Carrier-facilitated transport of Cd(II) through a supported liquid membrane containing thiacalix[4]arene derivatives as ionophore

The feasibility of a facilitated transport process of cadmium ions through a SLM system incorporating new extractant agents, thiacalix[4]arenes, was studied. These molecules have sulfur atoms instead of usual methylene bridges. The chemical modification of the upper or the lower rim provides a great variety of supra molecules having different complexation ability and different conformational behaviour. The efficiency of the transport across the inner membrane organic liquid phase is shown to depend on the chemical (affinity) and structural (conformational states possible) parameters of these complexing molecules. In this work, two different thiacalix[4]arenes were selected as effective ionophore for the treatment of liquid media loaded in Cd(II). The results show that these thiacalix[4]arenes derivative ensure facilitated transport of cadmium cations through supported liquid membranes. Especially, the non-substituted thiacalix[4]arene can be considered as an effective extractant agent. The incidence of several parameters on transport efficiency such as pH of both aqueous solutions and carrier concentration was studied. The permeation of the species is due to a proton potential gradient (the driving force of the process) existing between the two opposite sides of the SLM. The initial flux, J, is found to be equal to 6.7.10-7 mol.m-2.s-1, under optimal experimental conditions.