Montgomery D, Barber K, Edayilam N, Oqujiuba K, Young S, Biotidara T, Gathers A, Danjaji M, Tharayil N, Martinez N, Powell B
Clemson University, Clemson, SC 29634, United States.
Clemson University, Clemson, SC 29634, United States.
J Environ Radioact. 2017 Jun;172:130-142. doi: 10.1016/j.jenvrad.2017.03.017. Epub 2017 Mar 27.
Batch sorption experiments were conducted with 0.5-50 ppb Tc, Cs, Np and U in the presence and absence of citrate and/or oxalate in a 25 g/L Savannah River Site (SRS) soil suspension. Citrate and oxalate were the ligands of choice due to their relevancy to plant exudates, the nuclides were selected for their wide range of biogeochemical behavior, and the soil from SRS was selected as a model Department of Energy (DOE) site soil. Batch samples were continually mixed on a rotary shaker and maintained at a pH of approximately 5. Analysis via ICP-MS indicated that sorption of Np increased with ligand concentration compared to baseline studies, as did sorption of Tc although to a lesser extent. The increased sorption of Np is proposed to be due to a combination of factors that are dependent on the ligand(s) present in the specific system including, ligand dissolution of the soil by citrate and formation of tertiary soil-oxalate-Np complexes. The increased Tc sorption is attributed to the dissolution of the soil by the ligands, leading to an increase in the number of available sorption sites for Tc. Uranium sorption decreased and dissolution of native uranium was also observed with increasing ligand concentration, thought to be a result of the formation of strong U-ligand complexes remaining in the aqueous phase. The majority of these effects were observed at the highest ligand concentrations of 50 mg/L. No notable changes were observed for the Cs system which is ascribed to the minimal interaction of Cs with these organic ligands.
在25 g/L的萨凡纳河工厂（SRS）土壤悬浮液中，在有和没有柠檬酸盐和/或草酸盐存在的情况下，对浓度为0.5 - 50 ppb的锝、铯、镎和铀进行了批量吸附实验。柠檬酸盐和草酸盐因其与植物分泌物的相关性而被选为配体，选择这些核素是因为它们具有广泛的生物地球化学行为，选择SRS的土壤作为能源部（DOE）场地土壤的模型。批量样品在旋转振荡器上持续混合，并保持在pH约为5的条件下。通过电感耦合等离子体质谱（ICP-MS）分析表明，与基线研究相比，镎的吸附随着配体浓度的增加而增加，锝的吸附也是如此，尽管程度较小。镎吸附增加被认为是由于多种因素的综合作用，这些因素取决于特定系统中存在的配体，包括柠檬酸盐对土壤的配体溶解以及三元土壤 - 草酸盐 - 镎络合物的形成。锝吸附增加归因于配体对土壤的溶解，导致锝可用吸附位点数量增加。随着配体浓度的增加，铀的吸附减少，并且还观察到天然铀的溶解，这被认为是形成了留在水相中的强铀 - 配体络合物的结果。这些影响大多在50 mg/L的最高配体浓度下观察到。对于铯系统未观察到明显变化，这归因于铯与这些有机配体的相互作用极小。
