Modification of the Pitzer equations for application to electrolyte + polar non-electrolyte mixtures

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 379; no. 1; pp. 63 - 69
• Main Authors: Fernández-Mérida, Luis, Rodríguez-Raposo, Raquel, García-García, Guillermo E., Esteso, Miguel A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 12.12.1994; Elsevier Science
• Subjects: Activity coefficients; Chemical thermodynamics; Chemistry; Electrolyte + polar non-electrolyte mixtures; Exact sciences and technology; General and physical chemistry; Mixtures; Modified Pitzer equations; Osmotic coefficients; Thermodynamic properties; Activity coefficients; Electrolyte + polar non-electrolyte mixtures; Modified Pitzer equations; Osmotic coefficients; Thermodynamics; Electrolyte solution; Binary system; Non electrolyte solution; Activity coefficient; Theoretical study; Osmotic coefficient; Polar solution
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/0022-0728(94)87125-6

The fitting of experimental osmotic and activity coefficient values to Pitzer equations requires the use of a large number of adjustable parameters when polar neutral species are present in the system. This is because the Pitzer equations consider the λ ion—neutral and λ neutral—neutral as constant interaction parameters for the fitting. The modification of the original Pitzer equations, by considering the dependence of these binary interaction parameters concerning the polar neutral components, on both the ionic strength and the neutral species concentration in the system, leads to a considerable improvement in these fittings. To test the applicability of these modified Pitzer equations, they were used to fit several series of data from the literature, related to pure aqueous solutions of different amino acids, or urea, as well as aqueous mixtures of an electrolyte plus an amino acid, or urea.