Aliquat 336 in Solvent Extraction Chemistry of Metallic ReO4- Anions.

A study of the liquid-liquid extraction of ReO4- anions from hydrochloric acid solutions using the ionic liquid Aliquat 336 (QCl: trialkyl(C8-C10)methylammonium chloride) via the well-known method of slope analysis along with the determination of the process parameters is presented. This study employs CCl4, CHCl3 and C6H12 as diluents. This study was carried out at room temperature (22 ± 2) °C and an aqueous/organic volumetric ratio of unity. The ligand effect on the complexation properties of ReO4- is quantitatively assessed in different organic media. The organic extract in chloroform media is examined through 1H, 13C and 15N NMR analysis as well as the HRMS technique and UV-Vis spectroscopy in order to view the anion exchange and ligand coordination in the organic phase solution. Final conclusions are given highlighting the role of the molecular diluent in complexation processes and selectivity involving ionic liquid ligands and various metal s-, p-, d- and f-cations. ReO4- ions have shown one of the best solvent extraction behaviors compared to other ions. For instance, the Aliquat 336 derivative bearing Cl- functions shows strongly enhanced extraction as well as pronounced separation abilities towards ReO4-.

Kinetic and Thermodynamic Studies of Precious Metals Sorption on Impregnated Lewatit VP OC 1026 from Chloride Solutions.

Precious metals are used in many branches of industries. Due to their rarity and diminishing natural resources, more and more new methods are being sought to recover them from secondary sources, which can be electronic waste or spent car exhaust converters. This paper presents the research on the recovery of precious metals from chloride solutions using the Aliquat 336-impregnated Lewatit VP OC 1026 sorbent. The study used a warm impregnation method without toxic solvents, which is beneficial for the environment. The maximal sorption capacities obtained for model solutions in 0.1 M HCl were: 95.6 mg/g for gold, 38.2 mg/g for palladium, and 36.2 mg/g for platinum. There were studied: kinetics and thermodynamics of sorption, as well as amounts of the sorbent, effects of phase contact time and HCl concentration on the sorption of precious metals. Positive values of enthalpy change ΔH° validate that the process is endothermic. The research was also carried out on a real leaching solution obtained by digesting a spent catalytic converter, containing small amounts of platinum group metals. Desorption of precious metal ions was conducted using 1 M thiourea in 1 M hydrochloric acid. The obtained impregnated sorbent proved to be effective for sorption of Au(III), Pd(II), Pt(IV) ions.

A New Impregnated Adsorbent for Noble Metal Ion Sorption.

Noble metals (NM) such as gold, platinum, palladium, and rhodium are widely applied in the electronics and automotive industries. Thus, the search for cheap and selective sorbents for noble metals is economically justified. Nitrolite does not sorb noble metal ions. A new impregnated sorbent was prepared. The natural sorbent Nitrolite was impregnated with Aliquat 336 using a new warm impregnation method. After the impregnation process, Nitrolite adsorbed platinum(IV), palladium(II), and gold(III) ions from the chloride solutions. The values of the sorption capacity for palladium(II) and platinum(IV) ions were 47.63 mg/g and 51.39 mg/g, respectively, from the 0.1 M HCl model solution. The sorption capacity for gold(III) ions was estimated to be 73.43 mg/g from the 0.1 M HCl model solution. An exhausted catalytic converter was leached, and platinum(IV), palladium(II), and rhodium(III) were transferred to the chloride solution. The impregnated sorbent Nitrolite-Aliquat 336 was used in the investigations of the platinum(IV), palladium(II), and rhodium(III) ions' sorption from a real solution. The impregnated sorbent Nitrolite-Aliquat 336 proved to be suitable for the recovery of platinum(IV) and palladium(II) ions, whereas rhodium ions were not sorbed from the leached solutions. Notably, 1 M thiourea in the 1 M HCl solution desorbed platinum(IV), palladium(II), and gold(III) above 94%.

Conversion of Lithium Chloride into Lithium Hydroxide by Solvent Extraction.

