geoscience.net logo
+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

A solid solution approach to standard state thermodynamic models of mineral surfaces


, : A solid solution approach to standard state thermodynamic models of mineral surfaces. Geological Society of America 41.7

Mineral reactivity and stability is inherently controlled by the presence, properties, and areas of mineral surfaces. Considerable progress has been made relating mineral dissolution/precipitation kinetics, surface adsorption, and solubility to mineral surface area, usually cast in terms of area of mineral surfaces per mole or unit of mass. However, simultaneous consideration of the thermodynamics of surface area-controlled processes and heterogeneous reactions between minerals, aqueous solutions, and other fluids in Earth's crust is hampered by the lack of suitable standard state descriptions of the presence and abundance of surfaces. A novel approach to this problem will be presented in which all minerals are considered to be solutions (in a structural, rather than chemical sense) between their surfaces (including the near-surface portions of crystals affected by the presence of the surface) and the bulk phase. The standard state thus adopted is unit activity of the pure phase (bulk mineral, mineral surface) at all temperatures and pressures. Mole fractions of the solution members may be calculated as a function of grain size through geometric models. Geometric calculations demonstrate that the mole fractions of the surface and bulk endmembers vary non-linearly with surface area. Given the typically nearly-linear dependence of enthalpies of reaction (e.g., heats of solution) with surface area for small grains, these models thus predict that mixing between the surface and the bulk is non-ideal. Calculations of the mixing and standard state thermodynamic properties of surface and bulk endmembers of titania and silica minerals demonstrate the veracity of this approach, and permit prediction of mineral stability as a function of grain size, temperature, pressure, and chemical potential. Specifically, observed properties of nano-phase minerals are predicted by these models, including the grain sizes at which the surface endmember is negligible (observed in heat of solution experiments) and stability crossovers at small grain sizes leading to initial formation of metastable minerals per the Ostwald Step Rule.

US$29.90


Other references

Stolk, A.H., 1980: Advantage, wheat. Advantage was bred in France and introduced to New Zealand in 1978. In trials in 1978-1980, it had good drought tolerance and was highly resistant to Puccinia striiformis. It is primarily suited to autumn sowing in Canterbury but will perform well...

Latour, J.M., 2003: Improving end-of-life care in the intensive care unit: are nurses involved?. Australian Critical Care 16(3): 84-85

Stone, T.W.; Collins, J.F., 1986: Activity of beta-kainic acid on neocortical neurons in vivo and hippocampal neurons in vitro. The beta-isomer of kainic acid has been reported to have anticonvulsant activity with a profile suggesting amino acid antagonism. The present study, on neurons in the cerebral cortex of anaesthetised rats or in hippocampal slices, shows that beta-...

Xu, W.; Zhai, Z.; Huang, K.; Zhang, N.; Yuan, Y.; Shang, Y.; Luo, Y., 2012: A novel universal primer-multiplex-PCR method with sequencing gel electrophoresis analysis. In this study, a novel universal primer-multiplex-PCR (UP-M-PCR) method adding a universal primer (UP) in the multiplex PCR reaction system was described. A universal adapter was designed in the 5'-end of each specific primer pairs which matc...

Bassiouny, M.A.; Pollack, R.L., 1987: Esthetic management of perimolysis with porcelain laminate veneers. This report deals with the dental manifestations of bulimia nervosa. Differential diagnosis of perimolysis was identified and compared with other manifestations of systemic or exogenous causal factors. Conservative cosmetic dental management of th...

Osemlak, J., 1971: Variation in the shape and size of the human uterus at different periods of life. Folia Morphologica 30(4): 497-510

Gowda, A.T.imme; Gowda, N.M.M.de, 2000: Application of azure A in the spectrophotometric determination of penicillin drugs. A simple, accurate, and rapid method for the quantitative analysis of two penicillin drugs is developed. The method is based on the formation of a blue penicillin-azure A ion pair that can be extracted into chloroform in phosphate-citric acid buff...

Hazlewood, C.; Chari, M.V.; Ericsson, A.D.; Windsor, N.; Benekendorfer, T.R., 1993: Nuclear magnetic resonance spectroscopy of human immunodeficiency virus (HIV1) positive sera. Physiological Chemistry and Physics and Medical Nmr 25(3): 219-222

Anonymous, 2013: Diabetes duration and health-related quality of life in individuals with onset of diabetes in the age group 15---34 years -- a Swedish population-based study using EQ-5D. Diabetes with onset in younger ages affects both length of life and health status due to debilitating and life-threatening long-term complications. In addition, episodes and fear of hypoglycaemia and of long-term consequences may have a substantia...

Merle, R.; Schroder, A.; Hamann, J., 2005: Cell function in the bovine mammary gland: interdependence of healthy and infected udder quarters. Current mastitis research has not completely explained udder defence mechanisms. In consideration of the anatomical construction of the udder, infection of one udder quarter is not considered to influence the immune status of neighbouring quarters...