Nuclear Waste Management Organization of Japan, 4-1-23 Shiba, Minato-ku, Tokyo 108-0014, Japan.
J Colloid Interface Sci. 2012 May 15;374(1):258-66. doi: 10.1016/j.jcis.2012.01.060. Epub 2012 Feb 8.
Time-resolved laser fluorescence spectroscopy (TRLFS) is an effective speciation technique for fluorescent metal ions and can be further extended by the parallel factor analysis (PARAFAC). The adsorption of Eu(3+) on kaolinite as well as gibbsite as a reference mineral was investigated by TRLFS together with batch adsorption measurements. The PAFAFAC modeling provided the fluorescence spectra, decay lifetimes, and relative intensity profiles of three Eu(3+) surface complexes with kaolinite; an outer-sphere (factor A) complex and two inner-sphere (factors B and C) complexes. Their intensity profiles qualitatively explained the measured adsorption of Eu(3+). Based on the TRLFS results in varied H(2)O/D(2)O media, it was shown that the outer-sphere complex exhibited more rapid fluorescence decay than Eu(3+) aquo ion, because of the energy transfer to the surface. Factor B was an inner-sphere complex, which became dominant at relatively high pH, high salt concentration and low Eu(3+) concentration. Its spectrum and lifetime were similar to those of Eu(3+) adsorbed on gibbsite, suggesting its occurrence on the edge face of the gibbsite layer of kaolinite. From the comparison with the spectra and lifetimes of crystalline or aqueous Eu(OH)(3), factor C was considered as a poly-nuclear surface complex of Eu(3+) formed at relatively high Eu(3+) concentration.
时间分辨激光荧光光谱法（TRLFS）是一种有效的荧光金属离子形态分析技术，通过平行因子分析（PARAFAC）可以进一步扩展。本研究采用 TRLFS 与批量吸附实验相结合，研究了 Eu(3+)在高岭石和三水铝石（参考矿物）上的吸附。PAFAFAC 模型提供了高岭石上三种 Eu(3+)表面配合物的荧光光谱、衰减寿命和相对强度分布；一个外配位（因子 A）配合物和两个内配位（因子 B 和 C）配合物。它们的强度分布定性地解释了测量的 Eu(3+)吸附。基于在不同 H(2)O/D(2)O 介质中的 TRLFS 结果，表明由于能量转移到表面，外配位配合物的荧光衰减比 Eu(3+)水合离子更快。因子 B 是一种内配位配合物，在相对较高的 pH 值、高盐浓度和低 Eu(3+)浓度下占主导地位。其光谱和寿命与在三水铝石上吸附的 Eu(3+)相似，表明其发生在高岭石的三水铝石层边缘面上。通过与结晶或水合 Eu(OH)(3)的光谱和寿命进行比较，因子 C 被认为是在相对高的 Eu(3+)浓度下形成的 Eu(3+)多核表面配合物。
