Facilitated Pertraction of p-Aminobenzoic Acid with Amberlite LA-2 in Presence of 1-Octanol

p-Aminobenzoic acid has been facilitated pertracted with Amberlite LA-2 dissolved in dichloromethane, using a U-shaped pertraction cell which allows obtaining the free liquid membrane. The pertraction has been a carrier out in the presence of 1-octanol added in the liquid membrane. The addition of the alcohol led to the increase for up to 3 times of the acid initial and final mass flows, this effect being directly related to the process variables (pH-gradient between the aqueous phases, carrier and alcohol concentrations inside the membrane phase, mixing intensity). But, the influence of 1-octanol on the transport capacity of the pertraction system was negative, its addition inducing the accumulation of PABA in the liquid membrane, and requiring the reevaluation and optimization of the acid reextraction from the membrane phase to the stripping one.     

Separation of rosmarinic acid by facilitated pertraction

Rosmarinic acid has been separated by facilitated pertraction with D2EHPA dissolved in dichloromethane. The pertraction has been carried out in presence of 1-octanol, added into the liquid membrane. The addition of the alcohol led to the increase for more than twice the rosmarinic acid initial and final mass flows, this effect being directly related to the process variables (pH-gradient between the aqueous phases, carrier and alcohol concentrations inside the membrane phase, mixing intensity). But, the influence of 1-octanol on the transport capacity of the pertraction system was negative, its addition inducing the accumulation of rosmarinic into the liquid membrane. Due to this effect, the reevaluation and optimization of the reextraction process from the membrane phase to the stripping are required.     

Kinetics and Mechanism of Copper Transfer by Hydroxy-Oximes in Three-Phase Liquid Systems

Abstract

A model of copper-facilitated transport in a three-liquid-phase pertraction system is proposed. The model takes into account the diffusional transport of copper species (ions and complexes) in all three liquids as well as the kinetics of chemical reactions. The latter, according to the model suggested, occurs in narrow reaction zones: aqueous layers adjacent to the donor membrane and acceptor-membrane interfaces. Experiments were carried out in a two-compartment agitated diffusion cell with a bulk liquid membrane: a 5% (vol) solution of the commercial copper extractant LIX 860 in C₁₁-C₁₃ normal paraffins. The donor solution used contained 1 g/L copper and the acceptor liquid was a 4.5 N aqueous solution of sulfuric acid. On the basis of experimentally obtained pertraction curves and the model suggested, it was found that the overall rate of the process is controlled by the diffusion of copper ions in the donor phase as well as by copper-complex decomposition. By applying an optimization procedure, the mass transfer coefficients and the rate constants were evaluated under the experimental conditions of this study.     

Silver Recovery from Dilute Aqueous Solutions Using Semi‐Batch RF‐Pertraction

Silver recovery from dilute nitrate solution was studied by using a rotating film‐pertraction technique in a semi‐continuous mode. Tri‐isobutylphosphine sulphide (TIBPS) dissolved in kerosene was used as a carrier and an aqueous ammonia solution as a stripping phase. A high transfer flux of silver ions during the pertraction process was observed. It was shown that the selectivity of silver transport through the TIBPS‐containing liquid membrane provides an excellent separation of silver from other metals such as copper, nickel, and iron presented in the treated solutions.     

Pertraction of cations in a hybrid membrane system containing soluble polymeric ionophores

A hybrid membrane system composed of two insoluble cation‐exchange membranes (Nafion) and a liquid membrane in between was studied. A series of organic and aqueous liquid membranes containing soluble polymers as macromolecular ionophores (macroionophores) was prepared and tested. The pertraction (membrane‐transport) characteristics of poly(ethylene glycol) and its ionizable derivatives, including as poly[poly(oxyethylene) phosphate] (PPOEP) and di‐[ω‐methoxy poly(oxyethylene)] phosphate, were measured and are discussed as dependent on the composition and molecular mass of a macroionophore. The liquid membrane composed of PPOEPs dissolved in dichloroethane combined the cation‐exchange properties with neutral coordination functionalities introduced by the poly(oxyethylene) backbone of this ionophore. The overall fluxes, facilitation factors, and the membrane system selectivity were measured in the carrier‐mediated pertraction of transient metal cations (Cu²⁺, Zn²⁺, Mn²⁺, Co²⁺, and Ni²⁺). PPOEP could facilitate the pertraction of Zn²⁺ and Cu²⁺ over Ni²⁺ and Co²⁺. In the case of an aquatic hybrid membrane system, high but nonselective ionic fluxes were observed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 99–109, 2002; DOI 10.1002/app.10263     

