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 LuCl₃ 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 ¹⁷⁷Lu(III) from labelled ¹⁷⁷Lu‐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.     

Optimization of microwave‐assisted extraction of protopine and allocryptopine from stems of Macleaya cordata (Willd) R. Br. using response surface methodology

The purpose of the research was to investigate the multiple response optimizations for the extraction of protopine and allocryptopine from the stems of Macleaya cordata (Willd) R. Br. by using microwave‐assisted extraction (MAE). A three‐level, three‐factor Box–Behnken design of response surface methodology was used to develop response model, and desirability function was employed to optimize the effects of main extraction parameters. Three variables, ethanol concentration (20–80%, v/v), extraction temperature (30–70°C) and solvent/solid ratio (10:1 to 30:1, mL/g), were investigated in this study. The results showed that the optimum parameters of MAE were ethanol concentration of 45.2 % (v/v), extraction temperature of 54.7°C and solvent/solid ratio of 20.4:1 (mL/g). Under these conditions, the extraction yields of protopine and allocryptopine were 89.4 and 102.0%, respectively, and the extracta sicca yield was 12.5%. The combination use of response surface methodology, Box‐Behnken design and the appropriate desirability function could provide an insight into a lab‐scale MAE process, and help to develop procedures for commercial production of active ingredients from medical plants.     

Analysis of alkaloids in Macleaya cordata (Willd.) R. Br. using high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry

A method for the analysis of alkaloids in Macleaya cordata (Willd.) R. Br. using high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS) was developed. Using protopine (PRO), allocryptopine (ALL), sanguinarine (SA), and chelerythrine (CHE) as the model components, different columns for the separation and different mobile phases for the signal intensities of alkaloids in ESI/MS were investigated, respectively. The results showed that good separation and high signal intensities can be obtained on a high carbon loading (17%) reversed-phase C(18) column with 30 mM formic acid in mobile phase for the analysis of alkaloids. Under the optimal separation condition and UV detection (284 nm), linearity of the six alkaloids was obtained over concentration range from 0.05 to 100.00 microg/ml. The limit of detection (LOD) was 1.62, 1.87, 1.79, 1.76, 1.10, and 0.94 ng/ml for SA, CHE, PRO, ALL, dihydrosanguinarine (DHSA), and dihydrochelerythrine (DHCHE), respectively. The LODs with ESI/MS detection were lower three orders of magnitude than those obtained with UV detection. The proposed method could be used to control quality of the raw materials of the herb more comprehensively.     

Comparison of solidification of floating drop and homogenous liquid–liquid microextractions for the extraction of two plasticizers from the water kept in PET‐bottles

Two approaches based on solidification of floating drop microextraction (SFDME) and homogenous liquid–liquid microextraction (HLLE) were compared for the extraction and preconcentration of di‐(2‐ethylhexyl) phthalate (DEHP) and di‐(2‐ethylhexyl) adipate (DEHA) from the mineral water samples. In SFDME, a floated drop of the mixture of acetophenone/1‐undecanol (1:8) was exposed on the surface of the aqueous solution and extraction was permitted to occur. In HLLE, a homogenous ternary solvent system was used by water/methanol/chloroform and the phase separation phenomenon occurred by salt addition. Under the optimal conditions, the LODs for the two target plasticizers (DEHA and DEHP), obtained by SFDME–GC‐FID and HLLE–GC‐FID, were ranged from 0.03 to 0.01 μg/L and 0.02 to 0.01 μg/L, respectively. HLLE provided higher preconcentration factors (472.5‐ and 551.2‐fold) within the shorter extraction time as well as better RSDs (4.5–6.9%). While, in SFDME, high preconcentration factors in the range of 162–198 and good RSDs in the range of 5.2–9.6% were obtained. Both methods were applied for the analysis of two plasticizers in different water samples and two target plasticizers were found in the bottled mineral water after the expiring time and the boiling water was exposed to a polyethylene vial.     

Separation of Trivalent Samarium through Facilitated Stripping Dispersion Hollow Fiber Liquid Membrane Using p204 as Mobile Carrier

The separation of Sm(III) through stripping dispersion hollow fiber liquid membrane system (SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HCl solution as the stripping solution and membrane solution of di(2‐ethylhexyl) phosphoric acid (p204) dissolved in kerosene, has been studied. A set of factors were studied, including pH value, initial concentration of Sm(III) and different ionic strength of feed phase, volume ratio of membrane solution and stripping solution (O/W), HCl concentration, carrier concentration, different stripping agents of dispersion phase on Sm(III) separation. Experimental results indicate that the optimum separation conditions of Sm(III) were obtained as that HCl concentration was 4.00 mol/L, p204 concentration was 0.150 mol/L, and volume ratio of membrane solution and stripping solution (O/W) was 1.00 in the dispersion phase, and pH value was 4.60 in the feed phase. Ionic strength had no obvious effect on separation of Sm(III). When initial Sm(III) concentration was 1.00×10^?4 mol/L, the separation rate of Sm(III) was up to 93.5% in 85 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The modeled results were in good agreement with the experiment data.     

