Passage of water and electrolytes through natural and artificial keratin membranes

Abstract

The feasibility of reconstituting dissolved α-keratin was tested by rekeratinizing bovine hoof into sheets through electrodialysis. The aim was to produce a membrane that simulated the permeability characteristics of the shed snake skin. Voltage densities of 10, 15, and 25 V/cm were successful in forming thin, fragile membranes on the surface of a dialysis membrane. Average Na flux rates of 291, 133, and 121 μmol/cm 2·h respectively were found and with the addition of linoleic acid could be lowered to 2.97 μmol/cm 2·h. Permeability characteristics of shed snake skin, turtle scutes, and bovine hoof slices were tested at pressures up to 300 lb/in 2 and compared to the commercial reverse osmosis membrane, SEPA 97. The first three are composed of keratin and the latter of cellulose acetate. Both types of shed snake skin tested showed an immediate and complete passage of fluid with no salt rejection. Turtle scute section and thin (60 μm) sections of bovine hoof allowed the passage of no fluid and therefore retained 100% of the salt. Rekeratinized membranes were too delicate to perform high pressure permeability tests on. SEPA 97 had an average fluid passage rate of 180 μl/cm 2·h and a salt rejection rate of only 16%. Both values being lower than publicized.