Determination of the ionic composition of perfluorinated sulfocationite membranes based on Donnan potential estimates

An express method for determination of the membrane ionic composition is developed based on the possibility of estimating the Donnan potential difference on the individual studied-solution/membrane interface. The Donnan potential is assessed using a new device one end of which serves as the ion-selective electrode sensor. The ionic composition of perfluorinated sulfocationite membranes is determined in systems with mixed inorganic electrolyte solutions by comparing the Donnan potentials in a given system and the reference system. As the reference, a system with perfluorinated sulfocationic membrane and individual potassium chloride solutions is used. The time of one measurement does not exceed 10–15 min. The accuracy and sensitivity of determination were 3% and 0.02 mmol/g, respectively.