不同温度下Np(Ⅳ)在北山地下水中的溶解度

    Solubility of Np(Ⅳ) in Beishan Groundwater at Different Temperatures

    • 摘要: 采用过饱和法研究了低氧条件下、30℃和60℃时Np(Ⅳ)在去离子水和甘肃北山地下水中的溶解度。结果表明,30℃时Np(Ⅳ)在去离子水和北山地下水中的溶解度分别为(3.4±1.0)×10-9mol/L和(1.0±0.3)×10-8mol/L;60℃时Np(Ⅳ)在去离子水和北山地下水中的溶解度分别为(1.9±0.6)×10-8mol/L和(3.7±0.5)×10-8mol/L;Np(Ⅳ)的溶解度随着温度升高而增加。同时利用SIT理论计算了实验条件下的热力学常数,确定了去离子水和北山地下水中的溶解度控制固相为Np(OH)4(am);去离子水体系中Np(Ⅳ)主要以Np(OH)4(aq)的形式存在,在北山地下水体系中Np(Ⅳ)主要以Np(OH)4(aq)和Np(CO32(OH)22-的形式存在。

       

      Abstract: The solubilities of Np(Ⅳ) in deionized water and groundwater were measured by oversaturation method at 30℃ and 60℃ and pH around 8.20. Na2S2O4 was added to keep the oxidation state of Np(Ⅳ) unchanged. The solubilities of Np(Ⅳ) in deionized water and groundwater are found to be (3.4±1.0)×10-9 mol/L and (1.0±0.3)×10-8 mol/L respectively at 30℃, and (1.9±0.6)×10-8 mol/L and (3.7±0.5)×10-8 mol/L at 60℃. The solubilities of Np(Ⅳ) in deionized water and groundwater increase as temperature increasing. The thermodynamic data at zero ionic strength were calculated at experiment condition by using the “Specific Ion Interaction Theory (SIT)”. The solubility-controlling solids in deionized water and groundwater are identified as Np(OH)4(am) by thermodynamic calculation. The dominant aqueous species are deduced to be Np(OH)4(aq) in deionized water, Np(OH)4(aq) and Np(CO32(OH)22- in groundwater.

       

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