93Nb MAS NMR of niobium containing silicotitanate exchange materials

Crystalline silicotitanate (CST), HNa3Ti4Si2O14.4H(2)O, is a highly selective Cs ion exchanger, making it an attractive material for removal of (CS)-C-137 from nuclear waste solutions. The Cs selectivity can be improved further by replacing a fraction of the framework titanium with niobium to form Nb-CST. High-speed Nb-93 magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy was utilized to characterize framework changes as a function of Cs loading in a series of Nb-CST materials. Based on these 93 Nb MAS NMR studies it is argued that the niobium octahedra present in Nb-CST have near uniform Nb-O bond lengths and are slightly distorted from cubic symmetry.