A hydrometallurgical process is described for conversion of an aqueous solution of lithium chloride into an aqueous solution of lithium hydroxide via a chloride/hydroxide anion exchange reaction by solvent extraction. The organic phase comprises a quaternary ammonium chloride and a hydrophobic phenol in a diluent. The best results were observed for a mixture of the quaternary ammonium chloride Aliquat 336 and 2,6-di-tert-butylphenol (1:1 molar ratio) in the aliphatic diluent Shellsol D70. The solvent extraction process involves two steps. In the first step, the organic phase is contacted with an aqueous sodium hydroxide solution. The phenol is deprotonated, and a chloride ion is simultaneously transferred to the aqueous phase, leading to in situ formation of a quaternary ammonium phenolate in the organic phase. The organic phase, comprising the quaternary ammonium phenolate, is contacted in the second step with an aqueous lithium chloride solution. This contact converts the phenolate into the corresponding phenol by protonation with water extracted to the organic phase, followed by a transfer of hydroxide ions to the aqueous phase and chloride ions to the organic phase. As a result, the aqueous lithium chloride solution is transformed into a lithium hydroxide solution. The process has been demonstrated in continuous counter-current mode in mixer-settlers. Solid battery-grade lithium hydroxide monohydrate was obtained from the aqueous solution by crystallization or by antisolvent precipitation with isopropanol. The process consumes no chemicals other than sodium hydroxide. No waste is generated, with the exception of an aqueous sodium chloride solution. Supplementary Information: The online version contains supplementary material available at 10.1007/s40831-022-00629-2.

Efficient separation of arsenic species of oxyanion As (III) and As (V) by using effective polymer inclusion membranes (PIM).

The heavy metal contaminant arsenic exist in the form of arsenite (As(III)) and arsenate (As(V)) ions. These ions are highly carcinogenic that are usually present in the ground water. To date, most of the designed polymer inclusion membrane (PIM) involved only about separation without differentiating the oxidation states. Thus, there is a research gap on separation of element with different oxidation states. Thus, this study addresses such research gap which have been not explored previously. To extract such ions from water, the present study involves fabrication of PIM by varying the compositions of the base polymer, carrier and plasticizer. Also effect of the strip solution, and transport properties were studied. High performance membrane was obtained with 50% (w/w) Aliquat 336 and 50% (w/w) Cellulose triacetate (CTA). The production of 1 m2 of PIM may cost approximately 0.08-0.16$. Also, we have combined the separation capacity of polymer inclusion membrane (PIM) with the sensitivity and elemental detection using atomic absorption spectrometry (AAS) to detect and separate As(III) and As(V). AAS is limited to detecting only elemental arsenic (As) and does not distinguish between As(III) and As(V). Further, to address such limitations in this current study we were able to separate As(V) from As(III) within 5 h. In addition, to provide sole solution a device was fabricated to extract As(V) in the field studies which displayed outstanding efficiency of 99.7 ± 0.2%. The extracted samples was tested in AAS to differentiate between oxidation states of the arsenic species and these important results are supportive in finding out the redox potential of water and for other geochemical explorations.

Development and application of a membrane assisted solvent extraction-molecularly imprinted polymer based passive sampler for monitoring of selected pharmaceuticals in surface water.

In this work, we demonstrate the development, evaluation and pre-liminary application of a novel passive sampler for monitoring of selected pharmaceuticals in environmental waters. The samplers were calibrated in laboratory-based experiments to obtain sampling rates (Rs) for carbamazepine, methocarbamol, etilefrine, venlafaxine and nevirapine. Passive sampling was based on the diffusion of the target pharmaceuticals from surface water through a membrane bag which housed an ionic liquid as a green receiving solvent and a molecularly imprinted polymer. Effects of biofouling, deployment time and solvent type for the receiver phase were optimized for selective uptake of analytes in surface water. Notably, there was a decrease in the uptake of selected pharmaceuticals and consequently a decrease in their sampling rates in the presence of biofouling. The optimum matrix-matched sampling rates ranged from 0.0007 - 0.0018 L d-1 whilst the method detection and quantification limits ranged from 2.45 - 3.26 ng L-1 and 8.06 - 10.81 ng L-1, respectively. The optimized passive sampler was deployed in a dam situated in the heart of a typical highly populated township in the Gauteng Province of South Africa. Only etilefrine and methocarbamol were detected and quantified at maximum time weighted average concentrations of 12.88 and 72.29 ng L-1, respectively.

New Insights on the Effects of Water on Polymer Inclusion Membranes Containing Aliquat 336 Derivatives as Carriers.

