Pillared Montmorillonites: Cesium-Selective Ion-Exchange Materials

• Published in: Separation science and technology 1999-01, Vol.34 (12), p.2293-2305
• Main Authors: SYLVESTER, PAUL, CLEARFIELD, ABRAHAM, DIAZ‡, RICARDO J.
• Format: Article
• Language: English
• Subjects: Cesium; Groundwater; Ion exchange; Montmorillonite; Pillared clay
• ISSN: 0149-6395; 1520-5754
• DOI: 10.1081/SS-100100773

A zirconia-pillared and an alumina-pillared montmorillonite clay were found to exhibit high K d s for trace levels of cesium (2.5 ppb) in the presence of high concentrations of Ca 2+ Mg 2+ and Na + ions with distribution coefficients (K d s for 137 Cs exceeding 1×10 5 mL/g over a wide range of competing ion concentrations. An excess of K + ions, however, caused a dramatic reduction in the Cs K d s for both of the materials. These results were in contrast to the parent montmorillonite which exhibited far lower K d s for 137 Cs, particularly in the presence of high concentrations of Mg 2+ and Ca 2 . Batch tests in simulated groundwaters showed that both pillared clays efficiently removed 137 Cs from solution, with the best K d s being approximately 8.5 × 10 5 mL/g in a potassium-free groundwater. The materials performed less well in a groundwater with a high potassium concentration, but still gave K d s similar to commercially available zeolites. The rate of 137 Cs uptake was found to be rapid with both the alumina- and zirconia-pillared clays extracting > 90% of the 137 Cs from a 0.1 M NaNO 3 solution within 5 minutes. ‡ Undergraduate Research Scholar