Development of Liquid Membrane Pertraction for the Removal and Recovery of Chromium from Aqueous Effluents

Abstract

Liquid membrane pertraction combines the loading and stripping steps of solvent extraction into a single unit operation, allowing the continuous removal and concentration of a given species. In this paper the feasibility of applying liquid membrane pertraction to the recovery of chromium (Cr(VI) from aqueous effluents with the objective of reducing levels to below allowable discharge limits has been examined. A continuous laboratory-scale liquid membrane pertractor was constructed to solve a variety of problems associated with the treatment of Cr(VI)-bearing streams. Various operational factors such as feed velocity, strip velocity, membrane velocity, and composition of the inlet feed were then examined. Satisfactory continuous runs lasting up to 22 days were achieved. Chromium levels in synthetic waste could be reduced from 200–300 mg/L down to 1 mg/L, well within most allowable discharge limits. Experiments showed that the strip phase can be concentrated with inlet Cr(VI) concentrations of 2000 ppm Cr(VI), with indications that it should be possible at even higher concentrations.     

Selective Separation of Cinnamic and p‐Methoxycinnamic Acids by Facilitated Pertraction

Abstract

Cinnamic acid can be selectively separated from p‐methoxycinnamic acid by facilitated pertraction with Amberlite LA‐2 dissolved in dichloromethane, using a U‐shaped pertraction cell which allows obtaining the free liquid membrane. The pertraction has been analyzed by means of initial and final mass flows, permeability and selectivity factors. The main factors which control the pertraction selectivity were identified to be the pH‐gradient between the feed and stripping phase and the mixing intensity of the aqueous phases. The maximum selectivity factor has been recorded for pH=2 of feed phase, pH=8 of stripping phase, rotation speed lower than 300 rpm, and carrier concentration higher than 40 g/l.     

Study on Facilitated Pertraction of Folic Acid in Pseudosteady-State Regime

The influences of the pH-gradient between the feed and stripping phases and of carrier concentration inside the membrane phase on the efficiency of facilitated pertraction of folic acid with Amberlite LA-2 in pseudosteady-state mode have been analyzed. The experiments have been carried out using a U-shaped pertraction cell which allowed to easily maintaining the liquid membrane between the two aqueous phases. On the basis of the experimental data and theoretical investigation on pseudosteady-state regime, two models describing the acid accumulation inside the liquid membrane by means of the permeability factor have been developed for two pH-values of feed phases (5.2 and 3, respectively). The proposed models offer good concordance with the experimental data and can be useful for facilitated pertraction optimization.     

Comparitive study on facilitated pertraction of succinic acid using TRI‐n‐octylamine without and with 1‐octanol

Succinic acid has been pertracted with TOA using free liquid membranes without or with 1‐octanol. The addition of the alcohol led to the increase of up to 2.8–3 times of the acid's initial and final mass flows. At the same time, the influence of 1‐octanol on the transport capacity of the pertraction system was negative, its addition inducing the accumulation of succinic acid into the liquid membrane. A mathematical model describing the acid accumulation inside the liquid membrane has been developed for pertraction systems without and with 1‐octanol and offers good concordance with the experimental data. © 2012 Canadian Society for Chemical Engineering     

Mathematical model for swelling in a liquid emulsion membrane system

Application of the liquid emulsion membrane (LEM) technology to the industrial scale is hindered by the challenges imposed by stability of the emulsion during the transfer of the solute (pertraction). One of the important factors which leads to the instability is swelling. Emulsion undergoes swelling due to the osmotic gradient across the membrane as well as due to the occlusion of the external phase into the membrane phase; the latter is caused by the hydrodynamic deformation of the membrane globules. In the present work, we have studied swelling of the emulsion phase in a water-in-oil-in-water type LEM system. Nitric acid is the internal aqueous phase and is encapsulated in organic membrane phase composed of DEHPA–kerosene-SPAN80. Demineralised water is used as the external phase. The effect of the composition of the system and the hydrodynamic condition on the rate of swelling has been studied. A mathematical model has been developed to describe the effects of the relevant parameters on swelling of the emulsion. The globules of the emulsion are viewed as having a core-shell structure, based on the visual evidence. The model takes into account both the osmotic and the occlusion modes of swelling and also the leakage of the internal phase. The predictions of the model are found to be in good agreement with the experiments. The model would be useful for evaluating the rate of pertraction of a solute through the membrane–strip combination used in the present study. The study would also be useful for tuning the design and the operating parameters in LEM pertraction to achieve minimum swelling of the emulsion.     

