Liquid Membrane System Research Articles

A study of zinc borne waste water treatment with dispersion supported liquid membrane

This paper based on a theoretical study of the supported liquid membrane separation technology, explores the appropriate liquid membrane separation system, makes a study on the Pb (II) transmission behavior in the PC-88A-kerosene-HCl dispersion supported liquid membrane system and reviews influence of the feed liquid pH value, volume ratio between the membrane liquid and analytic agent, HCI concentration during analytic phase and initial Pb (II) transmission concentration. The results show that the migration of Pb (II) is well completed for 190 min with the migration rate being up to 95% on the premise that the feed liquid pH is equal to 6.0, Pb (II) initial concentration of 3.0 × 10−3 mol/L, HCl concentration during the stripped and dispersed phase is 4.0 mol/L, volume ratio between the stripped liquid and organic phase is 40:160 and that of the conventional supported liquid membrane is only 72.4%. The dispersion supported liquid membrane is characterized by higher transmission efficiency, stable membrane system and long membrane service life. The procedure has provided accurate results with zinc borne waste water treatment.

Kinetic Model for Solute Diffusion in Liquid Membrane Systems

In this study, a mathematical model for the kinetics of solute transport in liquid membrane systems (LMSs) has been formulated. This model merged the mechanisms of consecutive and reversible processes with a “semi-derived” diffusion expression, resulting in equations that describe solute concentrations in the three sections (donor, acceptor and membrane). These equations have been refined into linear forms, which are satisfying in the special conditions for simplification obtaining the important kinetic constants of the process experimentally.

A study on phenol migration by coupling the liquid membrane in the ionic liquid

The environmental pollution of phenol is primarily taken as a result of wastewater discharged from some special chemical plants. It is the common pollutant to be controlled in industrial wastewater, and therefore, how to effectively minimize its environmental pollution by the phenolic pollutants treatment and recovery becomes an important subject. This paper aims to make a study on the support liquid membrane separation from phenolic wastewater in hydrated environment. The process of separation is conducted with hydrophobic ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate [BMIM]PF6 prepared by the microwave synthesis method based on fundamental solvent extraction research and applied to the inner coupling liquid membrane system. as the purpose is to migrate phenol in the simulated wastewater and survey the temperature, stirring speed, feed liquid phase acidity, initial concentration and NaOH concentration in the stripping phase influence on the phenol migration to obtain the preferred condition for migration. The said condition is as follows: The temperature of 300 K, the stirring speed ranging from 350 to 400 rpm, the feed liquid phase pH of 3.65, and NaOH concentration of 0.8 mol/L in the stripping phase. In the system, phenol is approximated to 100% in migration rate and the ionic liquid may be recycled for several times.

Performance of combined displacement ventilation and cooled ceiling liquid desiccant membrane system in Beirut climate

The performance of the chilled ceiling (CC) displacement ventilation (DV) systems is constrained by latent load removal capacity and cost of supply air dehumidification to prevent condensation on the ceiling. In this study, a liquid desiccant dehumidification membrane cycle (LDMC) is mathematically modelled to replace the CC and remove directly latent and sensible load from indoor space through the membrane. The desiccant system is coupled with the DV system. An optimized operational strategy is adopted while allowing ceiling temperature to drop to lower values than conventional CC/DV. The optimized LDMC-C/DV system was implemented in an office space in Beirut climate. It was found that decreasing the membrane liquid desiccant temperature resulted in a significant decrease in the total cooling energy of the system, while increasing the solar heating energy of the desiccant regeneration. At optimal set points, a decrease of 49% in energy consumption was observed compared to the conventional CC/DV system.

A supported liquid membrane system for the selective recovery of rare earth elements from neodymium-based permanent magnets

ABSTRACTThe rare earth elements (REEs) play a vital role in the development of green energy and high-tech industries. In order to meet the fast-growing demand and to ensure sufficient supply of the REEs, it is essential to develop an efficient REE recovery process from post-consumer REE-containing products. In this research effort, we have developed a supported liquid membrane system utilizing polymeric hollow fiber modules to extract REEs from neodymium-based magnets with neutral extractants such as tetraoctyl digylcol amide (TODGA). The effect of process variables such as REE concentration, molar concentration of acid, and membrane area on REE recovery was investigated. We have demonstrated the selective extraction and recovery of REEs such as Nd, Pr, and Dy without co-extraction of non-REEs from permanent NdFeB magnets through the supported liquid membrane system. The extracted REEs were then recovered by precipitation followed by the annealing step to obtain crystalline REE powders in nearly pure form. The recovered REE oxides were characterized by X-ray diffraction, scanning electron microscope coupled with energy-dispersive X-ray spectroscopy, and inductively coupled plasma–optical emission spectroscopy.

