Separation Science and Technology, Vol.37, No.16, 3703-3714, 2002
Cesium extraction from a novel chemical decontamination process solvent using magnetic microparticles
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,) Cs-135) 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 Cs-137 from HEDPA solution. Results indicate that the kinetics are rapid, reaching similar to95% of equilibrium within 10 min. The distribution coefficient (K-d) was between 3000 and 10,000 mL/g (90-98% Cs-137 removed) depending on particle mass-to-solution volume ratios. The excellent sorption of Cs-137 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.