Estimation of activity coefficients in concentrated sulfite-sulfate solutions


  • G. M. Rosenblatt

    1. Materials and Molecular Research Divison, Lawrence Berkeley Laboratory and Department of Chemistry, University of California, Berkeley, CA 94720
    2. Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
    Current affiliation:
    1. Los Alamos National Laboratory, Los Alamos, N.M. 87545
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The electrolyte theory of Pitzer and coworkers is used to estimate geometric mean-ion activity coefficients in strong electrolyte solutions at 25–55°C. By using Pitzer's equations with ion-pair parameters estimated in this paper, one can calculate activity coefficients to moderately high ionic strengths in aqueous mixtures containing the following ions: Na+, K+, Mg2+, Ca2+, Cl, ClOmath image, ClOmath image, HCOmath image, HSOmath image, COmath image, SOmath image, SOmath image, and S2Omath image. Mixtures containing these ions are present in CaO/CaSO4 flue gas desulfurization units and in laboratory experiments aimed at understanding the chemistry occurring in such units. The computed activity coefficients are relatively insensitive to the values of the estimated quantities. The basis of the estimates, as well as their effect on calculated activity coefficients, is discussed. It is concluded that activity coefficients are estimated with an accuracy of ±25% or better.