Extraction and membrane transport of lanthanides with dynameric constitutional framework carriers

Dynamic covalent polymers or dynamers, generated from reversibly interacting monomers, offer the possibility to generate molecular-controlled materials with addressable domains which are different from these of former monomers and based on structural relationships between the network components. Herein, constitutional dynamic frameworks of Jeffamine-type macromonomers cross-linked via trifunctional core centers have been used as a dynameric-electrolyte network in liquid and solid membrane systems for lanthanide recognition, extraction and transport. The transport is based on the partition ability of lanthanides (La+3, Lu+3, and Eu+3) within functional dynameric network bearing polyether and imine groups. Interestingly, the lanthanides are extracted and selectively transported through the membrane, only in the presence of constitutional cross-linked frameworks, while the former Jeffamine monomers have been shown high extraction yields, but any selectivity. This would be explained by the formation of molecularly addressable recognition “pockets” in which the recognition/diffusional selective percolation pathways might exist. It implies that such dynameric frameworks have high selectivity towards La+3, Lu+3 relative to Eu+3 that may be separated.

Kinetic Model for Solute Diffusion in Liquid Membrane Systems

In this study, a mathematical model for the kinetics of solute transport in liquid membrane systems (LMSs) has been formulated. This model merged the mechanisms of consecutive and reversible processes with a “semi-derived” diffusion expression, resulting in equations that describe solute concentrations in the three sections (donor, acceptor and membrane). These equations have been refined into linear forms, which are satisfying in the special conditions for simplification obtaining the important kinetic constants of the process experimentally.

Bulk Liquid Membrane Process for The Transport and Kinetics Study of Malachite Green From Textile Wastewater

A bulk liquid membrane (BLM) system contained Di (2-ethyl hexyl) phosphoric acid (D2EHPA) as an extractant was used for transport of malachite green (MG) dye from textile wastewater. D2EHPA present in n-hexane is an effective, efficient and highly selective carrier for the transport of MG dye through BLM. Maximum transport 88% was observed at 0.24M concentration of D2EHPA in the membrane phase and 7 moles concentration of acetic acid in the receiving phase after 300 min. The effect of parameters influencing the transport of MG dye such as pH and concentration of dye in the donor solution, extractant concentration in the membrane phase, nature of the organic solvent, the composition of receiving phase, stirring speed and kinetics parameter were elucidated. First order irreversible reaction kinetics k1 and k2 were applied for the transport of MG dye from aqueous phase BLM phase and BLM to acceptor phase. The accumulation of MG in BLM phase and the rate controlling step under different experimental conditions were also discussed. Finally, the proposed liquid membrane was effectively applied for MG dye transport from textile wastewater.

Studies on the macrocycle mediated transport of some metal cations through a bulk liquid membrane system using kryptofix 22

Studies on the macrocycle mediated transport of some metal cations through a bulk liquid membrane system using kryptofix 22

A new method for estimation of the overall mass transfer coefficient in pertraction

The pertraction of benzoic acid was studied in an agitated bulk liquid membrane system. The simultaneous effect of the operational parameters such as initial feed phase concentration (cf0), bulk liquid membrane volume (VLM) as well as a molecular descriptor (MD) which represent the organic solvent is discussed. The response surface methodology with a full factorial design and multiple linear regression analysis was applied for the description of the dependence of benzoic acid fluxes on selected parameters and descriptors.It was experimentally confirmed that the response surface methodology enables the determination of the parameter which can be considered as the apparent overall mass transfer coefficient dependent on the volume of the liquid membrane and the liquid membrane solvent in the studied system.It was additionally found that the extended linear regression models with two and/or three factor interaction terms describe over 99.5% of the total variance between the maximum output fluxes of benzoic acid and selected variables. To evaluate the prediction accuracy of the empirical regression models, the standard validation procedures were carried out. For example, the highest prediction accuracy (over 99.5%) was achieved in the case of the models involving three variables (cf0 and VLM parameters and 3D Wiener index (W3D)), and additionally, two factor interaction terms (cf0×VLM, cf0×W3D,VLM×W3D).Alternatively, similar models with comparable prediction accuracy but exploiting the squared Moriguchi octanol–water partition coefficient (MLOGP2) or reciprocal hyper-detour index (Rww) can be formulated. However, in this case, the models involves three factors interaction term (cf0×VLM×MD).

