Transport of Iron and Cobalt Complex Ions through Liquid Membrane Mediated by Methyltrioctylammonium Ion with the Aid of Redox Reaction

Abstract

A new type of carrier-mediated metal transport through liquid membrane is presented. The system involves redox reactions rather than acid-base reactions which have often been utilized in metal transport systems. Iron ion was selectively transported and concentrated through the membrane via a chloride complex by use of a lipophilic quaternary ammonium ion, methyltrioctylammonium (MTOA, Q⁺), as a carrier. The two aqueous solutions of different redox potentials were separated by a polymer-supported liquid membrane in which MTOA · chloride (Q⁺·CI^?) was dissolved as the carrier. Iron(III) ion in hydrochloric acid media formed a FeCl₄ ^? type complex which was readily extracted to the organic membrane phase as an ion-pair complex Q⁺·FeCl₄ ^?. On contact with a reducing agent on the other side of the membrane, iron(III) was reduced to iron(II) and liberated into aqueous solution; the chloride complexes of iron(II) are too hydrophilic to stay in the membrane phase. On the other hand, cobalt ion was transported via nitrilotriacetic acid (NTA) complex by MTOA carrier in a similar manner to the iron transport. The nature of the transport reactions was studied under various operational conditions (redox agents, carrier and ligand concentration, pH, coexisting metals, etc.). The extension of these transport reactions to a water-in-oil-in-water type emulsion system as well as to a photoassisted transport system was studied.     

Transport of Co(II) Ions through Di(2-ethylhexyl) Phosphoric Acid-CCl4 Supported Liquid Membranes

Abstract

A liquid membrane transport study of Co(II) using di(2-ethylhexyl) phosphoric acid (D2EPHA) as carrier and CCl₄, as diluent supported on polypropylene microporous film has been carried out. The carrier concentration in the membrane and HCl concentration in the stripping phase have been varied to see the effect on transport of Co(II) ions across the membrane. Maximum flux and permeability values of 1.23 × 10^?5 mol · m^?2 · s^?1 and 7.66 × 10^?11 m²/s, respectively, at a 0.87 mol/dm³ carrier concentration in the membrane have been found. At 1 mol/dm³ HCl concentration in the stripping phase the flux and permeability have maximum values of 1.4 mol · m^?2 · s^?1 and 5.27 × 10^?11 m²/s, respectively. The distribution coefficient of Co(II) ions into organic phase has been found to increase with increasing carrier concentration. The diffusion coefficient determined varies from 13.73 × 10^?11 to 0.83 × 10^?11 m²/s, which is the reverse order of the values of the distribution coefficient and explains the permeability of the Co(II) D2EPHA complex through the membrane.     

Kinetic Study of an Effective Pb(II) Transport through a Bulk Liquid Membrane Containing Calix[6]arene Hexaester Derivative as a Carrier

The article describes transport of Pb(II) through bulk liquid membrane (BLM) containing calix[6]arene hexaester derivative (1) as a carrier. The effect of various parameters such as temperature, carrier concentration, stirring speed and type of solvent on the Pb(II) transport efficiency of the carrier through BLM was evaluated. The activation energy values for the extraction and re-extraction were found as 56.33 kJ mol^?1 and 14.79 kJ mol^?1, respectively. These values demonstrate that the process is diffusionally controlled by Pb(II). Observations indicate that the membrane entrance and exit rate constants (k₁, k₂) increase with increasing stirring speed as well as carrier concentration and decrease with increasing temperature. The effect of solvent on k₁ and k₂ was found to be in the order of CH₂Cl₂ > CHCl₃ > CCl₄.     

Highly Efficient and Selective Transport of Au(III) through a Bulk Liquid Membrane using Potassium-dicyclohexyl-18-crown-6 as Carrier

Abstract

The facilitated transport of Au(III) through a chloroform bulk liquid membrane containing potassium-dicyclohexyl-18-crown-6 as a selective ion carrier was designed. Au(III) as [AuBr₄]^?, quantitatively transported across the liquid membrane. In the receiving phase, L-cysteine acts as a specific stripping agent. The amount of Au(III) transported through the liquid membrane after 120 minutes was (96.2±1.3)%. The type of halide and its concentration, pH of source and receiving phase and also the type of stripping agents were optimized. The selectivity and efficiency of gold(III) transport from aqueous solutions containing various metal ions were investigated. The presence of EDTA in the source phase diminished drastically the competitive effect of interfering metals ion.     

