Abstract:Pattern recognition methods were used to treat the experimentally measured data of Pitzer’s coefficients of 107 electrolytes, to find the relationships between the ionic structural parameters of these electrolytes and Pitzer’s coefficients. It is found that these relationships can be approximately expressed as linear equations of four dimensionless numbers, (R₊/R_-), (R₊+R_-)/Z₊Z_-, (Z₊/Z_-) and (R_t/R_l), where R₊ and R_- are the cationic and anionic radii respectively; Z₊ and Z_- are the cationic and anionic charge numbers respectively, and (R_t/R_l) denotes the nonsphericity of some non-spherical ions. Besides, it is found that the difference of the nuclear magnetic resonance measured rotational relaxation time of water molecules around cations and anions, |Δτ|, has good correlation with Pitzer’s coefficients. The relationships can be interpreted by the theory of corresponding states of ionic solutions. Based on the relationships, an example of application to some hydrometallurgical process was discussed.

Key words: concentrated electrolyte solutions; Pitzer’s coefficients; ionic parameters; corresponding state theory