Problem associated with the use of TBP for LEM extraction of U(VI) and attempt to overcome this problem using other ligands

Efficacy of extraction of U(VI) by liquid emulsion membrane (LEM) using TOPO, D2EHPA and TOA

“…This can be explained in terms of higher acid extraction capability of high level of TOPO concentration at higher acid level (within the experimental range) concentration, is high in LEM extraction. We find that the percent extraction of U(VI) increases with increase in TOPO concentration initially (up to the coded level near to ?0.6) and beyond which there is a fall which can be explained based on our previous study that with increasing TOPO concentration acid extraction increases in strip phase causing reduction in U(IV) extraction [17]. Figure 3b, shows the interaction between the TOPO concentration X 1TOPO ð Þand concentration of surfactant in organic phase X 3Abil ð Þwhich shows maxima of extraction at around mean level of the coded variable revealed that influence of TOPO is quadratic (nonlinear).…”

“…In our previous study we have studied rate of extraction of U(VI) using LEM with varying one at a time each of the individual parameter viz. (i) concentration of ligand, (ii) initial concentration of acid in the feed phase, initial concentration of U(VI) in feed, (iii) speed of emulsifier, (iv) speed of petraction, (v) strip phase and remaining parameters were kept as constant [17]. 1 Schematic diagram of LEM extraction procedures M DC motor, C controller and tachometer, E emulsifier, P primary emulsion, I internal strip phase, G emulsion globules, F external feed phase (aqueous), R raffinate (aqueous), S secondary emulsion containing extract/strip phase, J rotating Jack/sliding assembly The rate constant of extraction of U(VI), k were calculated for all such cases.…”

“…The choice of these parameters was based on the results of our pervious studies [17]. Also, the following parameters were fixed a priori as optimal (again based on the previous studies [14,17]) and were not subjected to optimization.…”

“…The choice of these parameters was based on the results of our pervious studies [17]. Also, the following parameters were fixed a priori as optimal (again based on the previous studies [14,17]) and were not subjected to optimization. The composition of the internal strip phase which was 0.5MNa 2 CO 3 for the LEM extraction involving TOPO or TOA, or 2 M H 2 SO 4 for the LEM extraction involving D2EHPA and speed of pertraction.…”

“…However, no correlation studies on the impact of these vital factors on LEM extraction was carried out. The previous study by the author [17] established the following factors to be most influential for extraction of U(VI) using LEM.…”