Liquid–liquid extraction of cadmium(II) by Cyanex 923 and its application to a solid‐supported liquid membrane system

The extraction of cadmium(II) by Cyanex 923 (a mixture of alkylphosphine oxides) in Solvesso 100 from hydrochloric acid solution has been investigated. The extraction reaction is exothermic. The numerical analysis of metal distribution data suggests the formation of CdCl₂.2L, HCdCl₃.2L and H₂CdCl₄.2L (L = ligand) in the organic phase. The results obtained for cadmium(II) distribution have been implemented in a solid‐supported liquid membrane system. The influences of feed phase stirring speed (400–1400 min^?1), membrane composition (carrier concentration: 0.06–1 mol dm^?3) and metal concentration (0.01–0.08 g dm^?3) on cadmium transport have been investigated. Copyright © 2005 Society of Chemical Industry     

Solid Phase Extraction and Determination of Ultra Trace Amounts of Copper using Activated Carbon Modified by N,N′‐Bis(Salicylidene)‐1,2‐Phenylenediamine

Abstract

N,N′‐bis(salicylidene)‐1,2‐phenylenediamine(salophen) modified activated carbon was prepared and used as an effective sorbent for solid phase extraction of Cu(II) ions from aqueous solutions. The salophen modified activated carbon showed a high sorption affinity for Cu(II). In this method a column mode was used for preconcentration of copper(II) in the pH range 3.5–6.5. The retained copper was eluted with 0.1 mol l^?1 EDTA and determined by atomic absorption spectrometry. The calibration graph was linear over the copper concentration in the range 0.05–1.5 µg ml ^?1. Five replicate determination of 0.4 µg ml^?1 of copper(II) gave a mean absorbance of 0.385 with a relative standard deviation of 1.35%. The detection limit was 0.0133 µg ml^?1. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for determination of copper in various real samples.     

Liquid Membrane Transport of Hg(II) by an Azocalix[4]arene Derivative

Abstract

A kinetic study of Hg(II) transport from an aqueous donor solution into an aqueous acceptor solution through a liquid membrane containing 25,26,27–tribenzoyloxy‐28‐hydroxy‐5,11,17,23‐tetra‐(4‐n‐butylphenylazo)calix[4]arene 1 as a carrier was studied. The kinetic parameters (k ₁, k ₂, R _m ^max, t _max, J _d ^max, J _a ^max) for the transport were investigated in terms of the effect of temperature, the stirring rate, the carrier concentration, and the type of solvent. The kinetics of transport was analyzed in the formalism of two consecutive irreversible first‐order reactions. The membrane entrance rate, and exit rate constants were increased with increasing of temperature stirring rate, and carrier concentration. The membrane entrance rate and exit rate constants depended on the type of solvent and was found to be in order of CH₂Cl₂> CHCl₃> CCl₄. The activation energy values are calculated as 30.67±2.64 and 57.33±4.90 kj mol^?1 for extraction and reextraction, respectively. The values of calculated activation energy indicate that the process is diffusionally controlled by species.     

Transport of Cr(VI) from HCl Media Using (PJMTH+Cl−) Ionic Liquid as Carrier by Advanced Membrane Extraction Processing

The transport of Cr(VI) from acidic media through pseudo-emulsion based membrane strip dispersion (PEMSD) containing the ionic liquid (PJMTH⁺Cl^?) as carrier in the form of a pseudo-emulsion with sodium hydroxide has been investigated. The ionic liquid was generated in situ by reaction of the primary amine Primene JMT and HCl. The transport of Cr(VI) is evaluated as a function of various experimental variables: stirring speed in the feed phase, concentration of Cr(VI) and HCl in the feed phase, carrier concentration, and organic diluents in pseudo-emulsion, and NaOH concentration in pseudo-emulsion as strippant. In PEMSD, pseudo-emulsion is an emulsion that is formed temporarily between the organic and the stripping solutions. Both solutions are separated when the stirring device is stopped. The value of the overall permeation coefficient obtained under standard experimental conditions was 3.1 × 10^?3 cm s^?1, whereas the transport process is controlled by diffusion of chromium species in the stagnant film of the feed phase. The performance of the system against other carriers (amines, quaternary phosphonium salt and quaternary ammonium salt) was also evaluated.     

