A comparative evaluation of the liquid-liquid extraction and pertraction efficiency of a both-side diglycolamide-functionalized calix[4]arene with analogous upper and lower-rim calixarenes for actinide separations

A lower-rim (L-I), an upper-rim (L-II), and a both-side (L-III) diglycolamide-functionalized calix[4]arene were evaluated for the extraction of actinide ions such as UO22+, Pu4+, and Am3+ and fission product element ions such as Eu3+, Cs+, and Sr2+ from dilute nitric acid feed solutions. Conditions for quantitative extraction and stripping were found out and the kinetics of it were investigated for the extraction of Am3+. Though the actinide ions were generally extracted efficiently, UO22+ was poorly extracted. Supported liquid membrane (SLM) studies were carried out using the diglycolamide-functionalized calix[4]arenes under varying feed acidities and carrier extractant concentrations and the results compared with that of TODGA under identical conditions. A 0.01 M EDTA solution (pH 3.0) was found to yield quantitative transport of Am(III) using the extractants L-I–L-III. The transport efficiency of the carrier solvent system was Eu3+>Pu4+>Am3+⪢UO22+. Diffusion coefficient values were both calculated by the Wilke-Chang equation and determined by the lag-time method. The SLM showed a poor stability, which did not improve by strip dispersion efforts.