The sorption of Eu species onto nano-size silica-water interfaces was investigated using fluorescence spectroscopy for pH ranges of 1-8.5 and an initial Eu concentration (C Eu) of 2×10 -4 M. The sorption rate...The sorption of Eu species onto nano-size silica-water interfaces was investigated using fluorescence spectroscopy for pH ranges of 1-8.5 and an initial Eu concentration (C Eu) of 2×10 -4 M. The sorption rate of Eu was initially low, but significantly increased at pH>4. The sorption density of Eu species on a silica surface was ～1.58×10 -7 mol/m2 when the dissolved Eu species were completely sorbed onto silica-water interfaces at pH=～5.8. The sorbed Eu species at pH<6 is aquo Eu 3+, which is sorbed onto silica-water interfaces as an outer-sphere complex at pH<5, but may be sorbed as an inner-sphere bidentate complex at 5<pH<6, due to the decrease of N H 2O to ～6 at pH=6. At pH=6-8.5, Eu(OH)+ 2, Eu(CO 3)+ and Eu(CO 3)- 2 formed in the solutions, and Eu(CO 3)+ is dominant at pH=～7.5. These ions may be sorbed onto silica-water interfaces as inner-sphere bidentate complexes.展开更多
文摘The sorption of Eu species onto nano-size silica-water interfaces was investigated using fluorescence spectroscopy for pH ranges of 1-8.5 and an initial Eu concentration (C Eu) of 2×10 -4 M. The sorption rate of Eu was initially low, but significantly increased at pH>4. The sorption density of Eu species on a silica surface was ～1.58×10 -7 mol/m2 when the dissolved Eu species were completely sorbed onto silica-water interfaces at pH=～5.8. The sorbed Eu species at pH<6 is aquo Eu 3+, which is sorbed onto silica-water interfaces as an outer-sphere complex at pH<5, but may be sorbed as an inner-sphere bidentate complex at 5<pH<6, due to the decrease of N H 2O to ～6 at pH=6. At pH=6-8.5, Eu(OH)+ 2, Eu(CO 3)+ and Eu(CO 3)- 2 formed in the solutions, and Eu(CO 3)+ is dominant at pH=～7.5. These ions may be sorbed onto silica-water interfaces as inner-sphere bidentate complexes.
