Diglycolamide-functionalized calix[4]arene for Am(III) recovery from radioactive wastes: liquid membrane studies using a hollow fiber contactor

The transport of Am(III) from nitric acid feeds was investigated using hollow fiber supported liquid membrane (HFSLM) containing a diglycolamide-functionalized calix[4]arene (C4DGA) as the carrier extractant. The effect of feed acidity and Nd(III) concentration (used to represent Am(III)) in the feed on the permeation of Am(III) was investigated. Complete permeation of Am(III) from the source to the receiver phase was possible within 30 min at tracer scale. The permeation of the metal ion was unaffected with the feed HNO3 concentration in the range of 2–4 M while the presence of macro quantities of Nd(III) in the feed solution suppressed the metal ion transport rates. The permeability coefficient, mass transfer coefficient, and various diffusional parameters of the diffusing metal–ligand complex were calculated to understand Am(III) transport behavior. The transport rates of Am(III) were predicted by a mathematical model with an excellent match between the experimental and calculated data. The present study gives an opportunity to use exotic ligands for radioactive waste treatment using a very low extractant inventory using HFSLM