Properties of micellar solutions. Part 1. - Self-diffusion of sodium ions in sodium dodecyl sulphate solutions

The self-diffusion coefficients of sodium ions in aqueous solutions of sodium dodecyl sulphate have been measured. Above the critical micelle concentration the rate of diffusion of the sodium ions is reduced. This effect cannot be adequately accounted for simply in terms of ion binding. An alternative explanation which ascribes the reduction of the counter-ion diffusion to the effect of the electrostatic fields of the micelles gives a more satisfactory agreement with the experimental results.