Surface characterization of polymer inclusion membranes (PIMs) using the polymers cellulose triacetate and polyvinyl chloride, containing different ionic liquids (ILs) as carriers, has been performed. Three different ILs have been tested: commercial trioctyl methylammonium chloride (Aliquat 336-AlqCl-) and two derivatives bearing the counter anion NO3- or SCN- (AlqNO3 and AlqSCN, respectively). Surface analysis was performed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) for both dry membranes and PIMs immersed for 4 days in ultrapure water to investigate the effect of the interaction of water with the membrane's morphology and composition. XPS analysis of the PIMs revealed that immersion in ultrapure water causes a decrease in the atomic concentration percentage (A.C.%) of the specific IL atoms (Cl, S, and N) when compared with dry samples. Moreover, SEM images of the PIMs containing the IL AlqNO3 showed an alteration in the morphology of the membrane due to water contact at surface level, whereas no changes were observed at a bulk level. These changes in the surface composition of the water equilibrated PIMs may be associated with the solubilization of the IL in the water solution, which, therefore, may affect the reactivity of the membrane's surface. To better understand this effect, PIMs containing both AlqCl and AlqNO3 as carriers were used for arsenic (V) transport. It was found that AlqCl was the most effective IL and that the effectivity of the PIM on As(V) removal was not affected after five cycles of the membrane's reuse.

Catalytic Transformation of Triglycerides to Biodiesel with SiO2-SO3H and Quaternary Ammonium Salts in Toluene or DMSO.

SiO2-SO3H, with a surface area of 115 m2·g-1, pore volumes of 0.38 cm3·g-1 and 1.32 mmol H+/g, was used as a transesterification catalyst. Triglycerides of waste cooking oil reacted with methanol in refluxing toluene to yield mixtures of diglycerides, monoglycerides and fatty acid methyl esters (FAMEs) in the presence of 20% (w/w) catalyst/oil using the hydrophilic sulfonated silica (SiO2-SO3H) catalyst alone or with the addition of 10% (w/w) co-catalyst/oil [(Bun4N)(BF4) or Aliquat 336]. The addition of the ammonium salts to the catalyst lead to a decrease in the amounts of diglycerides in the products, but the concentrations of monoglycerides increased. Mixtures of (Bun4N)(BF4)/catalyst were superior to catalyst alone or Aliquat 336/catalyst for promoting the production of mixtures with high concentrations of FAMEs. The same experiments were repeated using DMSO as the solvent. The use of the more polar solvent resulted in excellent conversion of the triglycerides to FAME esters with all three-catalyst media. A simplified mechanism is presented to account for the experimental results.

On the Potential of a Poly(vinylidenefluoride-co-hexafluoropropylene) Polymer Inclusion Membrane Containing Aliquat® 336 and Dibutyl Phthalate for V(V) Extraction from Sulfate Solutions.

A polymer inclusion membrane (PIM) composed of 50 wt% base polymer poly(vinylidenefluoride-co-hexafluoropropylene), 40 wt% extractant Aliquat® 336, and 10 wt% dibutyl phthalate as plasticizer/modifier provided the efficient extraction of vanadium(V) (initial concentration 50 mg L-1) from 0.1 M sulfate solutions (pH 2.5). The average mass and thickness of the PIMs (diameter 3.5 cm) were 0.057 g and 46 µm, respectively. It was suggested that V(V) was extracted as VO2SO4- via an anion exchange mechanism. The maximum PIM capacity was estimated to be ~56 mg of V(V)/g for the PIM. Quantitative back-extraction was achieved with a 50 mL solution of 6 M H2SO4/1 v/v% of H2O2. It was assumed that the back-extraction process involved the oxidation of VO2+ to VO(O2)+ by H2O2. The newly developed PIM, with the optimized composition mentioned above, exhibited an excellent selectivity for V(V) in the presence of metallic species present in digests of spent alumina hydrodesulfurization catalysts. Co-extraction of Mo(VI) with V(V) was eliminated by its selective extraction at pH 1.1. Characterization of the optimized PIM was performed by contact angle measurements, atomic-force microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis/derivatives thermogravimetric analysis and stress-strain measurements. Replacement of dibutyl phthalate with 2-nitrophenyloctyl ether improved the stability of the studied PIMs.

Environmental friendly approach for selective extraction and recovery of molybdenum (Mo) from a sulphate mediated spent Ni-Mo/Al2O3 catalyst baked leach liquor.

