Supported Liquid Membrane Research Articles

Selective separation of tungsten from the model and industrial effluents through supported liquid membrane

In this study, a selective separation of tungsten W (VI) from a mixed salt solution was done through a liquid-membrane technology. The transport of W (VI) across the supported liquid membrane was also applied on real sample. Tertiary amine (Tri-n-dodecylamine) was used as an organic carrier and a supported liquid membrane of polypropylene separator (celgard 2400) was used in this experimental work. The selective separation of W (VI) was optimized by various parameters i.e., concentration of metal in feed, concentartion of stripping agent, type of stripping reagents, carrier concentration and pH effect. The extraction of W(VI) was maximized by the concentration of carrier up to 0.2 mol/dm3 diluted in n-hexane. The optimum concentration of sodium hydroxide was 0.2 mol/dm3 in the strip phase. The transport of tungsten increases by the increase of the pH of feed solution to basic from acidic up to the pH 8. At pH 8 in the feed phase, tri-n-dodecylamine efficiently extracted W (VI) from feed through anion exchange mechanism. The time duration for the transport of tungsten was 6 h at room temperature. The optimized reaction of W(VI) for the selective separation was applied on the scheelite ore with 93% recoved. The single membrane was used in all experiments, which confirmed the durability and stability of polypropylene membrane.

Separation of alkali metal cations by a supported liquid membrane (SLM) operating under electro dialysis (ED) conditions

This study demonstrates the effective separation of alkali metal cations using a Supported Liquid Membrane (SLM) containing lipophilic, negatively charged borate moieties, operating under electro dialysis conditions. The selectivity of the membrane is essentially based on differences in dehydration energy and mobility between ion species. The system favors the ion species with the largest crystal radius, despite its lower mobility. In mixtures of K+ and Na+, the SLM separates K+ from Na+ with a separation efficiency ranging from ~20% to 90%, depending on the feed solution composition. With solutions containing either K+ or Na+ and Li+, the K+/Na+ over Li+ separation efficiency is nearly 100%. Addition of 15-crown-5 derivative does not improve SLM behavior, but slows down the K+ current by approximately 30% whereas the Na+ current remains unaffected. As supported by simulations, the free K+ and Na+ ratio in the membrane (and with that the current ratio) is entirely defined by partitioning and the feed concentration ratio, regardless the presence of 15-crown-5. As a result, the current ratio of two ion species can be described exclusively in terms of their feed concentrations and crystal radii because the latter parameter defines both partitioning and mobility.

Supported liquid membranes based on deep eutectic solvents for gas separation processes

Deep eutectic mixtures (DES) have been proposed in the last years as viable and more sustainable solvents, in a myriad of applications. CO2 capture or adsorption is one of those possible applications, where DES can act as an alternative to the amine-based solvents that are currently being used in carbon capture and sequestration (CCS) processes. In this work, different choline chloride DES were prepared, and CO2 solubility and diffusivity coefficients were measured. The DES were immobilized in a PTFE porous support, and the pure gas permeability of 3 different gases (N2, CO2 and CH4) was assessed, as well as DES supported liquid membranes ideal selectivity. An enzyme that is able to convert CO2 into bicarbonate was also added to the DES and DES supported membranes, in order to increase the transport towards CO2. The tested DES show solubility values in line with the ones reported in literature for related DES family and ionic liquids. Solubility and diffusivity of CO2 showed the best results in the DES composed of choline chloride and urea, showing even higher values when the enzyme was dispersed. The supported liquid membranes show higher permeability towards CO2, especially in DES with choline chloride and urea. The membrane containing this DES also showed high selectivity for CO2/CH4, with values above the Robeson upper bound. This proves that DES supported membranes are a viable strategy for CO2 adsorption/sequestration and that the prepared membranes may have applications in gas separation processes, particularly in the separation of CO2 from CH4, as in the case of natural gas streams treatment or biogas.

Dispersion-free extraction of In(III) from HCl solutions using a supported liquid membrane containing the HA324H+Cl\u2212 ionic liquid as the carrier

By reaction of HCl and the tertiary amine HA324, an ionic liquid denoted HA324H+Cl− was generated and used in the transport of indium(III) from HCl solutions. Metal transport experiments were carried out with a supported liquid membrane, and several variables affecting the permeation of indium(III) across the membrane were tested: stirring speed, metal and acid concentrations in the feed solutions and the carrier concentration in the supported organic solution. The metal transport results were also compared with those obtained using different carriers in the solid support. A model that described indium(III) transport across the membrane was proposed, and the corresponding diffusional parameters were estimated.

