Studies in Facilitated Transport of Nitric Oxide through Immobilized Liquid Membranes

Abstract

An experimental technique for studying facilitated transport through immobilized liquid membranes in a batch mode is presented along with its mathematical analysis. Results obtained with two carrier ions [Fe(II) and Zn(II)] in the solvent N-cyclohexyl-2-pyrrolidone are compared. The effects of carrier ion concentration and of initial pressure difference are studied. Facilitation factors (ratio of facilitated flux to the flux without any carrier ion) up to 8.1 were observed.     

Two-Dimensional Permeate Transport with Facilitated Transport Membranes

Abstract

An analytical model has been developed for steady-state permeate transport with facilitated transport membranes. The model contains no adjustable parameters. The model accounts for both axial permeate transport parallel to the membrane and facilitated permeate transport through the membrane. The model predicts the fraction of permeate separated through the membrane as a function of physical properties and operating conditions. The model was derived for a cylindrical geometry but can be applied to a planar geometry. Also, the model could be used for the simple diffusion case when no facilitation is present. Reasonable agreement with experimental data is presented.     

Kinetic Efficiency Factors for Facilitated Transport Membranes

Abstract

A kinetic efficiency factor (η) is defined for facilitated transport membranes. η is defined as the actual facilitated flux divided by the facilitated flux under reaction equilibrium conditions. η is correlated with an inverse Damkohler number ε. A dimensionless equilibrium constant K and mobility ratio a also affect the value of η. η is shown to be useful in determining the operating regime of the system, comparing actual performance to maximum attainable, and providing a qualitative measure of the time to reach steady-state conditions.     

固定载体促进传递研究进展

固定载体促进传递是兼具高通量和高选择性的膜分离技术. 本文分析了国内外的研究现状，综述了固定载体促进传递的机理，讨论了载体固定化的方法，指出了目前需要解决的问题并对其发展前景作了预测.     

CO2通过合成聚合物膜的促进传递

Two kinds of fixed carrier membrane materials containing secondary amine and carboxyl groups which can be used as carriers of CO2 were prepared. One was poly(N-vinyl-7-sodium aminobutyrate)(PVSA), which was obtained through the hydrolysis of polyvinylpyrrolidone (PVP) synthesized with N-vinylpyrrolidone(NVP) by radical polymerization. The other was poly(N-vinyl-7-sodium aminobutyrate-co-sodium acrylate)(VSA-SA), which was obtained through the hydrolysis of copolymer of N-vinylpyrrolidone and acrylamide(AAm) (NVP-AAm). The composite membranes were developed with PVSA or VSA-SA as active layer and polysulfone (PS) as support membranes. The permeation rates of pure CO2 and CH4 gas as well as binary mixtures of CO2/CH4 through the composite membranes were measured. The results show that the composite membranes present better CO2 permeation rates than other fixed carrier membranes do reported in literature. For example, at 26℃, 1330 Pa of CO2 pressure, the PVSA/PS composite membrane displays a CO2 permeation     

CO2 Separation Using Facilitated Transport Ion Exchange Membranes

Abstract

The use of ion-exchange membranes as supports for facilitated transport of C0₂ is demonstrated. Two different ionomer films were evaluated. The ionomers were a perfluorosul-fonic acid film and a sulfonated polybenzimida-zole film. Sodium (Na⁺) was exchanged into the membrane for diffusion experiments and ethylene-diamine (EDA) was exchanged for facilitated transport experiments. The results indicate that thin perfluorosulfonic acid membranes provide the best CO₂ flux and can also provide exceptionally high selectivity.     

CO2在全氟羧酸离子交换膜内促进传质特性的研究

本文以全氟羧酸离子交换膜为支撑体、乙二胺(EDA)为活性络合剂、制备促进传质膜。在常用的工业条件下,测定了纯CO_2以及CO_2/N_2二元混合物在该膜内的渗透通量。实测结果表明,此膜对CO_2的促进因子可达13.8,而对CO_2/N_2的分离因子高达316。本文假设促进传质过程的控制步骤为气体在膜相的扩散,据此导出了相应的机理模型,该模型与实测结果吻合良好。     

Separation of Zinc and Bismuth by Facilitated Transport through Activated Composite Membranes

Abstract

This paper reports the results on the further development of activated composite membranes (ACM) containing di‐2‐ethyhexyl‐dithiophosphoric acid (D2EHDTPA) as a carrier. The selectivity and transport properties of D2EHDTPA‐based ACMs towards different metal ions including bismuth and zinc appear to be interconnected with each other. It has been shown that unlike the liquid‐liquid extraction of bismuth, the use of D2EHDTPA‐ACM permits to recover and to concentrate bismuth from a highly saline medium without irreversible destruction of the carrier. The difference in the rates of bismuth and zinc transport through ACMs permits their separation since the former is concentrated in the stripping solution and the latter retains in the feed compartment of the membrane cell.     

