Liquid-phase microextraction in a single hollow fibre - determination of mass transfer coefficient

In this study, the mass transfer coefficient of two local anesthetics in liquid-phase microextraction (LPME), which is performed in a single hollow fibre, was investigated. Previously developed mathematical model has been applied for the determination of the overall mass transfer coefficient based on the acceptor phase, KA, in an unsteady-state LPMEPhysical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

Single-stage and two-stage solvent extraction of Tl(III) in hollow-fiber contactors under recirculation mode of operation

This paper presents the experimental results of thallium (III) extraction from NaCl/H2SO4 solution with butyl acetate in hollow-fiber membrane contactors. The experiments were performed using laboratory made modules consisting of hydrophobic polypropylene or polyvinylidene fluoride fibers of different effective membrane areas. The aqueous phase was recirculated between the module and a mixed reservoir, and the organic phase was fed at the shell side in once-through mode. The influences of the aqueous and organic phase flow rate on the overall mass transfer coefficient were investigated. The experimental results are discussed in terms of the fraction of Tl(III) removed from the aqueous phase reservoir and the mean Tl(III) flux through the interfacial area. The results can be used for the design of a hollow-fiber contractor based extraction process that can be utilized in production of the radiopharmaceutical (TlCl)-Tl-201

Application of ACD/LABS 12 program for determination of conditions for experimental membrane extraction of pesticides

This paper analyzes the conditions for membrane extraction of pesticides using ACD / LABS 12 program. The program contains a large database of more than 2000 compounds and their ionized species, for determining the pKa, further analysis includes 600 new compounds confirmed by Hammett’s equation, which gives more precise values for logD and solubility. The 16 pesticides of different classes (organophosphates, carbamates, carbamidas, neonicotinoids etc.) and polarities commonly used in Serbia were examined. The program is used to calculate logD, pKa and solubility at different pH values for the mixture of pesticides. Based on the calculated values, the conditions for the extraction of pesticides in water using two-phase liquid-liquid membrane extraction were optimized

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

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 fiber 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 fiber membrane, with stagnant acceptor phase in the lumen, immersed into a donor phase reservoir; and (ii) a U-shaped module containing a single hollow fiber 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 mm of operation at the donor phase flow rate of 5.3 cm(3) min(-1), the acceptor phase flow rate of 0.4 cm(3) 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 Reynolds numbers of Re = 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 x 10(-5) m s(-1) to 8.8 x 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 fiber

Dispersion-free solvent extraction of thallium(III) in hollow fiber contactors

Dispersion-free extraction of thallium(III) from NaCl/H2SO4 solution into butyl acetate has been studied using hydrophobic polypropylene and polyvinylidene fluoride hollow fibers of different effective lengths. The aqueous feed solution flowed inside the fibers and the organic phase was fed at the shell side. The influence of phase flow rates on the mass transfer coefficients was investigated, and correlations between the Sherwood and Graetz numbers were developed. The overall resistance to mass transfer is controlled by the feed-side mass transfer coefficient due to the high partition coefficient of HTlCl4 between the phases. The obtained results are discussed in terms of extraction efficiency, thallium flux through the interfacial area, and the length of the transfer unit as a function of the feed flow rate and the effective fiber length. The extraction efficiency was independent of the organic phase flow rate

Purification of the anti-IgE monoclonal antibody E1 from ascitic fluid

Contemporary biochemical methods for protein purification were applied for the isolation of anti-IgE monoclonal antibody E1 from mouse ascitic fluid. The yield of monoclonal antibody E1 in each of the isolated fractions was estimated by determining the total protein concentration and the specific concentration of IgG1. The homogeneity and purity of the isolated protein was determined by SDS PAG electrophoresis. Precipitation methods (ammonium sulphate, polyethylene glycol, caprylic acid, rivanol) were used, alternatively or successively, as the first step in the isolation of MoAb E1. Higher levels of purity of monoclonal antibody E1 were obtained using chromatographic methods (ion exchange chromatography, gel filtration and affinity chromatography). The best result (97% purity and 77% yield) was obtained by affinity chromatography on Staphylococcal protein A

Liquid-phase membrane extraction of targeted pesticides from manufacturing wastewaters in a hollow fibre contactor with feed-stream recycle

A two-phase membrane extraction in a hollow fibre contactor with feed-stream recycle was applied to remove selected pesticides (tebufenozide, linuron, imidacloprid, acetamiprid and dimethoate) from their mixed aqueous solutions. The contactor consisted of 50 polypropylene hollow fibres impregnated with 5% tri-n-octylphosphine oxide in di-n-hexyl ether. For low-polar pesticides with log P2 (tebufenozide and linuron), the maximum removal efficiency increased linearly from 85% to 96% with increasing the feed flow rate. The maximum removal efficiencies of more polar pesticides were significantly higher under feed recirculation (86%) than in a continuous single-pass operation (30%). It was found from the Wilsons plot that the mass transfer resistance of the liquid membrane can be neglected for low-polar pesticides. The pesticide removals from commercial formulations were similar to those from pure pesticide solutions, indicating that built-in adjuvants did not affect the extraction process

Removal of the Selected Pesticides from a Water Solution by Applying Hollow Fiber Liquid-Liquid Membrane Extraction

A supported liquid membrane extraction of different pesticides (acetamiprid, dimethoate, imidacloprid, linuron, and tebufenozide) from an aqueous solution containing 20 mg dm(-3) of each pesticide by 5% TOPO (tri-n-octylphosphine oxide) in DHE (di-n-hexyl ether) has been investigated in a hollow fiber contactor having an aqueous feed/organic interfacial area of 15.4 cm(2). In a single-pass operation, the maximum removal efficiency of 95% was achieved for the most nonpolar (log P = 4.38) pesticide tebufenozide at the feed flow rate of 0.5 cm(3) min(-1). The diffusion through the boundary layer of the feed stream was a rate-controlling step in the extraction of nonpolar pesticides (linuron and tebufenozide) with a mass-transfer coefficient in the feed stream being proportional to the feed flow rate raised to the power of 0.51-0.57. The maximum overall mass-transfer coefficient based on the feed phase of K-F = 0.18 cm min(-1) was obtained for tebufenozide at the feed flow rate of 1.8 cm(3) min(-1). The organic phase entrapped in the membrane pores offered a major resistance to the mass transfer of polar pesticides (log P LT 1) and accounted for 85% of the overall mass-transfer resistance for imidacloprid at 1.8 cm(3) min(-1). The pesticides removed from the feed solution were almost completely accumulated in the organic phase but were recovered from the membrane pores to a large extent (50-90%) by rinsing the membrane with methanol after extraction

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

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

Purification of the anti-IgE monoclonal antibody E1 from ascitic fluid

Contemporary biochemical methods for protein purification were applied for the isolation of anti-IgE monoclonal antibody E1 from mouse ascitic fluid. The yield of monoclonal antibody E1 in each of the isolated fractions was estimated by determining the total protein concentration and the specific concentration of IgG1. The homogeneity and purity of the isolated protein was determined by SDS PAG electrophoresis. Precipitation methods (ammonium sulphate, polyethylene glycol, caprylic acid, rivanol) were used, alternatively or successively, as the first step in the isolation of MoAb E1. Higher levels of purity of monoclonal antibody E1 were obtained using chromatographic methods (ion exchange chromatography, gel filtration and affinity chromatography). The best result (97% purity and 77% yield) was obtained by affinity chromatography on Staphylococcal protein A