CESIUM EXTRACTION FROM A NOVEL CHEMICAL DECONTAMINATION PROCESS SOLVENT USING MAGNETIC MICROPARTICLES

Abstract

The chemical, 1-hydroxyethane-1,1-diphosphonic acid (HEDPA), has been the subject of recent publications and patents regarding decontamination and decommissioning applications, and its superiority as a decontamination agent has been highlighted in various field demonstrations. To recycle the aqueous HEDPA solvent and/or facilitate waste formation, it would be advantageous to remove dissolved radionuclides that originated from the contaminated surfaces. Cesium isotopes (^{137, 135}Cs) comprise the vast majority of radioactivity found in potential applications at nuclear power facilities.

The present study evaluated magnetic microparticles containing embedded silicotitanate powders for uptake of ¹³⁷Cs from HEDPA solution. Results indicate that the kinetics are rapid, reaching ∼95% of equilibrium within 10 min. The distribution coefficient (K _d) was between 3000 and 10,000 mL/g (90–98% ¹³⁷Cs removed) depending on particle mass-to-solution volume ratios. The excellent sorption of ¹³⁷Cs indicates that particle batches may be reused many times without a reduction in extraction efficiency. However, particle degradation and magnetic susceptibility reduction may be a problem due to the dissolution of the magnetite component by the diphosphonic acid. This may be overcome by substituting the magnetite component with other ferromagnetic materials such as Ni or Co alloys.

^*The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

Keywords:

• Cesium extraction
• Magnetic microparticles
• Silico-titanates
• HEDPA

ACKNOWLEDGMENTS

The authors thank C. Conner of the Chemical Technology Division at ANL for supplying the ¹³⁷Cs and H. Arafat for useful suggestions. This work was supported by the U.S. Department of Energy, Office of Environmental Management under guidance of the National Spent Nuclear Fuel Program under contract W-31-109-ENG-38.

Notes

^*The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

^*Unless a less porous polymeric matrix is used. The hydrophobic nature of such a matrix might have adverse effects on the quality of mixing between the solid and liquid phase.