Facilitated transport of Am(III) through a flat-sheet supported liquid membrane (FSSLM) containing tetra(2-ethyl hexyl) diglycolamide (TEHDGA) as carrier

Facilitated transport of Am(III) in nitric acid medium using tetra(2-ethyl hexyl) diglycolamide (TEHDGA) in n-dodecane as carrier was studied. It was aimed at finding out the physico-chemical model for the transport of Am(III) using TEHDGA/n-dodecane as carrier under various experimental parameters like feed acidity, carrier concentration, varying strippant, varying membrane pore size, etc. The feed acidity and carrier concentrations were varied from 1 M to 6 M HNO3 and 0.1 M to 0.3 M TEHDGA/n-dodecane, respectively. The transport of Am(III) increased with increase in feed acidity and carrier concentration reaching maximum at 3 M HNO3 and 0.2 M TEHDGA/n-dodecane, respectively. Several stripping agents were tested and 0.1 M HNO3 was found to be the most suitable stripping agent for this system. Almost quantitative transport of Am(III) was observed at about 180 min with feed acidity of 3 M HNO3, 0.1 M HNO3 as strippant and 0.2 M TEHDGA/n-dodecane as carrier. The pore size of the membrane support was varied from 0.20 mu m to 5 wm and the permeation coefficient increased with increase in pore size up to 0.45 mu m (2.43 x 10(-3) cm/s), and then decreased with further increase in pore size. The plot between permeation coefficient vs. (membrane thickness)(-1) was linear which showed that the Am(III) transport was membrane diffusion limited. The membrane diffusion coefficient calculated from the graph was found to be 1.27 x 10(-6) cm(2)/s and its theoretical value was 1.22 x 10(-6) cm(2)/s. The stability of the carrier against leaching out of the membrane support as well as the integrity of membrane support was studied over a period of 30 days and was found to be satisfactory within the studied time period. (c) 2008 Elsevier B.V. All rights reserved.