On the Permselectivity of Potassium Ion with Ion Exchange Membrane Method

Studies on the Separation of Potassium Ion from Sea Water (2)

Abstract

For the purpose of electrodialytic concentration of potassium ion from sea water with ion exchange membranes, several experiments were carried out to find the effect of various current density or feed rate on the permselectivity coefficient, i. e. T^K_Naof potassium ion against sodium ion.
Also, the effects of total salt concentration or composition of the feed solution on the potassium permselectivity were examined with mixed solution of sodium chloride and potassium chloride.
The results were as follows:
1) The permselectivity coeff. T^K_Naincreased with a decrease in current density and an increase in feed rate, and the effect of the latter was found remarkable.
In the electrodialytic concentration of sea water, the value of T^K_Nawas about 2.6 at current density 1.0A/dm², and feed rate 40cm/sec.
2) The permselectivity coeff. T^K_Nawas exponentially related to feed velocity under the constant current density.
3) There was almost no effect as to the variation of the mol ratio of potassium ion to sodium ion on the potassium permeability, but the permselectivity coeff. T^K_Nadecreased with an increase in concentration of feed solution. These phenomena were caused due to the variation in concentration for the selectivity coeff. K^K_Naof the membrane.