Theoretical prediction of the thermodynamic behavior of aqueous electrolytes by high pressures and temperatures; IV, Calculation of activity coefficients, osmotic coefficients, and apparent molal and standard and relative partial molal properties to 600 degrees C and 5kb

Helgeson, Harold C.; Kirkham, David H.; Flowers, George C.

doi:10.2475/ajs.281.10.1249

Cited by 1,608 publications

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“…Solubility products (K so ) for C-(A-)S-H, and effective saturation indices (SI*) for relevant solid phases, were calculated from experimental data obtained here. Activity coefficients were calculated using the extended Debye-Hückel equation (in Truesdell-Jones form) with ion size and extended term parameter for KOH ( = 3.67 Å and b = 0.123 kg/mol) [37]. The thermodynamic properties of the aqueous species and solid phases used in these calculations are shown in Appendix A.…”

Section: C-(a-)s-mentioning

confidence: 99%

Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

Myers

L’Hôpital

Provis

et al. 2015

Cement and Concrete Research

323

130

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. KeywordsTemperature, Calcium-Silicate-Hydrate (C-S-H), Thermodynamic Calculations, Hydration Products, Blended Cement. AbstractThere exists limited information regarding the effect of temperature on the structure and solubility of calcium aluminosilicate hydrate (C-A-S-H). Here, calcium (alumino)silicate hydrate (C-(A-)S-H) is synthesised at Ca/Si = 1, Al/Si ≤ 0.15 and equilibrated at 7-80°C. These systems increase in phase-purity, long-range order, and degree of polymerisation of C-(A-)S-H chains at higher temperatures; the most highly polymerised, crystalline and crosslinked C-(A-)S-H product is formed at Al/Si = 0.1 and 80°C. Solubility products for C-(A-)S-H were calculated via determination of the solid-phase compositions and measurements of the concentrations of dissolved species in contact with the solid products, and show that the solubilities of C-(A-)S-H change slightly, within the experimental uncertainty, as a function of Al/Si ratio and temperature between 7°C and 80°C. These results are important in the development of thermodynamic models for C-(A-)S-H to enable accurate thermodynamic modelling of cement-based materials. IntroductionTemperatures experienced by cement and concrete based construction materials in service can vary greatly, due to heat evolution from cement hydration, variable ambient environmental conditions, steam curing, and other factors. understanding of the nature of C-S-H and other constituent phases in these systems at equilibrium [6][7][8][9] has meant that hydrated neat PC materials can be accurately described by thermodynamic modelling at temperatures from 5°C to above 80°C [10]. Extending this analysis to the CaO-Al 2 O 3 -SiO 2 -H 2 O system represents a major step toward applying this technique to hydrated PC blends with high replacement levels of supplementary cementitious materials, which are not fully described by existing thermodynamic models [11]. This will enable a much deeper understanding of the chemistry and phase composition, and hence durability, of these materials in service.The chemistry and structure of calcium (alumino)silicate hydrate (C-(A-)S-H) products at ambient conditions have been the subject of sustained research for more than half a...

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Section: C-(a-)s-mentioning

confidence: 99%

Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

Myers

L’Hôpital

Provis

et al. 2015

Cement and Concrete Research

323

130

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“…Activity coefficients were calculated using an extended Debye-Hü ckel equation with A, B, and å values of 0.5101, 0.3285, and 5.22, respectively (Helgeson et al, 1981). Saturation state values were then calculated by comparing the resulting Q values to the equilibrium constants, K, for the respective mineral, according to Eq.…”

Section: Saturation States Calculationsmentioning

confidence: 99%

The effects of non-metabolizing bacterial cells on the precipitation of U, Pb and Ca phosphates

