Modeling chemical activity effects in strong ionic solutions

A new simple mathematical model for calculating the chemical activity coeff icients of ions in electrolytic solutions is presented. The model was devel oped to account for the particular behavior of concentrated solutions for w hich short-range and long-range interactions between ions are important. Th e new model is essentially a modified version of the Davies equation. Given its simple mathematical form, it can be easily implemented in a numerical code aimed at modeling ionic transport phenomena in saturated porous materi als. The transport equations of charged particles in concentrated solutions are also presented. Numerical results are shown and compared with experime ntal results. Applications of the model to ionic diffusion problems in satu rated porous media are also shown. (C) 1999 Elsevier Science B.V. All right s reserved.