ELECTRO-REDUCTIVE STRIPPING OF VANADIUM IN SOLVENT-EXTRACTION PROCESS FOR SEPARATION OF VANADIUM AND MOLYBDENUM USING TRI-N-OCTYLMETHYLAMMONIUM CHLORIDE

The electro-reductive stripping of vanadium from benzene containing vanadyl and molybdate anions and tri-n-octylmethylammonium chloride (TOMAC) as extractant was studied. A two-compartment cell separated by a cation exchange membrane (Nafion 417) and equipped with platinum electrodes was used. The pentavalent vanadyl anion was reduced to tetravalent vanadyl cation at the aqueous phase/electrode interface and was stripped selectively, with the molybdenum remaining in the organic phase. At a low agitation speeds, such as 300 min-1, in both the organic and aqueous phases, the stripping rate was influenced by mass transfer of the vanadyl anion from the organic into aqueous phase, while it was influenced by diffusion and the electrochemical reduction of vanadyl ion at a higher agitation speeds. The organic solution after the electro-reductive stripping was reusable for the extraction of vanadium and molybdenum without any extra treatment.