Raman spectroscopic investigation of speciation in MgSO4(aq)

Rudolph, Wolfram W.; Irmer, G.; Hefter, Glenn

doi:10.1039/b308951g

Cited by 168 publications

(235 citation statements)

References 58 publications

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“…In other words, UO2 2+ and SO4 2-are highly associated in the Urich phase. This is in line with previous studies suggesting that the ion association increases with increasing sulfate concentration [21,43].…”

Section: Uo2so4 Concentration Of the Immiscible Fluidssupporting

confidence: 82%

“…1015 and 1028 cm -1 . It has been reported that the v1(SO4 2-) band becomes broader and the wavenumber increases with the increase of the length of inner-sphere ion pairs in aqueous MgSO4 solution [21,23,[35][36]. Considering the obvious higher-wavenumber shift of the v1(SO4 2-) band (Fig.…”

Section: Ion Association Between Uo2 2+ and So4 2-mentioning

confidence: 99%

“…980 cm -1 should arise from unassociated SO4 2-, whereas the v1(SO4 2-) components at ca. 992 cm -1 and 1002 cm -1 may represent the contribution from contact ion pair and triple ion pair, respectively [20][21][22][23][24]. However, it's difficult to make clear assignments for the v1(SO4 2-) components at ca.…”

Section: Ion Association Between Uo2 2+ and So4 2-mentioning

confidence: 99%

“…980 cm -1 [34]. Both v1(UO2 2+ ) and v1(SO4 2-) bands can serve as indictors to investigate the complexation in the UO2SO4-H2O system because these two Raman bands are sensitive to changes in coordination environment [13][14][17][18][19][20][21][22][23].…”

Section: Ion Association Between Uo2 2+ and So4 2-mentioning

confidence: 99%

“…In fact, Raman spectra of the v1(SO4 2-) band can also be used to investigate the ion interaction between UO2 2+ and SO4 2-in aqueous solution because the complexation will influence the S-O vibrations of sulfate and cause a shift in the v1(SO4 2-) band, which has been well documented in aqueous MgSO4 solutions [20][21][22][23][24]. However, nearly all of the documented Raman spectroscopic descriptions of aqueous UO2SO4 solutions were conducted at ambient temperature and focused on the v1(UO2 2+ ) mode, which limits our knowledge on the UO2 2+ -SO4 2-association at high temperatures as well as the factors inducing the liquid-liquid immiscibility.…”

Section: Introductionmentioning

confidence: 99%

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In situ observations of liquid–liquid phase separation in aqueous ZnSO4 solutions at temperatures up to 400 °C: Implications for Zn2+–SO42− association and evolution of submarine hydrothermal fluids

Wang

Wan

et al. 2016

Geochimica et Cosmochimica Acta

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spectroscopic observations of the liquid-liquid immiscibility in aqueous uranyl sulfate solutions at temperatures up to 420 circ C, The Journal of Supercritical Fluids http://dx.doi.org/10. 1016/j.supflu.2016.03.005 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 2. The immiscible liquids are either UO2SO4-rich (Urich) or UO2SO4-poor (Upoor).3. Analyses of UO2 2+ and SO4 2-spectra imply increasing ion association upon heating.4. Decrease of ion hydration in Urich phase due to increasing concentration upon heating.5. Reversible strong UO2 2+ -SO4 2-association results in the liquid-liquid immiscibility. AbstractThe phase behaviors of aqueous UO2SO4 solutions were investigated in situ with a microscope and a Raman spectrometer at temperatures from 25 to 420 ºC. Resultsshow 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 o 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)

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Section: Uo2so4 Concentration Of the Immiscible Fluidssupporting

confidence: 82%

Section: Ion Association Between Uo2 2+ and So4 2-mentioning

confidence: 99%

Section: Ion Association Between Uo2 2+ and So4 2-mentioning

confidence: 99%

Section: Ion Association Between Uo2 2+ and So4 2-mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In situ observations of liquid–liquid phase separation in aqueous ZnSO4 solutions at temperatures up to 400 °C: Implications for Zn2+–SO42− association and evolution of submarine hydrothermal fluids

Wang

Wan

et al. 2016

Geochimica et Cosmochimica Acta

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Interactions of Ions with Other Solutes

Marcus

2015

Ions in Solution and Their Solvation

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The impact of stoichiometry on the initial steps of crystal formation: Stability and lifetime of charged triple‐ion complexes

Koskamp,

Seepma,

Peters

et al. 2024

Chemistry A European J

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Minerals form in nature from solutions with varying ratios of their lattice ions, yet non‐stoichiometric conditions have generally been overlooked in investigations of new formation (nucleation) of ionic crystals. Here, we investigated the influence of cation:anion‐ratio in the solution on the initial steps of nucleation by studying positively and negatively charged triple ion complexes and subsequent particle size evolution. Our model systems are carbonates and sulfates of calcium and barium, as it was recently shown that solution stoichiometry affects the timing and rate of their nucleation. Molecular dynamics (MD) simulations and dynamic light scattering (DLS) flow experiments show that nucleation correlates with the stability and lifetime of the initial complexes, which were significantly impacted by the cation:anion stoichiometry and ion type. Specifically, Ba(SO4)22‐ had higher association constants and its lifetime was twofold longer than Ba2SO42+. Similar trends were observed for BaCO3 and CaSO4. Contrastingly, for CaCO3, Ca(CO3)22‐ had lower association constants and its lifetime was shorter than Ca2CO32+. These trends in stability and lifetime follow the same asymmetrical behaviour as observed experimentally for particle formation using techniques like DLS. This suggests a causal relationship between the stability and lifetime of the initial charged complexes and the nucleation under non‐stoichiometric conditions.

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Raman spectroscopic investigation of speciation in MgSO4(aq)

Cited by 168 publications

References 58 publications

In situ observations of liquid–liquid phase separation in aqueous ZnSO4 solutions at temperatures up to 400 °C: Implications for Zn2+–SO42− association and evolution of submarine hydrothermal fluids

In situ observations of liquid–liquid phase separation in aqueous ZnSO4 solutions at temperatures up to 400 °C: Implications for Zn2+–SO42− association and evolution of submarine hydrothermal fluids

Interactions of Ions with Other Solutes

The impact of stoichiometry on the initial steps of crystal formation: Stability and lifetime of charged triple‐ion complexes

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