Nitroprusside-PEO Enthalpic Interaction as a Driving Force for Partitioning of the [Fe(CN)5NO]2- Anion in Aqueous Two-Phase Systems Formed by Poly(ethylene oxide) and Sulfate Sal

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• 作者：Luis Henrique M. da Silva ; Maria C. Hespanhol da Silva ; Roney A. N. de Aquino ; Kelly R. Francisco ; Marcus V. C. Cardoso ; Luis A. Minim ; Jane S. R. Coimbra
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：November 23, 2006
• 年：2006
• 卷：110
• 期：46
• 页码：23540 - 23546
• 全文大小：114K
• 年卷期：v.110,no.46(November 23, 2006)
• ISSN：1520-5207

文摘

Ions are known to concentrate in the salt-enriched phase of aqueous two-phase systems, with the only knownexception being the pertechnetate anion, TcO₄^-. We have discovered a second ion, nitroprusside anion (NP),which is markedly transferred from the salt phase to the polymer phase. The partitioning behavior of[Fe(CN)₅NO]^2- anion was investigated in ATPS formed by poly(ethylene oxide) of molar mass 3350 and35000 g mol^-1, and different sulfate salts (Na₂SO₄, Li₂SO₄, and MgSO₄). On the basis of a model, thenitroprusside high affinity for the macromolecular phase was attributed to an enthalpic specific interactionbetween the anion and ethylene oxide unit. Partition coefficients increased exponentially with tie-line lengthincrease, reaching values as high as 1000 and showing a relationship very dependent on the salt nature, butindependent of the polymer molar mass.