Internally consistent thermodynamic data for magnesium sulfate hydrates

Grevel, Klaus‐Dieter; Majzlan, Juraj

doi:10.1016/j.gca.2009.08.005

Cited by 56 publications

(38 citation statements)

References 34 publications

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“…1. As concluded by Grevel and Majzlan (2009), starkeyite is metastable with respect to kieserite formation, but kieserite formation is known to be very sluggish under typical dehydration conditions (Steiger et al, 2011). Therefore, Fig.…”

Section: Introductionmentioning

confidence: 89%

“…Two measurement series were performed. The measured values given in the figure for kieserite (n = 1), sanderite (n = 2), hexahydrite (n = 6), and epsomite (n = 7) were taken from Grevel and Majzlan (2009); for starkeyite (n = 4) and the trihydrate (n = 3) see this study. The value for anhydrous Mg sulfate (n = 0) was taken from Ko and Daut (1979).…”

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

“…In their case study, Grevel and Majzlan (2009) performed a MAP analysis based on a simultaneous treatment of calorimetric data and constraints given from relevant reversal experiments (van't Hoff et al, 1912;Seal, 2003, 2007) according to the hydration-dehydration reaction…”

Section: Refinement Of the Thermodynamic Datamentioning

confidence: 99%

“…1 shows an extended field of metastable existence of starkeyite, which makes this phase a major reaction product in dehydration reactions. However, the data for starkeyite in the database of Grevel and Majzlan (2009) were derived from estimates; therefore, direct measurements for this phase were strongly desired which defines the major aim of the present study. We have obtained D f H 0 298 of synthetic starkeyite by solution calorimetry in water at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO₄·4H₂O (Starkeyite) and MgSO₄·3H₂O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates

et al. 2012

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The enthalpies of formation of synthetic MgSO 4 $4H 2 O (starkeyite) and MgSO 4 $3H 2 O were obtained by solution calorimetry at T = 298.15 K. The resulting enthalpies of formation from the elements areThe standard entropy of starkeyite was derived from low-temperature heat capacity measurements acquired with a physical property measurement system (PPMS) in the temperature range 5 K < T < 300 K:Additionally, differential scanning calorimetry (DSC) measurements with a Perkin Elmer Diamond DSC in the temperature range 270 K < T < 300 K were performed to check the reproducibility of the PPMS measurements around ambient temperature.The experimental C p data of starkeyite between 229 and 303 K were fitted with a Maier-Kelley polynomial, yielding C p (T) = 107.925 + 0.5532$T -1048894$T -2 . The hydration state of all Mg sulfate hydrates changes in response to local temperature and humidity conditions. Based on recently reported equilibrium relative humidities and the new standard properties described above, the internally consistent thermodynamic database for the MgSO 4 $nH 2 O system was refined by a mathematical programming (MAP) analysis.As can be seen from the resulting phase diagrams, starkeyite is metastable in the entire T-%RH range. Due to kinetic limitations of kieserite formation, metastable occurrence of starkeyite might be possible under martian conditions.

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Section: Introductionmentioning

confidence: 89%

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

Section: Refinement Of the Thermodynamic Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO₄·4H₂O (Starkeyite) and MgSO₄·3H₂O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates

et al. 2012

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“…The chemical reactions considered in the simulation are summarized in Table 2. The psychrometric law was used to calculate the capillary effect on water activity: (Grevel andMajzlan 2009, Wang et al 2009). …”

Section: Geochemistrymentioning

confidence: 99%

Modeling the influence of MgSO4 invariant points on multiphase reactive transport process during saline soil evaporation

