Extraction efficiency:

The trend in the behaviours of Zn (II) and Cd (II) is similar to each other. In both the cases, there is a broad maxima in extraction around 2 M HCl. This behaviour is quite analogous to their sorption on solid anion exchangers from HCl medium. The similarity can be explained on the fact that the extraction in these amines is due to an anion exchange mechanism. We see more or less similar trend in all the amines diluted in both the diluents.

For Hg (II), the extraction efficiency increases with decreasing HCl concentration with a tendency to attain a limiting value around 0.2 M HCl. The only exception to this is Aliquat 336 in which the extraction is very high and remains almost constant over the whole range. Of all the liquid anion exchangers elaborate here, the behaviour in Aliquat 336 is the closest to solid anion exchangers.

The extractive power of various amines for all the three metal ions follows the expected order i.e., primary amine < secondary amine < tertiary amine < quaternary ammonium salt. However, the extractions of these elements in a particular amine are in accordance with the stability of their chlorocomplexes in aqueous solution i.e., Zn < Cd < Hg.

It may be important to point out that if these amines are equilibrated with 1M HCl and the extraction of the said metal ions is observed as a function of molarity of LiCl, the trends are similar to those observed with HCl. A Slightly higher extraction is observed along with LiCl because of higher hydration tendency of Li⁺ ions.