Microporous Framework (Nb, Fe)-Silicate with Much Potential to Remove Rare-Earth Elements from Waters.

Nanoparticles of a new small-pore metal silicate formulated as Na 2.9 (Nb 1.55 Fe 0.45 )Si 2 O 10  ⋅ xH 2 O and exhibiting the structure of previously reported Rb 2 (Nb 2 O 4 )(Si 2 O 6 ) ⋅ H 2 O have been synthesized under mild hydrothermal conditions. Replacement of the bulky Rb + by smaller Na + ions was accomplished by stabilizing the framework structure via partial occupancy of the Nb 5+ sites by Fe 3+ ions. Exploratory ion-exchange assays evidence the considerable potential of this new silicate to remove rare-earth elements from aqueous solutions.