Salting-out phase separation of the mixture of 2-propanol and water for selective extraction of cobalt(II) in the presence of manganese(II), nickel(II), and copper(II)

The selective separation of cobalt(II) in the presence of manganese(II), nickel(II), and copper(II) was studied by using the mixture of 2-propanol with water through the addition of CaCl2 in the concentration range of 3.0–6.5 mol dm−3. Cobalt(II) was extracted to the extent of 94.4% into the 2-propanol phase at 6.5 mol dm−3 CaCl2. The extraction of other metal ions such as Mn(II), Ni(II), and Cu(II) was much lower than that of Co(II), but they were completely stripped to the aqueous phase by using an aqueous solution containing CaCl2. Thus, selective separation of cobalt(II) from these elements was attained by using the mixture of 2-propanol with water. Cobalt(II) was extracted as CoCl42− with Ca2+ from the aqueous solution into the organic phase. The detailed extraction mechanism involving the ion pair of Ca2+ and CoCl42− has been proposed to explain this extraction.