Transport Studies of Iodine Through Liquid Membrane System

Transport of iodine by a charge-transfer mechanism through a bulk organic liquid membrane system containing calixarene based on donor-type carriers was studied. It was found that the transport of iodine is facilitated by n-donor carriers depending on the pH of the source phase. The color of iodine solutions on the source side turned from brown to colorless. The passage of iodine through the organic bulk liquid membrane was governed by donor-acceptor interaction between n-donor atoms in the carrier and sigma-acceptor (iodine atoms) and by the diffusion of an n-sigma-type charge-transfer complex in the membrane followed to release by the Lewis acid-base interaction in the aqueous phase. The transport by the new carrier arises both from the different extraction equilibrium constants between the aqueous phase and donor-acceptor interaction with iodine and the carrier in the organic phase.