Uptake of cesium and strontium cations by potassium-depleted phlogopite

Abstract Phlogopite mica was equilibrated with 1.0 N sodium chloride (NaCl)–0.2 N sodium tetraphenylborate (NaTPB)–0.01 M disodium ethylenediaminetetraacetic acid (EDTA) solution at room temperature resulting in an almost complete removal (92%) of the mica's interlayer K. X-ray powder diffraction analysis provides additional evidence that hydrated Na + ions had almost completely replaced the interlayer K + . Following equilibration, the c -axis spacing of the mica increased from 10.0 A to approximately 12.2 A. Cesium and Sr ion exchange isotherms indicate that K-depleted phlogopite is highly selective for both elements, the Cs + exchange capacity is 1.26 meq/g or 65% of the theoretical cation exchange capacity and the Sr 2+ exchange capacity is 1.94 meq/g or 100% of the theoretical exchange capacity of the mica. Kielland plots indicated that the mica was selective for Cs + when the equivalent exchange capacity of Cs + in the exchanger phase ( X¯ Cs ) was 2+ when X¯ Sr + equilibrated mica utilizing XRD indicated that a collapse of the c -axis spacing had occurred. Based on the high selectivity of 2+ and Cs + , this material may prove useful as an inorganic ion exchanger for these radioactive isotopes.