Electromembrane extraction of chlorprothixene, haloperidol and risperidone from whole blood and urine

Separation of antipsychotic drugs from whole blood and urine is of great importance for clinic and forensic laboratories. In this work, chlorprothixene, haloperidol and risperidone representing the first and second generations of antipsychotic drugs were studied. Among them, chlorprothixene and risperidone were investigated for the first time by electromembrane extraction (EME). After the screening, 2-nitrophenyl octyl ether (NPOE) was used as the supported liquid membrane (SLM). The EME performance for spiked water (pH 2), whole blood and urine was tested and optimized individually. Using NPOE and 60 V, efficient EME was achieved from urine and whole blood with trifluoroacetic acid as the acceptor solution. The equilibrium time required for EME was dependent on the sample matrices. The steady-state of EME was reached in 30 min and 20 min for whole blood and urine, respectively. At steady-state, the EME recoveries of the targets from different sample matrices were satisfactory, and were in the range of 74%-100%. The proposed EME approach combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was evaluated using whole blood and urine. The obtained linearity was 1-200 ng mL-1, and the coefficient of determination (R2) was ≥ 0.9853 for haloperidol and ≥ 0.9936 for chlorprothixene and risperidone. The limit of detection (LOD) and accuracy for all the targets ranged from 0.2-0.6 ng mL-1 and 102%-110%, respectively, and the repeatability at low (1 ng mL-1), medium (10 ng mL-1) and high (200 ng mL-1) concentration was ≤ 12% (RSD). Finally, the validated approach was successfully used to determine chlorprothixene, risperidone and haloperidol in whole blood and urine from rats, which were treated with chlorprothixene, risperidone and haloperidol at low therapeutic dose, respectively.

Selective separation of cobalt and nickel using a stable supported ionic liquid membrane

The selective separation of cobalt from nickel is of major importance for the recovery of cobalt from primary or secondary sources, as well as for analytical purposes. In this paper, the extraction of cobalt from the mixtures was examined using a supported liquid membrane employing the undiluted hydrophobic ionic liquid, namely tri(hexyl)tetradecyl phosphonium chloride [P66614][Cl], as a carrier and polyvinylidene difluoride (PVDF) as a membrane material.In the preliminary study, the efficiency of this supported ionic liquid membrane (SILM) for the cobalt extraction was evaluated by conventional static mode sorption experiments. Up to 86% of cobalt can be recovered under optimal conditions (by contacting SILM with 9.8 cm2 in 5 mL of aqueous phase for 1 h at 100 rpm, with 9 mol·L−1 HCl in the aqueous phase).Next, metal ion transport through a flat sheet SILM was investigated with pure water as a receiving phase. Permeation coefficients values of 2.2 × 10−6 m·s−1 and 8.0 × 10−6 m·s−1 were obtained with a hydrophobic and a hydrophilic membrane, respectively. The SILM showed selectivity for cobalt over nickel with separation factors as high as 218. Membrane stability was proven to be excellent, since the same SILM was used three times without losses of performances.

Electromembrane extraction of barbiturates using tributyl phosphate as an efficient supported liquid membrane

In this fundamental work, tributyl phosphate (TBP) with zero hydrogen-bond acidity was for the first time discovered as an efficient supported liquid membrane (SLM) for EMEof acidic drugs (barbiturates) due to its high polarity-polarizability. This discovery indicated that strong dipole-dipole interaction induced by high polarity-polarizability played an important role for efficient EME of acidic drugs. In addition, three barbiturates were successfully extracted for the first time from human whole blood and urine samples by EME with recoveries up to 90%. Interestingly, efficient EME of barbiturates from biological samples required much lower extraction voltage than that from buffer samples. This was due to the significant contribution from LPME during the EME process, when EME was conducted from the samples with just partially ionized analytes. EME combined with HPLC-UV and LC-MS were validated using whole blood and urine, respectively. In all cases, the linearity (R2) was >0.99 within the reported linear range. Repeatability at three concentrations was satisfactory (<12%), and the limits of detection (LOD, S/N = 3) were in the ranges of 0.44–4.30 ng mL−1 and 0.14–0.69 μg mL−1 for EME-LC-MS and EME-HPLC-UV, respectively. Finally, the validated methods were successfully applied for the identification and quantification of barbiturates in whole blood and urine samples for a forensic case, indicating that EME could be used in routine toxicological analysis. Thus, we believe that EME has great potential as a green, efficient and alternative sample preparation method not only in the field of analytical chemistry but also in the fields of forensic science and clinical medicine.

