Chemical Model of the FeCl<SUB>3</SUB>-HCl-H<SUB>2</SUB>O Solutions at 25&deg;C

Abstract

A chemical model was developed to calculate the equilibrium concentrations of chemical species in the FeCl 3 -HCl-H 2 O system at 25 C by using chemical equilibria, mass and charge balance equations. The activity coefficients of solutes and the activity of water were calculated with the Bromley equation. The interaction parameters for the individual chemical complexes, which were necessary to calculate the activity coefficients, were obtained from the reported interaction parameters between ions. By applying this model, the distribution of iron species with the electrolyte concentrations was obtained. In the experimental ranges of the ionic strength of solution up to 7.28 m, the experimental pH values were in good agreement with the predicted pH values.

Experimental studies of equilibrium iron isotope fractionation in ferric aquo–chloro complexes

“…NO 3 -should be similar to, or slightly smaller than, that of C0. Speciation modeling of the aqueous ferric chloride complexes (this work and others such as Rabinowitch and Stockmayer, 1942;Bjerrum and Lukes, 1986;Bethke, 1996;Lee et al, 2003) indicates that the initial concentration of chloride, the acidity, and the ionic strength of the solution determine the relative concentration of each FeCl complex. As the Cl -/ Fe 3+ ratio increases, the relative abundances of species with more Fe-Cl bonds increases.…”

Modeling the effects of bond environment on equilibrium iron isotope fractionation in ferric aquo-chloro complexes

“…The major aqueous complexes present in low-pH solutions of ferric chloride are Fe III ðH 2 OÞ 6 3þ , Fe III (H 2 O) 5 Cl 2+ , Fe III ðH 2 OÞ 4 Cl 2 þ , Fe III ðH 2 OÞ 3 Cl 3 0 , and Fe III Cl 4 À (e.g., Bjerrum and Lukes, 1986;Lee et al, 2003). Fe III ðH 2 OÞCl 5 2À and Fe III Cl 6 3À may also be present in small amounts (e.g., Shamir, 1991;Inada and Funahashi, 1999).…”

Solvent Extraction Equilibria of FeCl<SUB>3</SUB> with TBP

“…6) The interaction parameters between ferric ion and anion were obtained by utilizing the data reported in the literature. 7,8) The predicted distribution coefficients have been compared with those measured.…”