SALTING EFFECT OF POLAR ORGANIC COMPOUND IN ELECTROLYTE SOLUTIONS (I) An Improvement in Scaled Particle Theory and Its Application in D2EHPA-Alkali Chloride-H2O Ternary Systems

In this paper, the sealed particle theory (SPT) is improved by considering various interactions among particles in solution and then is applied to ternary systems with a polar organic compound. The salting effect constants of di(2-ethyl-hexyl) phoshoric acid (D(2)EHPA) in alkali chloride solutions were determined by tracer technique. By comparing the results calculated by the improved SPT formulas with the experimental values, it seems that the improved SPT formulas are much better than the previous if the parameters are chosen properly. It is found that the calculated results are sensitive to the ionic radii and the hardcore diameter of the non-electrolyte. A method, based on the packing factor, is also suggested to estimate the hardcore diameter of the non-electrolyte.