The Role of Internal Droplet Size on Emulsion Stability and the Extraction Performance of Kraft Lignin Removal from Pulping Wastewater in Emulsion Liquid Membrane Process

It has been discovered that the size of internal droplets in primary emulsion determines emulsion dispersion and stability in emulsion liquid membrane (ELM) process for removal of lignin from pulping wastewater. Generally, primary emulsion contains kerosene, Aliquat 336, sodium bicarbonate, as well as Span 80 as diluent, carrier, internal phase, and surfactant, respectively. Hence, this study had looked into the parameters, including concentration of surfactant, carrier, and stripping agent; emulsification speed and time; as well as agitation speed and time. As a result, the diameter of the smallest droplets (1.4 µm) was formed with maximum lignin extraction (95%), minimum swelling (5%) at 3% (w/v) surfactant concentration, 12,000 rpm of emulsification within 5 minutes, 0.01 M of Aliquat 336, 0.1 M of NaHCO_3, and 250 rpm of extraction within 10 minutes.     

Extraction of L-Lysine from Its Dilute Aqueous Solutions by Rotating Film Pertraction

Removal and concentration of L-lysine in a three liquid phase pertraction system was studied using a laboratory three stage rotating disk pertractor. A 5% (vol) solution of Di-2-ethyl hexyl phosphoric acid (D2EHPA) in normal paraffins was used as an intermediate membrane liquid. The amino acid was extracted from its dilute aqueous solution (feed F) and concentrated in the stripping liquid R—a 1N solution of HCl in water. D2EHPA dissolved in the membrane liquid played the role of a ion exchange carrier. It was found that the most important parameters controlling the efficiency of this continuous pertraction process are the speed of disk rotation and the feed solution flowrate. The counter-current flow arrangement in the apparatus and the high flowrate ratio chosen provided nearly complete removal of solute from the feed as well as a concentrated solution of L-lysine.     

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...     

Dysprosium pertraction through facilitated supported liquid membrane using D2EHPA as carrier

The pertraction of dysprosium (Dy) through a supported liquid membrane (SLM) system consisting of PTFE (polytetrafluoroethylene) support, D2EHPA (di-2-ethylhexyl phosphoric acid) dissolved in kerosene as membrane solution, and HNO₃ solution as stripping solution, was studied. The experiments were designed by the Taguchi method in order to investigate the effects of initial Dy concentration, feed phase pH, different stripping solution concentration, and D2EHPA concentration in the membrane phase on Dy pertraction. Optimal experimental conditions for Dy pertraction were obtained using an analysis of variance (ANOVA) (feed concentration: 130 mg L^?1, D2EHPA concentration: 0.90 M, feed phase pH: 5, stripping phase concentration: 2 M). In addition, the stability of the carrier in terms of its leaching from the membrane support was studied over a period of 6 days and was found to be satisfactory over that time.     

Pertraction of methylene blue using a mixture of D2EHPA/M2EHPA and sesame oil as a liquid membrane

An experimental study on the pertraction of methylene blue (MB) through a supported liquid membrane (SLM) using a mixture of mono-(2-etylhexyl) ester of phosphoric acid (M2EHPA) and bis-(2-etylhexyl) ester of phosphoric acid (D2EHPA) and sesame oil as the liquid membrane (LM) was performed. Parameters affecting the pertraction of MB such as initial MB concentration, carrier concentration, feed phase pH, and stripping phase concentration were analyzed. Optimal experimental conditions for MB pertraction (permeability of 5.63 × 10^?6) were obtained after a 7 h separation with the MB concentration in the feed phase of 80 mg L^?1, D2EHPA/M2EHPA concentration in membrane phase of 40 vol. %, feed pH of 6, and acetic acid concentration in the stripping phase of 0.4 mol L^?1. Kinetics of transport and stability of the SLM system were also studied and the mass transfer coefficient for this system was evaluated. Scanning electron microscopy (SEM) was used to morphologically characterize the membrane surface.     

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.     