Selective Recovery of Alkaloids from Glaucium Flavum Crantz Using Integrated Process Extraction-Pertraction

Abstract

Selective recovery of aporphine alkaloids from Glaucium flavum Crantz was studied. The alkaloids were successfully recovered from aqueous solutions, including native extracts of Glaucium flavum Crantz, applying pertraction in a rotating discs contactor. As a liquid membrane n-heptane and as receiving solution diluted phosphoric acid were used. Pertraction was also coupled to solid-liquid extraction in order to simultaneously purify the extract obtained from the plant. This integrated extraction-pertraction process was very simple, rapid, and efficient. The permeation of alkaloids through the liquid membrane was very selective and their purity in the receiving solution was 88.7%.     

Extraction and pertraction of phenol through bulk liquid membranes

The extraction and pertraction of phenol through a bulk liquid membrane (BLM) with Cyanex^® 923, Amberlite^® LA‐2 and trioctylamine (TOA) as carriers were studied. Cyanex^® 923 was selected as the best carrier for pertraction. The distribution coefficient of phenol for solvents with carrier and pure n‐alkanes, the individual mass‐transfer coefficient at the extraction interface and the initial flux of phenol through the extraction interface (J_Fo) decreased in the order: Cyanex^® 923 > Amberlite^® LA‐2 > TOA ? pure n‐alkanes. The opposite order was observed for the value of the mass‐transfer coefficient in BLM and the maximum flux of phenol through the stripping interface (J_Rmax). At constant driving forces the maximum fluxes through the extraction and stripping interfaces were similar when amine carriers were used. However, J_Rmax was lower than J_Fo for Cyanex^® 923. Although the kinetics of stripping was the rate‐determining step, the flux of phenol was significantly higher than in pertraction with amine carriers. The adsorption of the carrier at aqueous phase/membrane interfaces was probably responsible for the rapid and slow transfer of phenol through the extraction and stripping interface, respectively. Copyright © 2004 Society of Chemical Industry     

聚四氟乙烯膜气体吸收数学模型和孔隙率的影响

膜吸收是将膜分离与传统的吸收技术相结合的一种新型分离技术。在这些过程中经常使用多孔膜,多孔膜对过程的传质性能有一定的影响。对不同孔隙率的微孔聚四氟乙烯(PTFE)疏水性平板膜的膜气体吸收过程中液相传质性能进行了实验研究。当采用去离子水-CO2吸收体系时,多孔膜的孔隙率对液相传质性能没有影响;当采用NaOH水溶液-CO2吸收体系时,多孔膜的孔隙率对液相传质性能有明显的影响。在相同流速下,孔隙率大的膜液相传质系数高于孔隙率小的膜。以双膜理论为指导,建立了多孔膜气体吸收过程中液相传质模型。用该模型描述多孔膜孔隙率对液相传质系数的影响,其结果与实验数据具有良好的一致性。     

The Transport of Copper(II) through Hollow Fiber Renewal Liquid Membrane and Hollow Fiber Supported Liquid Membrane

Abstract

In this paper, hollow fiber renewal liquid membrane (HFRLM) and hollow fiber supported liquid membrane (HFSLM) were used to simultaneously remove and recover copper(II) from aqueous solutions, and the transport performance of these two techniques were compared under the similar conditions for the system of CuSO₄ +D2EHPA in kerosene +HCl. The results showed that the HFRLM process was more stable than the HFSLM process. The HFRLM process had a higher overall mass transfer coefficient than that of HFSLM process in single-pass experiments. These were because the renewal effect of the liquid membrane layer could reduce the mass transfer resistance of the lumen side and replenish the loss of the membrane liquid in the HFRLM process. The transport results were better in the HFRLM process than that in the HFSLM process with recycling experiments. Therefore, HFRLM technique is a promising method for simultaneous removal and recovery of heavy metal from aqueous solutions.     

