Abstract The anion-exchange extraction of zinc chloride, bromide, iodide, and thiocyanate complexes by solutions of alkyldimethylbenzylammonium chlorides (R–N+(CH3)2–CH2C6H5 Cl–) and alkyldimethylethylbenzylammonium chlorides (R–N+(CH3)2–CH2CH2C6H5 Cl–), where R is a linear alkyl chain predominantly containing C12–C14 groups, in organic solvents (toluene, carbon tetrachloride, ethyl acetate, isobutyl alcohol, and nitrobenzene) was studied. The composition of the potential-determining zinc complexes was established from the analysis of calibration plots E = f(pCZn(II)) constructed using zinc sulfate solutions in the presence of 1 M KCl, 2 M KBr, 3 M KI, and 1 M KSCN, taking into account the electrochemical characteristics of the indicator electrode, which was an ion-selective electrode with a membrane based on a nitrobenzene solution of tetradecylammonium bromide. The extraction process was quantitatively evaluated using the distribution coefficient D, calculated from the zinc concentrations in the aqueous phase before and after extraction. The dependence of the distribution coefficient on the dielectric constant of the organic solvent, as well as on the concentration, stability, and hydrophobicity of zinc anionic complexes, was demonstrated. For zinc(II) halide and thiocyanate complexes, the minimum D values were obtained in the low-polarity solvents toluene and carbon tetrachloride, whereas the maximum values were observed in the highly polar solvents isobutyl alcohol and nitrobenzene. It was experimentally established that, in the series [Zn(NCS)4]2– > [ZnI4]2– > [ZnCl4]2– > [ZnBr4]2–, the value of D decreases for all systems studied. Thus, during the extraction of 1.0 × 10–4 M zinc complex solutions, the distribution coefficient decreased by a factor of 2.3 for carbon tetrachloride and by a factor of 3.4 for isobutyl alcohol. A more pronounced decrease in D was observed for 1.0 × 10–2 M solutions of zinc complexes, namely by factors of 3.1 and 3.7, respectively. The observed trend is associated with both the stability of the corresponding zinc complexes in aqueous solutions and their hydrophobicity.

Extraction of Zinc Halide and Thiocyanate Complexes by Organic Solutions of Quaternary Ammonium Salts

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发表日期：

2026年7月1日

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Y. I. Matyushkina,
A. A. Shabarin

摘要

Abstract

The anion-exchange extraction of zinc chloride, bromide, iodide, and thiocyanate complexes by solutions of alkyldimethylbenzylammonium chlorides (R–N⁺(CH₃)₂–CH₂C₆H₅ Cl^–) and alkyldimethylethylbenzylammonium chlorides (R–N⁺(CH₃)₂–CH₂CH₂C₆H₅ Cl^–), where R is a linear alkyl chain predominantly containing C₁₂–C₁₄ groups, in organic solvents (toluene, carbon tetrachloride, ethyl acetate, isobutyl alcohol, and nitrobenzene) was studied. The composition of the potential-determining zinc complexes was established from the analysis of calibration plots E = f(pC_Zn(II)) constructed using zinc sulfate solutions in the presence of 1 M KCl, 2 M KBr, 3 M KI, and 1 M KSCN, taking into account the electrochemical characteristics of the indicator electrode, which was an ion-selective electrode with a membrane based on a nitrobenzene solution of tetradecylammonium bromide. The extraction process was quantitatively evaluated using the distribution coefficient D, calculated from the zinc concentrations in the aqueous phase before and after extraction. The dependence of the distribution coefficient on the dielectric constant of the organic solvent, as well as on the concentration, stability, and hydrophobicity of zinc anionic complexes, was demonstrated. For zinc(II) halide and thiocyanate complexes, the minimum D values were obtained in the low-polarity solvents toluene and carbon tetrachloride, whereas the maximum values were observed in the highly polar solvents isobutyl alcohol and nitrobenzene. It was experimentally established that, in the series [Zn(NCS)₄]^2– > [ZnI₄]^2– > [ZnCl₄]^2– > [ZnBr₄]^2–, the value of D decreases for all systems studied. Thus, during the extraction of 1.0 × 10^–4 M zinc complex solutions, the distribution coefficient decreased by a factor of 2.3 for carbon tetrachloride and by a factor of 3.4 for isobutyl alcohol. A more pronounced decrease in D was observed for 1.0 × 10^–2 M solutions of zinc complexes, namely by factors of 3.1 and 3.7, respectively. The observed trend is associated with both the stability of the corresponding zinc complexes in aqueous solutions and their hydrophobicity.