Liquid Membrane Permeation Research Articles

Experimental studies on removal of arsenites from industrial effluents using tridodecylamine supported liquid membrane.

In this article, we report the efficient removal of arsenic in the form of arsenite (As(III)) from an aqueous solution which was applied on the industrial effluents. A flat-sheet polypropylene-supported liquid membrane (SLM) was clamped between the feed phase and strip phase in a liquid membrane permeator setup using tridodecylamine (TDDA) as carrier for extraction of As(III). We have optimized the reaction in changing different parameters such as metal, acid concentration in feed phase, strip phase concentration, and carrier concentration for the maximum As(III) transport through the SLM. The flux value, time of extraction, the stoichiometry of the complex formed, and membrane stability were also investigated. As a result of different experiments performed, we find the best conditions of 0.1mol/L of TDDA, 1.0mol/L of HCl in feed phase at optimum pH1, and 1.0mol/L of NaOH in stripping phase for the maximum As(III) removal. The optimized reaction was utilized on effluent collected from different industries. During repeated set of experiments on a single polypropylene membrane, it was found that it could withstand five consecutive experiments. Moreover, as high as 93% of extraction efficiency was achieved in 180min.

Reactive Extraction of Lactic Acid, Formic Acid and Acetic Acid from Aqueous Solutions with Tri-n-octylamine/1-Octanol/n-Undecane

The present work develops the basics for the isolation of lactic acid, acetic acid and formic acid from a single as well as a mixed feed stream, as is present, for example, in fermentation broth for lactic acid production. Modelling of the phase equilibria data is performed using the law of mass action and shows that the acids are extracted according to their pka value, where formic acid is preferably extracted in comparison to lactic and acetic acid. Back-extraction was performed by 1 M NaHCO3 solution and shows the same tendency regarding the pka value. Based on lactic acid, the solvent phase composition, consisting of tri-n-octylamine/1-octanol/n-undecane, was optimized in terms of the distribution coefficient. The data clearly indicate that, compared to physical extraction, mass transfer can be massively enhanced by reactive extraction. With increasing tri-n-octylamine and 1-octanol concentration, the equilibrium constant increases. However, even when mass transfer increases, tri-n-octylamine concentrations above 40 wt%, lead to third phase formation, which needs to be prevented for technical application. The presented data are the basis for the transfer to liquid membrane permeation, which enables the handling of emulsion tending systems.

Emulsion Prevention with Supported Liquid Membrane Permeation

AbstractThe urge to achieve climate protection goals and a more prevalent interest in finding alternatives to fossil fuel‐based products focus attention increasingly on cascade raw material utilization, respectively, to intensify commercial production processes. The present project provides a study on the combination of liquid‐liquid extraction and esterification using the system acetic acid/octanol and 4‐dodecylbenzenesulfonic acid as catalyst. The surfactant 4‐dodecylbenzenesulfonic acid causes emulsification during extraction, but emulsification was successfully avoided by using supported liquid membrane permeation equipment.

Recovery of Fe and Mn from aqueous solution with solvent extraction and liquid membrane permeation using ionic liquids

Recovery of Fe and Mn from aqueous solution with solvent extraction and liquid membrane permeation using ionic liquids

Liquid Membrane Permeation with Supported Liquid Membranes and their Application in Li-ion Battery Recycling

A study of liquid membrane permeation with supported flat sheet membranes was performed. The goal of the project was to improve the stability and accuracy of supported liquid membranes (SLM) by avoiding short circuiting of phases with technical measures. Mass transfer and stability tests were carried out with the test system Zn2+|HDEHPA|H+. The effect of operation conditions on mass transfer and accumulation of Zn2+ in the stripping phase was investigated. A process for the recycling of Li-ion batteries including two SLM separation stages was developed. Experimental findings confirmed the feasibility of this process, yielding high purity streams of aqueous copper, cobalt, and lithium solutions.

