Ligand-grafted biomaterials for adsorptive separations of uranium in solution

Many organic molecules, particularly biologicals, contain functional groups (ligands) that actively interact with metal ions in solution by adsorption , ion exchange, or chelation/coordination/complexation. Water-soluble organ ics have limitations as reagents for metal-ion separations from aqueous sol utions. However, if the ligand molecule(s) are grafted on to an insoluble m atrix the resulting ligand(s)-containing product becomes useful for separat ions applications related to metal recovery or remediation. It was discover ed that biomolecules containing a primary amino group, secondary amino grou p, or hydroxyl group could be grafted into a polyurethane polymeric network via in situ polymerization reactions. With carboxyl groups, grafted materi al showed goon selectivity among a group of divalent metal cations, and a u ranium-binding capacity of more than 10 mg/g of polymer. The material can b e regenerated by sodium bicarbonate or sodium carbonate solution and reused . Data from a stirred-tank reactor showed fast uranium-binding kinetics, an d breakthrough-elution studies with a packed-column reactor indicated promi sing process behavior.