Conditions:

The results of different plots drawn at different conditions gave the following results:

i) The plot of log D vs pH at constant metal ion, acid and amine concentration for both Zn (II) and Cd (II) gave straight line with slope near two. That suggests release of two protons through the utilization of two acid molecules per metal atom to neutralize the charge on the metal ion.

ii) The plot of log D vs log [amine]o  at constant metal ion, pH and acid gave straight lines for both the metal ions with all the three acids. The slopes for aliphatic and heterocyclic amine were one and two, respectively. This suggests the incorporation of one molecule of n- butylamine, dibutylamine and tributylamine and two molecules of β- picoline, pyridine or quinoline when any of the three acids is used.

iii) To calculate the acid molecules required for solvation of the extracted species the concentration of the acid viz. propionic butyric or valeric at constant metal ion, pH and amine concentration. It is found that with the increase in the concentration of the acids, the extraction increases. That is also observed in which with the increase in the number of carbon atoms in the acid, the extraction efficiency increases and shows the following order:

propionic < butyric < valeric

iv) Log - log plots of distribution ratio vs dimeric acid concentration in the organic phase gives straight lines with slope corresponding to n - p + x/2. For both the metal ions and with all the three acids, this value comes to around two and one for aliphatic and heterocyclic amines. Through substituting the values of n and p, the value of x is calculated. It is clear from the result that in the case of both the metal ions, three molecules of acid are involved while only two acid molecules solvate the species in the case of heterocyclic amines.