Stability analysis of environmentally benign green emulsion liquid membrane

A new stable green emulsion liquid membrane (GELM) was formulated by selecting the environmentally benign vegetable oils. The rice bran oil (RBO) based GELM has shown better stability in comparison to that obtained from other oils. GELM was prepared using 10?mL RBO, 0.25 [M] NaOH concentration, 2 (v/v, %) surfactant concentration, 0.4 (v/v) phase ratio, 2000?rpm emulsification speed, and 20?min emulsification time. Under these optimum conditions, GELM has been found to be stable for 120?±?2?min (no significant phase change) and has shown complete phase separation after 4 hours. Therefore, RBO as a green solvent has high potential to be applied in several ELM process applications.     

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.     

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。     

Uranium extraction enhancement form phosphoric acid by emulsion liquid membrane

This work is mainly concerned with the uranium extraction from phosphoric acid commercially produced by Abu Zaabal Fertilizers and Chemical Co., Egypt. This target would realize a dual purpose where the phosphate ore is considered as an alternative source of uranium besides eliminating its environmental contamination. The applied procedures are that of the new technology of emulsion liquid membrane. Authors have indeed pointed out that the variables explored still leave open to question the roles of stripping at the internal interface as well as the bulk transfer of uranium in the internal phase. For this purpose, two reducing agents are studied as additives to two organic solvent systems; namely the organophosphorous synergistic mixture of D2EHPA/TOPO as well as the tridodecyl amine. The relevant factors have first been optimized upon synthetic uraniferous phosphoric acid solution followed by the application upon the commercial acid after purification. These factors include the concentration of solvent system and the used emulsifier, acid concentration of the external and internal phases besides the nature and concentration of the reductant added to the internal phase. In addition, the permeation time as well as the oxidation state of the external phase was studied. All these factors have indeed been studied under different mixing speeds ranging from 300 up to 1,000 rpm. Ascorbic acid concentration, 1 % as an additive to the internal phosphoric acid phase (40 % P₂O₅) resulted in 95 % uranium extraction efficiency at the lower speed of 600 rpm.     

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.     

Pertraction of cadmium and zinc ions using a supported liquid membrane impregnated with different carriers

An experimental study on the removal of Cd²⁺ and Zn²⁺ through a supported liquid membrane using a mixture of mono-(2-etylhexyl) ester of phosphoric acid (M2EHPA) and bis-(2-etylhexyl) ester of phosphoric acid (D2EHPA) as carriers is presented. Parameters affecting the Cd²⁺ and Zn²⁺ pertraction such as feed concentration, carrier concentration, pH of the stripping phase, and TBP (tributyl phosphate) concentration were analyzed using the Taguchi method. Optimal experimental conditions for Cd²⁺ and Zn²⁺ pertraction were obtained using the analysis of variance (ANOVA) after a 6 h separation with the initial feed concentration of 8.9 × 10^?4 mol L^?1, carrier concentration of 20 vol. %, TBP concentration of 4 vol. %, and pH of 0.5. Then, under optimum conditions, a comparison of M2EHPA, D2EHPA, and bis-(2,4,4-trimethylpentyl)monothiophosphinic acid (Cyanex 302) was performed. Effective pertraction of Cd²⁺ and Zn²⁺ using these carriers was observed in the following order: mixture of M2EHPA and D2EHPA, D2EHPA, Cyanex 302. It was also found that the presence of one metal ion in the feed solution reduces the pertraction rate of the other one.     