CO2通过合成聚合物膜的促进传递

Two kinds of fixed carrier membrane materials containing secondary amine and carboxyl groups whichcan be used as carriers of CO2 were prepared. One was poly(N-vinyl-γ-sodium aminobutyrate)(PVSA), whichwas obtained through the hydrolysis of polyvinylpyrrolidone (PVP) synthesized with N-vinylpyrrolidone(NVP) byradical polymerization. The other was poly(N-vinyl-γ-sodium aminobutyrate-co-sodium acrylate)(VSA-SA), whichwas obtained through the hydrolysis of copolymer of N-vinylpyrrolidone and acrylamide(AAm) (NVP-AAm). Thecomposite membranes were developed with PVSA or VSA-SA as active layer and polysulfone (PS) as supportmembranes. The permeation rates of pure CO2 and CH4 gas as well as binary mixtures of CO2/CH4 throughthe composite membranes were measured. The results show that the composite membranes present better CO2permeation rates than other fixed carrier membranes do reported in literature. For example, at 26℃, 1330 Pa of CO2pressure, the PVSA/PS composite membrane displays a CO2 permeation rate of 5.95 × 10-7 cm3.cm-2.s-1.pa-1with CO2/CH4 ideal separation factor of 212.1. At 20℃, 6400Pa of CO2 pressure, the VSA-SA/PS compositemembrane displays a CO2 permeation rate of 4.24 × 10-8 cm3@cm-2.s-1.Pa-1 with CO2/CH4 ideal separationfactor of 429.7. The results with the gas mixtures are not as good as those obtained with pure gas because ofthe coupling effects between CO2 and CH4. The heat cross-linked membrane shows good separation factor due todensification of the polymer.     

液体表面活性剂膜的传质模型

本文提出了一个新的关于液膜传质的模型.该模型不仅考虑了溶质在乳状液球内核中的渗透过程,还考虑了由表面活性剂所致的界面阻力升高效应,因而更加准确地描述了液膜体系的传质过程.该模型的另一个特点是考虑了在传质过程中膜的破裂,从而使数学模型更加迫近液膜体系的实际情况.实验结果与理论分析均表明,溶质透过乳状液外围的表面活性剂薄层的分子扩散是整个液膜传质过程的速率控制段.这一结论将导致对液膜结构更加深刻的理解,并将有助于液膜体系的改进.     

Characteristics of Lactic Acid Transport in Supported Liquid Membranes

Abstract

Transport of lactic acid in supported liquid membranes containing tertiary amines (Alamine 336, Henkel Corp.) as the carrier was investigated. Both equilibrium extraction constants (K _t) and effective diffusion coefficients (D) of the acid-amine complex were measured for systems with various diluents. Larger K _t values and, thus, more efficient extraction were found when diluents were used, especially with oleyl alcohol which improved the polarity of the oil membrane and led to an approximately sixtyfold increase in the K _t value. Experimental results of D for different supported liquid membranes were found in the range of 2 to 7 × 10^?7 cm²/s. Although much lower than those predicted by the Wilke-Chang equation, the values are consistent in the orders of magnitude with the literature results for other permeates in similar supported liquid membranes.     

Some Aromatic Amine Transport through Emulsion Liquid Membranes

Abstract

This paper reports the permeation of 10 aromatic amines through emulsion liquid membranes and estimates of the apparent diffusion coefficients and apparent moving rates.     

Modeling of Facilitated Transport of Phenylalanine by Emulsion Liquid Membranes with Di(2-ethylhexyl)phosphoric Acid as a Carrier

ABSTRACT

A mathematical model is developed in this paper to simulate the facilitated transport of phenylalanine (Phe) in emulsion liquid membrane (ELM) systems with di(2-ethylhexyl)phosphoric acid as a carrier. The model takes into account the mass transfer in both the external aqueous phase and the organic membrane phase interfacial reaction as well as membrane breakage during agitation. The model is tested by comparing theoretical predications with experimental results using Phe extraction by ELM processes. It is found that the model is valid for simulating the facilitated transport of Phe with ELM under various experimental conditions.     