Dunham‐Cheatham

Xue

Bunker

et al. 2011

Geochimica et Cosmochimica Acta

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In this study, we test the potential for passive cell wall biomineralization by determining the effects of non-metabolizing bacteria on the precipitation of uranyl, lead, and calcium phosphates from a range of over-saturated conditions. Experiments were performed using Gram-positive Bacillus subtilis and Gram-negative Shewanella oneidensis MR-1. After equilibration, the aqueous phases were sampled and the remaining metal and P concentrations were analyzed using inductively coupled plasmaoptical emission spectroscopy (ICP-OES); the solid phases were collected and analyzed using X-ray diffractometry (XRD), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS).At the lower degrees of over-saturation studied, bacterial cells exerted no discernable effect on the mode of precipitation of the metal phosphates, with homogeneous precipitation occurring exclusively. However, at higher saturation states in the U system, we observed heterogeneous mineralization and extensive nucleation of hydrogen uranyl phosphate (HUP) mineralization throughout the fabric of the bacterial cell walls. This mineral nucleation effect was observed in both B. subtilis and S. oneidensis cells. In both cases, the biogenic mineral precipitates formed under the higher saturation state conditions were significantly smaller than those that formed in the abiotic controls.The cell wall nucleation effects that occurred in some of the U systems were not observed under any of the saturation state conditions studied in the Pb or Ca systems. The presence of B. subtilis significantly decreased the extent of precipitation in the U system, but had little effect in the Pb and Ca systems. At least part of this effect is due to higher solubility of the nanoscale HUP precipitate relative to macroscopic HUP. This study documents several effects of non-metabolizing bacterial cells on the nature and extent of metal phosphate precipitation. Each of these effects likely contributes to higher metal mobilities in geologic media, but the effects are not universal, and occur only with some elements and only under a subset of the conditions studied.

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“…For example, water has an unusually large static dielectric constant e 0 ∼ 78 at ambient conditions; however, at the vapor-liquid critical point at 647 K, e 0 deceases to less than 10 (9), implying that ionwater interactions in solution are greatly modified. In turn these changes affect the solubility of minerals and hence chemical reactions occurring in aqueous solutions under pressure (10,11).…”

mentioning

confidence: 99%

Dielectric properties of water under extreme conditions and transport of carbonates in the deep Earth

Pan¹,

Spanu²,

Harrison

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

184

150

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Water is a major component of fluids in the Earth's mantle, where its properties are substantially different from those at ambient conditions. At the pressures and temperatures of the mantle, experiments on aqueous fluids are challenging, and several fundamental properties of water are poorly known; e.g., its dielectric constant has not been measured. This lack of knowledge of water dielectric properties greatly limits our ability to model water-rock interactions and, in general, our understanding of aqueous fluids below the Earth's crust. Using ab initio molecular dynamics, we computed the dielectric constant of water under the conditions of the Earth's upper mantle, and we predicted the solubility products of carbonate minerals. We found that MgCO 3 (magnesite)-insoluble in water under ambient conditions-becomes at least slightly soluble at the bottom of the upper mantle, suggesting that water may transport significant quantities of oxidized carbon. Our results suggest that aqueous carbonates could leave the subducting lithosphere during dehydration reactions and could be injected into the overlying lithosphere. The Earth's deep carbon could possibly be recycled through aqueous transport on a large scale through subduction zones.water solvation properties | carbon cycle | ab initio simulations | supercritical water W ater, a major component of fluids in the Earth's mantle (1, 2), is expected to play a substantial role in hydrothermal reactions occurring in the deep Earth at supercritical conditions (3, 4). Pressure (P) and temperature (T) increase with increasing depth (5) and at ∼400 km, where seismic discontinuities define the bottom boundary of the upper mantle, the pressure can reach ∼13 GPa and the temperature can be as high as 1,700 K (6-8). In this regime the properties of water and thus of aqueous fluids are remarkably different from those at ambient conditions. For example, water has an unusually large static dielectric constant e 0 ∼ 78 at ambient conditions; however, at the vapor-liquid critical point at 647 K, e 0 deceases to less than 10 (9), implying that ionwater interactions in solution are greatly modified. In turn these changes affect the solubility of minerals and hence chemical reactions occurring in aqueous solutions under pressure (10, 11).Measurements of the dielectric constant of water date back to the 1890s (12), but they are still limited to P < 0.5 GPa and T < 900 K, corresponding to crustal metamorphic conditions. Indeed, it is challenging to measure e 0 at high P and T because water becomes highly corrosive (11). Several models correlating experimental data suggested extrapolations of e 0 to ∼1 GPa and ∼1,300 K (e.g., refs. 13-15), which corresponds to only very shallow mantle conditions under the oceans; however, deeper mantle conditions relevant to plate tectonic processes could not be reached and different extrapolations showed poor agreement with each other (1). The current lack of knowledge of the dielectric constant of water under the P and T of the mantle hampers our ability...

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Theoretical prediction of the thermodynamic behavior of aqueous electrolytes by high pressures and temperatures; IV, Calculation of activity coefficients, osmotic coefficients, and apparent molal and standard and relative partial molal properties to 600 degrees C and 5kb

Cited by 1,608 publications

References 0 publications

Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

The effects of non-metabolizing bacterial cells on the precipitation of U, Pb and Ca phosphates

Dielectric properties of water under extreme conditions and transport of carbonates in the deep Earth

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