CO2 separation by supported liquid membranes synthesized with natural deep eutectic solvents.

Betaine-based natural deep eutectic solvents (NADESs), a new class of green solvents, were immobilized into a porous polyvinylidene fluoride (PVDF) support and evaluated for the separation of CO2 from CO2/N2 and CO2/CH4 mixtures. Two types of NADESs were synthesized by mixing betaine (hydrogen bond acceptor-HBA) with malic acid and tartaric acid (hydrogen bond donors-HBD) respectively. FTIR and Raman spectroscopy were studied to confirm the synthesis and purity of the NADESs. The thermal strength of the NADESs was investigated using thermogravimetric analysis. The gas permeation results of the fabricated NADES-based-supported liquid membranes (NADES-SLMs) showed that the permeability of CO2 increased from 25.55 to 29.33Barrer on substitution of hydrogen bond donor from tartaric acid to malic acid. Similarly, the ideal CO2/CH4 selectivity varied from 51.1 to 56.4 as tartaric acid was replaced by malic acid as the HBD. The performance of NADES-SLMs was compared with the competing imidazolium-based-supported ionic liquid membranes, and proved NADES-SLMs as a promising alternative considering their green potential and comparable gas separation performance. The current effort for the exploitation of NADESs into PVDF membranes in this study is expected to open new routes for the efficient separation of CO2 from the industrial gas mixture.

Green imidazolium ionic liquid selectively facilitates Ce(III) ion transport through supported liquid membrane

ABSTRACT Cerium, a rare-earth element, is very important in industry and technology. It has particular applications in catalytic processes, hydrogen storage, lighting and polishing. The extraction of cerium ions can be carried out easily with solvent and membrane extraction processes from an aqueous medium. The process for the removal of cerium ions in a liquid membrane stabilised on the polytetrafluoroethylene (PTFE) was examined with the presence of imidazolium ionic liquid and organophosphorus extractants. The outcomes demonstrated that ionic liquid improves the extraction procedure and increases the permeation coefficient through the supported liquid membrane (SLM) membrane. The impact of process parameters such as the acidity of feed and recovery phase and concentration of carriers were investigated, and the maximum permeation coefficient was observed at 30%, 20% and 10% v/v for D2EHPA, TBP and C6MIM.NTF2 extractant concentrations, respectively, and cerium ions of 200 mg/L, feed pH of 6 and 2 M for the acidity of the stripping phase. Also, the resistances of both phases were modelled and calculated with the consideration of the rapid reaction in the interface with the first-order reactions.

Influence of acid-base dissociation equilibria during electromembrane extraction.

Electromembrane extraction is affected by acid-base equilibria of the extracted substances as well as coupled equilibria associated with the partitioning of neutral substances to the supported liquid membrane. A theoretical model for this was developed and verified experimentally in the current work using pure 2-nitrophenyl octyl ether as supported liquid membrane. From this model, extraction efficiency as a function of pH can be predicted. Substances with log P<0-2 are generally extracted with low efficiency. Substances with log P>2 are generally extracted with high efficiency when acceptor pH<pKaH - log P. Twelve basic drug substances (2.07<log P<6.57 and 6.03<pKaH <10.47) were extracted under different pH conditions with 2-nitrophenyl octyl ether as supported liquid membrane and fitted to the model. Seven of the drug substances behaved according to the model, while those with log P close to 2.0 deviated from prediction. The deviation was most probably caused by deprotonation and ion pairing within the supporting liquid membrane. Measured partition coefficients (log P) between 2-nitrophenyl octyl ether and water, were similar to traditional log P values between n-octanol and water. Thus, the latter have potential for pKaH - log P predictions.

