The Nucleation Kinetics of Calcium Sulfate Dihydrate in NaCl Solutions up to 6 m and 90°C

He, Shiliang; Oddo, J.E.; Tomson, Mason B.

doi:10.1006/jcis.1994.1042

Cited by 134 publications

(108 citation statements)

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“…Growth of gypsum is a relatively fast process and the saturation index of a supersaturated solution containing 0.5 M NaCl decreases from 0.17 to 0.04 in the time scale of a few hours when seed crystals are added (Brandse et al, 1977). In the absence of seeding crystals, the induction period for gypsum nucleation from homogeneous solution can be tens of hours at the determined levels of supersaturation in the pore water (He et al, 1994). Consequently, the observed gypsum supersaturation indicates that the pore water composition has been altered due to pyrite oxidation during storage or during pore water collection, but also the possibility of enhanced SO 4 and Ca release from the sample due to the applied pressure cannot be excluded as gypsum solubility increases with pressure (Blount and Dickson, 1973).…”

Section: Pore Water Obtained By Mechanical Squeezingmentioning

confidence: 99%

First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

Behrends

Veen

Hoving

et al. 2016

Netherlands Journal of Geosciences

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The Rupel Clay member in the Netherlands largely corresponds to the Boom Formation in Belgium, and this marine, clay-rich deposit is a potential candidate to host radioactive waste disposal facilities. Prediction of the speciation of radionuclides in Rupel Clay pore water and their retardation by interactions with Rupel Clay components requires knowledge about the composition of Rupel Clay pore water, the inventory of reactive solids and understanding of interactions between Rupel Clay and pore water. Here, we studied Rupel Clay material which was obtained from cores collected in the province of Zeeland, the Netherlands, and from drilling cuttings retrieved from a drilling in the province of Limburg, the Netherlands. Pore water was obtained by mechanical squeezing of Rupel Clay material from Zeeland. Additionally, anaerobic dilution experiments were performed in which the clay material was suspended with demineralised water or a 0.1 M NaHCO 3 solution. Solid-phase characterisation included determination of carbon, nitrogen and sulphur contents, measurement of cation exchange capacity (CEC) and sequential extraction of iron phases.In contrast to the pore water in Belgian Boom Clay, pore water collected from the location in Zeeland has a higher salinity, with chloride concentrations corresponding to 70-96% of those in seawater. The high chloride concentrations most likely result from the intrusion of ions from saline waters above the Rupel Clay in Zeeland. Cation exchange during salinisation might account for the observed deficit of marine cations (Na, K, Mg) and excess of Ca concentrations, in comparison with seawater. The measured CEC values at both locations in the Netherlands vary between 7 and 35 meq (100 g) −1 and are, for most samples, in the range reported for Boom Clay in Belgium (7-30 meq (100 g) −1 ).Pore water and solid-phase composition indicate that Rupel Clay from Zeeland has been affected by oxidation of pyrite or other Fe(II)-containing solids. When coupled to the dissolution of calcium carbonates, oxidation of pyrite can account for the elevated sulphate and calcium concentrations measured in some of the pore waters. The relatively low concentrations of pyrite, organic carbon and calcite in the Rupel Clay in Zeeland, in comparison to Limburg, might be an indicator for an oxidation event. Higher contents of dithionite-extractable Fe in Rupel Clay in Zeeland (0.7-2.6 mg Fe / g clay) than in Limburg (0.4-0.5 mg Fe / g clay) might also be a consequence of the oxidation of Fe(II) minerals. Oxidation in the past could have accompanied partial erosion of Rupel Clay in Zeeland before deposition of the Breda Formation. However, indications are given that oxidation occurred in some of the pore waters after sampling and that partial oxidation of the cores during storage cannot be excluded. Results from dilution experiments substantiate the influence of equilibration with calcium carbonates on pore water composition. Furthermore, removal of dissolved sulphate upon interaction with Rupel Clay has been...

