Flotation of perrhenates with cationic surfactants: Effect of surfactant's structure

An experimental investigation is presented on the flotation of perrhenate anions from diluted aqueous solutions (5.10^?5 M ) with numerous cationic surfactants of systematically varying molecular structure. Alkyltrimethyl-ammonium bromides, alkoxycarbonylmethyl-trimethylammonium chlorides, alkoxycarbonylmethyl-dimethylbenzylammonium chlorides, ethoxycarbonylmethyl-dimethylalkylammonium chlorides, N-substituted dodecylamines, and diquaternary ammonium bromides were investigated at their initial concentrations in the feed solution, 1.10^?4 M or 2.10^?4 M . It was found that both the length of the main hydrocarbon chain and of the short hydrocarbon groups govern the affinity of a cationic surfactant towards perrhenate anions. In order to achieve the effective flotation of perrhenate or similar anions the value of C:N atomic ratio for a tertiary or a quaternary ammonium surfactant should be in the range 15 to about 26. This value can be used as a primary criterion for the sufficient flotation capability of an alkylammonium surfactant.