Solvent extraction separation of molybdenum (Mo) from the sulphate mediated leach solution bearing Aluminium (Al) and Nickel (Ni) was carried out using N-Methyl-N, N, N-tri-octyl-ammonium chloride. Extensive investigation for extraction study molybdenum in the function of time, Eq.pH, extractant concentration, diluents, temperature, strip solution concentration and phase ratio(A:O) for both extraction and stripping was examined to attain a suitable condition on its selective and enriched extraction. As per the equilibrium study and increasing trend of Eq. pH (pHe) at the correspondence initial pH, it was apparent about association of 1 mol of H+ ion during extraction which with was further supported on extraction of Mo as HMO4- at the pHe of 3.48. The association of 1 mol of exrractant during the extraction of Mo was also well evident from the slope analysis study. This indicates about anion exchange phenomenon due to Cl- ion of the N-Methyl-N, N, N-tri-octyl-ammonium chloride (extractant) with HMo4- from aqueous phase during complex formation reaction. The FTIR of the organic sample before and after extraction further confirms in support of the complex formation of the molybdenum with the extractant during extraction. The extraction isotherm was constructed at optmum extraction condition: pHe of 3.48 with 0.08M N-Methyl-N, N, N-tri-octyl-ammonium chloride predicts on need of 2-counter current stages for quantitative extraction of Mo at A:O = 3:1. To investigate the regeneration behaviour of adopted extractant along with enriched stripping of molybdenum, ammoniacal reagents were used in stripping study. The stripping of Mo showed promising and efficient using the mixture of the ammoniacal reagents (NH4OH + NH4Cl) over the either of the solo reagents. The stripping Mc-Cabe Thiele diagram was plotted using 2M NH4OH + NH4Cl ensures on quantitative stripping of Mo at SO: SS = 2:1 at 2 no. of stages. Both extraction and stripping isotherm results are validated at predicted isotherm conditions by 6-cycles counter current simulation (CCS) study leading to obtain 6-fold enrichment of Mo in stripped solution phase. The subsequent enriched content of Mo (∼60 g/L) in stripped solution phase was precipitated out followed by calcinations 400 °C to obtain a high pure MoO3. The recovered calcined product as MoO3 resulted through the proposed processing approach was as ascertained from XRD analysis.

Possibility of New Active Substrates (ASs) to Be Used to Prevent the Migration of Heavy Metals to the Soil and Water Environments.

This paper aims to propose an alternative to the known permeable reactive barriers (PRBs). PRB is one of the methods, which is a reactive barrier placed below the ground, to clean up contaminated groundwater. New polymer active substrates (ASs) were used to prevent soil contamination by toxic heavy metals. The active substrates consisted of a mixture of poly(vinyl chloride), Aliquat 336, and bis(2-ethylhexyl)adipate, which was applied to the skeleton material (fiberglass or textile). Aliquat 336 was used as a binding agent for metal ions (Cr(VI), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II)). In contrast with the PRBs, the ASs (from AS-1 to AS-5) were obtained in a simple way using the pouring method. The obtained ASs could be recycled and reused. The active substrates were used for the binding of various metal ions from aqueous solutions and the examined soil. It was found that the active substrate AS-1 decreased the concentrations of nickel, cadmium, and lead by more than 50% and that of chromium by more than 90% in the aqueous solution. High sorption efficiency for chromium and zinc metals (81% and 66%) with the use of AS-2 was also found, owing to which the migration of metals from soil to water can be limited. In the soil environment, active substrate AS-5 with the addition of a plasticizer showed the greatest effectiveness. This solution resulted in a reduction in each tested metal ion of at least 50%, and reductions in cadmium, lead, and copper of over 70%.

Selective extraction and determination of Cr(VI) in food samples based on tandem electromembrane extraction followed by electrothermal atomic absorption spectrometry.

In this study, electromembrane extraction (EME) combined with micro-EME (µ-EME) was used for the selective extraction of Cr(VI) from food samples (milk powder, Ocimum basilicum, and fish samples). Electrothermal atomic absorption spectrometry was used for the quantification of Cr(VI). Under the optimized extraction conditions, the extraction recovery of Cr(VI) was 73.7%. This proposed method provided a linear range from 0.01 to 5.0 ng/mL and the limit of detection (LOD) and limit of quantification (LOQ) were 0.003 and 0.010 ng/mL. The %RSD (n = 5) was in the range of 11.2-11.8% at 0.05, 1.0 and 2.5 ng/mL of Cr(VI), and the enrichment factor was 584. The accuracy of the method was evaluated by analysis of SRM 2700 as a certified reference material (CRM) and result was in good agreement with the certified value.

