Jane S. R. |
Abstract: | The partitioning behavior of pentacyanonitrosilmetallate complexes[Fe(CN) 5 NO] (2-), [Mn(CN) 5 NO] 3(-), and [Cr(CN) 5 NO] 3(-)has been studied in aqueous two-phase systems (ATPS) formed by adding poly(ethylene oxide) (PEO; 4000 g mol (-1)) to an aqueous salt solution (Li2 SO4, Na2 SO4, CuSO4, or ZnSO4). The complexes partition coefficients ( K complex) in each of these ATPS have been determined as a function of increasing tie-line length (TLL) and temperature. Unlike the partition behavior of most ions, [Fe(CN) 5 NO] 2(-) and [Mn(CN) 5 NO] 3(-) anions are concentrated in the polymer-rich phase with K values depending on the nature of the central atom as follows: K [Fe(C N) 5 NO] 2 - >> K [ Mn (CN 5 NO] 3 - > K [C r (C N) 5 NO ]3 - . The effect of ATPS salts in the complex partitioning behavior has also been verified following the order Li2 SO 4 > Na2 SO 4 > ZnSO4. Thermodynamic analysis revealed that the presence of anions in the polymer-rich phase is caused by an EO-[M(CN) 5 NO] ( x- ) (M = Fe, Mn, or Cr) enthalpic interaction. However, when this enthalpic interaction is weak, as in the case of the [Cr(CN) 5 NO]3(-) anion ( K [Cr(CN 5 NO] 3 - < 1), entropic driving forces dominate the transfer process, then causing the anions to concentrate in the salt-rich phase. |
Palavras-chave: | Pentacyanonitrosylmetallate ATPS |
Editor: | American Chemical Society |
Tipo de Acesso: | Open Access |
URI: | https://www.ncbi.nlm.nih.gov/pubmed/18717547 http://www.locus.ufv.br/handle/123456789/13185 |
Data do documento: | 22-Ago-2008 |
Aparece nas coleções: | Artigos |
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