Liquid liquid extraction of tetravalent zirconium and hafnium from acidic chloride solutions has been investigated using 3-phenyl-4-acyl-5-isoxazolones in xylene such as 3-phenyl-4-benzoyl-5-isoxazolones (HPBI), 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone (HFBPI) and 3-phenyl-4-(4-toluoyl)-5-isoxazolone (HTPI). The extraction of zirconium(IV) / hafnium(IV) shows a ion exchange mechanism: MO2+ (aq) + 2 HA (org) <FONT FACE=Symbol>«</FONT> MOA2 (org) + 2 H+(aq), where M = Zr(IV) / Hf(IV) and HA = HPBI or HFBPI or HTPI. The variation of the D ([MOA2] (org) / [MO2+](aq); ratio of the possible extraction equilibrium species) values with an increase of the acid / extractant concentration showed a linear plot with a slope of 2. The effect of the nature of the diluents like carbon tetrachloride, cyclohexane, n-hexane, benzene, nitrobenzene, xylene, toluene and chloroform on the extraction of zirconium(IV) / hafnium(IV) has been studied. The extraction behavior of zirconium(IV) / hafnium(IV) was also compared with that of other metal ions like titanium(IV), aluminium(III) and iron(III), which can be generally associated with the metal ions studied.
3-phenyl-4-acyl-5-isoxazolones; extraction; zirconium(IV); hafnium(IV); acidic chloride solutions
