کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7963016 | 1514137 | 2018 | 20 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Influence of temperature on the dissolution kinetics of synthetic LaPO4-monazite in acidic media between 50 and 130â¯Â°C
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی انرژی
انرژی هسته ای و مهندسی
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چکیده انگلیسی
Single-phase monazite-type ceramics are discussed as waste forms for the safe disposal of surplus plutonium or separated minor actinides. To gain a deeper insight into the mechanism governing the dissolution of monazite-type compounds, the dissolution kinetics of synthetic LaPO4-monazite was systematically studied by dynamic dissolution experiments carried out in the temperature range from 50 to 130â¯Â°C in acidic media (0.01â¯M HNO3). The dissolution rates at far from equilibrium conditions increased from 3.2â¯Ãâ¯10â5â¯gâ¯mâ2â¯dâ1 at 50â¯Â°C to 2.5â¯Ãâ¯10â4â¯gâ¯mâ2â¯dâ1 at 130â¯Â°C. Two different temperature regions were observed, in which the normalised dissolution rates of LaPO4 have a diverging temperature dependence, indicating two different mechanisms of dissolution: namely surface-controlled dissolution (Tâ¯=â¯50-90â¯Â°C; Eaâ¯=â¯44â¯kJâ¯molâ1) and transport-controlled dissolution (Tâ¯=â¯90-130â¯Â°C; Eaâ¯=â¯7.5â¯kJâ¯molâ1). Complementary thermodynamic modelling studies of the dissolution of LaPO4 at the experimental conditions show that La-rhabdophane (LaPO4·0.667H2O) is the thermodynamically favoured phosphate phase in aqueous environments below about 100â¯Â°C. Apparently, the hydration of monazite and the formation of a thin surface layer consisting of rhabdophane is an intermediate step controlling the dissolution kinetics of the LaPO4 monazite ceramics in low temperature aqueous environments.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Nuclear Materials - Volume 509, October 2018, Pages 488-495
Journal: Journal of Nuclear Materials - Volume 509, October 2018, Pages 488-495
نویسندگان
Yulia Arinicheva, Clemence Gausse, Stefan Neumeier, Felix Brandt, Konstantin Rozov, Stéphanie Szenknect, Nicolas Dacheux, Dirk Bosbach, Guido Deissmann,