Pendelyuk O. Mixed hydrous manganese and titanium oxides as sorbents for removal of strontium and catalysts for gas phase oxidation of organic substances

The thesis deals with obtaining and an in-depth investigation of amorphous sorbents for strontium based on the MnO2-TiO2 system. It is found that from solutions containing the salts of manganese-II and hydrogen peroxide, alkalis precipitate Mn3O4 (hausmannite) or mixtures of hausmannite and MnOOH (manganite). By means of template synthesis, using potassium ions as templates, the sorbents of the highest affinity towards strontium ions are obtained. pH potentionetric titration and IR spectroscopy in the region of the vibrations of OH-bonds prove that the materials in question are protonated oxides, and the sorption on them can be considered as the ion exchange of surface ОН--groups by the hydrated Sr2+ ions. Their exchange capacity by strontium exceeds 90 mg/g, and selectivity coefficients are close to 110. In batch studies of the sorption of 90Sr, a high efficiency of the materials obtained has been proven in the removal of radiostrontium from both supernatant solutions accumulated in the reactor disassembly basins at Savannah River site, USA (Kd=60000-100000 mL/g) and waters collected under the Shelter erected over the destroyed Chernobyl 4th Block (Kd>30000 мл/г). In catalytic tests, it has been found that on mixtures of manganese and titanium dioxides, the complete conversion of propane and benzene to СО2 is attained at 250 ° С, and the complete transformation of СО to СО2 occurs at 175 °С.