Na+/H+ Ion-exchange Process on Layered Hydrous Titanium Dioxide

Abstract The Na+/H+ ion-exchange on layered hydrous titanium dioxide, H2Ti4O9·1.2–1.3H2O, has been studied from chemical and structural aspects. The ion-exchange reaction proceeded stepwise through two stages [0–50%, 50–72% conversion]. In stage I a discontinuous change in interlayer distance took place and the 1/2-exchanged phase with a widened interlayer distance appeared. The exchange in stage II proceeded via a solid solution and resulted in the 3/4-exchanged phase. The variation in unit cell dimensions indicates that these partially exchanged phases were formed by swelling the spacing of adjacent [Ti4O92−]n sheets. The structural and the thermoanalytical data can be interpreted on the basis of the structural model in which sodium ions and water molecules are arranged in a double row in the interlayer region.