Separation of Iron(III) with Ammonium Thiocyanate‐H 2 O‐n‐Propyl Alcohol Extraction System in the Presence of Sodium Chloride

The behavior and conditions of liquid‐liquid extraction‐separation of Fe(III) by ammonium thiocyanate‐H 2 O‐n‐propyl alcohol system in the presence of NaCl were studied, and the possible reactive mechanism of extraction of Fe(III) was deduced. The study showed that, in the presence of a given amount of NaCl, phases were separated thoroughly between n‐propyl alcohol and water. In the process of phase separation, the complex [Fe(SCN) n ] (3‐n) formed by NH 4 SCN and Fe(III) was quantitatively extracted into the n‐propyl alcohol phase. The extracted Fe(III) exists in the n‐propyl alcohol phase mainly as the forms of Fe(SCN) 2 + and Fe(SCN) 3 . Also, the relationship between extraction yield of Fe(III) and the amount of NH 4 SCN agreed well with the quadratic equation E = 0.54 + 58.14x − 8.39x 2 (E and x represent the recovery rate of Fe(III) and the volume (mL) of 0.1 M NH 4 SCN respectively). The quadratic R‐Square is 0.9990. With this method, Fe(III) can be completely separated from Co(II), Ni(II), Mn(II), Al(III), Bi(III) and Cd(II) at pH 1.0˜2.0. The present method was applied in determining Fe(III) in samples with satisfactory results such as relative standard deviation from 2.06% to 2.89% and recovery rate in the range of 98.4˜101.4%.