Highly selective carrier mediated transport of plutonium(IV) across a supported liquid membrane using two substituted tripodal amides

Plutonium-specific supported liquid membranes were developed and reported for the first time. The studies included in this paper are on the supported liquid membrane transport behavior of Pu(IV), Am(III) and U(VI) investigated using two tripodal amides viz. N,N,N,'N,'N,"N"-hexa-n-octylnitrilotriacetamide (HONTA) and N,N,N,'N,'N,"N"-hexa-n-dodecylnitrilotriacetamide (HDDNTA). The feed phase consisted of 3 M HNO3 while 0.5 M oxalic acid +0.5 M HNO3 was used as the strip phase. The SLM studies indicated 78.2% and 86.2% transport of plutonium(IV) after 4 h using 0.08 M concentrations of HONTA and HDDNTA, respectively, and the transport of Am(III) and U(VI) was <1% under identical feed acid conditions indicating a possible highly selective separation of Pu(IV) using HONTA as the carrier ligand from a mixture of Pu(IV), Am(III) and U(VI). The stability of the membrane was reasonably good up to 9 days. The activation energy of the transport process was determined using temperature variation studies with HONTA and HDDNTA indicating the transport process being kinetically as well as diffusion controlled. This work is highly relevant for the separation of Pu from radioactive feeds containing other actinide elements such as U and Am.