Physicochemistry of concentration mechanism of radioactive elements into zeolite and

Clay and zeolite minerals are usually characterized by considerably high adsorption or absorption effect of ions.Exactly，ions and anions are concentrated into mineral by substitution of crystallographic lattice and adsorption or absorption effect on the surface of mineral grains.In the present study some starting borosilicate glasses have been treated experimentally under the hydrothermal condition of a temperature of 200℃and a vapor pressure of 15.3 MPa In particular，the glass constituent elements such as Sr，Cs，Li and B have been examined in derail with respect to chemical behavior and distribution within zeolite formed in the present experiments。The present study program was established in order to apply for the assessment of geological disposal of high-level radioactive wastes.The starting borosilicate glasses consist of the system Na-Cs-Sr-B-Li-Si-Al-O.Experimental study has been performed by hydrothermal treatment of powdered borosilicate glass.The representative mineral…More species obtained in experiments is analcime(NaAlSi206·nH2O)belonging to zeolite group。Na lattice of analcime is substituted usually by Cs element The Cs-bearing and Na-free species is named as pollucite(CsAlSi2O6)。Pollucite is characterized by a deficient of H20 within its crystal In addition，the chemical reaction rate tends to decrease with the increase of Cs concentration of analcime。On the contrary，B and Li contribute obviously to progress in crystallization of analcime。The lattice parameter of analcime depends on amounts of Si of 48g site of the crystal，while the parameter doesn‘t necessarily depend on the contents of alkali or alkali earth elements.However the analcime formed from Li-bearing boroeilicate glass shows the feature of lattice properties larger than the one from Li-free borosilicate glass.Considering the charge balance of the crystal Li has to occupy the crystallographic lattice.The analcime formed from Sr-free borosilicate glass scarcely includes B，and the analcime formed from B-free borosilicate glass contains little Sr.It is concluded that the formation of Sr-bearing analcime should need necessarily B.Less

Clay and zeolite minerals are usually characterized by considerably high adsorption or absorption effect of ions. Exactly, ions and anions are concentrated into mineral by substitution of crystallographic lattice and adsorption or absorption effect on the surface of mineral grains. In the present study some starting borosilicate glasses have been treated experimentally under the hydrothermal condition of a temperature of 200℃ and a vapor pressure of 15.3MPa In particular, the glass constituent elements such as Sr, Cs, Li and B have been examined in derail with respect to chemical behavior and distribution within zeolite formed in the present experiments. The present study program was established in order to apply for the assessment of geological disposal of high-level radioactive wastes. The starting borosilicate glasses consist of the system Na-Cs-Sr-B-Li-Si-Al-O. Experimental study has been performed by hydrothermal treatment of powdered borosilicate glass. The representative mineral … More species obtained in experiments is analcime (NaAlSi206 ・ nH2O) belonging to zeolite group. Na lattice of analcime is substituted usually by Cs element The Cs-bearing and Na-free species is named as pollucite (CsAlSi2O6). Pollucite is characterized by a deficient of H20 within its crystal In addition, the chemical reaction rate tends to decrease with the increase of Cs concentration of analcime. On the contrary, B and Li contribute obviously to progress in crystallization of analcime. The lattice parameter of analcime depends on amounts of Si of 48g site of the crystal, while the parameter doesn't necessarily depend on the contents of alkali or alkali earth elements. However the analcime formed from Li-bearing boroeilicate glass shows the feature of lattice properties larger than the one from Li-free borosilicate glass. Considering the charge balance of the crystal Li has to occupy the crystallographic lattice. The analcime formed from Sr-free borosilicate glass scarcely includes B, and the analcime formed from B-free borosilicate glass contains little Sr. It is concluded that the formation of Sr-bearing analcime should need necessarily B. Less