Kinetic study on dissolution of UO2 powders in nitric acid
Kinetic study on dissolution of UO2 powders in nitric acid
复制标题
UO2粉末在硝酸中溶解的动力学研究
DOI：
10.1016/0022-3115(95)00059-3
复制
发表时间：
1995
影响因子：
3.1
通讯作者：
Y. Takashima
中科院分区：
文献类型：
--
作者：
Y. Ikeda;Y. Yasuike;K. Nishimura;S. Hasegawa;Y. Takashima
将90-150、300-355和850-1000 μm的UO 2粉末溶解在300 rpm搅拌的HNO 3溶液中。通过以0.2 ml/min的速度加入适当浓度的NaNO 2溶液，使HNO 2在溶剂溶液中的浓度保持恒定。在假定UO 2粉末为球形颗粒并从其外表面均匀溶解的情况下，分析了溶解反应。溶解速率常数（φ）以mol cm− 2 min − 1为单位，在不同浓度的HNO 3和HNO 2以及温度下测量。此外，还研究了UO 22+和NO3−离子对溶解速率的影响。结果表明，UO 22+离子对UO 2粉末的溶解速率没有促进作用，其表达式为φ =（ka+ kb[HNO 2]）[NO3-]T2.3（[NO3-]T=总硝酸盐浓度）。计算出ka和kb的活化能分别为79.5 ± 6.7和36.8 ± 2.9kJ/mol。在80°C，[HNO 3] = 8 M，[HNO 2] = 0.024M（M = mol/dm 3）时的φ值为8.5 × 10− 6 mol cm− 2 min −1。
UO2powders of 90–150, 300–355, and 850–1000 μm were dissolved in HNO3solutions stirred at 300 rpm. Concentrations of HNO2in dissolvent solutions were held constant by supplying NaNO2solutions of appropriate concentrations at 0.2 ml/min. The dissolution reactions were analyzed on the assumptions that the UO2powders are spherical particles and homogeneously dissolved from their external surface. Dissolution rate constants (φ) in mol cm−2min−1were measured at various concentrations of HNO3and HNO2, and temperatures. Furthermore, the effect of UO22+and NO3−ions on the dissolution rate was also examined. It was found that the dissolution rate of UO2powders is not accelerated by UO22+ions and expressed as φ = (ka+ kb[HNO2])[NO3−]T2.3([NO3−]T= total nitrate concentration). Activation energies (ΔE≠) for kaand kbwere evaluated to be 79.5 ± 6.7 and 36.8 ± 2.9 kJ/mol, respectively. The φ value at 80°C, [HNO3] = 8M, and [HNO2] = 0.024M (M = mol/dm3) is 8.5 × 10−6mol cm−2min−1.