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SORPTION BEHAVIOR OF ACTINOIDS ON WEATHERED MINERALS

锕系元素对风化矿物的吸附行为

基本信息

批准号：
07680521
负责人：
YAMAZAKI Hiromichi
金额：
$ 1.6万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Understanding the sorption behavior of nuclides having long-term radiological toxicity onto geological materials is central to the safety assessment of underground disposal of radioactive waste. In order to see the effect of crystal structure, crystallinity and surface conditions of various oxides and hydrous oxides on the sorption of metal ions, the sorption of tracer concentrations of Np(V) on naturally occurring iron and alumiun minerals, synthetic oxide powders and laboratory-prepared hydrous oxides was studied as a function of pH.The orders of their abilities to sorb Np(V) were hydrous oxides including oxyhydroxides and hydroxides > synthetic oxide powders > minerals (hematite, magnetite and corundum). These results suggest that the sorption of tracer concentrations of actinoids is controlled primarily by their crystal structures and subsidiarily by their surface areas, indicating that the transformation of oxides and hydrous oxides of iron and aluminum occurring in natural enviro … More nments will give a serious influence on the migration of radionuclides. The effects of metal ion saturation on the sorption of Eu(III) and Co(II) on goethite, gibbsite and laboratory-prepared amorphous iron and aluminum oxides were studied as a function of pH over a wide range of metal ion concentrations. When the metal ion concentrations were low, a simple Langmuir equation, assuming a single binding constant, was capable of describing sorption on these hydrous oxides. At high metal ion concentrations, sorption on goethite and gibbsite exhibited clear saturation maxima, indicating that sorption on these minerals was controlled by a simple one-to-one interaction between the metal ion and a binding site. Conversely, sorption on laboratory-prepared hydrous oxides continued to increase even at high metal ion concentrations, indicating that sorption on amorphous hydrous oxides proceeds through a somewhat different pathway, such as the formation of a pricipitate or a solid solution at the binding surface. Less

了解具有长期放射性毒性的核素对地质物质的吸附行为是放射性废物地下处置安全性评价的核心。为了观察各种氧化物和水合氧化物的晶体结构、结晶度和表面条件对金属离子吸附的影响，本文研究了Np(V)示踪剂浓度对天然存在的铁、铝矿物、合成氧化物粉末和实验室制备的水合氧化物吸附能力随ph值的变化规律。磁铁矿和刚玉)。这些结果表明，放线素对示踪剂浓度的吸附主要受其晶体结构的控制，其次受其表面积的控制，表明自然环境中铁和铝的氧化物和水合氧化物的转变，对放射性核素的迁移有严重的影响。在较宽的金属离子浓度范围内，研究了金属离子饱和度对Eu（III）和Co（II）在针铁矿、三水石和实验室制备的无定形铁和铝氧化物上吸附的影响。当金属离子浓度较低时，一个简单的Langmuir方程，假设一个单一的结合常数，能够描述这些水合氧化物的吸附。在高金属离子浓度下，针铁矿和三水石的吸附表现出明显的饱和最大值，表明这些矿物的吸附受金属离子与结合位点之间简单的一对一相互作用控制。相反，即使在高金属离子浓度下，实验室制备的水合氧化物上的吸附也继续增加，这表明在无定形水合氧化物上的吸附通过某种不同的途径进行，例如在结合表面形成沉淀或固溶体。少