Study of Mica Membranes with Known Pore Geometry Measurements of Electrical Conductivity

Abstract

The track‐etch technique is used to prepare mica membranes with known pore structure. The electrochemical properties of the pore wall in contact with aqueous KCl solutions are studied by measuring the electrical conductivity of the pore fluid. The experimental results are discussed in terms of the model of the membrane with narrow pores. The experiments indicate that the charge of the pore wall is a net charge formed by positive and negative charges. The negative charges are present in small surplus (about 10%). The total charge density corresponds to 1 elementary charge per 104 A2 of pore wall.

Modification of electrochemical properties of pore wall of track-etched mica membranes

“…In [5] it has been reported that the charge density of the unmodified pore wail of mica determined by conductivity measurements is smaller by a factor of 10 than that determined by measurements of membrane potential. In view of the findings of this study this difference is not real.…”

“…Details of the method of preparation are described in [5]. The membranes used in this study are characterized by the following data: active membrane area a = 1 cm-2; membrane thickness 6 = 8-10 4 cm; equivalent pore radius 2.10 -6 cm < F< 9.10 -6 cm (radius of cylindrical pores having the same area of cross section as the rhombic pore); number of pores per unit area r = 2 9 10 6 cm -2.…”