Selectivity Coefficients for Zn(CN)4 2-, Cd(CN)4 2-, and Hg(CN)4 2- from Continuous Foam Fractionation with a Quaternary Ammonium Surfactant

Abstract
An experimental study is presented on the continuous flow, foam fractionation of cyanide complex anions. Zn(CN)4 2-, Cd(CN)4 2-, and Hg(CN)4 2- form 7.5 × 10−6 to 1.5 × 10−5 M aqueous solutions with the quaternary ammonium surfactant, hexadecyltrimethylammonium iodide. The selectivity coefficients were determined for Zn(CN)4 2- vs I equal to 8.86. for Cd(CN)4 2- vs I equal to 21.79 and for Hg(CN)4 2- vs I equal to 25.12. The surfactant ion-exchange reaction with the studied complex ions was also suggested.