Surface speciation of Eu3+ adsorbed on kaolinite by time-resolved laser fluorescence spectroscopy (TRLFS) and parallel factor analysis (PARAFAC).
Surface speciation of Eu3+ adsorbed on kaolinite by time-resolved laser fluorescence spectroscopy (TRLFS) and parallel factor analysis (PARAFAC).
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DOI：
10.1016/j.jcis.2012.01.060
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发表时间：
2012-05
影响因子：
9.9
通讯作者：
Keisuke Ishida;Takumi Saito;N. Aoyagi;T. Kimura;R. Nagaishi;S. Nagasaki;Satoru Tanaka
中科院分区：
文献类型：
--
作者：
Keisuke Ishida;Takumi Saito;N. Aoyagi;T. Kimura;R. Nagaishi;S. Nagasaki;Satoru Tanaka
时间分辨激光荧光光谱(TRLFS)是一种有效的荧光金属离子形态分析技术，可通过平行因子分析(PARAFAC)进一步扩展。以高岭石和三水铝石为参比矿物，结合批量吸附实验研究了Eu3+在高岭石和三水铝石上的吸附行为。PAFAFAC模拟提供了三个Eu3+与高岭石表面的络合物、一个外球(因子A)络合物和两个内球(因子B和C)络合物的荧光光谱、衰减寿命和相对强度分布。它们的强度分布定性地解释了测量到的Eu3+的吸附。在不同的H2O/D2O介质中的TRLFS结果表明，由于能量转移到表面，外球配合物表现出比Eu3+水离子更快的荧光衰减。B因子是一种内球复合体，在较高的pH、较高的盐浓度和较低的Eu3+浓度下占优势。它的光谱和寿命与Eu3+吸附在三水铝石上的光谱和寿命相似，表明它发生在高岭石的三水铝石层的边面上。通过与Eu(OH)3晶体和水溶液的光谱和寿命的比较，认为因子C是在较高Eu3+浓度下形成的Eu3+的多核表面络合物。
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 Eu3+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 Eu3+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 Eu3+. Based on the TRLFS results in varied H2O/D2O media, it was shown that the outer-sphere complex exhibited more rapid fluorescence decay than Eu3+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 Eu3+concentration. Its spectrum and lifetime were similar to those of Eu3+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 Eu3+formed at relatively high Eu3+concentration.