ALGORITHMS FOR AB-INITIO CALCULATION OF ION ASSOCIATION IN THE SUPERCRITICAL H2O FLUIDS - 1/1 ELECTROLYTES

The algorhythms for prediction of association in 1 : 1 electrolytes without individual adjusting parameters are presented. The method involves algorythms both for calculation of nonelectrostatic and solvatation properties of ion pairs, The expressions for Born parameter values of a complex consisting of two nonpolarised hydrated ions are deduced. The proposed model is joined with Helgeson-Kirkham-Flowers equation of state for aqueous species thus the method could be applied for calculation of any thermodynamic properties of the ion pair. The comparison of the modeling calculations and available experimental data showed good agreement for the 1 : 1 electrolyte behavior description in the wide range of supercritical parameters (400-800 degrees C, 0.5-4.0 kbar).