Recovery of succinic acid from whey fermentation broth by reactive extraction coupled with multistage processes

Abstract Fermentative production of succinic acid (SA) from renewable resources such as whey is environmentally sustainable compared to petroleum-based synthesis. However, a major drawback of fermentation is the concurrent production of SA with byproducts such as lactic acid (LA), formic acid (FA) and acetic acid (AA). Therefore, appropriate downstream SA recovery and purification steps are significant in ensuring sustainable SA production. In this study, SA was fermented by Actinobacillus succinogenes and recovered in an integrated process consisting of ultrafiltration, vacuum distillation and reactive extraction. The extractant used was tri-n-octylamine (TOA) with 1-octanol as a diluent for both liquid-liquid (LLE) extraction and supported liquid membrane (SLM). The produced SA titer and yield was 11.16 g/L and 0.44 g/g, respectively. The steady state ultrafiltration permeate flux ranged from 31.18 to 33.42 L/m2h, and complete decolorization of the fermentation broth was achieved with 10 % (w/v) of powdered activated carbon. The extraction efficiency for LLE was 51.5 %, whereas SLM achieved 57.3 % recovery. SA exhibited transport and permeability coefficient of 0.00697 h−1 (R2 > 0.92) and 0.08605 cm h−1, respectively. Extraction of SA tremendously decreased as the aqueous pH was increased from 2 to 5. In SLM, initial SA flux was calculated as 9.65 g/m2h and doubled that of lactic acid. Selective extraction of only SA was not achieved; however, residue biological material and macromolecular substances were effectively removed. Herein, we clearly demonstrated that process integration applied in reactive extraction is a promising approach for recovery of SA from fermentation broth.

Pemisahan Perak dari Limbah Fotorontgen dengan Teknik Membran Cair Berpendukung Menggunakan Pengemban Gabungan TBP dan D2EHPA

The photorontgen process produces waste that is harmful to the environment because it contains silver ions that are toxic to living organisms. The silver content in photorontgent waste is 2000 mg / L, while the permissible threshold value for silver in aquatic is 0.1 - 1.0 mg / L, so the disposal of photorontgent waste into the waters will be dangerous. However, silver metal has high economic value so that silver metal separation from x-ray waste is required, in addition to reducing the environmental burden due to silver metal pollution, it is also expected to reuse the silver metal economically. The technique of separation that can be used is a supported liquid membrane (Supported Liquid Membrane, SLM). This technique has the advantage that its separation process is relatively easy because the extraction and stripping process takes place in one stage, the carrying solution as extractant is more stable in the supporting membrane and the amount of extractant required is small. This research studies the effect of waste dilution factors on the effieciency separation of silver from photorontgen waste. Separation was carried out at the optimum SLM condition by using combined carrier compound TBP and D2EHPA with a ratio of 0.25: 0.75, total concentration of 1 M in kerosene and 0.1 M HNO3 as stripping phase. Sample waste was diluted by a factor dilution 25, 50, 75 and 100 times. Measurement of metal content before and after separation is done with AAS. The results showed that the waste dilution factor influenced the efficiency of silver trasnpor through SLM. Percent of silver separation was obtained 21.33% in waste with 100 times dilution.

Highly selective transport of lithium across a supported liquid membrane

Lithium extraction is a major concern in view of the increase in battery manufacturing. Separation of lithium from associated sodium is still a challenging task due to the similar chemical behavior of these alkali metals. Lithium sources such as salt brines or seawater usually contain large amounts of sodium which requires a high selectivity for the lithium extraction process. In this study, we demonstrate the application of a supported liquid membrane (SLM) with very high selectivity for the separation of lithium from sodium. A synergistic extraction system made of heptafluoro-dimethyloctanedione (HFDOD) and tri-n-octylphosphine oxide (TOPO) ligands diluted in dodecane was selected based on its extraction efficiency (>99 % of lithium extracted) and selectivity for lithium over sodium (separation factor ca.400). Several experimental parameters were studied using a SLM made of HFDOD and TOPO (initial lithium concentration and sodium to lithium concentration ratio in the feed aqueous phase, HFDOD: TOPO ratio in the organic phase). It was found that high lithium permeation rates can be obtained even for low lithium concentrations and high sodium concentration. Membrane stability was evaluated and found to be poor, i.e. significant loss of performances was observed after one cycle of use, due to the leakage of the organic phase and change in HFDOD: TOPO ratio into it. The SLM system designed is suitable for the extraction of lithium from lowly concentrated solutions such as brines and seawater.

