URANYL IONS IN PERFLUORINATED (NAFION AND FLEMION) MEMBRANES - SPECTROSCOPIC AND PHOTOPHYSICAL PROPERTIES AND REACTIONS WITH POTASSIUM HYDROXIDE

被引:9
作者
KELLY, JM [1 ]
MEUNIER, HM [1 ]
MCCORMACK, DE [1 ]
MICHAS, A [1 ]
PINERI, M [1 ]
机构
[1] CEN,DEPT RECH FONDAMENTALE,F-38041 GRENOBLE,FRANCE
关键词
emission lifetime; Flemion; membrane-bound oxides; Nafion; perfluorinated ionomers; uranium;
D O I
10.1016/0032-3861(90)90374-8
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Absorption spectra, luminescence spectra and excited-state lifetimes of uranyl ions (UO2+2) incorporated in Nafion or Flemion membranes have been studied as a function of hydration. Marked changes in the nature of the spectra and emission lifetime are observed. Thus at 291 K the lifetime changes from 2.0μs in a water-swollen Nafion membrane to 640 μs in a thoroughly dried sample. The lifetime of the dried sample is temperature-invariant, whereas those of heavily hydrated samples show activation energies of 30 ± 2 kJ mol-1, suggesting that water plays a key role in the excited-state deactivation. A changeover in the decay mechanism is found for samples of intermediate water content. Energy transfer from excited UO2+2 to Eu3+ is observed, the effect being enhanced by membrane dehydration and being much more pronounced for Flemion membranes than for Nafion. Treatment of the UO2+2-containing membranes with aqueous KOH causes the formation of products concentrated near the membrane surface. The absorption spectra, luminescence spectra and X-ray diffraction of these materials have been compared with those of the oxides and uranates formed in solutions of various pH. Transmission electron microscopy reveals particles of less than 1 μm in size. © 1990.
引用
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页码:387 / 394
页数:8
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