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DOE OSTI · 1901702

Structure of Sulfuric Acid Solutions Using Pair Distribution Function Analysis

Kinnibrugh, Tiffany·Fister, Tim
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Abstract

Solvation and mesoscale ordering of sulfuric acid and other strong acid solutions leads to suppressed freezing points and strong rheological changes with varying concentration. While the solid-state structures are well-understood, studies focused on the evolving solvation structure in the solution phase have probed a limited concentration range (~1–6 M). This study applies a total scattering approach in both the wide-angle X-ray scattering (WAXS) and pair distribution function (PDF) regimes to elucidate the evolving solvation structure over its full range of acid concentration (0–18 M). The emergence of a prepeak in the WAXS regime at intermediate concentrations indicates a transition from noninteracting sulfate molecules in the dilute limit to sterically limited sulfates at concentrations near its deep eutectic point. Fits to the PDF data quantify this trend, showing a transition from octahedrally hydrated sulfates up to 6–7 M concentrations, followed by gradual dehydration, and eventually reaching a solution structure similar to that of water-in-salt electrolyte systems at high acid concentrations.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYlead acid batteriesrheological changeswater-in-salt electrolyte

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Kinnibrugh, Tiffany, Fister, Tim. 2022-04-18. Structure of Sulfuric Acid Solutions Using Pair Distribution Function Analysis. https://doi.org/10.1021/acs.jpcb.2c00523

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