Analytical Sciences


Abstract − Analytical Sciences, 27(6), 653 (2011).

Solid-Phase Extraction of Cobalt(II) from Lithium Chloride Solutions Using a Poly(vinyl chloride)-based Polymer Inclusion Membrane with Aliquat 336 as the Carrier
Shigehiro KAGAYA,*,** Robert W. CATTRALL,** and Spas D. KOLEV**
*Graduate School of Science and Engineering for Research, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
**School of Chemistry, The University of Melbourne, Victoria 3010, Australia
The extraction of cobalt(II) from solutions containing various concentrations of lithium chloride, hydrochloric acid, and mixtures of lithium chloride plus hydrochloric acid is reported using a poly(vinyl chloride) (PVC)-based polymer inclusion membrane (PIM) containing 40% (w/w) Aliquat 336 as a carrier. The extraction from lithium chloride solutions and mixtures with hydrochloric acid is shown to be more effective than extraction from hydrochloric acid solutions alone. The solution concentrations giving the highest amounts of extraction are 7 mol L−1 for lithium chloride and 8 mol L−1 lithium chloride plus 1 mol L−1 hydrochloric acid for mixed solutions. Cobalt(II) is easily stripped from the membrane using deionized water. The cobalt(II) species extracted into the membrane are CoCl42− for lithium chloride solutions and HCoCl4 for mixed solutions; these form ion-pairs with Aliquat 336. It is also shown that both lithium chloride and hydrochloric acid are extracted by the PIM and suppress the extraction of cobalt(II) by forming ion-pairs in the membrane (i.e. R3MeN+·HCl2 for hydrochloric acid and R3MeN+·LiCl2 for lithium chloride).