硅橡胶复合膜用于含酚水溶液渗透萃取传质过程

以苯酚为模型污染物,以氢氧化钠溶液为萃取液,利用平板复合膜［聚二甲基硅氧烷（PDMS）/聚偏氟乙烯（PVDF）］构造渗透萃取体系,系统地研究了该体系渗透萃取含酚水溶液的传质过程与特性。探讨了料液与萃取液的浓度及流量、运行温度等操作条件及活性层厚度对渗透萃取传质性能的影响。结果表明,pH>13时,总传质系数K_ov不随萃取液流量及浓度变化而变化;苯酚的液膜传质系数kf与膜面流动Reynolds数Re^0.46呈正比,传质通量与温度符合Arrhenius方程。在苯酚初始浓度5.0～15.0 g•L^-1范围内,K_ov为定值。活性皮层厚度为4、6、8 μm的膜扩散传质系数分别为15.0×10^-7、9.9×10^-7及7.5×10^-7m•s^-1（323.2 K）,较均质膜提高了2～4倍。苯酚在复合膜中的传质仍属膜阻控制的传质。     

Liquid Pertraction or Liquid Membranes—State of the Art

Abstract

Liquid pertraction? or liquid membranes appeared as a prospective separation process relatively recently. Due to its obvious advantages over solid membranes and liquid-liquid extraction, liquid pertraction has attracted the attention of many scientists and engineers. At present there are more than 160 research teams around the world exploring this new, emerging separation operation.     

New liquid membrane technology for simultaneous extraction and stripping of copper(II) from wastewater

In this paper, a new liquid membrane technique, hollow fiber renewal liquid membrane (HFRLM), is presented, which is based on the surface renewal theory, and integrates the advantages of fiber membrane extraction, liquid film permeation and other liquid membrane processes. The results from the system of CuSO₄+D2EHPA in kerosene+HCl show that the HFRLM process is very stable. The liquid membrane is renewed constantly during the process, the direct contact of organic droplets and aqueous phase provides large mass transfer area. These effects can significantly reduce the mass transfer resistance in the lumen side. Then the mixture of feed phase and organic phase flowing through the lumen side gives a higher mass transfer rate than that of stripping phase and organic phase, because the aqueous layer diffusion of feed phase is the rate-controlling step. The overall mass transfer coefficient increases with increasing flow rates and D2EHPA concentration in the organic phase, and with decreasing initial copper concentration in the feed phase. The overall mass transfer coefficient also increases with increasing pH in the feed phase, and reaches a maximum value at pH of 4.44, then decreases. Also, there is a favorable w/o volume ratio of 20:1 to 30:1 for this process. Compared with hollow fiber supported liquid membrane and hollow fiber membrane extraction processes, HFRLM process has a high mass transfer rate. Mathematical model for the HFRLM process based on the surface renewal theory is developed. The calculated results are in good agreement with experimental results under the conditions studied.     

Chiral separation by combining pertraction and preferential crystallization

This work describes the application of a hybrid two-step enantioselective separation process. As a first step, pertraction using supported liquid membranes provides an initial enrichment, while the following preferential crystallization delivers the enantiopure crystals as final product. Mandelic acid in water was studied as a model system. Using a suitable chiral selector, pertraction provides enrichments exceeding 10% and reaching up to 20% in the permeate phase, which was sufficient to allow for subsequent selective preferential crystallization. Based on the individual performances of pertraction and crystallization, overall yields and productivities are estimated. The calculated productivities are compared with values achievable in alternatively applicable chromatographic separation processes using chiral stationary phases. The realized hybrid pertraction-crystallization process is in its present state for the example considered still inferior to preparative chromatography. Strategies for further improvement are suggested.     

High-efficiency HFSLM for silver-ion pertraction from pharmaceutical wastewater and mass-transport models

Hollow fiber supported liquid membrane (HFSLM) is a favorable technique for the pertraction of metal ions, especially at very low metal concentration. In this work, the pertraction of silver ions from acidic pharmaceutical wastewater via HFSLM was investigated. Pharmaceutical wastewater containing 30 mg/dm³ of silver ions and 120 mg/dm³ of ferric ions was subjected to HFSLM as a feed solution. LIX 84-I dissolved in organic solvent together with Na₂S₂O₃·5H₂O solution was selected for use as a liquid membrane and a receiving solution, respectively. The influence of ferric ions on the pertraction of silver ions was studied firstly using wastewater with normal ferric ion concentration and secondly using wastewater with ferric ion precipitation by phosphoric acid solution. The highest pertraction of silver ions was achieved by using 0.1 M of LIX 84-I and 0.5 M of Na₂S₂O₃·5H₂O solution at pH of feed and receiving solutions of 3.5 and 2. The flow rates of feed and receiving solutions were 0.2 dm³/min. 0.6 mg/dm³ of silver ions that remained in the wastewater was below the mandatory discharge limit. No effect of normal ferric ion concentration in the wastewater on silver ion pertraction was observed. The crucial parameters were defined to confirm the efficiency and reliability of the system. Finally, the controlling transport regime of silver ion pertraction across HFSLM was determined by the diffusion flux and reaction flux models.