Modeling for mean ion activity coefficient of strong electrolyte system with new boundary conditions and ion-size parameters

doi:10.1016/j.cjche.2015.04.010

Abstract

Abstract: A rigorous approach is proposed to model the mean ion activity coefficient for strong electrolyte systems using the Poisson-Boltzmann equation. An effective screening radius similar to the Debye decay length is introduced to define the local composition and new boundary conditions for the central ion. The crystallographic ion size is also considered in the activity coefficient expressions derived and non-electrostatic contributions are neglected. Themodel is presented for aqueous strong electrolytes and compared with the classical Debye-Hückel (DH) limiting lawfor dilute solutions. The radial distribution function is compared with the DH andMonte Carlo studies. Themean ion activity coefficients are calculated for 1:1 aqueous solutions containing strong electrolytes composed of alkali halides. The individual ion activity coefficients andmean ion activity coefficients in mixed solvents are predicted with the new equations.

Key words: Activity coefficient, Electrolyte, Ion size, Poisson-Boltzmann equation

摘要： A rigorous approach is proposed to model the mean ion activity coefficient for strong electrolyte systems using the Poisson-Boltzmann equation. An effective screening radius similar to the Debye decay length is introduced to define the local composition and new boundary conditions for the central ion. The crystallographic ion size is also considered in the activity coefficient expressions derived and non-electrostatic contributions are neglected. Themodel is presented for aqueous strong electrolytes and compared with the classical Debye-Hückel (DH) limiting lawfor dilute solutions. The radial distribution function is compared with the DH andMonte Carlo studies. Themean ion activity coefficients are calculated for 1:1 aqueous solutions containing strong electrolytes composed of alkali halides. The individual ion activity coefficients andmean ion activity coefficients in mixed solvents are predicted with the new equations.

关键词: Activity coefficient, Electrolyte, Ion size, Poisson-Boltzmann equation

Miyi Li, Tao Fang. Modeling for mean ion activity coefficient of strong electrolyte system with new boundary conditions and ion-size parameters[J]. Chin.J.Chem.Eng., 2015, 23(7): 1169-1177.

Miyi Li, Tao Fang. Modeling for mean ion activity coefficient of strong electrolyte system with new boundary conditions and ion-size parameters[J]. Chinese Journal of Chemical Engineering, 2015, 23(7): 1169-1177.

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