Thermodynamics of Formation of Double Salts and Mixed Crystals from Aqueous Solutions

Abstract

For Abstract see ChemInform Abstract in Full Text.

Thermodynamic model for solution behavior and solid-liquid equilibrium in Na-Al(III)-Fe(III)-Cr(III)-Cl-H2O system at 25°C

“…1b). It shoud be notted that the accepted θ(Na,Al) value in [28] and [10] is mach higher, compare to other θ(Na,M) values for Na + -M 3+ common anion chloride and sulfate systems (see Table 3 in [5]). Our preliminary modeling study on the development of model for corresponding sulfate system Na-Al-SO4-H2O shows that θ(Na,Al) parameter from [28] can not fit well the solubility data in this ternary.…”

“…The system Na-Al(III)-Cr(III)-Fe(III)-Cl-H2O have been investigated according to the following scheme [5,8,9,19] evaluation of not-concentration restricted (β 0 , β 1 , (β 2 ) and C φ ) parameters for binary systems NaCl-H2O, AlCl3-H2O, FeCl3-H2O, and CrCl3-H2O, and determination of the chemical potential of solids precipitating from saturated binary solutions; determination of mixing parameters, i.e. evaluation of the following parameters: A) θ(Na,Al), and ψ(Na,Al,Cl) for ternary system NaCl-AlCl3-H2O; B) θ(Na,Fe), and ψ(Na,Fe,Cl) for ternary system NaCl-FeCl3-H2O; C) θ(Na,Cr), and ψ(Na,Cr,Cl) for ternary system NaCl-CrCl3-H2O; D) θ(Al,Fe), and ψ(Al,Fe,Cl) for ternary system AlCl3-FeCl3-H2O; E) θ(Al,Cr), and ψ(Al,Cr,Cl) for ternary system AlCl3-CrCl3-H2O, and F) θ (Cr,Fe), and ψ(Cr,Fe,Cl) for ternary system CrCl3-FeCl3-H2O.…”

“…The author evaluated the following values for mixing parameters: θ(Na,Fe(III) = -0.07, and ψ(Na,Fe(III),Cl) = -0.004. Here we tested how the mixing parameterization proposed by [5,21], fits the experimental water activity data in mixed solutions. As we show on next Figure (2a) the agreement between experiments and calculation is good: total sigma (σ) value for 97 water activity data points is less than 0.02.…”

“…The osmotic coefficients data for CrCl3-H2O system at 25 o C are available only up to m(max) = 1.4 mol.kg -1 , which is much below molality of saturation (m(sat)) of CrCl3.6H2O(s) (equals to 4.50 mol.kg -1 ) (see [5,17,41]. In a previous study [41] evaluate binary parameters for CrCl3-H2O system at 25 o C, using all available osmotic coefficients data for unsaturated solutions, and the data point at saturation, given in [27].…”

“…The specific interaction approach for describing electrolyte solutions to high concentration introduced by Pitzer [1,2] represents a significant advance in physical chemistry that has facilitated the construction of accurate thermodynamic models. It was showed that the Pitzer approach could be expanded to accurately calculate solubilities in complex brines and to predict the behavior of natural fluids at standard temeperature [3][4][5], as well as at wide range of temperatures from 0 o to 300 o C [6][7][8][9] , and from extremely low [10][11][12] to very high concentration of solutions [8,9,35]. However, the existing Pitzer's databases have different limitations as the number of implemented solution species and precipitating solids, the temperature and concentration ranges of application.…”