反萃分散组合液膜分离提取氨基酸

建立了分离提取蛋氨酸、亮氨酸、苯丙氨酸和色氨酸的磷酸二（2-乙基己基）酯(D2EHPA) 煤油-HCl反萃分散组合液膜体系,考察了料液相pH值、载体D2EHPA浓度、液膜相与反萃相体积比、反萃相组成、料液相与反萃分散相流速、传输时间以及支撑膜重复使用次数对氨基酸渗透系数和传输效率的影响。 在优化的条件下,建立的反萃分散组合液膜体系对4种氨基酸均可以获得大于35%的传输效率,其中色氨酸和亮氨酸的传输效率超过了79%,且传输效率呈Et,Trp＞Et,Leu＞Et,Phe＞Et,Met的趋势。 支撑膜重复使用25次,对氨基酸的传输效率没有明显改变。建立的液膜体系对考察的氨基酸展示了较高传输效率和优越的传输选择性,是一种简单和环境友好的分离技术。     

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.     

Membrane extraction for separation of copper cations from acid solution using polypropylene hollow fibre membrane

The membrane extraction of copper ions was carried out using hydrophobic poly(propylene) (PP) hollow fiber membrane modules and kerosene solutions containing organic extractant. The influences of different extractant on the extraction yield, mass transfer performance and mass transfer mechanism were studied. Compared with 2‐ethylhexyl phosphoric acid (2EHPA) and 2‐methyl‐5‐sulpho benzaldoxime (2M5SB), di‐(2‐ethylhexyl)phosphoric acid (D2EHPA) extractant system with high distribution coefficient exhibited higher extraction yield of 99.7%. The extraction equilibrium time, the final extraction yield and the total mass transfer coefficient were independent of the flow rates of two phases. The extraction equilibrium time and the final extraction yield at different flow rates of two phases were 80 min and near 99.5%, respectively. A mass transfer model of a complexation reaction describing the overall mass transfer resistance was controlled by interfacial reactions rather than the aqueous and organic boundary layer which could explain the effect of flow rate on the final extraction yield and the total mass transfer coefficient. This model showed that the mass transfer resistance and mass transfer coefficient were independent of Cu²⁺ when copper ion concentration was more than 0.06 g/L. However, when copper concentration was less than 0.06 g/l, the mass transfer resistance increased as Cu²⁺ concentration decreased, and the mass transfer coefficient decreased as Cu²⁺ concentration decreased. Extractant entrainment in the aqueous phase and membrane fouling were investigated primarily. It was found that the solvent entrainment could reduce to 10 ppm much lower than 200 ppm of the classic liquid–liquid extraction, and that the cleaning of contaminated membranes was not complete. However, it can be still concluded from this research that the membrane extraction in PP hollow fibre with D2EHPA extractant would be an effective and promising processing means for Cu²⁺ separation from aqueous solution. Copyright © 2005 John Wiley & Sons, Ltd.     

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.     

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.     

Transport of Tb3+in Dispersion Supported Liquid Membrane System with Carrier P507

The Tb³⁺ transport in dispersion supported liquid membrane (DSLM) consisting of polyvinylidene fluoride membrane (PVDF) as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2‐ethyl hexyl phosphonic acid‐mono‐2‐ethyl hexyl ester (P507) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb³⁺ and different ionic strength in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on transport of Tb³⁺ has also been investigated, respectively. As a result, the optimum transport conditon of Tb³⁺ was that concentration of HCl solution was 4.0 mol/L, concentration of P507 was 0.10 mol/L, and volume ratio of membrane solution and stripping solution was 1.0 in the dispersion phase, and pH value was 5.2 in the feed phase. Ionic strength had no obvious effect on transport of Tb³⁺. Under the optimum condition studied, when initial concentration of Tb³⁺ was 1.0×10^?4 mol/L, the transport rate of Tb³⁺ was up to 95.2% during the transport time of 95 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The results were in good agreement with the literature data.     

