Gibbs energy approach for aqueous processes with HF, HNO3, and CO2 ? CaCO3
Chemical thermodynamic calculations were used to represent vapor–liquid equilibria and chemical equilibria for aqueous systems with HF, HNO3, and CO2H2OCaCO3 solutions. The entropy production related to the dissolution reaction of calcite was calculated using multiphase thermodynamics and experiments carried out in this work. Modern simulation methods combined with experiments provide a useful tool for the research and design of new processes as well as evaluating changes in the operational conditions of chemical processes. These methods are used to study metallurgical, pulp, and paper industrial processes that involve the presented aqueous solutions. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1942–1947, 2004
Solubility of β-FeF3·3H2O in Mixtures of Nitric and Hydrofluoric Acid
The solubility of β-FeF3·3H2O has been measured in solutions with different concentrations of nitric acid (0 to 7 m) and hydrofluoric acid (1 to 6 m) at the temperatures of (30, 40, and 50) °C. The total iron concentration at equilibrium was measured with inductively coupled plasma (ICP) spectroscopy. The solubility was evaluated in terms of the stepwise complexation of iron by fluoride ions at different ionic strength and temperature. The solubility of β-FeF3·3H2O increases with decreasing concentration of HF and HNO3 and increasing temperature.
Thermodynamics of electrolytes. Binary mixtures formed from aqueous NaCl, Na2SO4, CuCl2, and CuSO4, at 25°C
Osmotic coefficients to high ionic strengths are reported for five of the binary mixtures formed from NaCl, Na2SO4, CuCl2, and CuSO4; the sixth system studied, NaCl−Na2SO4, is one studied by Wu, Rush, and Scatchard. The equations recently developed by Pitzer are used successfully in the interpretation of the experimental results. Revised values are given for the activity and osmotic coefficients for pure CuSO4 and CuCl2 solutions.