Synthetic Inorganic Ion-Exchange Materials. LVIII. Hydrothermal Synthesis of a New Layered Lithium Titanate and Its Alkali Ion Exchange

Abstract A new crystalline hydrous lithium titanate, (Li1.81, H0.19)Ti2O5·2.2H2O, was synthesized hydrothermally at 190 °C by a reaction of hydrous titanium dioxide with LiOH solution. The compound has a layered structure and showed a C–base-centered orthorhombic system with the lattice constants, ao=16.66±0.02 Å, bo=3.797±0.002 Å, and co=3.007±0.003 Å. The lattice constants were changed to ao=18.08±0.03 Å, bo=3.784±0.003 Å, and co=2.998±0.002 Å upon conversion to the hydrogen form. The 8.5% increase in the ao value along the a axis suggests a layered structure. A hypothetical structure was proposed. The H+ form showed the ion-exchange selectivity at an ionic strength of 0.1 in the order of K+<Na+<Li+ at pH>6 and Li+<K+<Na+ at pH<6.