Ion flotation of dichromate and of complexed cyanide: Surfactants for qualitative analysis

Ion flotation studies have shown that a surface‐active agent is useful for qualitative analysis of complex ions in dilute aqueous solution, with the surfactant forming a particulate complex with the complex ion of concern. Experiments with a monovalent, cationic surfactant have established the prevalence of Cr 2 O 7 2− (HCrO 4 − ) and not CrO 4 2− ; of [Fe(CN) 6 ] 4− and [Fe(CN) 5 H 2 O] 3− ; and of [FeFe(CN) 6 ] 2− and not [FeFe(CN) 6 ] − or [Fe(CN) 6 ] 3− . The results can be contrasted to those with ions that do not form particulate complexes with the surfactant, such as HPO 4 2− and phenolate; with the latter, no qualitative analytical information can be gained. Ion flotation appears to be a promising technique in general for the determination of ionic species present in aqueous solution; the surfactant must react with the ion of significance to form a particulate complex and the initial surfactant concentration must be controlled carefully.