Recovery and Reuse of a Surfactant in Ion Flotation

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Abstract
The feasibility of virtually any commercial-scale ion flotation (foam separation) process depends on the recovery and reuse of the surfactant used as the flotation agent. For aqueous solutions of acid chromate complexed with a cationic quaternary ammonium salt, ethylhexadecyl-dimethylammonium bromide, a variety of paths are investigated to split the complex and to separate and recover the surfactant. These include acid chromate reduction with NaHSO3 or SnCl2 followed by sorption of the surfactant by and elution from a polymeric resin, Rohm and Haas Amberlite XAD-2. The most promising path is reduction of the acid chromate with NaHSO3 at pH 2–3, extraction with isopropanol—chloroform in a 1:1 ratio, vacuum distillation of the solvents, and redissolution of the surfactant in aqueous solution. The minimum HSO3/Cr ratio is established, distribution coefficients for the extraction are determined, and the recovered surfactant is tested in several ion flotation experiments, making a comparison with fresh surfactant.