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Protic ionic liquids (PILs), made from anhydrous mixtures of Bronsted acids HA and bases B (HA + B → BH+ + A−), occasionally suffer from limited ionicity. In cases of "poor" PILs (<10% ionicity, e.g., using carboxylic acids), past simulations have hinted that ion-pair association, more than incomplete proton transfer, is at fault. To improve upon the Fuoss equation for predicting the degree of ion pairing, new electrostatic equations (including induced dipoles) are presented, for ion-pair and other associations that occur in anhydrous amine/carboxylic acid mixtures. The equations present the association Gibbs energies ΔGA (and thus the association constants KA) as functions of three fundamental properties: the acid/base mixing ratio (n = xA/xB), the HA-to-B proton-transfer strength (ΔpKa,ε=78), and the dielectric constant (relative permittivity) of the mixture (ε). Parameter values were obtained from fits to constant-dielectric quantum chemistry data (obtained and presented here). These ΔGA functions were then used to predict ΔGioniz values for the net ion-generating (autoionization) equilibrium in carboxylic acid/amine mixtures: 2 B (H A) n ⇄ B (H A) n − d H B + + A (H A) n + d − 1 − , where n = xA/xB and d = degree of disproportionation. The agreement with experiment was excellent, demonstrating that these equations could have useful predictive power. [ABSTRACT FROM AUTHOR]

Solvent extraction studies using Cyanex®272 for the extraction of zinc from spent galvanized zinc-ash after leaching in hydrochloric acid (HCl) is reported. Elemental analysis of the spent galvanized material by X-ray fluorescence (XRF) showed the percentage content of zinc to be 93.6 % with ZnO being the major compound detected by X-ray diffraction (XRD) method. The leaching solution by 1 mol/L HCl examined by Aquamate Thermo-Electron Corporation UV-Visible spectrophotometer contains 2991 mg/L zinc with other elements: Mn, Cu, Zn, Cr, Cd and Pb occuring from low to trace levels (= 1%). The results of solvent extraction of zinc by 0.25 mol/L Cyanex®272 in kerozene yielded 85.21 % extraction efficiency within 25 minutes at 27 ° 2°C. At optimal conditions, the study showed that a phase ratio of 1:1 for the organic: aqueous phase extracted 96.6 % of the total zinc into the organic phase at pH 4, of which 98 % of the loaded organic phase was quantitatively stripped by 0.1 mol/L HCl solution. By McCabe Thiele plot, three stages of counter-current extraction are required for the zinc to almost undergo complete extraction. [ABSTRACT FROM AUTHOR]