Modeling chemical and phase equilibria in geochemical systems using a speciation-based model

Wang, Peiming; Anderko, Andrzej; Springer, Ronald; Kosinski, Jerzy J.; Łencka, Małgorzata M.

doi:10.1016/j.gexplo.2009.09.003

Cited by 36 publications

(20 citation statements)

References 39 publications

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“…The OLI software is capable of calculating different chemical properties of complex aqueous systems based on an extensive thermodynamic database, which is described in detail elsewhere. [22][23][24] The effective charge (n eff ) of metal ions and their chloride complexes can be defined by taking X FeCl+ , X NiCl+ , X CrCl++ and X CrCl2+ into account:…”

Section: Modeled Concentration Gradients Of 1d Pit and C Satmentioning

confidence: 99%

Further Modeling of Chloride Concentration and Temperature Effects on 1D Pit Growth

Jun

Frankel

Sridhar³

2016

J. Electrochem. Soc.

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The product of diffusion coefficient and saturation concentration of metal ions (D M+ · C tot ) is associated with steady state dissolution of metal in corrosion pits. In our previous paper, D M+ · C tot was modeled for one dimensional (1D) pit dissolution of super 13Cr stainless steel (S13Cr) by taking into account the common ion effect, as well as viscosity and temperature influences. However, the modeled values were only half of the experimentally-measured D M+ · C tot , implying that D M+ and/or C tot were underestimated. To improve the modeling of D M+ · C tot , the effects of complexation and electromigration were additionally considered, which led to the definition of effective diffusion coefficient (D eff ) applicable for the diffusion of metal ionic species under the combined effect of viscosity, temperature and electric field inside a growing 1D pit. The newly modeled D eff · C tot values were very close to the experimental values, validating the modeling approach described in this paper. Dissolution of metal under steady state diffusion can be described by the modified Fick's first law, which relates the limiting current density (i lim ) with the product of diffusion coefficient (D M+ ) and concentration difference ( C M+ ) of the metal ion through the diffusion length (L):where F is the Faraday constant, and n is the charge of the metal ion.For the dissolution of metal in a one dimensional (1D) pit electrode, the concentration of metal ion outside of the pit is commonly assumed to be zero, 1-8 so that C M+ is simply the concentration of metal ion at the pit bottom (C M+ ). It is also usually supposed that L is equal to the pit depth (δ), 9-12 although the diffusion of metal ions may extend out of pit, forming additional layer of hemispherical diffusion and causing L to be longer than δ.11 The effect of this additional diffusion layer on i lim was found to diminish if δ of 1D pit with 1 mm diameter was greater than 0.4 mm (aspect ratio of pit depth/mouth: 0.4) for SS 304 11 and super martensitic stainless steel. 10 More recent study on 1D pit growth of SS 316L, however, has suggested that the length of additional diffusion layer (L') is approximately 40% of pit diameter, and δ should be much larger than L' to apply the L ≈ δ condition for the calculation of i lim . 13In a previous paper, the authors suggested that i lim in 1D pit electrode of super 13Cr stainless steel (S13Cr) can be related to the sum of D M+ · C M+ from each metal component, if the transport of all metal ions is under diffusion control.14 In this case, i lim can be expressed as:Here each C M+ is replaced by the concentration of metal ions at the pit bottom (C Fe2+/pb , C Cr3+/pb and C Ni2+/pb ). The content of Mo in S13Cr is small (2 wt% or 1.16 at%), so it was omitted for the calculation of i lim . For Eq. 2, three conditions were postulated: 1) The diffusion coefficients of all metal ions are the same (, 2) Fe 2+ is the major dissolved species, and the precipitating metal salt at the pit bottom is considered to be FeCl 2 at which ...

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Section: Modeled Concentration Gradients Of 1d Pit and C Satmentioning

confidence: 99%

Further Modeling of Chloride Concentration and Temperature Effects on 1D Pit Growth

Jun

Frankel

Sridhar³

2016

J. Electrochem. Soc.

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“…Indeed, pressured conditions may also be used for less common synthesis methods (e.g. [30]) or in geochemistry [31].…”

Section: Thermodynamic Guidelinesmentioning

confidence: 99%

Stability of Ba(Zr,Pr,Y)O3−δ materials for potential application in electrochemical devices

Antunes¹,

Mather²,

Frade³

et al. 2010

Journal of Solid State Chemistry

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“…To accurately determine the mass source/sink of a mineral, the thermodynamic properties of all chemical reactions involved in a mineralizing system under consideration have to be known. As quantitative modeling has become a standard procedure in geochemistry, there is a wealth of thermodynamic data available for a broad range of minerals, aqueous species and gases that allow the quantitative evaluation of mineral dissolution and precipitation (Barnes, 1997;Geiger et al, 2006a,b;Pokrovskii, 1999;Shock and Helgeson, 1988;Shock and Koretsky, 1995;Wang et al, 2010).…”

Section: Simulation Of Multi-process Aspects Of a Mineral Forming Systemmentioning

confidence: 99%

“…Since any numerical model involves fluid properties and thermodynamic data, another important fundamental issue that researchers involved in modeling hydrothermal or mineralized systems are presently concerned with is to realistically represent fluid properties and chemical reactions at high pressures, high temperatures and high ionic strengths as one would find in ore forming systems. While numerous efforts have been made to develop new equations of state and new fluid property models in recent years (Barnes, 1997;Geiger et al, 2006a,b;Pokrovskii, 1999;Shock and Helgeson, 1988;Shock and Koretsky, 1995;Wang et al, 2010), some are with focuses on systems of geochemical importance such as aqueous solutions containing ions or neutral molecules that exist in significant amount in mineralizing systems (Anderko and Lencka, 1998;Lencka et al, 1997;Wang and Anderko, 2008;Wang et al, 2002). Such models can provide not only various fluid properties that are relevant to modeling hydrodynamics of mineralization, such as density, viscosity, surface tension, diffusivity, and thermal conductivity, but also the thermodynamic properties of chemical reactions that are necessary for describing the fluid speciation and mineral dissolution/precipitation reactions, as well as the energy/heat absorbed or released from chemical reactions.…”

Section: Simulation Of Reactive Mass Transport Associated With a Minementioning

confidence: 99%

Some fundamental issues in computational hydrodynamics of mineralization: A review

Zhao

Reid

Regenauer-Lieb

2012

Journal of Geochemical Exploration

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Modeling chemical and phase equilibria in geochemical systems using a speciation-based model

Cited by 36 publications

References 39 publications

Further Modeling of Chloride Concentration and Temperature Effects on 1D Pit Growth

Further Modeling of Chloride Concentration and Temperature Effects on 1D Pit Growth

Stability of Ba(Zr,Pr,Y)O3−δ materials for potential application in electrochemical devices

Some fundamental issues in computational hydrodynamics of mineralization: A review

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