Interactions between ions and polyelectrolytes. A note on determination of ionic activities, with reference to a modified poisson-boltzmann treatment.

We compare the numerous available data on ionic activities, in the presence of polyelectrolytes, with evaluation of these quantities from a modified Poisson-Boltzmann equation in the framework of a cell model. This treatment gives an excellent description of the mean activity for various ions. The activity of counterions is well-predicted, that of co-ions is generally overestimated.