Extraction of molybdenum by a supported liquid membrane method

This is a report on the extraction of molybdenum(VI) ions using a supported liquid membrane, prepared by dissolving in kerosene, the extractant Alamine 336 (a long-chain tertiary amine) employed as mobile carrier. A flat hydrophobic microporous membrane was utilised as solid support. Appropriate conditions for Mo(VI) extraction through the liquid membrane were obtained from the results of liquid-liquid extraction and stripping partition experiments. The influence of feed solution acidity, the carrier extractant concentration in the organic liquid film and the content of strip agent on the metal flux through membrane were investigated. It was established that maximal extraction of metal is achieved at a pH 2.0 if sulphuric acid is used in the feed solution and at a pH value over 11.0 if Na₂CO₃ is used as strip agent. Moreover, the molybdenum extraction through membrane is enhanced when a 0.02 mol l⁻¹ content of the amine carrier in the organic phase is used. The present paper deals with an equilibrium investigation of the extraction of Mo(VI) by Alamine 336 and its permeation conditions through the liquid membrane, and examines a possible mechanism of extraction.     

Simultaneous reactive extraction separation of amino acids from water with D2EHPA in hollow fiber contactors

Reactive extraction separation of binary amino acids from water using a microporous hollow fiber has been studied, in which the acidic extractant di(2-ethylhexyl)phosphoric acid (D2EHPA) was selected as an active carrier dissolved in kerosene. l-Phenylalanine (Phe) was extracted from an aqueous solution through the shell side of module to the organic phase through the lumen of fiber in the extraction module, in which l-Phe was then back-extracted to stripping phase in stripping module. Experiments were conducted as a function of the initial feed concentration of equimolar Phe and l-aspartic acid (l-Asp) (5 mol/m³), feed pH (3–5), the carrier concentration (0.1–0.5 mol/dm³), and stripping acidity (0.1–2 mol/dm³). The effect of process variables on the separation factor of Phe/Asp and the possible transport resistances including aqueous-layer diffusion, membrane diffusion, organic-layer, and interfacial chemical reaction were quantitatively studied and discussed. The high separation factor (β) of Phe/Asp was obtained to be 18.5 at feed pH 5 and 2 mol/dm³ of strip solution (HCl). The extraction and stripping processes appear to rely on pH dependence of the distribution coefficient of amino acids in reactive extraction system. The separation factor (β) was enhanced in hollow fiber membrane (HFM) process compared with conventional solvent process, which was a result of the counter transport of hydrogen ions.     

Separation of lignosulfonate from its aqueous solution using supported liquid membrane

This paper presents an experimental and theoretical study on facilitated transport of lignosulfonate (LS) through a flat sheet supported liquid membrane using trioctylamine (TOA) as carrier and dichloroethane as diluent. The studies were carried out with various support materials and operating conditions (viz. carrier concentration, strip phase concentration, salt concentration, etc.) and their effects on the transport of LS. The results were analyzed to identify a suitable combination of support and operating condition that would yield best performance of the supported liquid membrane (SLM) in terms of fast and efficient transport of LS. The stability of the SLM was assessed in terms of loss of liquid from the pores of membrane support. The SLM is found to be stable till 10 h. Co-transport mechanism has been adopted in this work by using NaOH as the strip phase. It was observed that extraction of LS is increased with increase in concentration of NaOH up to a limiting value of 0.5 M NaOH. Difference of salt concentration between feed and strip phase considerably affect the separation process. The diffusional resistances of organic membrane (Δorg) and aqueous solution (Δaq) calculated from the permeation model, which is again a combination of three unique mechanisms viz., diffusion through a feed aqueous layer, a fast interfacial chemical reaction, and diffusion of carrier–complex through the organic membrane, are found to be 609.9 and 176.6 s cm⁻¹, respectively. The values of the diffusion coefficient in the membrane (D_org) and in the bulk organic phase (D_complex) are 1.67×10⁻⁹ and 6.68 × 10⁻⁸ m²s⁻¹, respectively. The extraction of LS is about 90%. Nearly 43% of LS can be recovered at optimum condition.     

