Synthesis and characterization of a novel layered tin(IV) phosphate with ion exchange properties

A novel layered tin(IV) phosphate, Sn(NH4PO4)(HPO4). 2H(2)O (delta-SnP-NH4) , was synthesized under mild hydrothermal conditions (190 degrees C) in the presence of urea. The treatment of this compound with mineral acids I:ave a new phase of tin(IV) bis(monohydrogenphosphate), Sn(HPO4)(2). 3H(2)O (del ta-SnP-H). The layered nature of the solid was confirmed from amine interca lation, exfoliation in alkaline media, and the ion exchange behavior toward s alkali and alkaline earth ions. High affinity (K-d(Cs) similar to 5 x 10( 4) to 2 x 10(5) mL g(-1)) and capacity (160-200 mg Cs+ per g of exchanger) for Cs+ makes these materials promising for selective radioactive cesium re moval from contaminated groundwater and nuclear waste. (C) 1999 Elsevier Sc ience Ltd.