Processing of Radioactive Waste Solution with Zeolites (I) : Thermal-Transformations of Na, Cs and Sr Forms of Zeolites
Thermal-transformations of several kinds of zeolites have been studied by means of differential thermal analysis (DTA), thermo-gravimetric analysis (TGA) and X-ray powder diffraction. Some synthetic zeolites (A, X, Y, mordenite), natural mordenite and clinoptilolite were used. Sodium forms of A and X zeolites recrystallized above 1000℃ to nepheline (NaAlSiO_4) , whereas the structure of zeolite Y, synthetic and natural mordenites, and clinoptilolite collapsed above around 900℃ and did not recrystallize below 1200℃. Cesium-form zeolites changed to pollucite (CsAlSi_2O_6) above 1000℃ for A and X, and above 1100℃ for Y. The mordenites and clinoptilolite were destroyed on heating above 1000℃ to form amorphous phases. In the case of Sr forms, A and X zeolites recrystallized to strontium aluminosilicate (SrAl_2Si_2O_8) above 1100℃ and Y zeolite above 1200℃ ; on the other hand, mordenite and clinoptilolite became amorphous above 1200℃. Microscopic examination and density measurement support these results.
- Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy
Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy 29 102-111, 1980