Abstract
The effect of diffusant size, shape and effective charge density, which govern various transport processes in a charged membrane was specially investigated at $25^{\circ}C$. The systems examined here were charged carboxyethyl cellulosic membranes with cesium chloride and tetraalkylammonium chlorides. Permeation coefficient was found to decrease with the increase of the hydrated radius of the ions in a sequence of cesium chloride>tetramethyl ammonium chloride>tetraethyl ammonium chloride> terrabutyl ammonium chloride. This sequence was interpreted by considering the partition sorption and the hydration of ions in hydrophilic membranes. The molar mobilities of ions in charged membranes were determined by use of the permeation measurement and the analysis by the Nernst-Planck-based equation in wide range of salt concentration. The molar mobility of counter-ions decreased with the increase of the stokes radius, while that of co-ions increased. The effective fixed changed density was found on the diffusant size and was explained by considering electrostatic binding by the negatively charged groups in the membranes.
