Synthesis and characterization of the ion exchange properties of a spherically granulated sodium aluminophosphatesilicate

Spherically granulated sodium aluminosilicophosphate (APS) of the empirical formula Na4Al4PSi18O46.5. 18H(2)O was synthesized by a gel method. The APS was characterized by elemental analysis, X-ray diffraction, TGA and Al-27, Si-28 and P-31 MAS NMR spectroscopy methods. Ion exchange of alkali, alkal ine 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 isoth erms of alkali, alkaline earth and some other divalent cations were determi ned and the corrected selectivity coefficients as a function of metal loadi ng 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 lo w affinity for alkali and alkaline earth metal ions. A testing of the APS i n complex solutions suggests that it could be a promising exchanger for tre atment of some specific nuclear waste and contaminated environmental and bi ological liquors from radioactive cesium and toxic heavy metal ions.