The Titanosilicate Glass Matrix for Immobilization of the Wastes Containing f-elements
The compositions of titanosilicated glasses were defined in the ternary system Na 2O-TiO 2-SiO 2, which provide not only a perfect glassy-like structure (body) formation, but also associative groups of mineral-like compounds-fresnoite (Ba 2TiSi 2O 8) and perovskite (SrTiO 3) were implemental as well. These associates can incorporate f-elements very firmly. To study how these associates can incorporate f-elements europium and uranium oxides were added to the system in amount of 3 wt.%. Transformation, which took place during the presynthesis of glasses and their crystallization, were investigated by X-ray diffraction (XRD) and differential-thermo analysis (DTA). Distribution of Eu and U throughout the melts body in steady state conditions was detected using laser-fluorescence method. As a result, Eu was uniformly distributed in the volume while U has a tendency has a tendency on sedimentation at bottom part due to gravitation. Oxidation state for Eu was (+3) and U was in (+6) state. Because glass networks were based mineral-like associates, namely fresnoite and perovskite, chemical durability of produced glasses was very high level, since equilibrium leach rate of Eu was 310 -6 g /m 2day and of U was 410 -6 g /m 2day.