Hydrothermal Synthesis of Framed Titanosilicates of the Ivanyukite Mineral Structure

Resumo

Phase formation within the Na₂O–TiO₂–SiO₂–H₂SO₄–H₂O system under hydrothermal treatment was studied in view of the development of new types of sorbents characterized by a framework structure similar to that of ivanyukite (Na₄(TiO)₄(SiO₄)₃ · 4–6Н₂О). The excess of silicon and sodium related to titanium (III) and (IV) along with an alkaline medium of pH values up to 12 causes the “supersaturation” of the salt mass and controls the formation rate of the sediments by stabilizing the phase composition, structure, and surface conditions. The specificity of interactions between SiO₄ tetrahedrons and TiO₆ octahedrons in ivanyukite promotes the formation of channels containing Na⁺ ions and water molecules. This effect combined with the developed mesoporous surface of the grains permits the use of synthetic ivanyukite as an effective ion exchanger.