Transport of Metal Ions through Chelating Membrane Containing Amidoxime Group -A Study of Permselective Membrane Prepared by Radiation Grafting. I.-

Abstract

The transport and the selective separation of Mg²⁺ and Cu₂₊ through an amidoxime groupcontaining membrane, which was synthesized by the radiation-induced grafting of acr ylonitrile onto a polyethylene membrane followed by amidoximation of cyano groups with hydroxylamine, were investigated.
These metal ions in neutral solutions in the source phase transport through the membrane into the receiving phase which is composed of various concentrations of sulfuric acid or acetic acid-sodium acetate solutions.
The rate of transport of Cu²⁺ and Me ions increased with increasing the initial H⁺ concentration in the receiving phase. Cu²⁺ and Mg²⁺ ions were transported with H⁺ trans fer as a driving force. Transport efficiency of Cu²⁺ through the membrane was higher th an that of Mg²⁺. The ratio of the concentration (Cu²⁺/Mg²⁺) in the receiving phase increased and thereafter decreased gradually with the time to reach finally almost the constant value of about 4.5.
The transport selectivity is caused by the difference in the adsorption equilibrium resulting from the complex formation constant of each metal ion with amidoxime group.
It was found that the transport selectivity of metal ion is greatly influe n ced by pH when the ion permselectivity process occurred by using amidoxime group as a carrier.