Effect of alkali ions (Na+, K+) on the solvent extraction of uranium(VI) with a di-carboxylated calix[4] arene

Abstract

The solvent extraction of uranium(VI) with a di-carboxylated calix[4]arne (LH2) in chloroform and 1,2-dichloroethane has been studied in the presence or absence of alkali ions (M=Na+,K+). For UO22+ when studied alone, a 1∶2 (metal: ligand) extracted species is evidenced, with a rather low associated extraction equilibrium constant. The efficiency of extraction increases drastically in the presence of alkali ions, due to the formation of heteronuclear complexes. In all cases, the extracted species are found to be both 1∶2∶2 and 1∶1∶2 (UO22+∶M∶LH2) mixed complexes, except in chloroform with K+, where only the latter is formed. In the case of Na+, mass spectrometry spectra confirm the existence of both homo and heteronuclear complexes as determined in the extraction studies.