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[PY-30] Investigation of the chemical stability of selenate-bearing sodalite and cancrinite and factors affecting its formation process

○Niko Dian Pahlevi¹, Binglin Guo¹, Keiko Sasaki¹ (1. Kyushu University, Department of Earth Resources Engineering)

Keywords:TCLP test, Selenate-bearing sodalite, Selenate-bearing cancrinite , Hydrothermal method

Matrix For Stable ⁷⁹ Se Retention Is Desired To Be Developed For Long - Term Storage. Sodalite (Na _{(6 Tasu 2 Y Tasu Z)} (AlSiO ₄ ) ₆ (X) _(Y) (OH) _Z .NH ₂ O) And Cancrinite Na _{(6 + 2y + z)} (AlSiO ₄ ) ₆ (X) _(y) (OH) _z .nH ₂ O) can be efficient matrix for selenate (SeO ₄ ^{2 -} Thus, in the present work work, the chemical stability of selenate-bearing sodalite and selenate-bearing cancrinite were investigated as Well As The Factors Affecting To The Formation Process.

TCLP Test Was Performed On The Solid Products To Evaluate Their Chemical Stability. It Was Revealed That The Solid Products Which Contain Very Low Weight Percent Of Cancrinite Showed Highest Chemical Stability. The Increase Of Cancrinite Weight Percent directly affected the chemical stability. not supported by XRD which are showing a decrease in d ₃₀₀ cancrinite peak intensity after TCLP test. SEM images also selenate-bearing sodalite after TCLP test was recorded as low as 1.2 ppm which are 71 times lower than selenate-bearing cancrinite (85.1 ppm). Meanwhile, These more than one borderline temperature, with an increase in the initial selenate concentration, the crystallized phase, immobilized selenate, changed from sodalite to cancrinite. These results indicated the hydrothermal temperature and the initial doped selenate affect the matrix phase to accommodate selenate.