Mathematical modeling of penicillin G extraction in an emulsion liquid membrane system containing only a surfactant in the membrane phase

An extraction experiment of penicillin G was performed in an emulsion liquid membrane system in which only ECA 4360J exists in the organic membrane phase without a predominant carrier, Amberlite LA-2, used in our previous works and it functions as a carrier as well as a surfactant. A permeation model for the present system has been developed as a primary study to examine the transport mechanism of penicillin G in the previous batch and continuous systems with two carriers of Amberlite LA-2 and ECA 4360J. The model takes into account the mass transfer in the external aqueous film, the extraction reaction between penicillin G and ECA 4360J at the external interface, the diffusion of penicillin G in the emulsion phase, the stripping reaction at the internal interface and the pH change of internal aqueous solution containing Na₂CO₃ with penicillin G transported into the internal phase. The experimental data were well fitted with the present model. Also, an expression for the reaction of penicillin G with ECA 4360J was obtained through a series of equilibrium measurements in liquid–liquid extraction system.     

Effect of volume ratio of internal aqueous phase to organic membrane phase (w/o ratio) of water-in-oil emulsion on penicillin G extraction by emulsion liquid membrane

The batch extraction of penicillin G from a model media was studied so as to obtain the optimal w/o ratio in an emulsion liquid membrane (ELM) system with the help of our previous works. First of all, the effects of organic solvents or surfactants in membrane phase on apparent degree of its extraction at various w/o ratios were investigated. The organic solvents and surfactants were kerosene/n-butyl acetate and Span 80/PARABAR 9551, respectively. The optimal composition between two surfactants for the highest apparent degree of extraction was obtained at each w/o ratio.With the optimal surfactant composition at each w/o ratio, citrate buffer solutions of three different concentrations having about pH 4.8 were selected as the external aqueous phase. The mass of Na₂CO₃ in the internal phase was kept constant for every w/o ratio in order to investigate the effects of w/o ratio on the degree of extraction under the same trapping mass of Na₂CO₃ for penicillin G. The highest possible concentration of Na₂CO₃ in the internal phase was chosen using balance equations and equilibrium expressions. In consequence, the highest actual degree of extraction of 98.2% and the lowest percentage of swelling of 36.0 were obtained in the specific ELM system with 0.41 M citrate buffer solution, 0.175 M Na₂CO₃ and w/o ratio of 1/1.     

Extraction of Priority Pollutant 4-Nitrophenol from Water by Emulsion Liquid Membrane: Emulsion Stability,Effect of Operational Conditions and Membrane Reuse

This work aims to the extraction of the priority pollutant 4-nitrophenol (4-NP) from water by emulsion liquid membrane (ELM). Liquid membrane consists of a diluent (hexane) and a surfactant (Span 80). Sodium carbonate solution was used as internal aqueous phase. Effects of important experimental conditions governing the stability of the W/O emulsion were investigated. Influence of operating parameters that affects the permeation of 4-NP such as surfactant concentration, emulsification time, sulfuric acid concentration in external phase, acid type in external phase, internal phase concentration, type of internal phase, stirring speed, volume ratio of internal phase to membrane phase, treatment ratio, 4-NP initial concentration, and diluent type was examined. This study also evaluated the effect of Na₂CO₃ concentration in the internal aqueous phase on the stripping of 4-NP. Additionally, the reuse of the recovered membrane was studied. Under most favorable conditions, practically all the 4-NP and aniline (AN) molecules present in the feed phase were extracted. The recovery of the membrane phase was total and the extraction of 4-NP was not decreased. The ELM treatment process represents a very interesting advanced separation process for the removal of 4-NP and AN from aqueous solutions.     

