Foam Separation of Anions: Hydration, Entropy, and Selectivity

Abstract

A selectivity coefficient for the foam separation of Fe(CN)₆ ^4-, Ag(S₂0₃)₂ ^3-, Cr₂0₇ ^2-, Cr0₄ ^2-, S₂0₃ ^2-, HP0₄ ^2-, and I⁻ from solutions containing ethylhexadecyldimethylammonium bromide is related to the absolute partial molal entropy of each ion. The entropy, which correlates well with the degree of hydration, enables an estimate of the selectivity of an ion flotation or foam fractionation by a surfactant.