Electrically assisted liquid-phase microextraction for determination of β2-receptor agonist drugs in wastewater

Electromembrane extraction followed by high‐performance liquid chromatography coupled with ultraviolet detection was validated for the determination and quantification of salbutamol (SB) and terbutaline in aqueous samples. A 200‐V electrical field was applied to extract the analytes from 2.5 mL sample solution with pH 3.0, through an organic phase which consisted of 80% 2‐nitrophenyl octyl ether, 10% di‐(2‐ethylhexyl) phosphate and 10% tris‐(2‐ethylhexyl)phosphate as supported liquid membrane into an acidic acceptor solution with pH 1.0, located inside the lumen of a hollow fiber. To achieve the best extraction conditions, the organic membrane composition was optimized separately and other parameters, such as extraction time, applied voltage and pH in sample solution and acceptor phase were studied using experimental design. Under optimal conditions, extraction recoveries of 53 and 43% were obtained for SB and terbutaline, respectively, which corresponded to preconcentration factors of 89 for SB and 72 for terbutaline. The method offers acceptable linearity with correlation coefficient higher than 0.9947 and relative standard deviation less than 4.7%. Finally, it was applied for analysis of drugs in wastewater samples.     

Hybrid liquid membrane (HLM) system in separation technologies

A novel liquid membrane system, denoted hybrid liquid membrane (HLM), was developed for the separation of solutes (metal ions, acids, etc.). It utilizes a solution of an extracting reagent (carrier solution), flowing between membranes. The membranes, which separate the carrier solution from feed and receiving (strip) solutions, enable the transport of solutes, but block the transfer of the carrier to the feed or to the strip. Blocking the carrier is achieved through membranes hydrophilic/hydrophobic or ion exchange properties, or through their rentention abilities, due to pore size.     

Recovery of manganese(II) by electrodialysis with liquid membranes based on di(2-ethylhexyl)phosphoric acid

Electrodialysis membrane extraction of manganese(II) from sulfuric acid solutions with liquid membranes containing di(2-ethylhexyl)phosphoric acid and tri-n-octylamine in 1,2-dichloroethane was studied. The effect of the electrodialysis conditions and the composition of the organic phase and aqueous solutions on the transport rate of manganese(II) ions was examined. The conditions of quantitative recovery of the metal from a 0.01 M MnSO₄ solution were determined.     

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...     

Application of europium(III) extraction with organophosphinic acid to liquid membrane transport

The extraction behavior of Eu(III) has been studied using di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA, HA) in kerosene. Europium was extracted as Eu(HA₂)₃ with the extraction constant of 2.0·10^–3. This extraction system was applied to the transport of Eu(III) across a DTMPPA liquid membrane supported on porous polytetrafluoroethylene. Europium was quantitatively moved through the liquid membrane containing 0.1M (HA)₂ as a mobile carrier from the feed solution of pH above 3 into the product solution of 0.1M HNO₃, yielding a concentration factor of ten. The transport rate increased with increasing pH and DTMPPA concentration.     

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.     

Dialkylphosphoric acids as carriers in separation of lanthanides and thorium on supported liquid membranes

Permeation of seven lanthanides (Ln) and thorium through a supported liquid membrane containing di-(n- octyl)phosphoric (DOPA) or di-(n-pentyl)phosphoric (DPPA) acid as a carrier has been studied as a function of the chemical composition of the system. The results have been compared with a previous study in which di-(2-ethylhexyl)phosphoric acid was used. Metal cations were transported from feed solutions of pH 1.1-4.8 (HNO(3)) into strip solutions of 0.015-0.1 mol l(-1) nitric acid. The ionic strength was kept constant at 0.1 mol l(-1) (HNO(3), KNO(3)). The initial lanthanide concentration and carrier concentration in the liquid membrane were varied from 0.5 to 500 mumol l(-1) and from 0.01 to 0.5 mol l(-1) respectively. To describe the mass transfer of metal cations, permeability coefficients have been determined by inductively-coupled plasma atomic emission spectroscopy or by on-line flow-injection analysis of metal concentrations in strip or feed solution. Probably as the result of a higher solubility of the carrier in aqueous media, transport of Ln with DPPA was not observed. By using DOPA, La, Ce, Pr, and Nd permeated through the membrane while transport of heavier Ln was partly or totally suppressed. This enables these four Ln (separation factor alpha = 3.0 for Nd and Sm) to be separated from the others. Furthermore, at a very low acidity gradient, only La (III) is transported over the membrane (alpha >/= 3.4 for La, Ce and next Ln). The seven elements from La to Tb can be separated from Th(IV) because no evidence of its permeation through the membrane was found under the conditions of Ln transport. In contrast to previous studies on Ln transport with dialkylphosphoric acid carrier, the possibility of participation of species other than Ln(AHA)(3) in the transport has been discussed. The decrease of permeability observed at higher Ln concentrations and higher pH of the feed solution has been explained as the result of formation of species, e.g. polymeric ones, that are unable to permeate through the membrane.     