Magnetic nano-Fe3O4 stabilized Pickering emulsion liquid membrane for selective extraction and separation

Emulsion liquid membrane (ELM) is a fast, effective and highly selective method for chemical separation, extraction and water treatment. However, an effective and economic method for demulsification after extraction process without changing the oil phase chemistry is still a great challenge, which restricts the commercial application of ELM. Hereby, for the first time, we reported a W/O/W Pickering emulsion liquid membrane (PELM) system in which the internal water in oil emulsion can be simply demulsified by magnetic or centrifugation force without causing obvious change in oil phase chemistry. Practically, we selected 4-methoxyphenol as extracting target in this report, and its extraction efficiency of over 86% was achieved by using surface modified Fe3O4 nanoparticle as the emulsifier.

Experimental Study on Performance of Modified Hybrid Liquid Membrane Process for Removal of Cadmium from Wastewater

Liquid membrane processes have attracted many interests in recent years for removal of heavy metals such as cadmium from industrial wastewaters. In this study, a modified hybrid liquid membrane system is introduced. The setup is worked by applying the water-insoluble dioctyl phthalate as the organic solvent. N-octanol and tetra butyl ammonium bromide are added to the organic phase to increase the system efficiency. The effects of different parameters such as pHs of the feed and stripping phases, the complexing agent concentration, the organic film thickness, initial concentration of cadmium, and the carrier concentration on the cadmium removal are studied. The results demonstrate the increase in the removal rate and capacity comparing to those of previously studied hybrid liquid membrane system. An electrical potential is then applied to the hybrid liquid membrane system. The results show higher removal rate and capacity compared to the corresponded values in the system without applying electrical potential.

Recovery of Mercury Using a Trioctylphosphine Oxide-Based Supported Liquid Membrane System

Abstract Transport of mercury ions (Hg (II)), through a polypropylene (Celgard 2400) supported liquid membrane (SLM), employing trioctylphosphine oxide (TOPO) as carrier and toluene as a solvent, has been investigated. The work was conducted under different operating conditions with respect to feed pH and concentration, carrier concentration, and stripping phase concentration to explore optimum conditions for maximum extraction of Hg (II) ions; 0.2 mol/L was the optimum concentration of TOPO for recovery of mercury. Experiments were conducted in the cotransport mode using hydrazine as the stripping reagent. It was observed that extraction of mercury increased with increase in concentration of hydrazine up to 0.05 mol/L when stirred at 1,500 rpm. Extraction of mercury was about 90%, under optimum conditions in 3 h. The present SLM was found to be stable for about 50 h of use.

Simultaneous extraction and stripping of uranium ions via multi-dropped liquid membrane system

An investigation on the separation of U(VI) from aqueous solutions via a multi dropped liquid membrane (MDLM) and its model is presented. A new method that is more advantageous than other liquid membrane techniques is applied. Di(2-ethylhexyl) phosphoric acid was used as a highly selective carrier for the transport of U(VI) ions through the MDLM. Maximum percentages of U(VI) extraction and stripping achieved were 98.9 % using 1.459 × 10–3 M D2EHPA as the extractant, 1 M NH4HCO3 as the stripping solution. The influences of pH and temperature on donor and acceptor phases, the influence of carrier phase concentrations and membrane’s flow velocity were investigated. For the description of relationships of U(VI) concentration in particular phases with time, a model based on the assumption of consecutive first-order reactions was proposed. The kinetic parameters (k1, k2, Rmmax, tmax, Jdmax, Jamax) were calculated for the interface reactions assuming two consecutive, irreversible first-order reactions. The activation energy value was calculated as 10.2 kcal mol-1 for extraction. The value of calculated activation energy indicates that the process is chemically controlled by U(VI) ions. The experiments have demonstrated that D2EHPA derivative is a good carrier for U(VI) transport through MDLM in the study.

Selective separation of salbutamol enantiomers with simultaneously synergistic extraction and stripping method

Enantioselective separation of salbutamol enantiomers was carried out through the simultaneously synergistic extraction and stripping method with Ο,Ο-dibenzoyl-(2S,3S)-tartaric acid (+)-DBTA and di (2-ethylhexyl) phosphoric acid (D2EHPA) as chiral and non-chiral extractants, respectively. Chiral recognition mechanism of salbutamol enantiomers with (+)-DBTA was investigated using the Density Functional Theory (DFT) methods. The results showed that the chiral recognition in separation process was realized by the hydrogen-bond interaction. The binding energy of the complex resulting from (+)-DBTA and R-salbutamol was −86.14kJ/mol, which was higher than that of the complex resulting from (+)-DBTA and S-salbutamol. The synergistic extraction experiment was preliminarily performed and the maximum separation factor was up to 1.65. Enantioseparation of salbutamol was conducted in the hollow fiber supported liquid membrane process. Various operating conditions, including the feed phase concentration, the component of membrane phase, the flow rate, and the pH of stripping side, were investigated. The results showed that the mass transfer resistance mainly focused on the membrane phase. The synergistic effect in liquid membrane system was also discussed. When the ratio of chiral to achiral extractant was 1.0:0.6, the separation factor was up to 2.0 in the stripping phase.

