SELECTIVITY IN FOAM SEPARATION BY CONTROL OF CHARGE ON EXTRACTING SOLUTE - METAL-CHLORO COMPLEXES

The application of selective concentration by foam separation of trace species via control of charge on these species has been investigated. The removal of anionic chloro complexes of iron(III), mercury (II), and cobalt(ll) has been examined. Distribution factors, F/C, as a function of hydrochloric acid concentration have been measured with the cationic surfactant, hexadecyltrimethylammonium bromide; the trends have been found to be similar to those obtained in ion-exchange measurements, with an anionic exchanger. In the case of iron(III), F/C has also been measured as a function of surfactant concentration, initial FeCL3 concentration, and % ethanol in water. Total reflux foam separation measurements were performed for selective removal. It was found that IO-7 M FeCl3 could be selectively removed in the presence of a 100-fold excess of HgCl2. Further, HgCI2 could be selectively concentrated at I M hydrochloric acid and 10-7 M in the presence of CoCl2. A model based on a mobile ion-exchanger surface is presented to explain qualitatively the trends observed. © 1969.