Purity Considerations and Interfacial Behavior of Solvent Extraction Systems

Abstract
The techniques to purify different components of a typical solvent extraction system, viz., n-hexane/di(2-ethylhexyl)phosphoric acid (HDEHP)/CaCl2 solution, are described. Data showing how the purity of the different components affects the interfacial tension (γ) are given. The interfacial behavior of the n-hexane/ HDEHP/0.01 mol dm−3 CaCl2 solution system was studied as a function of HDEHP concentration and aqueous phase pH. γ-log [HDEHP] curves were also determined at pH 4 when the aqueous phase contained 0.05 mol dm−3 MgCl2, CaCl2, SrCl2 or BaCl2. γ-log [HDEHP] curves revealed interaction of the metal ions with the extractant and exhibited a behavior reminiscent of aggregate formation when the aqueous phase contained Ca2+.