Neptunium(V) Sorption and Diffusion in Opalinus Clay

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• 作者：Tao Wu ; Samer Amayri ; Jakob Drebert ; Luc R. Van Loon ; Tobias Reich
• 刊名：Environmental Science & Technology
• 出版年：2009
• 出版时间：September 1, 2009
• 年：2009
• 卷：43
• 期：17
• 页码：6567-6571
• 全文大小：158K
• 年卷期：v.43,no.17(September 1, 2009)
• ISSN：1520-5851

文摘

The sorption and diffusion behavior of 8 × 10⁻⁶ M Np(V) in Opalinus Clay (OPA) with synthetic pore water (pH 7.6) as mobile phase was studied under ambient conditions by batch and diffusion experiments, respectively. The K_d value determined by batch experiments with OPA suspensions is equal to 0.025 ± 0.005 m³/kg. The diffusion-accessible porosity ε of intact OPA as determined by through- and out-diffusion experiments with tritiated water (HTO) is equal to 0.15 ± 0.01. The diffusion coefficient D_e and the rock capacity factor α of ²²Na⁺ in OPA were measured by through-, out-, and in-diffusion experiments and asserted the reliability of these diffusion techniques. For the diffusion of Np(V) in synthetic pore water, the capillary method gave D_w = (6.0 ± 1.0) × 10⁻¹⁰ m²/s. Due to the strong sorption of Np(V) on OPA, the diffusion of Np(V) was investigated by the in-diffusion technique. The diffusion parameters for Np(V) in OPA are D_e = (6.9 ± 1.1) × 10⁻¹² m²/s and α = 243 ± 4. This corresponds to K_d = 0.10 ± 0.01 m³/kg for the sorption of Np(V) in intact OPA.