Extraction of lutetium(III) from aqueous solutions by employing a single fibre‐supported liquid membrane

Abstract

Transport behaviour of Lu(III) across a polypropylene hollow fibre-supported liquid membrane containing di(2-ethylhexyl)phosphoric acid (DEHPA) in dihexyl ether as a carrier has been studied. The donor phase was LuCl(3) in the buffer solution consisting of 0.2 M sodium acetate at pH 2.5-5.0. A miniaturised system with a single hollow fibre has been operated in a batch mode. The concentration of Lu(III) was determined by indirect voltammetric method using Zn-EDTA complex. The effect of pH and volume of the donor phase, DEHPA concentration in the organic (liquid membrane) phase, the time of extraction and the content of the acceptor phase on the Lu(III) extraction and stripping behaviour was investigated. The results were discussed in terms of the pertraction and removal efficiency, the memory effect and the mean flux of Lu(III). The optimal conditions for the removal of (177)Lu(III) from labelled (177)Lu-radiopharmaceuticals were discussed and identified. The removal efficiency of Lu(III) greater than 99% was achieved at pH of the donor phase between 3.5 and 5.0 using DEHPA concentration in the organic phase of 0.47 M and the ratio of the donor to the acceptor phase of 182.

Mass transfer resistance in a liquid‐phase microextraction employing a single hollow fiber under unsteady‐state conditions

“…This result indicates the existence of resistance in the acceptor phase, probably due to the small contact area between the organic and the acceptor phase and the low volume of the acceptor phase. Moreover, the prolongation of extraction time from 1 to 24 h had no effect on the amount of Lu(III) re‐extracted into the acceptor phase . This indicates that diffusion through liquid membrane is not the main reason of Lu(III) mass transfer resistance.…”

“…Considering that the partition coefficient of Lu(III) between the organic phase and the acceptor phase was 0.2, as determined by liquid–liquid extraction in a separatory funnel , the resistance in the acceptor phase was probably not dominant resistance in the overall mass transfer resistance. In addition, the formation of a complex between Lu(III) ions and DEHPA molecules can be regarded as a fast reaction and therefore, the mass transfer resistances due to the complexation and decomplexation reactions can be neglected. Irrespective of the problems with accumulation of Lu in the organic phase, HF‐LPME is an efficient and easy to handle method for removal of free 177 Lu from the labeled radiopharmaceutical, suitable for small feed volumes, which is a very useful feature when working with radioactive materials.…”

“…In our previous study [20], we have proposed HF-LPME technique for removing free radionuclide 177 Lu(III) from a 177 Lu(III)-labeled compound in the production of radiopharmaceuticals for radiotherapy. Extraction of Lu(III) was facilitated using di(2-ethylhexyl)phosphoric acid (DEHPA) as a carrier dissolved in the organic phase.…”

Membrane-Assisted Liquid-Phase Extraction of Lu(III) in a U-Shaped Contactor with a Single Hollow Fiber Membrane

“…The optimum experimental conditions for the efficient removal of Lu(III) from the donor phase have been established in our previous study using stagnant (non-recirculating) HF-LPME system 24 . We have achieved the maximum removal efficiency of Lu(III) higher than 99 % after 2 h of operation at the donor-to-acceptor phase volume ratio of 180, pH 3.5 in the donor phase, and using 5% (v/v) DEHPA/DHE and 2 mol dm -3 HCl as the organic and acceptor phase, respectively.…”

“…The novel HF-LPE system was operated under continuous closed-loop recirculation of both the donor and acceptor phase with the aim of improving the efficiency of re-extraction of Lu(III) from the organic phase, which was the main bottleneck in the static system 24 . The influence of the donor flow rate on the mass transfer of Lu(III) in the applied system was also studied.…”