THE SOLVENT EXTRACTION OF ZINC FROM LITHIUM CHLORIDE BY ALIQUAT 336 CHLORIDE, BROMIDE AND IODIDE IN CHLOROFORM : AN ANALYTICAL INVESTIGATION

The extraction of zinc by Aliquat Cl in chloroform is studied as a function of LiCI concentration. A plot of log D versus total [Cl] shows that log D increases sharply from 0-2 M LiC then remains constant over a considerable range of concentrations ( 2-8 M ), before shooting up again from 8-14 M. Further work is carried out at 4 M LiCI to determine the extraction equation, and quantitative aspects determined such as a plot of log D versus log [Aliquat Cl], giving a ratio of 2:1 for extractant : metal . and the ratio [Cl / Zn], which is 2. In order to follow the exchange ofhalides across the interface, Aliquat Br and Aliquat I are used as extractants in chloroform to study the extraction of zinc chloride from 4 M LiCI. Organic and aqueous phases are analysed for halides and zinc, and the ratio [CI] / [Zn] in the organic phase determined to be 3 for both Aliquat Br and I at 4M LiCI, indicating extraction of ZnCl3 and not ZnCl at this concentration. Further work with these extractants based on plots of log D versus log [Aliquat X] ( X = Br, I ) is presented and extraction equations are proposed for these extractants, which fit the data. Extraction of zinc at 4 M LiCl by Aliquat Cl is then considered in terms of the extraction of the trichlorozincate (II) species, ZnCl3, and the extraction constant determined.