Augmenting Microbial Fuel Cell power by coupling with Supported Liquid Membrane permeation for zinc recovery

Simultaneous removal of organic and zinc contamination in parallel effluent streams using a Microbial Fuel Cell (MFC) would deliver a means of reducing environmental pollution whilst also recovering energy. A Microbial Fuel Cell system has been integrated with Supported Liquid Membrane (SLM) technology to simultaneously treat organic- and heavy metal containing wastewaters. The MFC anode was fed with synthetic wastewater containing 10 mM acetate, the MFC cathode chambers were fed with 400 mg L−1 Zn2+ and this then acted as a feed phase for SLM extraction. The MFC/SLM combination produces a synergistic effect which enhances the power performance of the MFC significantly; 0.233 mW compared to 0.094 mW in the control. It is shown that the 165 ± 7 mV difference between the MFC/SLM system and the MFC control is attributable to the lower cathode pH in the integrated system experiment, the consequent lower activation overpotential and higher oxygen reduction potential. The change in the substrate removal efficiency and Coulombic Efficiency (CE) compared to controls is small. Apart from the electrolyte conductivity, the conductivities of the bipolar and liquid membrane were also found to increase during operation. The diffusion coefficient of Zn2+ through the liquid membrane in the MFC/SLM (4.26*10−10 m2 s−1) is comparable to the SLM control (5.41*10−10 m2 s−1). The system demonstrates that within 72 h, 93 ± 4% of the zinc ions are removed from the feed phase, hence the Zn2+ removal rate is not significantly affected and is comparable to the SLM control (96 ± 1%), while MFC power output is significantly increased.

Enhancement of Permeation Rate of Nitrogen Heterocyclic Compounds for Emulsion Liquid Membrane Separation of Coal Tar Absorption Oil

This study investigates the liquid–liquid equilibrium measured between coal tar absorption oil and aqueous solution of methanol, ethylene glycol, diethylene glycol, triethylene glycol or 1,3-butandiol, which was expected to increase the distribution coefficients of the nitrogen heterocyclic compounds in the coal tar absorption oil. The distribution coefficients of the nitrogen heterocyclic and homocyclic compounds are found to be larger with the aqueous solution of each selected compound than those with water. The distribution coefficients of the nitrogen heterocyclic compounds are found to be higher than those of the homocyclic compounds. For the emulsion liquid membrane permeation, the aqueous solutions of the organic compounds are used as the membrane solutions. The nitrogen heterocyclic compounds selectively permeated with any membrane solution, and the permeation rates of the components in the absorption oil are found to be enhanced relative to those without additive in the membrane solution. The overall volumetric permeation coefficients increased as the distribution coefficients and the effects of the organic compounds in the membrane solution used in the present study.

New Developments in Liquid Membrane Permeation with Support Layers

AbstractIn einer Zeit steigender Rohstoffpreise und Rohstoffverknappung rücken Themen wie das Recycling von Schwermetallen in das Interesse der Öffentlichkeit. Die technologische Entwicklung der Flüssigmembranpermeation mit gestützten Membranen ist eine potenzielle Basis, um ein effizienteres Schwermetallrecycling umzusetzen. Verfahrenstechnische Fortschritte für die industrielle Umsetzung der Flüssigmembranpermeation mit gestützten Membranen werden erläutert.

Liquid Membrane Permeation of Nitrogen Heterocyclic Compounds Contained in Model Coal Tar Fraction

We investigated the separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction comprising four kinds of NHC [indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)], three kinds of bicyclic aromatic compound (BAC) [1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN) mixture with ten structural isomers (DMNs; regarded as one component)], biphenyl (Bp) and phenyl ether (Pe) by liquid membrane permeation (LMP). A batch-stirred tank was used as the permeation unit. An aqueous solution of saponin and n-hexane were used as the liquid membrane and the outer oil phase, respectively. Yield and selectivity of individual NHC was much larger than that of BAC, Bp and Pe. Increasing the initial mass fraction of the saponin to the membrane solution () and the initial volume fraction of O/W emulsion to total liquid in a stirred tank () resulted in deteriorating the yield of individual NHC, but increasing the stirring speed (N) resulted in improving the yield of each NHC. With increasing , the selectivity of each NHC based on DMNs increased. Increasing and N resulted in decreasing the selectivity of individual NHC based on DMNs. At an experimental condition fixed, the sequence of the yield and selectivity in reference to DMNs for each NHC was Q > Qu = iQ > In. Furthermore, we compared LPM method with methanol extraction method in view of the separation efficiency (yield, selectivity) of NHC.