Influences of Axial Mixing of Continuous Phase and Polydispersity of Emulsion Drops on Mass Transfer Performance in a Modified Rotating Disc Contactor for an Emulsion Liquid Membrane System

A mathematical model considering the effects of axial mixing of continuous phase and polydispersity of dispersed emulsion drops was developed to describe the mass transfer mechanism of an emulsion liquid membrane (ELM) in a modified rotating disc contactor (MRDC). The calculated results indicate that the axial mixing lowered the concentration gradient along the column, and the polydispersity caused the maldistribution of the interfacial area and the volume for the different sized drops, which also reduced the mass transfer performance. In order to evaluate the degree of the axial mixing and the polydispersity, the important variables affecting axial dispersion coefficient (EM), emulsion phase holdup (Φ), and drop size distribution (α and β) including rotating speed, flow ratio, total flow, surfactant concentration, and stirring paddle width were also studied. It was found that the standard deviation of the drop size (β) had same variation trend as the mean drop size (α). The increase in the rotating speed...

Selective Transport of Mercury(II) Ions across Supported Liquid Membrane with Thymine Derivative as Carrier

Abstract We describe a new highly selective supported liquid membrane (SLM) system made of a polypropylene flat sheet with a thymine derivative in kerosene as the carrier, for the selective transport of mercury ion. When the carrier existed in the membrane, only mercury ions were selectively transported. This SLM selectively separated mercury ions from a mixed solution of mercury and heavy metal ions. The hydrogen ion concentration in the receiving phase is a dominant factor in the mercury ion transport across the SLM.

Removal of acetic acid from simulated hemicellulosic hydrolysates by emulsion liquid membrane with organophosphorus extractants

Selective removal of acetic acid from simulated hemicellulosic hydrolysates containing xylose and sulfuric acid was attempted in a batch emulsion liquid membrane (ELM) system with organophosphorus extractants. Various experimental variables were used to develop a more energy-efficient ELM process. Total operation time of an ELM run with a very small quantity of trioctylphosphine oxide as the extractant was reduced to about a third of those required to attain almost the same extraction efficiency as obtained in previous ELM works without any extractant. Under specific conditions, acetic acid was selectively separated with a high degree of extraction and insignificant loss of xylose, and its purity and enrichment ratio in the stripping phase were higher than 92% and 6, respectively. Also, reused organic membrane solutions exhibited the extraction efficiency as high as fresh organic solutions did. These results showed that the current ELM process would be quite practical.

Ultrasound-assisted preparation of emulsion and its application in 1-naphthol wastewater treatment

A stable emulsion with NaOH as the inner phase, sorbitan monooleate (span80) as the surfactant, and kerosene, cyclohexane, n-heptane, methylbenzene or p-xylene as the organic membrane phase, was prepared successfully by a magnetic stirring apparatus at low stirring speed (720rev min−1) to make the pre-emulsion and then using the ultra-sonication devices. The separation efficiency in emulsion liquid membrane system to remove 1-naphthol was investigated. The parameters that affect the removal efficiency of 1-naphthol were studied systematically. At the optimal conditions, cyclohexane as the solvent phase, 2% NaOH as the inner phase, ultrasound time 5 minutes, the ratio of oil to inner phase 1:2, pH of feed phase without adjusted (pH = 6·4), contact time 15 minutes, ratio of emulsion to water 1:5, 1-naphthol removal can nearly reach 98% with a low level of 1·14% of emulsion leakage at 20 minutes.

Selective removal of zinc using tri-ethanolamine-based supported liquid membrane

This work is a comprehensive study on the selective removal of Zn (II) from aqueous solution using a flat-sheet polypropylene-supported liquid membrane system. Tri-ethanolamine (TEA) dissolved in cyclohexanone was used as a carrier for extraction of zinc ions through supported liquid membrane. Different parameters affecting the zinc ion transport were studied. The experiments were performed at various operating conditions such as metal and acid concentration in feed phase, strip phase concentration, and carrier concentration, to find the best set of parameters that would yield the maximum extraction. The extraction time, flux value, the stoichiometry of the complex formed, and membrane stability was also investigated. The experiments were performed in co-transport mode. The optimized conditions obtained for zinc ion transport are as follows: 2.30 × 10−4 mol/dm3 of Zn2+ ions and 1M of HCl in feed solution, 50% TEA in cyclohexanone in membrane phase, and 0.7M of NaOH in stripping phase. Under these optimum conditions, the membrane is stable for about 10 consecutive experiments. The extraction efficiency was found to be 87% in 120 min.