Selective Extraction of Co(II) in the Presence of Mn(II), Ni(II) and Cu(II) Using Salting-out Phase Separation Method

Abstract

Extraction of Co(II) in the presence of Mn(II), Ni(II) and Cu(II) has been studied using the mixture of 2-propanol with water upon the addition of CaCl2 in the concentration range of 3.0 – 5.0 mol dm-3 (M). Co(II) was extracted selectively to the extent of 80% into the 2-propanol phase at 5.0 M CaCl2. The percent of extraction of other transition metal ions, for example Mn(II), Ni(II) and Cu(II) was much lower than that of Co(II), but they were stripped in the aqueous phase upon addition of CaCl2. Therefore, selective extraction of Co(II) from these metal ions was attained by using the mixture of water and 2-propanol. Co(II) was extracted as CoCl42- from the aqueous phase into the 2-propanol phase through the formation of ion pair, Ca2+ - CoCl42-. A mechanism is proposed to explain the extraction.

Keywords

• salting-out phase separation
• extraction of Co(II)
• transition metal ions