Electrical Current and Fluxes of Ions

The electric current in an electrolyte solution is transported by ions only, as described in Equation 5.6  

i is the current density, I the current, A the membrane surface, F the Faraday constant, J the flux, and z the valence, the subscript i refers to cations and anions. Introducing Equation 5.8 and 5.9 and rearranging leads to  

i is the current density, C is the concentration, F is the Faraday constant, p is the electrical potential, z is the valence, D is the ion diffusivity, R is the gas constant, T is the absolute temperature, and the subscript i refers to anions and cations. 

The term (.RT/z QF)(dC /dz) has the dimensions of an electrical potential gradient and represents the concentration potential that is established between two electrolyte solutions of different concentrations. 

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