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Geochemistry and thermodynamics of transuranium elements in ultrafine interstice under deep geosphere.

深层地圈超细间隙中超铀元素的地球化学和热力学。

基本信息

批准号：
08458117
负责人：
NAGASAKI Shinya
金额：
$ 4.48万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

Investigation of the chemical behavior of lanthanides and actinidesin the geosphere is important for the safety assessment of high-level radioactive waste disposal. However, determination of speciation for lanthanides and actinides is difficult, because it is too hard to distinguish between metal ion and colloidal metal in aqueous solution. Laser-induced breakdown spectroscopy (LIBS) can detect both ions and microparticles of metals in aqueous solution, especially, high-sensitive to microparticles. In this study, we analyzed Eu(III) ion and Eu_2O_3 particle in aqueous solution by LIBS, and measures the hydrolysis behavior of Eu(III) in aqueous solution. Furthermore, we tried to detect the plasma emission of Eu(III) ions sorbed on TiO_2 particles.Plasma emission of Eu was observed at 420.505 nm both in Eu(III) aqueous solution and in Eu_2O_3 suspended solution. The emission line was generally used for quantitative analysis of Eu. The plasma emission intensity of Eu_2O_3 was higher than … More that of Eu(III) ions when Eu concentration was same, and absorption band of Eu(III) ions was observed in LIBS spectrum of Eu(III) apeous solution. These results indicated Eu(III) ions can be distinguished from Eu_2O_3 particles in aqueous solution by LIBS.The plasma emission intensity of Eu increased with Eu concentration. The intensity vs. concentration plot showed a good linearity in low concentration range (approximately 10^<-2> to 10^<-1> mol/dm^3 and 1O^<-5> to 10^<-4> mol/dm^3 for Eu(III) ions and Eu_2O_3 particles, respectively).The plasma emission intensity of Eu increased with pH of Eu(III) aqueous solution, and drastic increase of emission intensity was observed above pH=6. The tendency was similar with solubility curve of Sm(OH)_3, which calculated using stability constants in litrature[1]. This result suggested that LIBS is useful for measurement of hydrolysis and precipitation behavior of Eu(III) in aqueous solution.From plasma emission of Eu(III) ions sorbed on TiO_2 particles, it was found that only Eu(III) ions on TiO_2 may be detected by LIBS.because the emission from Eu(III) ions in solution was not observed. We also have tried to use time-resolved LIBS to analyze sorption form of Eu(III) ions.[1] K.A.Gschneider, Jr., L.Eyring, eds. "Handbook on the Physics and Chemistry of Rare Earths, Vol.15" Elsevior Science (1991) 431 Less

研究镧系元素和锕系元素在地圈中的化学行为对高放废物处置安全评价具有重要意义。然而，镧系元素和锕系元素在水溶液中的形态分析比较困难，因为在水溶液中很难区分金属离子和胶体金属。激光诱导击穿光谱（LIBS）可以同时检测水溶液中金属离子和微粒，特别是对微粒具有高灵敏度。本研究利用激光诱导背散射技术对水溶液中Eu（III）离子和Eu_2O_3粒子进行了分析，并测量了Eu（III）在水溶液中的水解行为。此外，我们还对Eu（III）离子吸附在TiO_2颗粒上的等离子体发射进行了研究，在Eu（III）水溶液和Eu_2O_3悬浮液中均观察到了Eu离子在420.505 nm处的等离子体发射。发射线通常用于Eu的定量分析。Eu_2O_3的等离子体发射强度高于 ...更多信息当Eu（III）浓度相同时，Eu（III）离子的吸收带明显增加，并且在Eu（III）水溶液的LIBS光谱中观察到Eu（III）离子的吸收带。结果表明，在水溶液中，Eu（III）离子和Eu_2O_3颗粒可以被LIBS区分开来，Eu离子的等离子体发射强度随Eu浓度的增加而增强。在低浓度范围内（Eu（III）离子和Eu_2O_3颗粒分别为10 <-2>~ 10 μ <-1>mol/dm^3和10 <-5>~ 10 μ <-4>mol/dm^3），Eu的等离子体发射强度与浓度呈良好的线性关系; Eu的等离子体发射强度随Eu（III）水溶液pH的增加而增加，当pH=6时，发射强度急剧增加。这一趋势与文献[1]中用稳定常数计算的Sm（OH）_3溶解度曲线相似。从Eu（III）离子吸附在TiO_2颗粒上的等离子体发射光谱可以看出，由于Eu（III）离子在溶液中的发射光谱不存在，LIBS只能检测到Eu（III）离子在TiO_2颗粒上的等离子体发射光谱。我们还尝试使用时间分辨LIBS来分析Eu（III）离子的吸附形式。[1]K.A.Gschneider，Jr. L.Eyring，eds.“稀土物理化学手册，第15卷”Elsevior Science（1991）431减