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 and separation of carboxylic acids through bulk liquid membranes containing tributylamine

In this study, transport and separation of carboxylic acids (formic, acetic, propionic, and butyric acids) from their aqueous solutions through bulk liquid membrane (BLM) containing tributylamine (TBA) and the parameters affecting the transport were investigated. The influence of the parameters on the separation process such as the stirring of membrane phase, the stripping phase type and concentration, the feed phase type, and the feed:membrane:stripping phase ratio (F/M/S phase ratio) were examined. In the experiments, 10% (w/w) acid solutions (formic, acetic, propionic, and butyric acids) were used as the feed phase, different concentrations of NaOH solutions within the range of 0–2?N were used as the stripping phase, and 0.5?mol/lt TBA, dissolved in oleyl alcohol, was used as the membrane phase. It was determined that the stirring of the membrane phase increases the transport of acids. In the case of 2 N NaOH solution in the stripping phase and F/M/S phase ratio 1:2:1 gave the best recovery (96.75%) for butyric acid. It was observed that BLM was an effective technique for the separation of carboxylic acids from aqueous solutions.     

Carrier-facilitated liquid membrane extraction of penicillin G from aqueous streams

Kinetics and mechanism for the carrier-facilitated transport of penicillin G from aqueous solutions through a supported liquid membrane containing Amberlite LA-2 were investigated. The strip phase was either phosphate buffer or sodium carbonate solution. Experiments were performed as a function of the pH, the concentrations of penicillin G in the feed phase and of amine in the membrane phase. A transport model was proposed considering aqueous film diffusion, interfacial chemical reaction, and membrane diffusion. The calculated rates were found to agree with the measured ones (average standard error, 12%). Under the conditions investigated (feed pH 5.02–7.83, penicillin G concentration 10–500 mol/m³, amine concentration 50–1000 mol/m³), the present transport process was shown to be governed by combined interfacial chemical reaction and membrane diffusion.     

Recovery of zinc from chloride media by batch pertraction in a rotating film contactor

A liquid membrane (pertraction) process of zinc recovery from acidic chloride solutions was studied applying a pertraction in a rotating film contactor (RFC). Tri-n-octylamine (TOA or R₃N) dissolved in n-octane was used as a carrier. The influence of the main process parameters, such as disc rotation velocity, hydrochloric acid concentration in the aqueous phases and carrier concentration in the membrane was investigated. Assuming the existence of two thin reaction layers in the feed and stripping solutions, adjacent to both water–oil interfaces, a mathematical model was developed to describe the zinc transport. On the basis of the experimental data obtained under various conditions and the model proposed, it was found that the extraction step is controlled mainly by the mass transfer resistance, whereas the stripping rate of zinc is controlled predominantly by the rate of zinc–carrier complex decomposition in the stripping side reaction layer.     

Kinetics of reductive stripping of Pu(IV) in the tributylphosphate-kerosene/nitric acid-water system using dihydroxyurea

The kinetics of the reductive stripping of plutonium(IV) by dihydroxyurea (DHU) in 30% TBP/kerosene-HNO₃ system was studied with a constant interfacial area cell. The stripping rate of plutonium(IV) increases with the increase of the stirring speed of two phases and the interfacial area. The activation energy of this process is 28.4 kJ/mol. Under the given experimental conditions, the mass transfer of Pu is not controlled by redox reaction, but controlled by molecular diffusion from the organic phase to organic film layer and from the aqueous film layer to aqueous phase. The rate equation of reductive stripping (process is controlled by diffusion) was obtained as: r ₀ = k′[Pu(IV)]₀[DHU]_a ^0.16[HNO₃]_a ^−0.34. The rate constant k′ is (5.0±0.4)·10⁻² (mol/L)^0.18·min⁻¹ at 18.0°C.     

Studies on extraction behaviour of molybdenum (VI) from acidic radioactive waste using 2(ethylhexyl) phosphonic acids,mono 2(ethylhexyl) ester (PC-88A)/<Emphasis Type="Italic">n</Emphasis>-dodecane

