Electrolyte conductivity in charged capillaries Original Research Article

The conductivity of symmetrical electrolytes within charged capillaries is studied by means of a space charge model. The present calculations allow for proper account of the individual diffusion coefficients of anions and cations in classical or fictitious electrolytes. A decrease in pore conductivity with increasing zeta potential values is put in evidence when the diffusion coefficient of coions exceeds that of the counterions. This phenomenon occurs at low zeta potential values and leads to a pore conductivity that may be significantly less than the conductivity of the bulk solution, especially when the diffuse layer occupies a non-negligible part of the pore. This reduced conductivity phenomenon also affects the value of the corrective factor that must be applied to the Smoluchowski equation for streaming potential.