Effect of Organic Co-Contaminants on Technetium and Rhenium Speciation and Solubility under Reducing Conditions

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• 作者：Estela Reinoso Maset ; Stephanie H. Sidhu ; Andrew Fisher ; Andrew Heydon ; Paul J. Worsfold ; Andrew J. Cartwright ; Miranda J. Keith-Roach
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：September 1, 2006
• 年：2006
• 卷：40
• 期：17
• 页码：5472 - 5477
• 全文大小：162K
• 年卷期：v.40,no.17(September 1, 2006)
• ISSN：1520-5851

文摘

The chemical and biogeochemical reduction of pertechnetate(TcO₄^-) and perrhenate (ReO₄^-) have been comparedalongside complexation of the reduced species by threeanthropogenic ligands relevant to nuclear waste (ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid(NTA), and isosaccharinic acid (ISA)). An HPLC size-exclusion column coupled to ICP-MS was used to separatethe species and quantify Tc and Re. During methoddevelopment, ReO₄^- showed recalcitrance to direct chemicalreduction by Sn(II) under conditions that readily reducedTcO₄^- and resulted in Tc(IV)-organic complexes. Inmicrocosm experiments of a silty loam soil containingTcO₄^-, ReO₄^-, and ISA (3.0 mM), EDTA (0.17 mM), or NTA(2.4 mM), anoxia developed to iron-reducing conditionsduring the 42 day experimental period. The majority of theTcO₄^- was reduced to particle-reactive Tc(IV) andremoved from solution during nitrate reduction, but therewas no chromatographic evidence of Tc(IV)-organiccomplexes in the porewater. Overall, the excess organiccomplexants added did not cause a measurable differencein the solubility of Tc(IV) over the control experiments inthis organic-rich (12% organic carbon) soil. ReO₄^- did notundergo reduction, as shown by the constant porewaterconcentration and the chromatographic data, and thus Redoes not function as an analogue for Tc under environmentalnitrate- and iron-reducing conditions.