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 )Si₂ O₁₀  ⋅ xH₂ O and exhibiting the structure of previously reported Rb₂ (Nb₂ O₄ )(Si₂ O₆ ) ⋅ H₂ 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 Nb⁵⁺ sites by Fe³⁺ ions. Exploratory ion-exchange assays evidence the considerable potential of this new silicate to remove rare-earth elements from aqueous solutions.