Effect of pore characteristics on carrier-facilitated transport of Am(III) across track-etched membranes

Track-etched membranes (TEMs) with well-defined pore characteristics were prepared by bombarding polycarbonate plastics with 161Dy ions of 13.0 MeV per nucleon energy and by bombarding polycarbonate plastics with fission fragments from a 252Cf source. In order to optimise the properties of TEMs for their applications as model supports in supported liquid membrane (SLM) studies, the transport of Am(III) across the SLM with TRUEX extractants (0.2 M n-octylphenyl (N,N-diisobutyl carbamoyl methyl) phosphine oxide (CMPO)+1.2 M tributyl phosphate (TBP) in dodecane) as carrier has been examined. The latent tracks formed by heavy-ions in the plastics were enlarged into well-defined pores by chemical etching. The geometry of the pores formed in the plastics was obtained by the track-etched model, based on the dynamics of pore etching. The TEMs were converted as supports for SLM studies by impregnating them with the carrier (0.2 M CMPO+1.2 M TBP in dodecane). The SLMs with different supports were used for studying the facilitated transport of Am(III). The permeation across the SLM formed by using TEM with 17% porosity was found to be comparable to those SLMs formed by using commercial membranes with much higher porosities. The comparison of permeability coefficients (P) obtained by using TEMs with 29–30 μm and 10 μm thickness indicated that P decreases linearly with thickness and hence transport of Am(III) is diffusion controlled, and reaction kinetics of extraction and stripping steps are fast.