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

Abstract

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)

Constructing a Super‐Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries

“…As the concentration increases, the presence of a Raman band (260 cm −1 ) has been assigned to [Zn 2+ ⋅OSO 3 2− ] ligand mode in the inner‐sphere complexes ion‐pair. As studied of vibration of Zn‐O mode in MOF pores, the amplified peak of [Zn 2+ ⋅OSO 3 2− ] ligand mode substantiated a more constrict complex ion, which seems impossible to be realized in solubility‐limited ZnSO 4 solutions . We then further analyzed the variation trend of O−H stretch vibration as concentration increases and found that band shift to high frequency (HOH−OH 2 stretch, 3264–3304 cm −1 , Figure c) .…”

“…In MOF pores, the ν‐SO 4 2− band remarkably shifts to higher frequency (ca. 992 cm −1 ), which indicates an unique solvation structure where Zn 2+ is highly constrained with anions to form a more close [Zn 2+ SO 4 2− ] ion association . Figure b exhibits a polarized band (Zn‐OH 2 vibration, ca.…”

Tracing Mineral Reactions Using Confocal Raman Spectroscopy

“…Similarly, the formation of immiscible, dense liquid phases at high temperatures has been identified in situ using the ratios of sulfate and OH Raman spectral band areas and the formation of new bands that correspond to polymeric mixtures [44,45]. These dense fluid phases play an important role in mineral nucleation [7] when it occurs via a non-classical route [46] as well as element transport [45].…”

Constructing a Super‐Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries

“…As studied of vibration of Zn-O mode in MOF pores, the amplified peak of [Zn 2+ ·OSO 3 2À ] ligand mode substantiated a more constrict complex ion, which seems impossible to be realized in solubility-limited ZnSO 4 solutions. [19] We then further analyzed the variation trend of OÀH stretch vibration as concentration increases and found that band shift to high frequency (HOHÀOH 2 stretch, 3264-3304 cm À1 , Figure 2 c). [20] This intensity of O À H stretch vibration is sharply suppressed, further confirming a small minority of water in MOF pores.…”

“…992 cm À1 ), which indicates an unique solvation structure where Zn 2+ is highly constrained with anions to form a more close [Zn 2+ SO 4 2À ] ion association. [19] Figure 2 b exhibits a polarized band (Zn-OH 2 vibration, ca. 390 cm À1 ), which can be appeared both in inner-sphere and outer-sphere ion-pairs.…”