Selective separation of trace nickel(II) and gold(I) ions via hollow fiber supported liquid membrane enhanced by synergistic extractants D2EHPA/TBP

This work presents the selective and simultaneous separation of nickel (Ni²⁺) and gold ([Au(CN)₂]⁻) ions, in trace amounts, from alkaline solution via hollow fiber supported liquid membrane (HFSLM) technique. HFSLM is challengingly carried out in real rinse wastewater generated by the ENIG plating process. The influence of various chemical parameters, including the type of extractant and their concentrations, molar ratios of mixed extractant as well as type of strippant, are also studied. The organophosphorus extractant mixtures of D2EHPA and TBP provide a synergistic effect for target Ni²⁺ ions but has an antagonistic effect as regards the extraction of non-target [Au(CN)₂]⁻ ions. Compared to other inorganic acids, HCl is seen to be the most suitable strippant for the selective stripping. Results demonstrate that percentages of extraction and stripping of Ni²⁺ ions achieved 85.7 and 83.2%, respectively. In contrast, percentages of extraction and stripping of non-target [Au(CN)₂]⁻ ions attained 15.6 and 1.94%.     

Determination of Melamine in Fresh Milk with Hollow Fiber Liquid Phase Microextraction Based on Ion-Pair Mechanism Combined with High Performance Liquid Chromatography

In this work, a novel analytical method based on hollow fiber liquid phase microextraction (HF-LPME) and high performance liquid chromatography (HPLC) was developed for the analysis of melamine in fresh milk. The conditions of the HF-LPME were investigated and optimized. As a result, a supported liquid membrane containing 6-undecanone and di-2-ethylhexyl phosphoric acid (D2EHPA) was selected. The extractions were made from 25 mL aqueous donor phase (prepared from milk) with pH 5.0 to a more acidic acceptor phase (36 µL 1 M HCl) and the mass transfer was driven by the proton gradient between these phases. Other optimum conditions of the HF-LPME were 60 min extraction time at 360 rpm stirring rate and an extraction factor of 21 times (extraction efficiency 3%) was obtained. The C8 column was operated at 1 mL/min at room temperature and the UV detection wavelength was 240 nm for HPLC. The mobile phase was 10 mM sodium n-octanesulfonate (pH 3.0) mixed with acetonitrile (85:15, v/v). The relative recovery of melamine for milk samples spiked with 0.5–25 mg/kg was in the range of 89.1–120.6% with the RSDs (n = 4) of 4.0–8.5%. It was found that the proposed method provided a linear range from 0.1 to 50 mg/kg (r ²  = 0.9993), method detection limit (MDL) of 0.003 mg/kg and method quantification limit (MQL) of 0.01 mg/kg. The obtained results demonstrated that HF-LPME combined with HPLC is a simple and cheap method for the determination of melamine in fresh milk.     

Synchronized extraction and purification of L-lactic acid from fermentation broth by emulsion liquid membrane technique

This study aims to investigate the recovery of L-lactic acid from fermentation broth by an emulsion liquid membrane (ELM), made up of sunflower oil as the diluent, Sorbitan monooleate (Span 80) as the surfactant, Aliquat 336 as the carrier, and sodium hydroxide (NaOH) solution as the internal aqueous phase. Particularly, the ELM process was properly set up, through the identification of the optimal ELM operating parameters on the final extraction efficiency of L-lactic acid, including Span 80 concentration, NaOH concentration, Aliquat 336 concentration, stirring speed, phase ratio, and treatment ratio. The obtained results showed that the extraction efficiency of L-lactic acid reached up to 99% under the following optimal conditions: 10 minutes after contact time, 4% w/w Span 80, 3% w/w Aliquat 336, 0.1?N solution of NaOH, stirring speed of 300?rpm, phase ratio 1, and treatment ratio 0.25. A stable system without considerable emulsion swelling and breakage was monitored using a dynamic light scattering (DLS) apparatus for the selected optimal ELM operating parameters.     

Mathematical modeling of silver extraction by an emulsion liquid membrane process

A general physical model of a typical batch extraction system employing an emulsion liquid membrane process for the extraction of silver has been developed. The model takes into account the extraction reaction between the silver ion and the carrier molecules at the external interface, the diffusion of the complex in the membrane phase, the stripping reaction at the internal interface and the reaction of silver ion with the reagent, HCL, in the internal phase to yield silver chloride incapable of permeating through the membrane phase. In addition, the leakage of the internal aqueous phase to the external aqueous phase due to membrane breakage has been incorporated in this model. The batch extraction of silver using D2EHPA as a carrier has been carried out under various experimental conditions. The experimental data can be well explained by the present model.     