Mathematical Modeling of Facilitated Liquid Membrane Transport Systems Containing lonically Charged Species

Abstract

A numerical model is presented which solves the transient nonlinear system of partial differential equations governing the facilitated transport of ionically charged species through a liquid membrane. The mathematical model is derived in dimensionless form and solved numerically. Facilitation factors and electrical potentials across the membrane are computed and compared to experimental results. This model is useful in predicting transient concentration, flux, and electrical potential gradients provided that the values of the required physical constants are known. It was noticed that transient facilitation factors are not affected by the transient electrical potential buildup, which indicates that both the pure diffusion and the faciltated transport of permeate are affected equally by the electrical effects of the ionically charged species.     

Separation of Propylene-Propane Mixture Using Immobilized Liquid Membrane via Facilitated Transport Mechanism

Abstract

Separation of propylene-propane mixtures using immobilized liquid membrane was investigated. A porous polymeric sheet was used as support to immobilize the liquid membrane. The effect of propylene partial pressure in feed stream, trans-membrane pressure, and carrier concentration on membrane separation performance was investigated and the results were evaluated in terms of separation factor, propylene permeability, and propane permeability. Propylene permeability ranged from 0.4 to 650 Barrer. Moreover, it was observed that for 30:70 (vol.%) propylene-propane mixture, at pressure 120 kPa and carrier concentration 20 wt.%, a separation factor of 480 was obtained.     

Carrier-Mediated Transport of Rare Earth Ions through Supported Liquid Membranes

Abstract

Fluxes of rare earth ions (Sc³⁺, Y³⁺, La³⁺, Sm³⁺, and Lu³⁺) across supported liquid membranes using mixtures of nitrophenyl octyl, heptyl, or phenyl ethers and tris(2-n-butoxyethyl) phosphate (TBEP) as solvents and some β-diketones as carriers were determined. The effects of membrane composition, pH of the source phase, and carrier concentration on the flux are demonstrated. The effect of membrane composition is further discussed from the values of the membrane potential and the viscosity and electrical conductivity of the solvents. A maximal flux of lanthanum is observed for the membranes by using mixtures consisting of equal volumes of the nitrophenol derivative and TBEP. The fluxes of the rare earths, except scandium, decrease rapidly with decreasing pH difference between the source and receiving phases. The difference in flux among the rare earths, except scandium, is small. The flux increases in the carrier order benzoyl- > thenoyl- > furoyltrifluoroacetones. The lanthanum flux is proportional to the carrier concentration.     

Facilitated Transport of Zinc Chloride through Hollow Fiber Supported Liquid Membrane. Part 1. Transport Mechanism

Abstract

The facilitated transport of zinc chloride through a liquid membrane of tri-n-octylamine dissolved in n-dodecane with 2-ethylhexyl alcohol, supported on a microporous polyethylene hollow fiber, has been studied in a series of three papers. This first paper deals with the transport mechanism. The distribution of zinc chloride between the liquid membrane phase and the aqueous hydrochloric acid solution was clarified. The characteristics of the support membrane and of the flow system were examined through phenol transport experiments. The initial permeation rate of zinc chloride was explained by the sum of film resistances in the two aqueous phases and a membrane phase resistance     

硅橡胶膜强化传热管的制备及其滴状冷凝传热研究

实验采用热处理法制备了滴状冷凝传热的硅橡胶膜强化传热管,107硅橡胶为最佳的制备材料,其水接触角为106.8°。传热效果较好传热管的制备条件为4%硅橡胶铸膜液、热处理温度350℃及惰性环境中处理1h,其热通量比沟槽管提高了约10%,比普通管提高了约80%左右;冷凝侧传热系数比沟槽管提高了30%,比普通管提高了约4倍左右。采用红外对制备的107硅橡胶膜强化传热管进行了表征,经过热处理硅橡胶会产生交联缩合。     

Carrier-Mediated Transport of Molybdenum(VI) through Supported Liquid Membranes

Abstract

The liquid membrane transport of Mo(VI) from an acidic solution into an alkaline stripping solution was carried out by using a mobile carrier, 5,8-diethyl-7-hydroxy-dodecan-6-one oxime (LIX 63). Further transport of MoO₄ ^2? from the alkaline solution was performed by using another carrier, trioctylmethylammonium chloride (TOMAC). Molybdenum(VI) was effectively transported through double membranes composed of LIX 63/dilute NaOH solution/TOMAC from a feed solution (10^?3 M HNO₃) into a product solution (1 M NaOH). Molybdenum(VI) was concentrated with high recovery into a small volume of product solution. The separation of Mo(VI) from several ions was performed by means of the double membranes.