Evaluation of the Synergistic Effects from Multi-Solvents in the Transfer of Sm(III) Ions into the Supported Liquid Membrane

Evaluation of the Synergistic Effects from Multi-Solvents in the Transfer of Sm(III) Ions into the Supported Liquid Membrane

Efficient recovery of neodymium and praseodymium from NdFeB magnet-leaching phase with and without ionic liquid as a carrier in the supported liquid membrane

In this study, the presence and absence of ionic liquids as a carrier in the SLM system was investigated for the extraction of praseodymium and neodymium ions from the NdFeB magnet-leaching solution. The rate of permeability coefficient in the ion transport process inside the supported liquid membrane was studied by utilizing the variation in the acidity of the source and stripping phases and the role of different carriers in the transport. The highest permeability coefficients were obtained with the synergistic system containing [C6MIM][NTf2], TOPO, and TPB extractants. The higher efficiency is related to the particular ionic property in the extraction of rare earth ions compared with TOPO, and TBP extractants diluted in kerosene. The experimental data of the acidity of the source and stripping phases showed that the neutral pH ~ 6 in the feed phase and the average acidity of 1.8 M nitric acid in the stripping phase were suitable for the transport of ions between both phases. The kinetics of ion transport inside the ionic liquid membrane based on logarithmic variations showed that the process of ion transfer inside the membrane follows the first-order kinetics. The investigation of stability with ionic liquids indicated that a more stable system was provided with ionic liquid as a green solvent in the carrier phase.

Transport of As (III) from Acidic Feed Solution through Supported Liquid Membrane Impregnated with Tri-n-dodecylamine and Recovery as As (V)

The transport of As (III) via supported liquid membrane containing tri-n-dodecylamine (TDDA) as carrier in acidic medium has been studied. Various factors affecting the transport of As (III) were evaluated. The effects of acid concentration (HCl), metal ion concentration, carrier, and strippant (NaOH) concentration on transport of As (III) were thoroughly examined. Mathematical transport model was presented considering the formation of complex between TDDA, acid, and As (III) at feed membrane interface, then the diffusion of this complex through membrane, and finally dissociation of the complex in basic medium at strip membrane interface. The predicted results of this model strongly agree with experimental ones. The stoichiometry of complex was determined on the basis of slope analysis of plots. The mechanism of transport was determined by coupled co-ion transport mechanism, with H+ and Cl− coupled ions. The optimized SLM was efficiently used for transport of As (III) from acidic feed solution into basic strippant NaOH and oxidized to less toxic form As (V) by adding H2O2.

Impact of ion balance in electromembrane extraction

Electromembrane extraction (EME) involves transfer of analyte ions from aqueous sample, through a supported liquid membrane (SLM), and into an aqueous acceptor solution under the influence of an external electrical field. In addition to target analyte ions, the sample also contains matrix ions, and both the sample and acceptor contains background buffer ions to control pH. The ratio between the total amount of ions in sample and acceptor defines the ion balance (χ). Previous publications have discussed the impact of ion balance, but conclusions are contradictory. Therefore, the current paper investigated the ion balance in more detail. From a theoretical point of view, low χ-values favor EME; buffer anions at high concentration in the acceptor migrate into the SLM, while target cations enters the SLM from the sample to maintain electroneutrality. A large number of experiments was performed in this paper to investigate the practical impact of ion balance. Twelve basic drugs were used as model analytes (0.0 < log P < 5.0), and 2-nitrophenyl octyl ether (NPOE) and NPOE + 5% di(2-ethylhexyl) phosphate (DEHP) were used as SLM. With formate buffer pH 3.75 as sample and acceptor, the impact of χ in the range 0.01–10 was studied without bias from differences in pH. Here model analytes were unaffected by ion balance. Buffers containing propionic, butyric, and valeric acid were also tested. These buffer ions migrated more into the SLM, and affected recoveries in several cases. However, this was due to ion pairing rather than effects of ion balance. Similar behaviors from sodium chloride and urine samples were observed with different χ-values. Thus, in the systems tested, almost no impact of ion balance was found, and this was attributed to very low partition of background buffer and matrix ions into the SLM. On the other hand, extractions were in several cases influenced by ion pairing phenomena.