Comparison of solvent extraction and supported liquid membrane permeation using an ionic liquid for concentrating penicillin G

Room temperature ionic liquids are emerging as alternative solvents for volatile organic compounds conventionally used in liquid–liquid extraction and liquid membrane separation. In this study, imidazolium-based ionic liquids, the hexafluorophosphates of 1- n-butyl-, 1- n-hexyl- and 1 -n-octyl-3-methyl imidazolium, and trioctylmethylammonium chloride (TOMAC) were used as ionic liquids. First the distribution coefficient of penicillin G between the buffer solution and ionic liquids was measured. Although imidazolium-based ionic liquids can extract penicillin G from the buffer aqueous solution, the extent was much lower than using butyl acetate, the conventional organic solvent. While the distribution ratio with TOMAC was comparable to butyl acetate, it was difficult to strip penicillin G from the TOMAC phase. Therefore, ionic liquids were applied to the supported liquid membrane system. Penicillin G permeated through the supported liquid membrane with imidazolium-based ionic liquids but uphill transport driven by pH difference was not observed. Uphill transport was achieved by using TOMAC as a membrane solution and chloride concentration difference as a driving force of permeation.

Modeling CO 2-facilitated transport across a diethanolamine liquid membrane

We compared experimental and model data for the facilitated transport of CO 2 from a CO 2–air mixture across an aqueous solution of diethanolamine (DEA) via a hollow fiber, contained liquid membrane (HFCLM) permeator. A two-step carbamate formation model was devised to analyze the data instead of the one-step mechanism used by previous investigators. The effects of DEA concentration, liquid membrane thickness and feed CO 2 concentration were also studied. With a 20% (wt) DEA liquid membrane and feed of 15% CO 2 in CO 2–air mixture at atmosphere pressure, the permeance reached 1.51E−8 mol/m 2 s Pa with a CO 2/N 2 selectivity of 115. Model predictions compared well with the experimental results at CO 2 concentrations of industrial importance. Short-term stability of the HFCLM permeator performance was examined. The system was stable during 5-days of testing.

Separation of Valuable Bicyclic Aromatic Components from Light Cycle Oil by an Emulsion Liquid Membrane

Emulsion liquid membrane permeation was used to separate bicyclic aromatic components [the naphthalene (NA) group components with carbon number 10–12] from light cycle oil (LCO). A batch‐stirred tank was used as a permeation unit. An aqueous solution of dimethylsulfoxide (DMSO) and saponin and n‐hexane were used as the liquid membrane and the outer oil phase, respectively. The smaller the carbon number of the NA group component, the higher were the permeation rate and selectivity in reference to a paraffin component [n‐nonane (NO)]. The larger the differences of carbon number among the NA group components with a different carbon number, the easier was the separation. The selectivity of aromatic components with the same carbon number was 1, so the separation between isomer components was difficult. Increasing the concentration of the permeation promoter (DMSO) into the liquid membrane and the stirring speed enhanced the permeability of the NA group components, yet reduced the selectivity. As the volume ratio of the solvent/(O/W) emulsion was increased, the permeability and selectivity of the NA group components were increased.

Permeation and concentration of compactin by a liquid membrane technique

A liquid membrane technique proved to be a possible method for the recovery process of compactin (ML-236B), a highly effective pharmaceutical compound for the treatment of hyperlipidemia, from its dilute aqueous solution. The kinetics and the mechanism for the transport process were discussed, and the effects of the operating parameters on the liquid membrane permeation could be quantitatively demonstrated. The distribution equilibrium of compactin was measured between the aqueous and the oil phases, in which toluene and mesitylene (1,3,5-trimethylbenzene) containing di- n-octylamine, a complexing agent, were used as the oil phase. The dissociation constant, the distribution coefficients and the reaction equilibrium constants were determined experimentally. A simple transport model was proposed that compactin molecules should permeate through two pathways: the physical diffusional permeation and the ion-pair complex permeation. Supported liquid membrane (SLM) experiments were conducted by adjusting pH values in the aqueous phases and the carrier concentration, and the individual mass transfer coefficients of the species were evaluated according to the proposed model. The overall mass transfer resistance was expressed as the sum of the local resistances in feed, membrane and stripping phases. With the increase of the carrier concentration, the resistance in the membrane phase became less important and the overall transfer rate was controlled by the diffusion in the aqueous layer, implying that an excessive carrier would be no longer effective. The work performed provides us the suggestion for setting the reasonable carrier concentration for the liquid membrane system concerned.