Solid phase extraction of zinc(II) using a PVC-based polymer inclusion membrane with di(2-ethylhexyl)phosphoric acid (D2EHPA) as the carrier

A polymer inclusion membrane (PIM) is reported consisting of 45% (m/m) di(2-ethylhexyl)phosphoric acid (D2EHPA) immobilized in poly(vinyl chloride) (PVC) for use as a solid phase absorbent for selectively extracting Zn(II) from aqueous solutions in the presence of Cd(II), Co(II), Cu(II), Ni(II) and Fe(II). Interference from Fe(III) in the sample is eliminated by precipitation with orthophosphate prior to the extraction of Zn(II). Studies using a dual compartment transport cell have shown that the Zn(II) flux (2.58 × 10⁻⁶ mol m⁻² s⁻¹) is comparable to that observed for supported liquid membranes. The stoichiometry of the extracted complex is shown to be ZnR₂·HR, where R is the D2EHPA anion.     

Separation of sanguinarine and chelerythrine in Macleaya cordata (Willd) R. Br. based on methyl acrylate-co-divinylbenzene macroporous adsorbents

Sanguinarine (SAN) and chelerythrine (CHE) are known as major effective components in the quaternary benzo[c]phenanthridine isoquinoline alkaloids (QBA) fraction of Macleaya cordata (Willd) R. Br. but possess different biological activities. In this study, a method for the separation of SAN and CHE based on methyl acrylate-co-divinylbenzene (MA-co-DVB) macroporous adsorbents was established. The relationship between the polarities of the adsorbents and their adsorption-desorption behaviors towards SAN and CHE was investigated. The results showed that, among three selected commercial adsorbents and seven synthesized macroporous polymeric adsorbents with different MA content, the adsorbent No. 5 with 50% MA content provided the best separation power, and the two alkaloids were separated successfully in a gradient eluent process with 60% (v/v) ethanol aqueous and 80% ethanol aqueous contained 8% acetic acid. Dynamic adsorption and desorption tests had been performed in the column packed with the adsorbent No. 5 for optimizing the process parameters. Under the optimized conditions, the ratio of SAN and CHE transformed from 2:1 in the QBA fraction of M. cordata to 1:13 and 25:1 in the products obtained from the two-step gradient elution, and the recoveries of both SAN and CHE were nearly 90%.     

Structure and aggregation behavior of cobalt-di(2-ethylhexy1)-phosphoric acid complexes in solvent extraction systems

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Kinetic study of l-isoleucine transport through a liquid membrane containing di(2-ethylhexyl) phosphoric acid in kerosene

A kinetic study of l-isoleucine transport through a liquid membrane containing di(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene is presented. The influences of pH in the aqueous feed solution, D2EHPA concentration in the organic phase, the stripping solution composition and H₂SO₄ concentration in the stripping solution were investigated, and the effects of stirring speed and temperature on the transport of l-isoleucine through a bulk liquid membrane (BLM) were studied. The kinetics of l-isoleucine transport could be analyzed in the formalism of a reversible pseudo-first-order reaction followed by an irreversible pseudo-first-order reaction. The pseudo-first-order apparent rate constants of the interfacial transport of l-isoleucine species are determined for the liquid membrane, at various temperatures. The apparent activation energy values are 21.3±1.9, 57.6±5.1 and 31.8±2.7 kJ mol⁻¹ for the extraction reaction, extraction back reaction and stripping reaction, respectively.     

Determination of di‐(2‐ethylhexyl)phthalate in environmental samples by liquid chromatography coupled with mass spectrometry

Di‐(2‐ethylhexyl)phthalate (DEHP) was determined in environmental samples such as water and soil. DEHP was extracted from water samples using SPE, whereas for soils pressurized liquid extraction was applied as extraction method, using hexane/acetone (1:1, v/v) as extractant solvent. The use of HPLC coupled to MS provides the basis of the selective determination of DEHP in the analyzed samples. The extraction procedures were validated and good results were found. Recoveries were ranged from 86.0 to 99.8% with RSD lower than 18% and LODs were 0.02 mg/kg and 0.03 μg/L for soils and water, respectively. Finally, the optimized methods were applied to the analysis of real samples and DEHP was not found above the LOQ (0.05 mg/kg) in soil samples whereas it was detected in water samples at concentrations ranging between 0.19 to 0.88 μg/L.     