An effective process for the separation of U(VI), Th(IV) from rare earth elements by using ionic liquid Cyphos IL 104

Separation and recovery of U(VI) and Th(IV) from rare earth minerals is a very challenging work in rare earth industrial production. In the present study, a homemade membrane emulsification circulation (MEC) extractor was used to separate U(VI) and Th(IV) from rare earth elements by using Cyphos IL 104 as an extractant. Batch experiments were carried out using a constant temperature oscillator to investigate the extraction parameters of the single element and the results indicated that Cyphos IL 104 could reach the extraction equilibrium within 30 min for all the three elements, i.e., U(VI), Th(IV), and Eu(III). Besides, the MEC extractor possessed a strong phase separation ability. The extraction efficiencies of U(VI), Th(IV), La(III), Eu(III) and Yb (III) increased with the increase of pH. La(III), Eu(III) and Yb(III) were hardly extracted when pH ≤ 1.50, which was beneficial for effectively separating U(VI) and Th(IV) from La(III), Eu(III) and Yb(III). In the multi-stages stripping experiments, when the stripping stage number was 3, the effective separation could be achieved by using HCl and H₂SO₄, since the stripping efficiency reached 80.0% and 100.0% for Th(IV) and U(VI), respectively. Slope method and FT-IR spectra showed that Cyphos IL 104 reacted with U(VI) and Th(IV) by chelation mechanism. The extraction of multi-elements indicated that U(VI) and Th(IV) could be well separated from the solution which contains all rare earth elements, and the extraction efficiencies of U(VI) and Th(IV) both were close to 100.0%. Based on the above experimental results, a flowchart for efficient separation of U(VI) and Th(IV) from rare earth elements was proposed.     

Zn(II), Cd(II) and Cu(II) separation through organic–inorganic Hybrid Membranes containing di-(2-ethylhexyl) phosphoric acid or di-(2-ethylhexyl) dithiophosphoric acid as a carrier

A membrane process for metal recovery from aqueous solutions was studied. Metal ions diffused from the feed solution to the stripping phase through an Hybrid Membrane containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) and/or di-(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) as a carrier. Such membranes were prepared by a sol–gel route including cellulose triacetate and polysiloxanes. Transport behaviour was evaluated for both carriers under similar experimental conditions. The transport experiments reported here concerned transport at different cycles and selectivity towards different metal ions. Using D2EHPA the membrane provided a selective transport of zinc to the stripping compartment of the membrane cell, while copper and cadmium remained in the feed compartment. Whereas, using D2EHDTPA as carrier the transport rate increased and the selectivity profiles were inverted in relation with those of D2EHPA. With a mixture of both extracting agents it was observed an intermediate behaviour in selective transport, being possible to modulate it.     

Membrane sampling with microdialysis coupled to HPLC/UV for on-line simultaneous determination of melamine and cyanuric acid in non-dairy coffee creamer

An on-line microdialysis/high-performance liquid chromatography method was developed for the simultaneous determination of melamine and cyanuric acid in non-dairy coffee creamer. To collect these analytes from aqueous samples, the microdialysis system featured a microdialysis probe incorporating a polyarylethersulfone membrane and employed 0.05 M HCl in 0.1% (v/v) MeOH as the perfusate, with optimal efficiency obtained at a flow rate of 1 μL min(-1). The chromatographic conditions were optimized when using a reverse-phase phenyl column and a mobile phase of phosphate buffer solution in 10% (v/v) MeOH, buffered at pH 3.0. Good linearity relationship (r(2) > 0.9987), intra- and inter-day precisions (RSDs < 6.6%), recoveries (96.9 - 105.0%), and limits of detection (melamine, 3 ppb; cyanuric acid, 150 ppb) were observed for the two analytes. This method has been successfully applied to simultaneous determination of melamine and cyanuric acid in commercial creamers with the recoveries in the range of 97.5 to 102.6%.     

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.