Zinc complexation in chloride-rich hydrothermal fluids (25–600 °C): A thermodynamic model derived from ab initio molecular dynamics

Organic, Gas, and Element Geochemistry of Hydrothermal Fluids of the Newly Discovered Extensive Hydrothermal Area in the Wallis and Futuna Region (SW Pacific)

“…Phase separation is of great importance in metal transportation and ore-forming processes, for example, [24,[49][50][51]. It also implies that seawater experiences dramatic changes in its physical and chemical properties as it reaches the super-or subcritical state.…”

Contrasting regimes of Cu, Zn and Pb transport in ore-forming hydrothermal fluids

“…The HKF parameters for the Pb hydroxide complexes Pb(OH) + , Pb(OH) 2 (aq), and Pb(OH) 3 − were taken from Shock et al (1997), and are based on experimental data at P sat up to T = 300°C (Tugarinov et al, 1975). Akinfiev and Tagirov (2014) recently derived HKF parameters for Zn chloride, hydrosulfide and hydroxide complexes based on a review of existing experimental studies; we used these properties except for Zn chloride complexes, where the more recent properties derived by Mei et al (2014b) were favored. Calculations conducted with Akinfiev and Tagirov (2014)'s Zn-chloride properties result in unrealistic Zn solubilities at high temperatures (N10 wt% Zn).…”

Palladium complexation in chloride- and bisulfide-rich fluids: Insights from ab initio molecular dynamics simulations and X-ray absorption spectroscopy

“…Using ab initio MD simulations, we can also explore the thermodynamics of metal complexation at hydrothermal conditions (e.g., Mei et al, 2013aMei et al, , 2014Mei et al, , 2015.…”

“…However, for most complexation reactions between metal and ligand (e.g., Cl -, HS -), the ligand residence time (e.g., ~300 μs for Zn(II)-Cl at 25 ˚C, Sharps et al, 1993) is far beyond the accessible ~100 ps timescale of ab initio MD simulations (see discussion in Mei et al, 2015). Using thermodynamic integration, however, we can calculate the free energy of complex formation in the course of a constrained molecular dynamics simulation.…”

“…The most straightforward approach is to integrate the time-averaged forces along a reaction path corresponding to the metalligand interatomic distances. This approach was used successfully for complexes in the Cu(I)-HS-Cl (Mei et al, 2013a) and Zn(II)-Cl systems (Mei et al, 2015). In the case of Cu(I), the calculated thermodynamic properties for the ligand exchange reactions compared well with the existing, well constrained experimentally-derived…”