| Abstract
| - A framework potassium titanium silicate K2TiSi3O9·H2O, compound I, was synthesizedby the reaction of a titanium−hydrogen peroxide complex and SiO2 in alkaline media undermild hydrothermal conditions (180 °C). This compound was converted to the correspondingsodium phase, Na2TiSi3O9·H2O (IV) and two proton-containing phases, K1.26H0.74TiSi3O9·1.8H2O (II) and K0.3H1.7TiSi3O9·2.4H2O (III) by ion exchange. These products were characterized by elemental analysis, TGA, FT-IR, MAS 29Si NMR, and X-ray diffraction. The ionexchange behavior of K2TiSi3O9·H2O and K0.3H1.7TiSi3O9·2H2O toward alkali, alkaline earth,and some transition metal ions solutions was studied. A high affinity of the protonic formof titanium trisilicate exchanger for cesium and potassium makes it promising forradionuclide-contaminated groundwater treatment and certain analytical separations. Thecrystal structure of K2TiSi3O9·H2O was found to be isomorphous with that of the zirconiumanalogue and contains a framework enclosing two types of tunnels. The exchange propertieswere interpreted on the basis of this structure and selectivity of the Zr and Ti phasesrationalized on the basis of the tunnel sizes. The structure of II was solved on the basis ofa monoclinic cell, whereas the K2TiSi3O9·H2O phase is orthorhombic. The relationship ofstructure II, monoclinic, to the parent orthorhombic structure is described. Phase III yieldeda complex X-ray pattern with evidence of disorder and a highly complex 29Si NMR spectrum.On reexchanging with K+, the original crystal lattice was restored.
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