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Denaturation of Water in Alkaline Melts
Xudong Zhang1, Oldamur Hollóczki2, Johannes Ingenmey3
1Faculty of Chemistry and Food Chemistry, TUD Dresden University of Technology, Dresden, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|December 3, 2025
Summary
Ultra-alkaline hydroflux significantly alters water's properties, reducing vapor pressure and restructuring its hydrogen bonds. This creates an intermediate state between alkaline solutions and molten salts with minimal water activity.
Area of Science:
- Physical Chemistry
- Solution Chemistry
- Materials Science
Background:
- Ultra-alkaline liquids, or hydroflux, exhibit unique properties due to extremely high base concentrations.
- Understanding water's behavior in these concentrated alkali hydroxide (AOH) systems is crucial for various chemical applications.
Purpose of the Study:
- To investigate the thermodynamic and structural alterations of water in ultra-alkaline hydroflux.
- To characterize the hydrogen bonding network and proton mobility in concentrated KOH-water mixtures.
Main Methods:
- Ab initio molecular dynamics simulations were employed to study water-alkali mixtures.
- Vapor pressure measurements were conducted at high base concentrations.
- Cluster population analysis was used to identify molecular structures and interactions.
Main Results:
- Hydroflux with molar ratios q(A) ≤ 2:1 showed significantly reduced vapor pressure, becoming negligible at q(A) = 0.8 (70 mol L⁻¹).
- Simulations revealed reorganized hydrogen bonding, shortened bonds, and frequent proton transfer events (Grotthuss diffusion).
- Significant populations of H₃O₂⁻ anions with near-symmetrical hydrogen bonds were observed.
Conclusions:
- Hydroflux acts as an intermediate between alkaline solutions and molten salts, with water exhibiting vanishing chemical activity.
- The observed structural changes and proton mobility highlight a fundamentally altered state of water in these systems.
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