Stripping dispersion hollow fiber liquid membrane containing carrier PC-88A and HNO3 for the extraction of Sm3+

Stripping dispersion hollow fiber liquid membrane system（SDHFLM） containing feed phase adding acetate buffer solution and dispersion solution with HNO₃ solution as the stripping solution and membrane solution of 2-ethyl hexyl phosphoric acid-mono-2-ethylhexyl ester（PC-88A） dissolved in kerosene,has been studied for the extraction of Sm³⁺.Many factors including pH value, volume ratio of membrane solution to stripping solution（OAV） and carrier concentration on Sm³⁺ extraction were investigated. Experimental results indicate that the optimum extraction conditions of Sm³⁺ were obtained as that PC-88A concentration was 0.120 mol/L,and OAV was 1.00 in the dispersion phase,and pH value was 4.80 in the feed phase.When initial Sm³⁺ concentration was 1.20×10^-4 mol/L,the extraction percentage of Sm³⁺ was up to 92.8%in 160 min.     

The effect of diluents on extraction of copper(II) with di(2-ethylhexyl)phosphoric acid

The liquid–liquid extraction of copper(II) from sulfate medium with di(2-ethylhexyl)phosphoric acid (D2EHPA, HL) at 25°C is studied with the following parameters: pH, concentration of the extractant, and the nature of diluent. The effect of the diluent using polar and nonpolar solvents in the extraction of copper(II) is discussed. The extracted copper(II) species were CuL₂ in 1-octanol and methyl isobutyl ketone and CuL₂ · 2HL in toluene, carbon tetrachloride, and cyclohexane. The extraction constants are evaluated for different diluents.     

Tb(III) Transport in Dispersion Supported Liquid Membrane System with D2EHPA as Carrier in Kerosene

The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb(III) and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, conc...     

Cloud point extraction equilibrium of lanthanum(III), europium(III) and lutetium(III) using di(2-ethylhexyl)phosphoric acid and Triton X-100

The cloud point extraction behaviors of lanthanoids(III) (Ln(III) = La(III), Eu(III) and Lu(III)) with and without di(2-ethylhexyl)phosphoric acid (HDEHP) using Triton X-100 were investigated. It was suggested that the extraction of Ln(III) into the surfactant-rich phase without added chelating agent was caused by the impurities contained in Triton X-100. The extraction percentage more than 91% for all Ln(III) metals was obtained using 3.0 × 10⁻⁵ mol dm⁻³ HDEHP and 2.0% (v/v) Triton X-100. From the equilibrium analysis, it was clarified that Ln(III) was extracted as Ln(DEHP)₃ into the surfactant-rich phase. The extraction constant of Ln(III) with HDEHP and 2.0% (v/v) Triton X-100 were also obtained.     

The use of a polymer inclusion membrane in flow injection analysis for the on-line separation and determination of zinc

This paper reports the first use of a polymer inclusion membrane (PIM) for on-line separation in flow injection analysis (FIA) involving simultaneous extraction and back-extraction. The FIA system containing the PIM separation module was used for the determination of Zn(II) in aqueous samples in the presence of Mg(II), Ca(II), Cd(II), Co(II), Ni(II), Cu(II), and Fe(III). The Fe(III) and Cu(II) interferences were eliminated by off-line precipitation with phosphate and on-line complexation with chloride, respectively. The concentration of Zn(II) was determined spectrophotometrically using 4-(2-pyridylazo) resorcinol (PAR). The optimal composition of the PIM consisted of 40% (m/m) di(2-ethlyhexyl) phosphoric acid (D2EHPA) as carrier, 10% (m/m) dioctyl phthalate (DOP) as plasticizer and 50% (m/m) poly(vinyl chloride) (PVC) as the base polymer. The optimized FIA system was characterized by a linear calibration curve in the range from 1.0 to 30.0 mg L⁻¹ Zn(II), a detection limit of 0.05 mg L⁻¹ and a relative standard deviation of 3.4% with a sampling rate of 4 h⁻¹. Reproducible results were obtained for 20 replicate injections over a 5 h period which demonstrated a good membrane stability. The FIA system was applied to the determination of Zn(II) in pharmaceuticals and samples from the galvanizing industry and very good agreement with atomic absorption spectrometry was obtained.     

