EXTRACTION ABILITY ESTIMATION OF AQUEOUS STRATIFIED SYSTEMS ON EXAMPLE OF COPPER (I, II), CADMIUM AND ZINC EXTRACTION FROM HYDROCHLORIC ACID SOLUTIONS

Abstract

The ability of diantipyrylalkanes to form liquid two-phase equilibrium without an organic solvent in systems with organic acids - benzoic and salicylic has been investigated. In most cases, the separation of systems is achieved when the ratio of the reagent: acid is 1 – 1.25: 1 – 1.12, heated to 85 °C and in the presence of mineral acids (HCl, H2SO4). The volume of the organic phase from 0.8 to 2.0 ml is sufficient for practical purposes, for example, for the extraction of macro or micro quantities of metal ions. It was established that diantipyrylmethane (reagent, L) or its homolog propyldianthipyrylmethane does not form stratification in systems with benzoic and salicylic acids in the absence of HCl or H2SO4 solutions. And, on the contrary, the more basic reagent - hexyldianthipyrylmethane stratifies solutions containing these organic acids without HCl or H2SO4. At the same time, the introduction of the latter provides the separation of aqueous systems with the participation of all reagents diantipyrylmethane, propyldianthipyrylmethane, and hexyldianthipyrylmethane. The volume of the organic phase is increased to 2.0 ml or more. The extraction of macroquantities of ions of cadmium (II) and zinc (II) was studied under optimal conditions of stratification. Chloride or sulfate ions served as ligands. The optimal conditions for the extraction of metal cations, the composition and mechanism of the extracted complexes were determined. The ratio of hexyldianthipyrylmethane : metal is determined by the saturation method, which turned out to be equal to hexyldianthipyrylmethane : Me2+ = 2 : 1. With this ratio, the organic phase becomes solid. Chemical analysis of the extract with an excess of hexyldianthipyrylmethane and benzoic acid for all components showed the ratio of hexyldianthipyrylmethane : H+ : Me2+ : Cl- : benzoic acid = 4.0 : 3.9 : 1.0 : 4.3 : 2.2, which corresponds to the complex (RH)2[MeCl4]∙2RH∙benzoic acid, solvated by two molecules of hexyldianthipyrylmethane benzoate.