I'm afraid that it will be strongly dependent on the medium in which you wish to deipserse your salts (on the dielectric constant, on the compexin ability, association tendencies). I think the best you can do is to look for analogous systems in the literature. Even there you will probably find only indirect data (consuctivites, moibilities).
thanks Prof. Banhegyi ,for your prompt comments. I do understand the same. I just want to estimate N/N0 as per the discussion available in Bhattacharya et al's paper in (Langmuir 2009, 25, 3276-3281).