Molecular simulation study of speciation in supercritical aqueous NaCl solutions

Chialvo, Ariel A.; Cummings, Peter T.; Simonson, J.M.; Mesmer, R.E.

doi:10.1016/s0167-7322(97)00079-2

Cited by 38 publications

(23 citation statements)

References 35 publications

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“…Molecular simulations and measurements [26,[39][40][41][42][43][44] show that the solvent density about an ion remains high in the vicinity of the ions. The primary solvation shell remains largely intact, but for mono-valent ions the density of solvent molecules beyond the primary solvation shell is weaklier correlated with the presence of the ion.…”

Section: Properties Of Water and Aqueous Solutions At High Temperaturmentioning

confidence: 99%

Influence of Salts During Hydrothermal Biomass Gasification: The Role of the Catalysed Water-Gas Shift Reaction

Kruse¹,

Dinjus²

2005

Zeitschrift Für Physikalische Chemie

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Biomass Gasification / Salt Effects / Supercritical Water / Water-Gas Shift ReactionNear-critical and supercritical water is an unusual reaction medium with extraordinary properties, varying with temperature and density. This opens the opportunity for new reactions and new technical processes. In the studies of synthesis reactions, total oxidation and biomass gasification interesting effects of salts are observed. These effects are assumed to be caused by complex formation, acidity/basicity or the presence of active hydrogen due to the water-gas shift reaction. The water-gas shift reaction is catalysed by salts and lead to the formation of hydrogen, which might react with other compounds.This article focuses on the salt effects during hydrogen production by biomass gasification in supercritical water. This is a very interesting process to make use of "wet biomass", which is up to now not applied in a technical process. Here salts influenced the main reactions pathways. Possible reasons are discussed.

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Section: Properties Of Water and Aqueous Solutions At High Temperaturmentioning

confidence: 99%

Influence of Salts During Hydrothermal Biomass Gasification: The Role of the Catalysed Water-Gas Shift Reaction

Kruse¹,

Dinjus²

2005

Zeitschrift Für Physikalische Chemie

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“…Subsequently, a number of simulations on the NaCl–H 2 O system have been done, especially with the goal of understanding the effects of temperature and density on ion hydration and clustering (e.g. Chialvo et al. 1996, 1997; Lyubartsev & Laaksonen 1996; Driesner et al.…”

Section: Applicationsmentioning

confidence: 99%

Metal complexation and ion association in hydrothermal fluids: insights from quantum chemistry and molecular dynamics

Sherman

2010

Geofluids

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Complexation by ligands in hydrothermal brines is a fundamental step in the transport of metals in the Earth's crust and the formation of ore deposits. Thermodynamic models of mineral solubility require an understanding of metal complexation as a function of pressure, temperature and composition. Over the past 40 years, mineral solubilities and complexation equilibria under hydrothermal conditions have been predicted by extrapolating thermodynamic quantities using equations of state based on the Born model of solvation. However, advances in theoretical algorithms and computational facilities mean that we can now explore hydrothermal fluids at the molecular level. Molecular or atomistic models of hydrothermal fluids avoid the approximations of the Born model and are necessary for any reliable prediction of metal complexation. First principles (quantum mechanical) calculations based on density functional theory can be easily used to predict the structures and relative energies of metal complexes in the ideal gas phase. However, calculations of metal complexation in condensed fluids as a function of temperature and pressure require sampling the configuration degrees of freedom using molecular dynamics (MD). Simulations of dilute solutions require very large systems (thousands of atoms) and very long simulation times; such calculations are only practical by treating the interatomic interactions using classical two-or threebody interatomic potentials. Although such calculations provide some fundamental insights into the nature of crustal fluids, simple two-or three-body classical potentials appear to be inadequate for reliably predicting metal complexation, especially in covalent systems such as Sn 2+ , Au 3+ and Cu + . Ab initio MD (i.e. where the bonding is treated quantum mechanically, but the molecular motions are treated classically) avoids the use of interatomic potentials. These calculations are practical for systems with hundreds of atoms over short times (<10 psec) but enable us to predict complexation as a function of pressure, temperature and composition. In this paper, I provide an introductory outline of the computational methods and illustrations of their application to NaCl brines and the complexation of Cu, Au, Sn and Zn.

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“…On the one hand, the simulation results for the transmission coefficient , y = k/kTsT for this reaction at ambient conditions indicate a value of -0.2 (Guhrdia et al, 1991;Rey and Guhrdia, 1992;Smith and Haymet, 1992). On the other hand, our molecular simulation studies at supercritical conditions indicate that this coefficient becomes very small, -0.05 (Chialvo et al, 1997). As a matter of fact, the literature reports transmission coefficients in the range of 1 to (Hirschfelder et al, 19541, that is, a hardly acceptable approximation for ,y = 1.…”

Section: Summary and Concluding Remarksmentioning

confidence: 70%

Solvation effect on kinetic rate constant of reactions in supercritical solvents

1998

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Molecular simulation study of speciation in supercritical aqueous NaCl solutions

Cited by 38 publications

References 35 publications

Influence of Salts During Hydrothermal Biomass Gasification: The Role of the Catalysed Water-Gas Shift Reaction

Influence of Salts During Hydrothermal Biomass Gasification: The Role of the Catalysed Water-Gas Shift Reaction

Metal complexation and ion association in hydrothermal fluids: insights from quantum chemistry and molecular dynamics

Solvation effect on kinetic rate constant of reactions in supercritical solvents

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