Microfluidic Fabrication of Micropolymer Inclusion Beads for the Recovery of Gold from Electronic Scrap.

A composite material, referred to as micropolymer inclusion beads (µPIBs), was fabricated for the first time using a microfluidic technique and applied successfully for the recovery of Au(III) from simulated digests of electronic scrap. Best results for the extraction of Au(III) were achieved with µPIBs consisting of 55% (m/m) poly(vinyl chloride) as the base polymer, 35% (m/m) Aliquat 336 as the extractant, and 10% (m/m) 1-tetradecanol as a modifier. The size and surface morphology of the µPIBs were examined using optical microscopy and scanning electron microscopy, respectively. A batch of 200 mg µPIBs allowed the complete and selective extraction of Au(III) (2.85 mg) from 50 mL of a simulated digest of electronic scrap containing other metal ions, including 1365 mg Cu(II). The extracted Au(III) was quantitatively stripped from the µPIBs into 50 mL of 0.1 mol L-1 solution of thiourea. No Cu(II) and only sub-microgram levels of Cd(II) and Zn(II) were detected in this solution, thus confirming the suitability of the µPIBs for the efficient recovery of Au(III) from digests of electronic scrap. The microfluidic method used in this study is expected to be applicable for the fabrication of µPIBs for the selective separation of other chemical species by varying the composition of the beads.

Hydration counteracts the separation of lanthanides by solvent extraction.

The extraction of lanthanides from aqueous nitrate solutions by quaternary ammonium nitrate ionic liquids (e.g., [A336][NO3]) shows a negative sequence (i.e., light lanthanides are more efficiently extracted than heavy lanthanides), which conflicts with the lanthanide contraction. In this study, we explored the origin of the negative sequence by investigating the extraction of lanthanides from ethylammonium nitrate by [A336][NO3]. The extraction shows a positive sequence, which is converted to a negative sequence with the addition of water. The transformation from positive to negative sequences reveals that the negative sequence is caused by the hydration of lanthanide ions: hydration of lanthanide ions counteracts the extraction. Therefore, the use of solvents that have weak solvation with lanthanide ions might enhance the separation of the elements by solvent extraction.

Mg-Al-CO3 layered double hydroxide reinforced polymer inclusion membrane as an extractant phase for thin-film microextraction of cyanide from environmental water samples.

In this paper, a flexible and efficient nano-reinforced polymer inclusion membrane (PIM) was fabricated and used for cyanide (CN-) extraction from water samples. Aliquat 336 (a liquid anion exchanger) was embedded in poly(vinyl chloride) (PVC) support as the extractant. Mg-Al-CO3 layered double hydroxide (LDH) with high surface area and anion exchange ability was applied to promote the extraction efficiency of PIM. A PIM comprising 56% PVC, 40% Aliquat 336, and 4% Mg-Al-CO3 LDH showed the best extraction efficiency. A single beam ultraviolet-visible spectrophotometer was used for the detection of cyanide. Surface morphology of the PIM was studied by field emission scanning electron microscopy. The experimental parameters influencing the extraction process were investigated and optimized. The intra- and inter-day relative standard deviations at two different concentrations were in the range of 2.8-7.6%. The dynamic range of the method was in the range of 5-500 µg L-1, and the detection limit was 1.4 µg L-1. The LDH reinforced PIM showed proper characteristics for the extraction of cyanide from real water and wastewater samples with recoveries between 82 and 115%.

First Report on a Solvent-Free Preparation of Polymer Inclusion Membranes with an Ionic Liquid.

A novel and environmentally-friendly procedure for the preparation of polymer inclusion membranes (PIMs) containing an ionic liquid is presented for the first time. Traditionally, PIMs are prepared by a solvent casting method with the use of harmful organic solvents. Here we report a new solvent-free procedure based on a thermal-compression technique which involve the melting of the components of the PIM and the application of a high pressure to the melted specimen to form a flat-sheet film. In our study, we have tested different polymers, such as two cellulose derivatives as well as two thermoplastic polymers, polyurethane (TPU) and poli ε-caprolactone (PCL). The ionic liquid (IL) trioctylmethylammonium chloride (Aliquat 336) has been used to produce PIMs with a fixed composition of 70% polymer-30% IL (w/w). Both TPU and PCL polymers provide successful membranes, which have been thoroughly characterized. PIMs based on the polymer PCL showed a high stability. To test whether the properties of the IL were affected by the preparation conditions, the extraction ability of Aliquat 336 was investigated for both PCL and TPU membranes in terms of Cr(VI) extraction. Satisfactory values (90% extraction) were obtained for both membranes tested, showing this novel procedure as a green alternative for the preparation of PIMs with ILs.