Americium pertraction across supported liquid membranes containing multiple diglycolamide ligands: Role of alkyl substitution and spacer length in carrier ligands

Liquid–liquid extraction and subsequent supported liquid membrane (SLM) transport studies involving Am3+ ion were carried out from nitric acid feed solutions using three N-pivot tripodal diglycolamide (DGA) ligands with varying substituent at the inner carboxamide N atom and spacer length. The ligand with an isopropyl substituent and with C2 spacer is termed as iPr3-TREN-DGA, while the one without alkyl substituent is termed as TREN-DGA. The third ligand with no substituent but a C3 spacer is termed as TRPN-DGA. The trend of metal ion extraction was iPr3-TREN-DGA > TRPN-DGA > TREN-DGA when solutions of ca. 1.0×10−3 M ligand in 95% n-dodecane+5% isodecanol were used. Stripping studies were carried out using 0.01M HNO3, 0.01M EDTA (at pH 3.0) and 1M α-HIBA (α-hydroxyisobutyric acid) The extraction and stripping kinetics studies suggested attainment of equilibrium in about 30minutes. The SLM studies were carried out in a two-compartment cell with 20mL feed as well as receiver phase volumes and PTFE (polytetrafluoroethylene) flat sheets as the solid support. The transport rates followed the same trend as that of the metal ion extraction study, suggesting comparable diffusion coefficients of the complexes (obtained by the lag-time method). Membrane stability studies indicated the best stability for the TRPN-DGA ligand.

Facilitated recovery of copper from ammoniacal solution by supported liquid membrane following multiple cooperative effects

One-step recovery of copper(II) from ammonia/ammonium sulfate solution by combining supported liquid membrane and electro-deposition process was investigated. The fundamental parameters enhancing copper transport through a supported liquid membrane, such as carrier concentration of N902 extractant in the membrane, H2SO4 concentration in the stripping phase, temperature and ultrasonication, were examined. The results show that three auxiliary measures including higher operating temperature, ultrasonic assistance and electro-deposition process can all improve copper transport efficiency. Nearly, all of copper in feed phase were transported across the supported liquid membrane by using simultaneously the electro-deposition process and ultrasonic assistance after 10 h with a flux of 3.35 × 10–5 mol m−2 s−1 under the optimal conditions: 100 mg L−1 copper in 1.0 mol L−1 each of ammonia and ammonium sulfate solution as the feed phase, 20 vol% N902 in kerosene as carrier, 80 g L−1 H2SO4 as the stripping phase, stirring rate of 800 rpm in two aqueous phases and operating temperature of 40 °C. In the meantime, 83.8% copper ions in stripping phase were recycled to particles deposited on the cathode surface. Furthermore, membrane stability was also evaluated and shown to be satisfactory for at least seven runs (70 h). Application of the assembled supported liquid membrane system has been found to be successful in the facilitated recovery of copper from ammoniacal solution.

Recovery of gadolinium ions based on supported ionic liquid membrane: parametric optimization via central composite design approach

Gadolinium is a contrast agent in magnetic resonance imaging, and the extraction and purification process has been very much considered due to the importance of its applications. The transport of gadolinium ions was investigated by utilizing the supported liquid membrane with mixtures of extractants as a carrier. The systematic conditions of the process were optimized based on the experimental design approach. At the first time, the effect of mixing of two extractants such as di-(2-ethylhexyl) phosphoric acid, tributyl phosphate extractants and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as a green environmental solvent was studied on the gadolinium ion transport and the optimal concentration was utilized in the preparation of carrier concentration. In the second time, the main variables such as reaction time, the concentration of gadolinium ions, acidity in the source and stripping phases were optimized equal to 6 h, 200 mg/L, 5 and 1.86 M, respectively. The permeability coefficients were calculated based on the predicted equation for the transport percent of gadolinium ions, and the results were in agreement with the calculated values from the experimental data (coefficient of determination equal to 0.959). Finally, the applicability of gadolinium extraction through the supported liquid membrane was confirmed in the process with the presence of ionic liquids.