The diffusivity of potassium chloride and sodium chloride in concentrated, saturated, and supersaturated aqueous solutions

Authors

  • Y. C. Chang,

    1. School of Chemical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0100
    Current affiliation:
    1. Eastman Kodak Co., Rochester, NY
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  • A. S. Myerson

    Corresponding author
    1. School of Chemical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0100
    Current affiliation:
    1. Dept. of Chemical Engineering, Polytechnic Institute of New York, Brooklyn, NY
    • School of Chemical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0100
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Abstract

The diffusion coefficients of potassium chloride and sodium chloride were measured in concentrated, saturated, and supersaturated solutions at 25°C employing Gouy interferometry. The results indicate a maximum in the diffusivity vs. concentration curve near saturation followed by a rapid decline in diffusivity toward zero with increasing concentration in the supersaturated region. This behavior supports the idea that the diffusion coefficient approaches zero at the spinodal concentration. The data were successfully correlated by modifying an empirical activity coefficient equation (Robinson and Stokes, 1955) to account for molecular cluster effects and employing the calculated activity coefficients along with a predictive equation for diffusivity in electrolytes (Robinson and Stokes, 1955).

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