Pressure-Driven Water Release from Magnesium Sulfate Hydrates: Thermodynamic and Mechanistic Insights
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Understanding the behavior of hydrated salts under pressure is essential for interpreting geochemical processes in planetary interiors and for developing (de)hydration-based technologies. In this study, we use density functional theory calculations to investigate the thermodynamics of pressure-induced dehydration in magnesium sulfate hydrates (MgSO 4 · n H 2 O, n = 11 and 7), where compression drives the release of water as dense ice polymorphs (such as ice II and VI) and the formation of hydrates with fewer water molecules. Our results show that dehydration becomes thermodynamically favorable at 0.8 GPa for MgSO 4 ·11H 2 O and 1.1 GPa for MgSO 4 ·7H 2 O, with ice VI emerging as the dominant crystallization product. Interaction energy analysis identifies interstitial, rather than metal-coordinated, water molecules as the dehydration initiation sites. Unlike thermal dehydration of MgSO 4 ·7H 2 O, which proceeds via MgSO 4 ·6H 2 O and water vapor, our calculations indicate that pressure-induced dehydration yields MgSO 4 ·5H 2 O and dense ice. These results highlight distinct mechanisms of dehydration under temperature and pressure and provide insight into hydrate behavior relevant to both thermochemical technologies and planetary environments.
Source: Inorganic Chemistry
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4415614055