Synergistic extraction of Fe-III using di-(2-ethylhexyl)phosphoric acid and 18-crown-6 in n-butanol

The liquid-liquid extraction of Fe-III from aqueous chloride solution by a mixture of 2-ethylhexylphosphoric acid and 18-crown-6 into n-butanol is reported. Spiked iron was determined by measuring its gamma-activity at energy. Synergism was observed in the extraction of labeled Fe-III into n-butanol. Stoichiometry of extracted species in both individual and mixed extraction was ascertained by slope ratio analysis. From the extraction data, overall equilibrium constants for binary and ternary extractions were calculated. Thermodynamic parameters controlling the nature of the extraction were also evaluated from the distribution ratio values obtained at different temperatures. Such results are important in order to explain the extraction mechanism.