The electrochemical potential and ionic activity coefficients. A possible correction for Debye-Hückel and Maxwell-Boltzmann equations for dilute electrolyte equilibria.
When the electrical contribution in the electrochemical potential of ionic species is reduced with a factor two from its traditional value, the ionic activity coefficients are closer to unity and need to account only for the short-range interactions at high concentrations. Such a change is needed to remove inconsistencies in the models and to comply with basic electrostatic principles. This will have serious implications, in many applications. For example, it will cause changes in many of the fundamental models that are used to explain measured data in the dilute range for the various disciplines that embrace classical electrochemistry. Examples are Debye-Hückel and Gouy-Chapman theories; Maxwell-Boltzmann distribution; Nernst theory; Donnan equilibrium, etc. These theories impact a wide range of observable phenomena such as activity coefficients of electrolytes, diffuse double layer capacitance, electrode potentials, membrane potentials, streaming potentials, electro-osmosis, flotation, sedimentation, corrosion, charged micellar behaviour, space-charge semiconductor behaviour, and electrical phenomena in biological tissue, e.g. membranes; cells; and nerves, etcetera.
van der Weg
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PB
Unilever R&D, Vlaardingen, The Netherlands. Peter-van-der.Weg@unilever.com