This paper describes the studies on the extraction of molybdenum (VI) from aqueous nitric acid medium by (2-ethylhexyl) phosphonic acid, mono (2-ethylhexyl) ester (PC-88A). The extraction affecting parameters such as concentration of HNO₃ in aqueous feed, effect of concentration of extractants, effect of diluents, and molybdenum concentration in the aqueous phase are investigated to optimize the extraction conditions for the quantitative separation of molybdenum from nitric acid medium. With increase of HNO₃ concentration in aqueous phase, percentage extraction was found to be decreased in all the cases. Percentage extraction of molybdenum increases with increase in PC-88A concentration till the 0.15 M of PC88A, and after that it becomes constant. Kerosene and n-dodecane was found to be most suitable diluents. Among the various strippants used 0.2 M (w/v) solution of Na₂CO₃ and 0.2 M (w/v) solution (NH₄)₂CO₃ are found to be the equally suitable for stripping of molybdenum from the loaded organic phase. The stripping of molybdenum from loaded organic layer by various reagents followed the order: (NH₄)₂CO₃ >Na₂CO₃ >0.1 M sodium salt of EDTA >2 M NaOH >8 M HNO₃. The optimized process conditions are employed to extract molybdenum (VI) from actual Davies–Gray waste as well as from diluted high level waste generated in the purex stream. More than 94% Mo(VI) was extracted from radioanalytical as well as from high level waste of purex process and quantitative recovery was achieved in both the cases when 0.2 M sodium carbonate was used as stripping agent.     

Voltammetric study on the mechanism of ion transfer caused by weak acids in the bilayer lipid membrane

The mechanism has been investigated by cyclic voltammetry for the ion transfer from one aqueous phase (W1) to another (W2) across a bilayer lipid membrane (BLM) in the presence of a typical uncoupler, carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP). Voltammograms for the ion transfer were in steady-state and showed rotated sigmoidal and symmetrical shape about the origin (0 V, 0 A). The magnitude of the ion transfer current at a given applied potential increased linearly with the concentration of FCCP in W2 up to 10⁻⁶ M and then became saturated. The ion transfer current also showed a bell-type dependence on pH centered around pH ≅ pK_a + 1, K_a being the dissociation constant of FCCP in aqueous phase. These properties have been well explained by our proposed model that the ion transfer current is attributable to the transfers of H⁺ and Na⁺ distributed in BLM. The hydrophilic counter ions, H⁺ and Na⁺, compensate the negative charge of the dissociated FCCP in BLM. The current intensity is predominantly governed by the concentration and the ion mobility of the counter cations.     

Membrane Distillation and Related Operations—A Review

Abstract

Membrane contactors represent an emerging technology in which the membrane is used as a tool for inter phase mass transfer operations: the membrane does not act as a selective barrier, but the separation is based on the phase equilibrium. In principle, all traditional stripping, scrubbing, absorption, evaporation, distillation, crystallization, emulsification, liquid‐liquid extraction, and mass transfer catalysis processes can be carried out according to this configuration. This review, specifically addressed to membrane distillation (MD), osmotic distillation (OD), and membrane crystallization (MCr), illustrates the fundamental concepts related to heat and mass transport phenomena through microporous membranes, appropriate membrane properties, and module design criteria. The most significant applications of these novel membrane operations, concerning pure/fresh water production, wastewater treatment, concentration of agro food solutions, and concentration/crystallization of organic and biological solutions, are also presented and discussed.     

Gas permeability of combined membrane systems with mobile liquid carrier

Gas transfer in a membrane system called a selective membrane valve (SMV) is studied. The SMV is a system consisting of two mobile gas phases, one mobile liquid phase, and two membranes acting as interfaces between gas and liquid. Such a membrane system has supplementary variable parameters and is designated for the separation of multicomponent gas mixtures. System permeability for individual gases (CO₂, O₂, and H₂) and its dependence on a flow rate of a liquid phase are studied. Time dependences of the non-steady state transfer of CO₂ through the immobile layer of chemisorbent (aqueous K₂CO₃ solution) at its different concentrations are studied for the first time. Two theoretical models are developed: the model of gas transfer through a selective membrane valve system with a mobile liquid absorbent (in the absence of chemical interaction) and the model of a non-steady-state transfer of CO₂ through the immobile layer of aqueous potassium carbonate solution. The first model makes it possible to determine gas-to-liquid diffusion coefficients; the second model permits us to plot kinetic permeability curves and to calculate system permeability with allowance for the CO₂ transfer accompanied by reversible chemical reaction with the carrier. The model dependences agree well with the experimental data.     

