Separation of carrier-free 90Y from 90Sr using flat sheet supported liquid membranes containing multiple diglycolamide-functionalized calix[4]arenes

Five diglycolamide-appended calix[4]arene (C4DGA) ligands, viz. C4DGA with no substituent (L-I), n-propyl (L-II), 3-pentyl (L-III), n-octyl (L-IV) and both side (L-V) substituents were evaluated for the separation of carrier free Y-90 from a Y-90-Sr-90 mixture using the flat sheet supported liquid membrane technique. Based on the results of earlier batch studies, the transport properties of the C4DGA ligands towards Y(III) and Sr(II) were monitored at two different feed acidities. The transport rates were significantly lower for 6M HNO3 as compared to 3M HNO3 as the feed. After 6h, the observed trend of Y(III) transport with the C4DGA ligands using a feed of 3M HNO3 was: L-I ~ L-III > L-V > L-IV > L-II which changed to L-III > L-I > L-IV > L-V > L-II for 6M HNO3 as the feed. With 3M HNO3 as feed, >97% Y(III) transport was obtained with L-I and L-III in 6h. Comparative Sr(II) transport was negligible resulting in high decontamination factors. In a one-step separation process, using L-I as the carrier ligand, pure Y-90 was obtained as the respective complex with either EDTA or DOTA. The highlights of this liquid membrane-based separation method comprise: its easiness, one-step separation, low ligand inventory, relatively pure product and continuous method.