The separation of nickel(II) and cobalt(III) from ammoniacal solutions with ACORGA M5640 (5-nonylsalicylaldoxime) as an extractant was investigated. The extraction of cobalt(III) decreased significantly due to the formation of Co(NH3)63+ above pH 4. Meanwhile, the extraction of nickel(II) increased above pH 4. The separation efficiency of both metals is sufficiently improved due to the oxidation of cobalt(II) to cobalt(III) in the ammoniacal solutoions and nickel(II) could be extracted preferentially from cobalt(III) with ACORGA M5640.
