CHANGES IN HYDRATION PROPERTIES OF SILICA-GEL IN A PROCESS OF ITS CARBONIZATION BY PYROLYSIS OF ACETYLACETONE ZN (TI) ACETYLACETONATES

Changes in hydration properties of different compounds in a process of formation of a complex adsorbent comprising carbon and TiO2 or Zn2SiO 4 on its surface were studied by H-1 NMR spectroscopy under conditions of a liquid phase freezing. Adsorbents were synthesized on the basis of a mesoporous silica gel, the surface of which was covered with a ca rbon layer formed in a process of a high temperature pyrolysis of acet ylacetone, Titanium oxide and zinc silicate on the surface of a parent silica gel were formed by a pyrolysis of acetylacetonates of the corr esponding metals. It has been revealed that the main types of surface- active sites for the adsorbed water molecules on the carbosil surface are the systems of condensed benzene nuclei of a carbon component of t he surface and hydroxyl groups of silica surface. Zn2SiO4 and TiO2 hav e been formed in a process of pyrolysis of the corresponding metal ace tylacetonates. Water bound with the oxide component of the carbosil su rface exceeds 80% of the total amount of the adsorbed water. The carbo n component of the surface is localized mainly in the narrowest pores. A minimum value in the free surface energy was recorded for the carbo sil sample. (C) 1998 Academic Press.