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Section: Pore Water Obtained By Mechanical Squeezingmentioning

confidence: 99%

First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

Behrends

Veen

Hoving

et al. 2016

Netherlands Journal of Geosciences

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“…Usando los datos experimentales disponibles para la nucleación del yeso (He et al, 1994;Lancia et al, 1999), hemos calculado (tanto para nucleación homogénea como heterogénea) el tiempo de inducción para tres salinidades: una disolución con calcio y sulfato exclusivamente (etiquetado 0 en la Figura 4), valores de salinidad (en términos de concentración de Na, Cl y Mg) idénticos a los encontrados en las aguas de Naica (etiquetado 1), y el doble de esta concentración (etiquetado 2). Los valores de solubilidad obtenidos con PHREEQC (Parkhurst and Appelo, 2003) se usaron para calcular los valores de sobresaturación y los tiempos de inducción de la Figura 4B.…”

Section: Nucleación Y Crecimiento De Los Megacristalesunclassified

Formación de megacristales naturales de yeso en Naica, México

García‐Ruiz¹,

Villasuso²,

Ayora³

et al. 2007

BSGM

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63 ResumenTrabajos de exploración en la mina de Naica (Chihuahua, México) han descubierto recientemente la existencia de varias cavidades que contenan cristales gigantes de yeso (CaSO 4 •2H 2 O) facetados y transparentes de hasta once metros de longitud. Desde el punto de vista del crecimiento cristalino, resulta evidente que estos grandes cristales debieron formarse a valores de sobresaturación muy bajos. El problema radica en explicar cómo las condiciones geoqu'micas adecuadas pudieron mantenerse durante un largo periodo de tiempo sin fl uctuaciones lo sufi cientemente grandes para evitar la nuevos eventos de nucleación. El análisis de inclusiones fl uidas muestra que los cristales crecieron a partir de fl uidos de baja salinidad a una temperatura de unos 54 °C, ligeramente por debajo de la temperatura a la que la solubilidad de la anhidrita (CaSO 4 ) iguala a la del yeso. Las composiciones isotópicas del azufre y del oxígeno medidas en los cristales de yeso son compatibles con la cristalización del yeso a partir de aguas enriquecidas en sulfato cálcico resultantes de la disolución de anhidrita previamente precipitada durante la mineralización hidrotermal tardía. Estas consideraciones sugieren que estos megacristales se formaron mediante un mecanismo autoalimentado controlado por la transición de fase en disolución anhidrita/yeso. Los cálculos de cinética de nucleación basados en datos de laboratorio muestran que este mecanismo explica la formación de estos cristales gigantes, aunque solo cuando tiene lugar en el estrecho intervalo de temperaturas identifi cado en nuestro estudio de inclusiones fl uidas. Estas condiciones singulares crean una maravilla natural, un lugar de gran interés cient'fi co y un fenómeno de mineralización extraordinario que debe ser preservado.Palabras clave: Yeso, selenita, cristalización, mineralogénesis, megacristales, Naica, cinética de nucleación, inclusiones fl uidas. AbstractExploration activities in the mine of Naica (Chihuahua, Mexico)

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“…The need for a critical nucleus for crystal growth arises from the high surface free energy per unit volume of small particles, as discussed in [23].…”

Section: Residence Timementioning

confidence: 99%

“…In previous induction time experiments [23,24,25], the supersaturated solution is in a closed system, and a model for conditions in a moving fluid was not needed.…”

Section: Theory Developmentmentioning

confidence: 99%

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Theoretical framework for predicting inorganic fouling in membrane distillation and experimental validation with calcium sulfate

Warsinger

Tow

Swaminathan

et al. 2017

Journal of Membrane Science

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A methodology for predicting scaling in membrane distillation (MD), which considers thermodynamics, kinetics, and fluid mechanics, is developed and experimentally validated with calcium sulfate. The theory predicts the incidence of scaling as a function of temperature, concentration, and flow conditions by comparing the nucleation induction time to the residence time and applying an experimental correction factor. The relevant residence time is identified by considering a volume of solution near the membrane surface that contains enough ions to form a nucleus of critical size. The theory is validated with fouling experiments using calcium sulfate as a model scalant over a range of temperatures (40-70°C), saturation indices, and flow rates. Although the model is validated with a bench-scale MD system, it is hoped to be compatible with large-scale systems that may have significant changes in concentration, temperature, and flow rate along the flow direction. At lower temperatures, the saturation index can be as high as 0.4-0.5 without scaling, but the safe concentration limit decreases with increasing temperature. Increasing the feed flow rate reduces concentration polarization and fluid residence time, both of which decrease the likelihood of fouling. The model is translated into easily readable maps outlining safe operating regimes. The theory and maps can be used to define the safe operating regime in MD over a wide range of conditions and system geometries. φ Experimental fitting parameter [-] 4

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The Nucleation Kinetics of Calcium Sulfate Dihydrate in NaCl Solutions up to 6 m and 90°C

Cited by 134 publications

References 0 publications

First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

Formación de megacristales naturales de yeso en Naica, México

Theoretical framework for predicting inorganic fouling in membrane distillation and experimental validation with calcium sulfate

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