首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Effect of humic acid on the pH-dependent adsorption of terbium (III) onto geological materials
Institution:1. Ocean College, Zhejiang University, Zhoushan 316021, PR China;2. College of Environment and Resources, Fuzhou University, Fuzhou, Fujian, PR China;3. Key Lab of Marine Ecosystem and Biogeochemistry, Second Institute of Oceanography of SOA, Hangzhou 310012, PR China;4. Department of Oceanography, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC;1. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, PR China;2. School of Environmental Studies, China University of Geosciences, Wuhan, 430074, PR China;3. Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA;4. Department of Earth and Environmental Sciences, University of Texas at Arlington, Arlington, TX 76019, USA
Abstract:Mobilization of actinides by interaction with humic colloids in aquifers is essentially determined by the geochemical conditions. In this study, the pH dependence of the influence of humic acid on metal adsorption on a variety of geological solids (kaolinite, phyllite, diabase, granite, sand) was investigated for Tb(III) as an analogue of trivalent actinides, using 160Tb as a radiotracer. Humic material was radiolabelled with 131I to allow experiments at low DOC concentrations, as encountered in subsurface systems in the far-field of a nuclear waste repository. For all solids, a changeover from mobilization to demobilization is observed on acidification. Except for phyllite, the reversal occurs at slightly acidic pH values, and is thus relevant in respect of risk assessments. A composite distribution model was employed to reproduce the changeover on the basis of the underlying constituent processes. For this purpose, humate complexation of Tb(III) and adsorption of humic acid as a function of pH were investigated as well. Although the ternary systems cannot be constructed quantitatively by combining the binary subsystems, the relevant interdependences are adequately described by the composite approach. For a more general discussion in view of the diversity of natural organic colloids, adsorption isotherms of various humic and fulvic acids on sand were compared.
Keywords:
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号