Uranium(VI) pertraction across a supported liquid membrane containing a branched diglycolamide carrier extractant: Part III: Mass transfer modeling

Abstract

Solvent extraction and facilitated transport of UO 2 2+ across supported liquid membrane containing N,N,N′,N′-tetra-2-ethylhexyldiglycolamide (T2EHDGA) in n-dodecane as the carrier extractant and 30% iso-decanol as the phase modifier were investigated from nitric acid feed solutions. Extraction constants were comparable to those reported earlier for the U(VI)-TODGA extraction system at 3.0 M HNO 3 feed conditions and consequently, the transport rates were comparable with the two extractants. > 80% U transport was reported in 5 h while using 3 M HNO 3 as the feed and 0.01 M HNO 3 as the receiver phase solution. Mass transport modeling of the facilitated transport of uranyl ion across PTFE supported liquid membranes was done by a developed mathematical model. Diffusion coefficients were calculated using Danesi's model as well as by lag time measurements. The transport was found to be diffusion controlled in the membrane phase and the permeability coefficient was calculated to be (3.20 ± 0.13) × 10 − 4 cm/s for the feed composition of 3 M HNO 3, receiver phase composition of 0.01 M HNO 3 and membrane carrier phase of 0.2 M T2EHDGA in n-dodecane containing 30% iso-decanol while the membrane diffusion coefficient was calculated to be (1.58 ± 0.16) × 10 − 6 cm 2/s.