HYBRID ORGANIC-INORGANIC FIXED SITE DIBENZO 18-CROWN-6 COMPLEXANT MEMBRANES

New heteropolysiloxane (HPS) materials containing the 12-bis[4-(10-ami nodecylcarbonyl)]-benzo-18-crown-6 and 2,3,11, 12-bis[4-(2-aminoethylc arbonyl)]-benzo-18-crown-6 compounds chemically linked in a reticulate silica matrix were synthesized by the sol-gel process. The preparatio n and the characterization of the HPS precursors are reported here. Fr om these materials, dialysis membranes used for the facilitated compet itive transport of silver/copper ions are obtained. The selectivity of the membranes is improved by the incorporation of the complexing mole cules which allow a better solubility of silver ions in the membrane. In accordance with the experimental results, a dual transport mechanis m is proposed, based on a reversible binding equilibrium solute/comple xing site and a solute diffusion between two complexing sites.