皂化P204/煤油微乳体系分离L-苯丙氨酸的研究

研究了P204-煤油-NaOH组成的微乳液膜配方及其稳定性。通过该液膜体系对L-苯丙氨酸水溶液进行提取实验,考察了P204的浓度、乳水比、外水相pH值、膜相重复使用次数、分离时间等对提取效率的影响。实验结果表明,微乳液膜不仅稳定性好,无明显溶胀和泄漏,分离速度快,而且分离效果好,可自动破乳,油相可重复多次使用,对L-苯丙氨酸的一次性提取率达88.25%。     

Separation of yttrium(III) from iron(III) through liquid membrane impregnated with di(2-ethylhexyl)phosphoric acid

The selective transport of yttrium(III) in the presence of iron(III) through a supported liquid membrane (SLM) has been investigated by using di(2-ethylhexyl)phosphoric acid (DEHPA) as a mobile carrier. Yttrium(III) with fast kinetics was preferentially transported from the feed solution of dilute acid into the product solution of 1M H₂SO₄, while most of iron(III) with slow kinetics remained in the feed solution. The effective separation of yttrium(III) from a large amount of iron(III) was accomplished by the selective transport of yttrium(III) through the SLM.     

Extraction and recovery of lignosulfonate from its aqueous solution using bulk liquid membrane

The paper presents an experimental study on the coupled transport of lignosulfonate (LS) through bulk liquid membrane (BLM) and thereby to identify the best set of solvent, operating conditions and mode of transport that would yield optimum performance of the BLM. Trioctylamine (TOA) is used as carrier. Among various solvents, tested for the above purpose, dichloroethane is found to be the best. The effects of operating condition, viz. pH, temperature, and carrier concentration, on the equilibrium distribution of LS are investigated. The effects of temperature, stirring of aqueous and organic phases, stirring speed, carrier concentration, initial feed and strip phase concentration on the separation of LS using BLM are also studied. It is observed that transport of LS can be enhanced by increasing the temperature and stirring speed of feed phase. Stirring of strip phase has no appreciable effects on the transport of LS. With increase in initial feed concentration the initial rate of the transport of LS is higher but continues for a longer time. Recovery of LS is much higher in co-transport mode in comparison to counter transport mode. Application of 1.25 M NaOH as stripping solution gives high recovery (70%) and high strip flux (70% of feed flux).     

Highly selective transport of silver ion through a supported liquid membrane using calix[4]pyrroles as suitable ion carriers

Facilitated transport of silver ion across a supported liquid membrane (SLM) by calix[4]pyrroles, as selective ion carriers, dissolved in kerosene has been investigated. The influences of fundamental parameters affecting the transport of silver ion including ion carrier concentration in the membrane phase, thiosulfate concentration in strip phase, picric acid concentration in the feed phase, stirring speed of aqueous phases, type of membrane solvent and time of transport have been studied. In the presence of thiosulfate as a suitable metal ion acceptor in the strip phase and picrate ion as ion pairing agent in the source phase, transport of silver occurs almost quantitatively after 75 min. The selectivity and efficiency of silver transport from aqueous solution containing Cu²⁺, Mg²⁺, Ni²⁺, Ca²⁺, Zn²⁺, Pb²⁺, Co²⁺, Al³⁺, Hg²⁺, Cd²⁺, Fe³⁺, Fe²⁺ and Cr³⁺ were investigated.