Extraction of strontium ion from sea water by contained liquid membrane permeator

To develop a liquid membrane permeator that extracts strontium ion from sea water effectively and continuously, we investigated the extraction of strontium ion from artificial and natural sea water in a contained liquid membrane permeator. The permeator consists of a liquid membrane and two cells for aqueous solutions. The liquid membrane containing D2EHPA(di-2-ethylhexyl-phosphoric acid) and DCH18C6(dicyclohexano-18-crown-6) is trapped between two hydrophobic microporous polyethylene films and separates sea water and the 0.2 M H2SO4 aqueous stripping solution. The effects of various operating parameters on the extraction of strontium ion were experimentally examined. The extractant of DCH18C6 -D2EHPA mixture in kerosene had a synergistic effect on the extraction of strontium ion. The permeator extracted strontium ion from sea water effectively and continuously with long membrane lifetime.

Recovery of Dimethylnaphthalene Isomers from Light Cycle Oil by O/W/O Emulsion Liquid Membrane Process.

This paper simulates a process for recovering dimethylnaphthalene isomers (DMN) from light cycle oil (LCO), a by-product in cracked gasoline manufacture. The process involves a multistage emulsion liquid membrane permeator for separating aromatics from paraffins in LCO and four distillation towers of which two towers are used to recover solvent from raffinate and permeate and the others are used to separate DMN from other aromatics in permeate. Stirred vessels are employed as contactors. Prior to the simulation, a series of continuous experiments on emulsion liquid membrane permeation were conducted to collect permeation coefficient data. The permeation coefficient data obtained was thereafter used to develop an empirical correlation needed for the simulation. During the simulation, the effects of permeator variables on the energy demands of the distillation towers and on the yield of DMN were investigated at a fixed DMN concentration in the product. The permeator variables studied included solvent-to-feed ratio, stirring rate, number of stages, permeator reflux ratio, and stage volume, as well as the kinds of solvents. DMN yield increased with stirring rate, number of stages, and stage volume, decreasing with permeator reflux ratio, and not affected significantly with solvent-to-feed ratio. The lighter the solvent, the lower were the energy demand and DMN yield. In the conditions of the study, about 80% of DMN in LCO could be recovered. Most of the energy consumed was used to recover the solvent. A quick analysis showed that the energy demands might be met by utilizing the raffinate obtained.

Isomer separation by a hollow fiber contained liquid membrane permeator

Continuous separation of different isomeric mixtures of organic compounds has been studied in laboratory scale by means of a hollow fiber contained liquid membrane permeator (HFCLMP). An aqueous liquid membrane based on cyclodextrin (CD) was successfully employed to separate two different typical equimolar isomeric mixtures present in an organic feed solution; the permeate phase employed the same organic solvent without any of the isomers. The first mixture was that of the structural isomers p-nitroaniline ( p-NA) and o-nitroaniline ( o-NA) in 80% n-octanol – 20% n-heptane used as the organic solvent. For a once-through operation, the selectivity for p-NA over o-NA was found to be almost 5 (∼4.6) at a concentration of 0.7 M β-CD; a 50–50 feed mixture was treated to yield a permeate stream mixture of 82–18 in favor of p-NA. The performance was stable. The second mixture employed stereoisomers, cis-stilbene and trans-stilbene, using liquid membranes having 0.02–0.2 M β-CD concentration. The maximum selectivity of cis-stilbene over trans-stilbene achieved in this separation was always less than 2, whereas pure water was selective for trans-stilbene over cis-stilbene.

