Abstract
The retention profile of uranyl ions from aqueous media by polyether-type-based polyurethane foams (PUFs) was studied to gain more information regarding the mechanism of uranyl ions extraction. The influence of pH, extraction time, picric acid (PC), crown ether (CE) and uranyl ions concentration on the sorption step by the PUFs was studied. The data revealed that the sorption of uranyl (II) ions involved formation of a ternary complex ion associate between uranyl (II) ions with crown ether and picric acid and its retention is highly dependent on the parameters studied. The dependency of the sorption percentage on the parameters was explained in a manner consistent with a “solvent extraction” mechanism. The kinetics of uranyl ions sorption onto crown-ether-loaded PUFs was found fast and followed a first-order rate constant in the presence of picric acid in the aqueous phase. The sorption data were also followed Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherms over the entire concentration range of uranyl ions employed. Thus, a dual-mode sorption mechanism involves absorption related to “solvent extraction” and an added component for surface adsorption may be operated simultaneously. The proposed retention procedures were applied successfully for the determination of uranyl (II) ions and picric acid in aqueous media.