Phase equilibria and volumetric properties for the system NaCl-CaCl₂-H₂O

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dc.contributor.authorOakes, Charles Stegeren
dc.contributor.committeechairBodnar, Robert J.en
dc.contributor.committeememberSimonson, John M.en
dc.contributor.committeememberHewitt, David A.en
dc.contributor.committeememberTracy, Robert J.en
dc.contributor.committeememberRimstidt, J. Donalden
dc.contributor.departmentGeological Sciencesen
dc.date.accessioned2014-03-14T21:20:45Zen
dc.date.adate2005-10-10en
dc.date.available2014-03-14T21:20:45Zen
dc.date.issued1992en
dc.date.rdate2005-10-10en
dc.date.sdate2005-10-10en
dc.description.abstractLow temperature phase relations in the ice-stable field of the system NaCl-CaCl₂-H₂O were determined under 1 atm. total pressure along the NaCl-H₂O and CaCl₂-H₂O binaries and along five pseudobinaries with constant NaCl/(NaCl+CaCl₂) weight ratios. The results are in excellent agreement with published data along the NaCl-H₂O binary but show large discrepancies when compared to previous determinations of the ice liquidus along the CaCl₂-H₂O binary and in the NaCl-CaCl₂-H₂O ternary. At moderate to high salinities, isotherms cross the ice sub-field at lower total salt concentrations than previously reported. In addition, NaCl/(NaCl+CaCl₂) weight ratios estimated from hydrohalite- and ice-melting temperatures may be low by as much as 15%. Relative densities were measured for NaCl(aq) and CaCl₂(aq) solutions to 250°C and 400 bars and over the range of ionic strengths 0.2 - 5.5 and 0.2 - 19.2 mol·kg⁻¹, respectively. The results span the pressure and temperature of earlier volumetric studies and extend to higher molalities than reported previously. The relative densities have been fitted as apparent molar volumes (V<sub>Φ</sub>) using the Pitzer ion-interaction treatment, with appropriate expressions chosen for the temperature- and pressure-dependence of the virial coefficients of the model. The results presented for NaCl(aq) are in good agreement with published results to 250°C. The results presented for CaCl₂(aq) are in good agreement with published values to approximately 125°C. Above 125°C the inter- and intralaboratory precision of the published data deteriorate and are often in very poor agreement with the data from this Study. The representation for V<sub>Φ</sub> for CaCl₂(aq) was integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. CaCl₂ activity coefficients (γ±) have been derived to 250°C, 400 bars and 4 mol·kg⁻¹ using published fits of CaCl₂ activity coefficient data along the vapor saturation surface and the pressure dependence determined in this work. The volumetric data indicate that the mean ionic activity coefficient, γ±(CaCl₂), increases by a maximum of 32% at 400 bars, 250°C, and 4 mol·kg⁻¹ as compared with its value at saturation pressure. Relative densities were also measured for several ternary { NaCl+CaCl₂}(aq) solutions at 25 and 35°C and 1 atm. These results substantially expand the volumetric data base for ternary solutions. Based on the results of this study most of the previously reported 308.15 K density data in the ternary appear to contain large errors.en
dc.description.degreePh. D.en
dc.format.extentxii, 120 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-10102005-131612en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10102005-131612/en
dc.identifier.urihttp://hdl.handle.net/10919/39729en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1992.O243.pdfen
dc.relation.isformatofOCLC# 29179395en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1992.O243en
dc.subject.lcshFluid inclusionsen
dc.subject.lcshMineralogyen
dc.titlePhase equilibria and volumetric properties for the system NaCl-CaCl₂-H₂Oen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineGeological Sciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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