Separation of Mo(VI), V(V), Ni(II), Al(III) from synthetic hydrochloric acidic leaching solution of spent catalysts by solvent extraction with ionic liquid

The recovery of metals from spent petroleum catalysts has been attracting much attention owing to an increase in the metal demand. In this work, bi-functional ionic liquid, ALi-D2, in kerosene synthesized by Aliquat336 and D2EHPA was employed for the separation of Mo(VI), V(V), Ni(II) and Al(III) from the synthetic HCl leaching solution of spent petroleum catalyst. The metal ions were efficiently separated by adjusting the concentration of ALi-D2 and acidity of the leaching solution. First, Mo(VI) was selectively extracted into ALi-D2 together with a small amount of V(V). The co-extracted V(V) was removed from the loaded ALi-D2 by selective stripping with H2SO4 solution. Then the Mo(VI) was stripped from the stripped ALi-D2 with NH4OH solution. Second, the V(V) in the raffinate was selectively extracted by ALi-D2 over Al(III) and Ni(II). Al(III) was selectively extracted over Ni(II) from the raffinate by extraction with ALi-D2 after adjusting the pH at 2. The solvent extraction reaction of metal ions by ALi-D2 was identified by applying slope analysis method. The interaction between extractant and metal complexes was analyzed by FT-IR spectra. A process was proposed to separate the four metal ions in the leaching solution based on the results.