Gamazo

Saaltink

Carrera

et al. 2013

Physics and Chemistry of the Earth, Parts A/B/C

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Please cite this article as: Gamazo, P., Saaltink, M.W., Carrera, J., Slooten, L., Bea, S.A., Gran, M., Modeling the influence of MgSO 4 invariant points on multiphase reactive transport process during saline soil evaporation, Physics and Chemistry of the Earth (2013), doi: http://dx.doi.org/10.1016/j.pce. 2013.02.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Modeling the influence of MgSO Abstract:In the present work, we modeled a laboratory experiment where a sand column saturated with a MgSO 4 solution is subject to evaporation. We used a compositional formulation capable of representing the effect of geochemistry on flow and transport for concentrated solutions under extreme dry conditions. The model accounts for the water sink/sources terms due to hydrated mineral dissolution/precipitation and the occurrence of invariant points, which prescribe the water activity. Results show that the occurrence of the invariant points at the top of the domain could affect the vapor flux at the column top and salt precipitation along the column. In fact, the invariant points occurrence could explain the spatial fluctuation on the salt precipitates formation. Results also suggest that the complex hydrochemical interactions occurring during soil salinization, including osmotic effects, are crucial not only to understand the salt precipitation, but also the evaporation rate. Keywords:• soil evaporation• coupling effects• multiphase reactive transport Highlights:• Modeling evaporation of sand column with MgSO 4 solution.• Model involves oven dry conditions, high salinity, hydrated mineral precipitation.• Coupling effects: geochemical reactions on water content and therefore on flow.• Modeling invariant points: mineral paragenesis prescribes water activity.

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Magnesium sulfate as a key mineral for the detection of organic molecules on Mars using pyrolysis

et al. 2016

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International audiencePyrolysis of soil or rock samples is the preferred preparation technique used on Mars to search for organic molecules up today. During pyrolysis, oxichlorines present in the soil of Mars release oxidant species that alter the organic molecules potentially contained in the samples collected by the space probes. This process can explain the difficulty experienced by in situ exploration probes to detect organic materials in Mars soil samples until recently. Within a few months, the Curiosity rover should reach and analyze for the first time soils rich in sulfates which could induce a different behavior of the organics during the pyrolysis compared with the types of soils analyzed up today. For this reason, we systematically studied the pyrolysis of organic molecules trapped in magnesium sulfate, in the presence or absence of calcium perchlorate. Our results show that organics trapped in magnesium sulfate can undergo some oxidation and sulfuration during the pyrolysis. But these sulfates are also shown to protect organics trapped inside the crystal lattice and/or present in fluid inclusions from the oxidation induced by the decomposition of calcium perchlorate, and probably other oxychlorine phases currently detected on Mars. Trapped organics may also be protected from degradation processes induced by other minerals present in the sample, at least until these organics are released from the pyrolyzed sulfate mineral (~700 °C in our experiment). Hence, we suggest magnesium sulfate as one of the minerals to target in priority for the search of organic molecules by the Curiosity and ExoMars 2018 rovers

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Internally consistent thermodynamic data for magnesium sulfate hydrates

Cited by 56 publications

References 34 publications

Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO₄·4H₂O (Starkeyite) and MgSO₄·3H₂O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates

Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO₄·4H₂O (Starkeyite) and MgSO₄·3H₂O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates

Modeling the influence of MgSO4 invariant points on multiphase reactive transport process during saline soil evaporation

Magnesium sulfate as a key mineral for the detection of organic molecules on Mars using pyrolysis

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Internally consistent thermodynamic data for magnesium sulfate hydrates

Cited by 56 publications

References 34 publications

Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO4·4H2O (Starkeyite) and MgSO4·3H2O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates

Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO4·4H2O (Starkeyite) and MgSO4·3H2O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates

Modeling the influence of MgSO4 invariant points on multiphase reactive transport process during saline soil evaporation

Magnesium sulfate as a key mineral for the detection of organic molecules on Mars using pyrolysis

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Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO₄·4H₂O (Starkeyite) and MgSO₄·3H₂O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates

Experimentally Determined Standard Thermodynamic Properties of Synthetic MgSO₄·4H₂O (Starkeyite) and MgSO₄·3H₂O: A Revised Internally Consistent Thermodynamic Data Set for Magnesium Sulfate Hydrates