SYNTHESIS AND CHARACTERIZATION OF THE ION EXCHANGE PROPERTIES OF A SPHERICALLY GRANULATED SODIUM ALUMINOPHOSPHATESILICATE

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Abstract
Spherically granulated sodium aluminosilicophosphate (APS) of the empirical formula Na4Al4PS18O46.5 18H2O was synthesized by a gel method. The APS was characterized by elemental analysis, X-ray diffraction, TGA and 27AI, 28Si and 31P MAS NMR spectroscopy methods. Ion exchange of alkali, alkaline earth and some other divalent metal cations by APS was studied in batch conditions. It was found that the APS has a cation exchange capacity of 2.5 meq/g and exhibits rapid kinetics of ion exchange. The ion exchange isotherms of alkali, alkaline earth and some other divalent cations were determined and the corrected selectivity coefficients as a function of metal loading were analyzed. It was found that APS exhibits a high affinity for cesium ion, a moderate affinity for some heavy metal cations (Pb2+, Zn+) and a low affinity for alkali and alkaline earth metal ions. A testing of the APS in complex solutions suggests that it could be a promising exchanger for treatment of some specific nuclear waste and contaminated environmental and biological liquors from radioactive cesium and toxic heavy metal ions.