Separation of cobalt(II) from nickel(II) by solid-phase extraction into Aliquat 336 chloride immobilized in poly(vinyl chloride)

Abstract

A solid-phase absorbent obtained by the immobilization of Aliquat 336 chloride in poly(vinyl chloride) is reported to extract preferentially Co(II) from its 7 M hydrochloric acid solutions containing Ni(II). Under the experimental conditions there was no extraction of Ni(II) which allowed the complete separation of these two ions. Co(II) was rapidly and quantitatively back-extracted with deionised water. A mechanism for the extraction of Co(II) is proposed based on the formation of the ion-pair A+[HCoCl4]- where A+ is the Aliquat 336 cation. Fe(III) and Cd(II), usually present in Co(II) and Ni(II) samples, were also extracted into the solid-phase absorbent though at a slower rate than Co(II)..