Ligand confinement and pure aqueous medium synthesis of novel ion imprinted membranes for advanced rare earth separation

Abstract

Molecular imprinting technology has been proved an efficient strategy for separation, however ion imprinting was not so high-performance. Pure aqueous phase synthesis and ligand assistance are two prominent improvement strategies so far. This article developed a novel rare earth yttrium(Y) ion imprinted membrane (Y-IIM) in pure aqueous phase, and applied a high-performance rare earth extractant Cyanex272 as ligand in membrane basement to confine the imprinted polymerization process. Firstly, polymer inclusion membrane (PIM) containing copolymer poly(vinyl alcohol-co-ethylene) as hydrophilic additive and Cyanex272 as interior ion ligand was synthesized. Then ion imprinting in aqueous phase was initiated through redox polymerization. Results confirmed that Y-IIMs performed superior hydrophility and Cyanex272 presented improved thermal stability. Imprinted aggregates distributed separately on membrane surfaces and inner walls, as a result of the confinement by the coordination between Y and Cyanex272 ligand. The adsorption capacity on Y was 3 times that of non-imprinted membranes, and the Y-IIMs exhibited superior permeation ability for Y than Ho and Er, indicating the realization of expected specific recognition affinity for Y through ligand confinement and aqueous medium synthesis.