Cloud-Point Extraction for Selective Removal of Gd(III) and La(III) with 8-Hydroxyquinoline

Abstract

Abstract:A less-common extraction procedure, cloud-point extraction, is used with a lipophilic chelating agent (8-hydroxyquinoline) to extract and separate lanthanum(III) and gadolinium(lll) ions from an aqueous solution. Surfactant solutions are used in conjunction with 8-hydroxyquinoline to form a lanthanide complex that is extracted into the micellar phase at a temperature above the cloud-point temperature. The structure of the lipophilic part of the nonionic surfactant, the chelating agent-metal molar ratio, and the cloud-point temperature are identified as factors determining the extraction efficiency and selectivity. With Triton X-114, a selectivity higher than 30 and a decontamination factor of 50 for Gd(IlI) indicate that micelle-mediated cloud-point extraction is promising for the specific separation of actinide ions from nuclear waste. Finally, a microwave procedure is proposed to decrease the duration of the experiment to less than 6 min.