The effect of the physical properties of the liquid phase on the gas-liquid mass transfer coefficient in two- and three-phase agitated systems

The results of studies concerning two- and three-phase systems in an agitated vessel are presented. The aim of our research was to investigate the effect of the physical properties of the liquid phase on the value of the volumetric gas-liquid mass transfer coefficient in mechanically agitated gas-liquid and gas-solid-liquid systems. Our experimental studies were conducted in a vessel with an internal diameter of 0.288 m. The flat bottom vessel, equipped with four baffles, was filled with liquid up to a height equal to the inner diameter. The liquid volume was 0.02 m³. Three high-speed impellers of a diameter equal to 0.33 of the vessel diameter were used: Rushton turbine (RT), Smith turbine (CD 6), or A 315 impeller. The measurements were carried out in coalescing and non-coalescing systems. Distilled water and aqueous solutions of an electrolyte (sodium chloride) of two different concentrations were used as the liquid phase. The gas phase was air. In the three-phase system, particles of sea sand were used as solid phase. The measurements were conducted at five different gas-flow rates and three particle loadings. Volumetric gas-liquid mass transfer coefficients were measured using the dynamic method. The presence and concentration of an electrolyte strongly affected the value of the gas-liquid mass transfer coefficient in both two- and three-phase systems. For all agitators used, significantly higher k _l a coefficient values were obtained in the 0.4 kmol m⁻³ and 0.8 kmol m⁻³ aqueous NaCl solutions compared with the data for a coalescing system (with distilled water as the liquid phase). The k _l a coefficient did not exhibit a linear relationship with the electrolyte concentration. An increase in the sodium chloride concentration from 0.4 kmol m⁻³ to 0.8 kmol m⁻³ caused a considerable decrease in the volumetric mass transfer coefficient in both the two-phase and three-phase systems. It was concluded that the mass transfer processes improved at a certain concentration of ions; however, above this concentration no further increase in k _l a could be achieved.     

协同萃取液膜体系从Li+、Na+、K+混合溶液中提取Li+

从卤水、海水中提取Li是目前较为活跃的研究课题。用液膜法从Li~+、Na~+、K~+混合溶液中分离Li~+的报道很少。协同效应在乳状液型液膜中的应用还未见报道。本文采用噻吩甲酰三氟丙酮(HTTA)和磷酸三丁酯(TBP)作为混合载体的液膜体系,快速、高效地从Li~+、Na~+、K~+的混合溶液中分离、浓缩Li~+,为从卤水、海水中提取Li~+提供了重要的依据。     

Dependence of primary and secondary emulsion formation on the concentration of TBP,HNO3 and additives

Model studies on TBP—diluent—aqueous HNO₃ extraction systems were performed to establish the mechanism of emulsyfying during the reprocessing of spent reactor fuel with mixtures of TBP solutions. The systems of interest were emulsified under fixed conditions. The rate of separation of the primary emulsion as well as the turbidity of each phase were determined. The experiments were performed on mixtures of pure components of the extraction systems. Emulsion stability was investigated in terms of the influence of such factors as main products of TBP decay, the type of diluents, HNO₃ concentration and concentration of TBP in different diluents.     

Transport of99mTc across TBP-kerosene oil supported liquid membranes

Transport of^99mTc across tri-n-butylphosphate (TBP) kerosene oil supported liquid membranes (SLM) has been studied under various conditions. Presence of dichromate ions helps avoid activity scavenging effects. Concentration increase of TBP, the complexing carrier used in the present study has a positive effect on flux (J) and permeability (P) of these ions, as up to 2.87M there is an increase in J and P values. HCl concentration in the feed solution increases J and P with their maximum values at 2.5–3.0M HCl in the feed. Above this concentration there is a decrease in flux and permeability of^99mTc(VII) ions. The given ions are stripped with LiCl or NaCl solutions but more with NaOH. The optimum conditions of transport of the given ions are 2.5M HCl concentration in the feed, 2.87M TBP concentration in the membrane and 1M NaOH concentration in the strip solution. Equations have been developed to indicate the relation between flux, J, viscosity, of TBP in organic membrane phase, temperature, T, [H⁺], in the aqueous feed solutions and Tc ion concentration in the feed solution. Based on P, the values determined from liquid membrane experiments, the quantitative flux values of Tc(VII) ions were also determined as a function of TBP concentration in the membranes, and HCl and Tc concentration in the feed solution using the given equations. This experimental technique provides quantitative results from trace level activity transfer experiments.     

