Adsorption of Plutonium Oxide Nanoparticles

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• 作者：Moritz Schmidt ; Richard E. Wilson ; Sang Soo Lee ; L. Soderholm ; P. Fenter
• 刊名：Langmuir
• 出版年：2012
• 出版时间：February 7, 2012
• 年：2012
• 卷：28
• 期：5
• 页码：2620-2627
• 全文大小：413K
• 年卷期：v.28,no.5(February 7, 2012)
• ISSN：1520-5827

文摘

Adsorption of monodisperse cubic plutonium oxide nanoparticles (鈥淧u-NP鈥? [Pu₃₈O₅₆Cl_x(H₂O)_y]^(40-x)+, with a fluorite-related lattice, approximately 1 nm in edge size) to the muscovite (001) basal plane from aqueous solutions was observed in situ (in 100 mM NaCl background electrolyte at pH 2.6). Uptake capacity of the surface quantified by 伪-spectrometry was 0.92 渭g Pu/cm², corresponding to 10.8 Pu per unit cell area (A_UC). This amount is significantly larger than that of Pu⁴⁺ needed for satisfying the negative surface charge (0.25 Pu⁴⁺ for 1 e^{鈥?/sup>/A_UC). The adsorbed Pu-NPs cover 17% of the surface area, determined by X-ray reflectivity (XR). This correlates to one Pu-NP for every 14 unit cells of muscovite, suggesting that each particle compensates the charge of the unit cells onto which it adsorbs as well as those in its direct proximity. Structural investigation by resonant anomalous X-ray reflectivity distinguished two different sorption states of Pu-NPs on the surface at two different regimes of distance from the surface. A fraction of Pu is distributed within 11 脜 from the surface. The distribution width matches the Pu-NP size, indicating that this species represents Pu-NPs adsorbed directly on the surface. Beyond the first layer, an additional fraction of sorbed Pu was observed to extend more broadly up to more than 100 脜 from the surface. This distribution is interpreted as resulting from 鈥渟tacking鈥?or aggregation of the nanoparticles driven by sorption and accumulation of Pu-NPs at the interface although these Pu-NPs do not aggregate in the solution. These results are the first in situ observation of the interaction of nanoparticles with a charged mineral鈥搘ater interface yielding information important to understanding the environmental transport of Pu and other nanophase inorganic species.}