The Sorption Processes of U(VI) onto SiO2 in the Presence of Phosphate: from Binary Surface Species to Precipitation
| Autor: | Vinzenz Brendler, Timothy E. Payne, Katharina Müller, Karsten Heim, Madlen Stockmann, M. Josick Comarmond, Harald Foerstendorf, Robin Steudtner |
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| Rok vydání: | 2016 |
| Předmět: |
Ternary numeral system
Aqueous solution Silica gel Inorganic chemistry Sorption General Chemistry 010501 environmental sciences 010403 inorganic & nuclear chemistry Phosphate Uranyl 01 natural sciences 0104 chemical sciences chemistry.chemical_compound Adsorption chemistry Attenuated total reflection Environmental Chemistry 0105 earth and related environmental sciences |
| Zdroj: | Environmental Science & Technology 50(2016)21, 11610-11618 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/acs.est.6b02075 |
| Popis: | The ternary system containing aqueous U(VI), aqueous phosphate and solid SiO2 was comprehensively investigated using a batch sorption technique, in situ attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy, time-resolved laser-induced fluorescence spectroscopy (TRLFS), and Surface Complexation Modeling (SCM). The batch sorption studies on silica gel (10 g/L) in the pH range 2.5 to 5 showed no significant increase in U(VI) uptake in the presence of phosphate at equimolar concentration of 20 µM, but significant increase in U(VI) uptake was observed for higher phosphate concentrations. In situ infrared and luminescence spectroscopic studies evidence the formation of two binary U(VI) surface species in the absence of phosphate, whereas after prolonged sorption in the presence of phosphate, the formation of a surface precipitate, most likely an autunite-like phase, is strongly suggested. From SCM, excellent fitting results were obtained exclusively considering two binary uranyl surface species and the formation of a solid uranyl phosphate phase. The results of this study indicate that the sorption of U(VI) on SiO2 in the presence of inorganic phosphate initially involves binary surface-sorption species and evolves towards surface precipitation. |
| Databáze: | OpenAIRE |
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