Extraction of hafnium(IV) with N-benzoyl-N-phenylhydroxylamine solutions from strongly acid solutions containing dimethyl sulphoxide or hexamethylphosphor triamine

Abstract

The extraction of hafnium(IV) with N-benzoyl-N-phenylhydroxylamine solutions in chloroform or toluene from strongly acid (HClO4) solutions of dimethyl sulfoxide or hexamethylphosphor triamide has been studied. These substances were found to suppress the conversion of the extraction mechanism from ion exchange to solvation: while in solutions free of these substances this conversion takes place at HClO4 concentrations of about 4 mol l-1, in the mixed aqueous-organic (polar) phase the requisite acid concentrations are considerably higher. The possible causes of this effect are discussed.