Polymeric Chelators for Metal Ion Extraction and Separation

Physical Sciences : Chemical

Available for licensing


  • Bradley Holliday, Ph.D. , Chemistry and Biochemistry

Background/unmet need

Nuclear waste reprocessing, or recycling, is an important process that allows more energy to be produced from and provides safer long term storage for spent nuclear fuel. Nuclear fuel that has been utilized is still made up primarily of uranium; however, the trace impurities that are created during power generation result in a decrease in power generation efficiency, and these same trace impurities have extremely long half-lives, posing extreme engineering challenges to safe storage.

The current process by which spent nuclear fuel rods are recycled involves dissolving the fuel in acidic aqueous media and then, through a series of liquid-liquid extractions, separating different elemental components of the mixture. The liquid-liquid extractions involve biphasic mixtures of organic solvents such as kerosene with the acidic aqueous fuel mixture. The process used to achieve the selective extraction and separation of the components of the mixture uses carefully designed chelator molecules that are dissolved in the organic solvent and selectively bind different ions in the fuel mixture.

Invention Description

This invention is comprised of a polymeric material with pendant chelator functionalities. These chelator groups serve to efficiently and selectively bind ions in the aqueous media and transfer these ions to the organic solvent. Additionally, this polymeric material is synthesized upon a block copolymer backbone, so other functional moieties may also be incorporated either in separate blocks or randomly throughout the polymer backbone. The other functional groups can be used to impart important additional properties to the material. In one form of the invention, the polymeric chelator can be used in a single-phase extraction procedure, eliminating the need for the organic phase altogether.

In another embodiment, electrically conducting polymeric material with pendant chelator functionalities serve to efficiently and selectively bind ions from aqueous media into a heterogeneous insoluble polymer film. Subsequently, the redox properties of this conducting polymeric material can be utilized to exclude the metal ions into a different solution without stripping reagents or salt gradients. Importantly, because the process can be easily cycled, very modest separation efficiencies can be exploited to achieve complete separation.


  • Eliminates need for organic phase during extraction
  • Increased ion selectivity


  • Selectively binds actinides over lanthanides
  • Displays very high extraction efficiency
  • Can achieve extractions in a single-phase environment
  • Modular design to easily incorporate new/different chelator groups for different applications
  • Block copolymer material to modify properties by incorporating additional monomer blocks with different properties

Market potential/applications

Nuclear waste recycling
Waste water treatment
Geothermal brine extraction

Development Stage

Proof of concept