Efficient transport of Am(III) from nitric acid medium using a new conformationally constrained (N,N,N′,N′-tetra-2-ethylhexyl)7-oxabicyclo[2.2.1]heptane-2,3-dicarboxamide across a supported liquid membrane

Graphical abstract: A conformationally constrained diamide, (N,N,N′,N′-tetra-2-ethylhexyl) 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxamide (OBDA) was found to transport Am(III) from HNO₃ medium across a Supported Liquid Membrane with good transport rate, diffusion coefficient and selectivity over fission products. - Highlights: The highlights of the work are as follows: • Efficient transport of Am(III) in SLM from HNO₃ using 0.1 M OBDA as carrier. • Very high transport rate (∼95% in 1 h) of Am(III). • Higher permeability co-efficient value compared to TEHDGA. • The OBDA loaded SLM can be used for multiple cycles of operation. - Abstract: Am(III) is one of the most hazardous radionuclide present in nuclear fuel cycle. A new conformationally constrained diamide, (N,N,N′,N′-tetra-2-ethylhexyl)7-oxabicyclo[2.2.1]heptane-2,3-dicarboxamide (OBDA) was studied for Am(III) transport from HNO₃ medium across a Supported Liquid Membrane. Transport rate was observed to be significantly fast with ∼95% transport of Am(III) within 1 h using 0.1 M OBDA in the presence of 15% isodecyl alcohol (IDA)/n-dodecane as carrier. The mechanism of transport was investigated by studying various parameters like feed HNO₃/NaNO₃ concentration, OBDA concentration in the membrane, membrane pore size, membrane thickness etc. From these studies, the mechanism of transport was found to be diffusion controlled with diffusion co-efficient value of 5.1 × 10⁻⁶ cm²/s. The membrane was found to be highly selective for tri- and tetra-valent actinides, and trivalent lanthanides. OBDA based membrane was found to be stable for at least for ten consecutive cycles of operation.