Extraction of Zn (II) ions in an polypropylene glycol 425 - sodium chloride - water aqueous two-phase system

Abstract

Abstract Liquid-liquid extraction is one of the most used separation methods in chemical technology for recovery and separation of metal ions, other inorganic and organic substances. It is known that for extraction of Zn(II) the most frequently used extractants are D2EHPA, Aliquat 336, etc., diluted in an organic solvent. The use of these reagents does not meet the principles of “green” chemistry. Thus, in the present work, the extraction system based on polypropylene glycol 425 and sodium chloride for the extraction of Zn(II) ions from aqueous solutions is proposed. Equilibrium values of the distribution coefficient in the proposed aqueous two-phase system have been determined. Dependence of metal distribution coefficient on time of phase contact is obtained, time to reach equilibrium was 10 minutes. The isotherm of Zn(II) extraction obtained in the proposed system is a straight line, which indicates the independence of the distribution coefficient from the initial concentration of metal in the solution. The received experimental data can be used at the creation of “green” schemes of processing of Ni-MH batteries.