Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c
The phase behaviors of aqueous UO2SO4 solutions were investigated in situ with a microscope and a Raman spectrometer at temperatures from 25 to 420 °C. Results show that aqueous UO2SO4 solution separated into UO2SO4-rich (Urich) and UO2SO4-poor (Upoor) liquid phases coexisted with a vapor phase at =...
| Main Authors: | , , , , , , , |
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| Format: | Journal Article |
| Published: |
Elsevier BV
2016
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| Online Access: | http://hdl.handle.net/20.500.11937/46346 |
| _version_ | 1848757531757772800 |
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| author | Wang, X. Wan, Y. Hu, W. Chou, I. Cai, S. Lin, N. Zhu, Q. Li, Zhen |
| author_facet | Wang, X. Wan, Y. Hu, W. Chou, I. Cai, S. Lin, N. Zhu, Q. Li, Zhen |
| author_sort | Wang, X. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The phase behaviors of aqueous UO2SO4 solutions were investigated in situ with a microscope and a Raman spectrometer at temperatures from 25 to 420 °C. Results show that aqueous UO2SO4 solution separated into UO2SO4-rich (Urich) and UO2SO4-poor (Upoor) liquid phases coexisted with a vapor phase at =285.8 ± 0.5 °C. Both visual and Raman spectroscopic investigations suggest that a reversible strong UO2 2+-SO4 2- association was responsible for the liquid-liquid immiscibility in aqueous UO2SO4 solutions. Main evidences were summarized as: (1) the liquid-liquid phase separation temperature decreases with increasing UO2SO4 concentration up to 0.54 mol/kg, and then increased at greater concentrations, characterizing a lower critical solution temperature (LCST) at 285.8 °C ± 0.5 °C. LCST is commonly accepted as a diagnostic feature of polymer solutions; (2) analyses of the shapes of the Raman spectra of v1(UO2 2+) and v1(SO4 2-) bands show that the UO2 2+-SO4 2- association becomes stronger at elevated temperatures, especially in the immiscible Urich phase; and (3) with increasing temperature, the Urich phase becomes more concentrated, whereas the Upoor phase becomes more dilute, indicating that the hydration of UO2 2+ and SO4 2- cannot be maintained in the Urich phase. Destruction of the hydration spheres of UO2 2+ and SO4 2- further favors the ion association in the Urich phase. These results are important for describing similar sulfate solutions at elevated temperatures, especially under supercritical conditions. |
| first_indexed | 2025-11-14T09:29:35Z |
| format | Journal Article |
| id | curtin-20.500.11937-46346 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:29:35Z |
| publishDate | 2016 |
| publisher | Elsevier BV |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-463462018-03-09T02:41:19Z Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c Wang, X. Wan, Y. Hu, W. Chou, I. Cai, S. Lin, N. Zhu, Q. Li, Zhen The phase behaviors of aqueous UO2SO4 solutions were investigated in situ with a microscope and a Raman spectrometer at temperatures from 25 to 420 °C. Results show that aqueous UO2SO4 solution separated into UO2SO4-rich (Urich) and UO2SO4-poor (Upoor) liquid phases coexisted with a vapor phase at =285.8 ± 0.5 °C. Both visual and Raman spectroscopic investigations suggest that a reversible strong UO2 2+-SO4 2- association was responsible for the liquid-liquid immiscibility in aqueous UO2SO4 solutions. Main evidences were summarized as: (1) the liquid-liquid phase separation temperature decreases with increasing UO2SO4 concentration up to 0.54 mol/kg, and then increased at greater concentrations, characterizing a lower critical solution temperature (LCST) at 285.8 °C ± 0.5 °C. LCST is commonly accepted as a diagnostic feature of polymer solutions; (2) analyses of the shapes of the Raman spectra of v1(UO2 2+) and v1(SO4 2-) bands show that the UO2 2+-SO4 2- association becomes stronger at elevated temperatures, especially in the immiscible Urich phase; and (3) with increasing temperature, the Urich phase becomes more concentrated, whereas the Upoor phase becomes more dilute, indicating that the hydration of UO2 2+ and SO4 2- cannot be maintained in the Urich phase. Destruction of the hydration spheres of UO2 2+ and SO4 2- further favors the ion association in the Urich phase. These results are important for describing similar sulfate solutions at elevated temperatures, especially under supercritical conditions. 2016 Journal Article http://hdl.handle.net/20.500.11937/46346 10.1016/j.supflu.2016.03.005 Elsevier BV fulltext |
| spellingShingle | Wang, X. Wan, Y. Hu, W. Chou, I. Cai, S. Lin, N. Zhu, Q. Li, Zhen Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c |
| title | Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c |
| title_full | Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c |
| title_fullStr | Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c |
| title_full_unstemmed | Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c |
| title_short | Visual and in situ Raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c |
| title_sort | visual and in situ raman spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 °c |
| url | http://hdl.handle.net/20.500.11937/46346 |