Abstract
The solvent extraction of LaIII from picrate media was carried out with a dichloromethane solution containing large cavity size crown ethers (> 4A), namely dibenzo-[24]-crown-8 (DB24C8), dicyclohexano-[24]-crown-8 (DCH24C8) and dibenzo-[30]-crown-10 (DB30C10). It was found that LaIII was poorly extracted when DB30C10 was used, whereas both DB24C8 and DCH24C8 were good extractants. However, DB24C8 was preferred over DCH24C8 owing to its superior selectivity over the other lanthanides. The effects of variables such as solvent, counter ion concentration, pH, ligand concentration, equilibration time, stripping agent and selectivity over other elements were investigated. Under the optimized conditions, LaIII was quantitatively extracted from 0.0002 mol l–1 picric acid at pH 9 with 0.02 mol l–1 DB24C8 in dichloromethane. The extracted metal ion was stripped from the organic phase with 0.5 mol l–1 perchloric acid, and its concentration determined spectrophotometrically at 651.5 nm as its complex with Arsenazo III (pH, 3.2). A significant selectivity for LaIII over other lanthanides was observed. Replicate analysis of a monazite sand sample for lanthanum yielded results comparable to those obtained by atomic absorption spectrometry. The composition of the extracted species, viz., LaIII: DB24C8: picrate, was 1:1:3.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