3D printed resin-coated device for uranium (VI) extraction.

Laser-based stereolithography (SLA) 3D printing has been applied to construct a 3D printed device as support for uranium(VI) extraction, using a quaternary ammonium salt in liquid and solid form. As proof of concept, a simple process was carried out to immobilize a selective and commercial resin (TEVA resin), in all the surface area of the non-cured SLA 3D printed device, becoming immobilized after UV photocuring. Besides, a coat of Aliquat®336 covering the surface of the cured SLA 3D printed device was tested. Both 3D printed devices as supported for liquid and solid extractant were characterized. Better results in terms of precision were obtained by using TEVA resin (RSD 2.9%), which was satisfactory optimized, reaching a LOD of 0.03 ng U(VI), and a durability of 10 consecutive extractions, maintaining a recovery of 90% with 5% RSD. The 3D printed device is able to preconcentrate up to a sample volume of 30 mL, without any additional pretreatment. The uranium detection was performed with an ICP-MS. Satisfactorily results were obtained analyzing reference material, e.g. phosphogypsum and water matrices from intercomparison exercises, at a confidence level of 95%.

Novel Aliquat-336 impregnated chitosan beads for the adsorptive removal of anionic azo dyes.

In this study, novel Aliquat-336 impregnated chitosan conjugation beads (CS-AL) were synthesised through the reaction of amino groups of chitosan with tricaprylylmethylammonium chloride. The prepared CS-AL was characterised by XRD, FTIR, SEM, EDX and BET analyses. The FTIR analysis showed that the Aliquat-336 ionic liquid was successfully inserted into the chitosan beads structure. It was used as an efficient adsorbent for the fast removal of Methyl orange and Alizarin, as two anionic azo dye models. The optimum adsorbent dosage was 2 g/L with high adsorption behaviour in a wide pH range of 7-11. The adsorption kinetics of the studied dyes onto CS-AL was well described by the pseudo-second-order model. In addition, the adsorption equilibrium study showed that it was fitted by the Langmuir isotherm model. The CS-AL beads could be easily separated by filtration after the adsorption process. The adsorption property of prepared CS-AL conjugation beads suggested it as a novel adsorbent for wastewater treatment.

Extraction Kinetics of As(V) by Aliquat-336 Using Asymmetric PVDF Hollow-Fiber Membrane Contactors.

This work focuses on the study of the mass transfer of arsenic(V) through asymmetric polyvinylidene fluoride hollow-fiber membrane contactors using Aliquat-336 as an extractant. In the first part of this work, the fibers were prepared and characterized by SEM and by determining their thickness and porosity. From SEM pictures, an asymmetric structure was obtained that was characterized by an inner sponge-like structure and outer finger-like structure with a pore radius and porosity about 0.11 µm and 80%, respectively. In the second part, the prepared fibers were used as membrane contactors for the study of mass transfer of arsenic(V), investigating the effect of several parameters such as pH, temperature, and initial concentration of the feed. The overall mass transfer coefficient of As(V) was around 6 × 10⁻6 cm/s.

Applicability of a Supported Liquid Membrane in the Enrichment and Determination of Cadmium from Complex Aqueous Samples.

A supported liquid membrane is developed for the separation of Cd from either high in salinity or acidity aqueous media. The membrane consisted of a durapore (polyvinylidene difluoride) polymeric support impregnated with a 0.5 M Aliquat 336 solution in decaline. The effect of carrier concentration, organic solvent and feed and receiving solutions on the metal permeability is studied. This system allows the effective transport of trace levels of Cd through the formation of CdCl42−, which is the predominant species responsible for the extraction process, in both NaCl and HCl solutions. The supported liquid membrane system in a hollow fibre configuration allows the enrichment and separation of trace levels of Cd from spiked seawater samples, facilitating the analytical determination of this toxic metal.