Extraction of cadmium from aqueous solutions by emulsion liquid membrane (ELM) using three different carriers dissolved in a 70:30 ratio of sunflower oil to kerosene

This study explores the use of novel green emulation liquid membranes (GELMs) for the simultaneous extraction and stripping of Cd (II) from aqueous solutions. A solute is transported through the membrane due to the presence of the carrier and then concentrated in the internal phase. Soybean, sunflower, corn, and canola oils were used to form green substitutes to petroleum-based organic diluents for use as GELMs. Bis-(2-ethylhexyl) phosphate (D2EHPA), tri-butyl- phosphate (TBP), and trioctylamine (TOA) were the extractants, span 80 was the emulsifier, and HCl or H₂SO₄ was used as the stripping agent. The best conditions for maximum extraction efficiency (98.68%), stripping efficiency (97.14%), and lowest membrane breakage (0.9%) were achieved using a mixture of sunflower oil and kerosene in the ratio of 70:30. The other optimum values of the variables were: 2% (v/v) Span 80, 10 min emulsification time, 12700 rpm emulsification speed, 400 rpm of agitation speed, 5% (v/v) D2EHPA, an external phase pH was 3.5, an internal phase of 0.25 M HCl, and 5:1 of the treat ratio (external phase to emulsion) at 10 min contact time. The synthesized membrane was reused eight times, with approximately the same efficiency and no significant breakage during the first seven cycles.     

The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid–liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]) and tri-sodium citrate (Na₃Cit) are taken. The apparent molar volume of transfer of [C₄mim][Br] from water to aqueous solutions of Na₃Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C₄mim][Br] from water to aqueous solutions of Na₃Cit have negative values. The effects of temperature and the addition of Na₃Cit and [C₄mim][Br] on the liquid–liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na₃Cit triggers a salting-out effect, leading to significant upward shifts of the liquid–liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of entropy and enthalpy are the driving forces for biphasic formation.     

Uphill transport of uranium across a liquid membrane

A liquid membrane was prepared by entrapping tributyl phosphate (TBP) in a cellulose triacetate (TAC) membrane matrix. The membrane was used to separate two aqueous solutions, one acidic and the other alkaline, which were saturated with TBP to prevent its loss from the membrane. Uphill transport of uranium was achieved with the TBP liquid membrane. Both solutions containing TBP were stirred magnetically. When the initial concentration of uranium in the two solutions was 3.5 mM, more than 50% of the uranium contained in the acidic solution was transported to the alkaline solution across the liquid membrane within 5 h. A transport mechanism is described in which the membrane-bound TBP acts as a mobile carrier for uranium.     

Extraction and stripping study of strontium ions across D2EHPA-TBP-kerosene oil based supported liquid membranes

A Sr ion transport study across D2EHPA-TBP kerosene oil based liquid membranes supported on microporous polypropylene film has been performed. The parameters studied were the effect of di(2-ethylhexyl)phosphoric acid (D2EHPA) and TBP concentration variation in the membrane liquid, HNO₃ concentration variation in the stripping phase and citric acid concentration variation in the feed solution. The optimum conditions of transport are 0.3 mol/dm³ D2EHPA, 0.1 mol/dm³ TBP, 0.01 mol/dm³ citric acid in feed and 2 mol/dm³ HNO₃ in the stripping phase. The mechanism of transport observed is counter-ion coupled transport. The coupling ions are protons. The maximum flux for Sr ion transport observed is 5.33·10^–5 mol·m^–2·s^–1 and maximum permeability under optimum conditions observed is 8.08·10^–11 m^–2·s^–1.