Separation of Hydrocarbons by Liquid Surfactant Membrane with a Batch Stirred Vessel

Extraction experiments on liquid membrane permeation were conducted in a batch stirred vessel to separate aromatics from an aromatics-nonaromatics binary mixture as an inner oil phase in the emulsion. The investigations were conducted under various material systems (hydrocarbon feeds, aqueous membrane phases) and the mass transfer coefficient in the emulsion (dispersed phase) was measured. Independently of the system of hydrocarbon feed and aqueous membrane solution, the mass transfer coefficient of the dispersed phase could be correlated with the dimensionless stirring time and the solubility of the aqueous membrane phase. The batchwise results agree fairly well with previous results reported for continuous operation.

The Effect of Sodium Dodecyl Sulfate and M-α-Cyclodextrin on the Solubility and Partitioning of Xylenes in Aqueous Solutions

The solubility and the partitioning ofp- ando-xylene in aqueous solutions containing M-α-CD, a partially methylated α-cyclodextrin, and the anionic surfactant sodium dodecyl sulfate (SDS) were studied by extraction experiments to evaluate the applicability of liquid membrane permeation for the separation of xylene isomeres. Experiments were carried out with the pure xylenes and 1:1 mixtures ofo- andp-xylene. The interactions of M-α-CD and SDS and their effects on the solubility and partitioning of xylenes were investigated. M-α-CD was found to form 1:1 complexes withp- ando-xylene. Formation constants were determined as 141M−1forp-xylene and 48M−1foro-xylene, respectively, which are higher than those reported with nonmethylated α-CD. This can be explained by additional hydrophobic interactions with the methyl groups of the cyclodextrin. In contrast to the solubility in CD solutions,o-xylene was found to be more soluble thanp-xylene in aqueous solutions of SDS. At constant concentrations of M-α-CD the addition of SDS led to the displacement ofp-xylene from the cyclodextrin cavity, which resulted in a decrease in its solubility. This decrease lasted until micelles were formed. Due to the solubilization ofp-xylene in the micelles, further addition of SDS resulted in a linear increase in the solubility ofp-xylene. However, at constant CD concentrations the solubility ofo-xylene increased with the addition of SDS until about 5 mmol/liter SDS. This might be attributed to the formation of a ternary complex consisting of cyclodextrin,o-xylene, and SDS. At SDS concentrations greater than 5 mmol/liter, the solubility ofo-xylene decreased, which was probably due to the formation of a more stable complex between SDS and M-α-CD. An addition of SDS beyond a critical concentration (CMC), where micelles are formed, resulted again in a linear increase ofo-xylene solubility. The CMC was found to depend linearly on the concentration of M-α-CD in aqueous solution. Extraction experiments with a 1:1 mixture ofo- andp-xylene showed that the two xylenes and SDS are in competition for M-α-CD. Since surfactants are always present when using emulsion liquid membranes and due to the complex interactions between SDS, the xylenes, and M-α-CD, no sufficient selectivity for the separation of the xylenes by liquid membrane permeation could be achieved.

Recovery of heavy metals by a combination of two processes: Cementation and liquid membrane permeation

A Zinc Plant effluent was treated by applying two processes: Cementation and Liquid Membrane Permeation. The effluent was a synthetic aqueous solution with 1700 ppm of Zn, 600 ppm of Cd and 100 ppm of Cu. Due to the high contents of Cd and Cu, it was proposed to apply Cementation with zinc powder before applying Emulsion Liquid Membranes in order to remove these metals. The influence of several variables on zinc permeation was studied. The use of nonylphenol in the membrane was tested. The presence of this reagent promotes the stripping step but a concentration higher than 1 % wt. is not beneficial because promotes the occurrence of osmosis and occlusion.

A modified hollow fiber contained liquid membrane technique for gas separation at high pressures

The hollow fiber contained liquid membrane (HFCLM) permeation technique has been modified by using microporous fibers having a thin nonporous silicone coating to handle higher gas pressures. Separation of various CO 2-N 2 mixtures have been studied over a feed pressure range of 50–200 psig. Pure water and aqueous 20% diethanolamine (DEA) were used as a liquid membranes. Two modes of operation, conventional polymeric membrane and sweep gas mode, were investigated. Permeator conditions studied include liquid membrane pressure higher and lower than the feed pressure. The aqueos 20% DEA resulted in significantly higher overall CO 2 permeabilities and selectivity. A mathematical model was developed which included the pressure drop inside the fiber bores. Numerical simulations of the model describe the experimental results well.