Separation of traces of heavy metals from an iron matrix by use of an emulsion liquid membrane.
An emulsion liquid membrane method has been developed for separating traces of heavy metals from an iron matrix. A 1.0-mL volume of aqueous iron(III) solution (pH 2.0) was emulsified with a mixture of 0.6 mL toluene, 2.4 mL n -heptane, and 80 mg sorbitan monooleate (Span-80). The resulting water-in-oil type emulsion was gradually injected into 25 mL of 1.5 mol L(-1) hydrochloric acid solution containing 30 mmol L(-1) 8-quinolinol and 1.0 mol L(-1) of ammonium sulfate and was dispersed as numerous tiny globules by stirring for 40 min. More than 90% of the iron(III) diffused through the oil layer to the external hydrochloric acid solution with the aid of complexation with 8-quinolinol, whereas trace heavy metals, e.g. Cr(III), Mn(II), Co(II), Ni(II), Cu(II), and Pb(II), remained quantitatively in the internal aqueous phase. After collecting the dispersed emulsion globules, they were demulsified and trace metals in the segregated aqueous phase were determined by graphite-furnace atomic absorption spectrometry. Owing to sufficient removal of the iron matrix trace metal impurities in high-purity iron were successfully determined without interference, as was confirmed by analysis of certified reference materials.
Kageyama
Tomohiro
T
Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, 464-8603 Nagoya, Japan.
Matsumiya
Hiroaki
H
Hiraide
Masataka
M
D004655:Emulsions / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008567:Membranes, Artificial; D019216:Metals, Heavy / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013499:Surface Properties
D004655:Emulsions; D008567:Membranes, Artificial; D019216:Metals, Heavy; D007501:Iron