AQUEOUS SOLUBILITY OF SOLVENT EXTRACTION REAGENTS: A MONOLAYER DISSOLUTION METHOD

ABSTRACT An experimental method, based on Langmuir film balance techniques, Is presented for determining the aqueous solubility of sparingly soluble solvent extraction reagents. According to this method, the reagent of interest is spread as a monomolecular film on a Langmuir trough and the contraction of the film area accompanying extractant dissolution is monitored as a function of time while maintaining a constant film pressure. Quantitative analysis of the diffusion-controlled film dissolution kinetics yields the extractant concentration in equilibrium with the monolayer at a specified constant surface pressure. Solubility data obtained by applying this method to dinonylnaphthalene sulfonic acid (HDNNS) and 2-hydroxy-5-nonylbenzophenone oxime (HBPO, active extractant in LIX65N) are reported.