Uranium(VI) Adsorption and Surface Complexation Modeling onto Background Sediments from the F-Area Savannah River Site

详细信息    查看全文

• 作者：Wenming Dong ; Tetsu K. Tokunaga ; James A. Davis ; Jiamin Wan
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：February 7, 2012
• 年：2012
• 卷：46
• 期：3
• 页码：1565-1571
• 全文大小：378K
• 年卷期：v.46,no.3(February 7, 2012)
• ISSN：1520-5851

文摘

The mobility of an acidic uranium waste plume in the F-Area of Savannah River Site is of great concern. In order to understand and predict uranium mobility, U(VI) adsorption experiments were performed as a function of pH using background F-Area aquifer sediments and reference goethite and kaolinite (major reactive phases of F-Area sediments), and a component-additivity (CA) based surface complexation model (SCM) was developed. Our experimental results indicate that the fine fractions (鈮?5 渭m) in sediments control U(VI) adsorption due to their large surface area, although the quartz sands show a stronger adsorption ability per unit surface area than the fine fractions at pH < 5.0. Kaolinite is a more important sorbent for U(VI) at pH < 4.0, while goethite plays a major role at pH > 4.0. Our CA model combines an existing U(VI) SCM for goethite and a modified U(VI) SCM for kaolinite along with estimated relative surface area abundances of these component minerals. The modeling approach successfully predicts U(VI) adsorption behavior by the background F-Area sediments. The model suggests that exchange sites on kaolinite dominate U(VI) adsorption at pH < 4.0, goethite and kaolinite edge sites cocontribute to U(VI) adsorption at pH 4.0鈥?.0, and goethite dominates U(VI) adsorption at pH > 6.0.