The use of a polymer inclusion membrane in a paper-based sensor for the selective determination of Cu(II)

A disposable paper-based sensor (PBS) is described for the determination of Cu(II) in natural and waste waters at approximately 2 cents per measurement. The device makes use of a polymer inclusion membrane (PIM) to provide the selectivity for Cu(II). The PIM consists of 40 wt% di(2-ethlyhexyl) phosphoric acid (D2EHPA) as the carrier, 10 wt% dioctyl phthalate (DOP) as a plasticizer, 49.5 wt% poly(vinyl chloride) (PVC) as the base polymer and 0.5 wt% (m m⁻¹) 1-(2′-pyridylazo)-2-naphthol (PAN) as the colourimetric reagent. High selectivity under mildly acidic conditions (HCl, pH 2.0) is achieved for Cu(II) in the presence of frequently encountered metal ions in natural and waste waters such as Fe(III), Al(III), Zn(II), Cd(II), Pb(II), Ca(II), Mg(II), and Ni(II).     

Online high‐pH reversed‐phase liquid chromatography × low‐pH reversed‐phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension for the analysis of alkaloids in Macleaya cordata (willd.) R. Br

An online high‐pH reversed‐phase liquid chromatography× low‐pH reversed‐phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension was constructed to separate and identify alkaloids from Macleaya cordata (willd.) R. Br. The modulation was performed by using a dual second dimensional columns interface combined with a make‐up dilution pump, which is responsible for dilution and neutralization of the first dimensional effluent, and the dual second dimensional columns integrated the trapping and the separation function to reduce the second dimension system dead volume. Taking advantage of the dissociable characteristics of alkaloids, mobile phases with different pH values were applied in the first dimension (pH 9.0) and the second dimension (pH 2.6) to improve the orthogonality of two‐dimension separation. Besides, the pulse elution gradient in first dimension and second dimensional gradient were carefully optimized and much better separation was achieved compared to the separation with the traditional two‐dimensional liquid chromatography approach. Finally, mass measurement was performed for alkaloids in M. cordata (willd.) R. Br. by coupling proposed two‐dimensional liquid chromatography system with triple quadrupole mass spectrometry, and 39 alkaloids were successfully identified by comparing the obtained result with the former reported results.     

Analytical Methods for Determining the Concentration Ratio in Mixtures of Trioctylphosphine Oxide and Di(2-Ethylhexyl)Phosphoric Acid

Abstract

Analytical methods are described for determining the concentration ratio of trioctylphosphine oxide (TOPO) and di(2-ethylhexyl)phosphoric acid (D₂ EHPA) in hydrocarbon solvents or in mixtures where the D₂ EHPA is the solvent. The Electron Spectroscopy for Chemical Analysis (ESCA) method was used to analyze the mixtures for the relative amounts of phosphine oxide-phosphorus to phosphoric acid-phosphorus as well as the variance with the mixture composition of the Ols/P2p signal intensity. The nmr signal strength of the protons of the oxymethylene group of the D₂ EHPA and the signal strength of the other protons of D₂ EHPA and TOPO were measured in solutions of varying concentrations of D₂ EHPA and TOPO. Mass spectral comparisons of the molecular ion strengths of TOPO and D₂ EHPA were also correlated with mixture composition.     

Emulsion liquid membrane extraction of Ni(II) and Co(II) from acidic chloride solutions using bis-(2-ethylhexyl) phosphoric acid as extractant

An emulsion liquid membrane process using bis-(2-ethylhexyl) phosphoric acid (D2EHPA) to extract and separate Ni(II) and Co(II) from acidic chloride solutions is described. Liquid membrane consists of a diluent, a surfactant (Span 80), and an extractant (D2EHPA). Hydrochloric acid was used as the stripping solution. The important parameters governing the permeation of nickel and their effect on the separation process have been studied. These parameters are stirring speed, feed phase pH, surfactant concentration, extractant concentration, stripping phase concentration, phase ratio, initial concentration of metal, and treatment ratio. The optimum conditions have been determined. The separation factors of Ni(II) with respect to Co(II), based on initial feed concentration, have been experimentally determined. Furthermore, the extraction selectivity for Co(II) over Ni(II) has been improved by using D2EHPA during the initial minutes.     

Kinetics of europium(III) transport through a liquid membrane containing HEH(EHP) in kerosene

Coupled transport of Eu(III) ions through a bulk liquid membrane containing mono(2-ethylhexyl)2-ethylhexyl phosphonate [HEH(EHP)] in kerosene has been examined. The influences of the carrier concentration, the HCl concentration in the stripping solution, the pH in the feed solution and the temperature were investigated. The transport of the Eu(III) ions is coupled by counter-transport of protons. The kinetics of the Eu(III) transport could be analyzed in the formalism of two consecutive irreversible first order reactions. The pseudo-first order apparent rate constants of the interfacial transport of the Eu(III) species are determined, varying temperature. The activation energy values are 14.0±1.0 and 54.0±3.4 kJ mol⁻¹ for extraction and stripping, respectively.