QUANTITATIVE REMOVAL OF URANYL IONS FROM AQUEOUS-SOLUTIONS USING MICELLAR-ENHANCED ULTRAFILTRATION

Quantitative removal of uranyl ions present in aqueous solutions at the mu-g ml-1 concentration level was achieved using the micellar-enhanced ultrafiltration technique. Suitable chelating micelles were formed by dissolving selective hydrophobic acyclic ligands in the usual amphiphilic aggregates. These ligand-doped micelles accumulate the uranyl ions through the formation of tightly bound chelates. The aggregates and their guest metal complexes were successively separated by ultrafiltration through hydrophilic membranes of suitable pore size. The efficiency of the process is related to the affinity of the ligands for the micelles. Non-ionic and cationic surfactants were investigated. Quantitative retention of the analyte in the surfactant-rich retentate solution was achieved when working with cetyltrimethylammonium bromide micelles. The uranyl recovery was significantly increased by introducing trioctylphosphine oxide as an auxiliary ligand, which allowed for very efficient preconcentrations at lower pH.