Theoretical investigations of the experimentally observed selectivity of a cobalt imprinted polymer

A cobalt imprinted polymer synthesised, for reducing the volume of radioactive waste generated during nuclear reactor decontaminations, using vinylbenzyl iminodiacetate (VbIDA) as the functional ligand, has been found to be selective for cobaltous ions over excess ferrous ions. The selectivity of the polymer has been investigated through theoretical calculation of the formation energies of complexes involved by using the ab-initio density functional theory (DFT) code SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms). The formation energies of complexes of Fe2+, Co2+, Cu2+ and Ni2+ with the free functional ligands as well as with ligands attached to the crosslinkers have been calculated. The calculations revealed that the ferrous forms an unstable complex with the ligands attached to the crosslinkers. The formation energy calculation results were found to corroborate the experimentally observed selectivity order.