Separation of yttrium from strontium by hollow fibre supported liquid membrane containing di(2-ethylhexyl)phosphoric acid

Separation of Y(III) from Sr(II) was performed using the hollow fibre membrane contactor operated in a recirculation mode. The steady-state was established after ~5 h of operation and the maximum removal of Y(III) from the donor to the acceptor was achieved at the donor flow rate of 4.7 cm3 min-1. The investigated system showed promising results as a method which could be potentially applied for the preparation of 90Sr/90Y generator system

Membrane-assisted liquid phase extraction of Lu(III) in U-shaped contactor with a single hollow fibre membrane under recirculation mode of operation

Extraction of Lu(III) from an aqueous LuCl3 solution at pH 3.5 into an organic phase containing 5% (v/v) di(2-ethylhexyl)phosphoric acid (DEHPA) in di-n-hexyl ether (DHE) immobilized within a polypropylene hollow fibre membrane and a simultaneous back-extraction of Lu(III) into 2 mol dm-3 HCl solution has been investigated using two miniaturized supported liquid membrane (SLM) systems: (i) a single hollow fibre membrane, with stagnant acceptor phase in the lumen, immersed into a donor phase reservoir; (ii) U-shaped module containing a single hollow fibre membrane with a closed-loop recirculation of aqueous phases through the module. In the stagnant SLM system, the maximum extraction efficiency was 8.8% due to limited acceptor volume and absence of flow within the lumen. In recirculating SLM system, after 80 min of operation at the donor phase flow rate of 5.3 cm3 min-1, the acceptor phase flow rate of 0.4 cm3 min-1 and the donor-to-acceptor phase volume ratio of 6.7, the equilibrium removal efficiency of Lu(III) reached 88% and less than 5% of Lu(III) extracted from the feed solution was kept in the organic phase. For shell side flow of the donor phase at the Reynolds number of 3−34, the overall mass transfer coefficient was proportional to the donor flow rate raised to the power of 0.63 and increased from 2.3 to 8.8 × 10-5 m s-1. The rate-limiting step was the mass transfer of Lu(III) within the boundary layer of the donor phase adjacent to the outer wall of the hollow fibre

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

In this study, the mass transport resistance in liquid-phase microextraction (LPME) in a single hollow fiber was investigated. A mathematical model has been developed for the determination of the overall mass transfer coefficient based on the acceptor phase in an unsteady state. The overall mass transfer coefficient in LPME in a single hollow fiber has been estimated from time-dependent concentration of extracted analyte in the acceptor phase while maintaining a constant analyte concentration in the donor phase. It can be achieved either using a high volume of donor to acceptor phase ratio or tuning the extraction conditions to obtain a low-enrichment factor, so that the analyte concentration in the sample is not significantly influenced by the mass transfer. Two extraction systems have been used to test experimentally the developed model: the extraction of Lu(III) from a buffer solution and the extraction of three local anesthetics from a buffer or plasma solution. The mass transfer resistance, defined as a reciprocal values of the mass transfer coefficient, was found to be 1.2 x 103 cm-1 min for Lu(III) under optimal conditions and from 1.96 to 3.3 x 103 cm-1 min for the local anesthetics depending on the acceptor pH and the hydrophobicity of the drug