Phase equilibria and volumetric properties for the System NaCl-CaCl{sub 2}-H{sub 2}O

Thesis/Dissertation · Sat May 01 04:00:00 EDT 1993

OSTI ID:10153689

Oakes, C S

Low temperature phase relations in the ice-stable field of the system NaCl-CaCl{sub 2}-H{sub 2}O were determined under 1 atm. total pressure along the NaCl-H{sub 2}O and CaCl{sub 2}-H{sub 2}O binaries and along five pseudobinaries with constant NaCl/(NaCl+CaCl{sub 2}) weight ratios. The results are in excellent agreement with published data along the NaCl-H{sub 2}O binary but show large discrepancies when compared to previous determinations of the ice liquidus alone, the CaCl{sub 2}-H{sub 2}O binary and in the NaCl-CaCl{sub 2}-H{sub 2}O ternary. At moderate to high salinities, isotherms cross the ice sub-field at lower total salt concentrations than previously reported. In addition, NaCl(NaCl+CaCl{sub 2}) 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 CaCl{sub 2}(aq) solutions to 250{degrees}C and 400 bars and over the range of ionic strengths 0.2--5.5 and 0.2--19.2 mol{center_dot}kg{sup {minus}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 {phi}}) 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{degrees}C. The results presented for CaCl{sub 2}(aq) are in good agreement with published values to approximately 125{degrees}C.

• Research Organization: Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG05-89ER14065; AC05-84OR21400
• OSTI ID: 10153689
• Report Number(s): DOE/ER/14065--T1; ON: DE93013590
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201
CALCIUM CHLORIDES
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
DENSITY
EQUILIBRIUM
EXPERIMENTAL DATA
ICE
PHASE DIAGRAMS
PRESSURE EFFECTS
SODIUM CHLORIDES
SOLUTIONS
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
WATER