Function of the salting out agents:

As regards the extraction of metal nitrates, a particular aspect has received special attention i.e., the role of salting out agents. It has been observed that the addition of nitrate salts to the aqueous phase greatly enhances the extraction. The extraction of uranyl and thorium nitrate in ether is greatly enhanced by the addition of ammonium nitrate. It was found that other metal nitrates could be used for the purpose but the multivalent nitrates with pronounced hydration tendencies proved to be the most effective. The function of the salting out agents is considered to be three-fold as is given below:

i) Providing a higher concentration of complexing anion which by the Law of Mass Action, would increase the concentration of the complex and thus, improve the extraction.

ii) Water will bind to the ions of salting out agent and thus, become unavailable as free solvent to compete with the organic phase for partitioning.

iii) The addition of salt will lower the dielectric constant of the aqueous phase which will favour the formation of ion association complex. It is the neutral ion association complex which is getting extracted.