Highly Efficient and Selective Transport of Cu(II) with a Cooperative Carrier Composed of Tetraaza-14-Crown-4 and Oleic Acid through a Bulk Liquid Membrane

Tetraaza-14-crown-4 and oleic acid was successfully applied for transport of Cu(II) in chloroform bulk liquid membrane. The uphill moving of Cu(II) during the liquid membrane transport process has occurred. The main effective variable such as the type of the metal ion acceptor in the receiving phase and its concentration, tetraaza-14-crown-4 and oleic acid concentration in the organic phase on the efficiency of the ion-transport system were examined. By using L-cysteine as a metal ion acceptor in the receiving phase, the maximum amount of copper (II) transported across the liquid membrane was achieved to 96 ± 1.5% after 140 minutes. The selectivity of copper ion transport from the aqueous solutions containing Pb²⁺, Tl⁺, Ag⁺, Co²⁺, Ni²⁺, Mg²⁺, Zn²⁺, Hg²⁺, Cd²⁺ and Ca²⁺ ions were investigated. In the presence of CH₃COONH₄ and Na₄P₂O₇ as suitable masking agents in the source phase, the interfering effects of Pb⁺² and Cd²⁺ were diminished drastically.     

Coupled Transport of Zr(IV) through Tri-n-butylphosphate-Xylene-Based Supported Liquid Membranes

Abstract

The transport of Zr(IV) through tri-n-butylphosphate-xylene-based liquid membranes, supported in a polypropylene hydrophobic microporous film, has been studied. The concentration of HNO₃ in the feed solution and tri-n-butylphosphate (TBP) carrier in the membrane were varied, and the flux and permeability coefficients were determined. The optimum conditions found for maximum flux were determined to be 10 mol/dm³ HNO₃ and 2.93 mol/dm³ TBP with a flux value of 12.9 × 10^?6 mol · m^?2 · s^?1. The solvent extraction study revealed that 1.25 to 3.5 protons are involved in zirconium transport, and that two molecules of TBP are involved in the complex formation. The value of protons involved varies with acid concentration. The zirconium ion transport is coupled with nitrate ions transport.     

Transport of Hg2+ Ions across a Supported Liquid Membrane Containing Calix[4]arene Nitrile Derivatives as a Specific Ion Carrrier

Abstract

The transport behavior of Hg²⁺ from aqueous solution through a flat‐sheet‐supported liquid membrane (SLM) has been investigated by using of calix[4]arene derivatives (1 and 2) as carriers and Celgrad 2400 and 2500 as the solid support. The effect of solvent type and anions such as chloride and nitrate ions on the transport of Hg²⁺ was examined. Danesi mass transfer model was used to calculate the permeability coefficients for each parameter studied. The highest values of permeability were obtained with 2‐nitrophenyl ethyl ether (NPOE) solvent and the influence was found to be in the order, NPOE>chloroform>xylene. The transport efficiency on the supported liquid membrane was dependent on the type of carrier, its characteristics, and the type of the solvent.     

Characterization of a Macrocycle-Mediated Dual Module Hollow Fiber Membrane Contactor for Making Cation Separations

Abstract

Separation of metal cations in aqueous solution by a macrocyclemediated Dual Hollow Fiber Membrane Contactor is described. The advantages of this type of supported liquid membrane configuration include easily accessible source, receiving and membrane phases; transport rates competitive with those of other types of membranes; and the potential for continuous operation. The new system was investigated to determine the effect of aqueous solution flow rate and membrane solvent stirring rate on Na⁺ and K⁺ transport using dicyclohexano-18-crown-6 as the carrier. The results demonstrated that transport increases with increasing stirring speed, but remains constant with increased aqueous flow rate through the fibers within the range of four to twelve m1/min. The membrane solvents hexane, toluene, octane, 1-octanol, 4-methyl-2-pentanone, octanal, and 2-octanone were tested for their ability to preserve membrane integrity in the presence of aqueous solutions of low pH, and to maximize transport. Of these solvents, 2-octanone was found to be most effective in minimizing acid diffusion across the membrane, while giving the highest facilitated K⁺ transport rate. Quantitative transport using 18-crown-6 was observed for K⁺ over Na⁺ (all solvents studied) and Ba²⁺ and Sr²⁺ over Ca²⁺ (only octanol was studied).     

Two-Component Emulsion Liquid Membranes with Macromolecular Carriers of Divalent lons

Abstract

Experimental investigations are presented on the application of poly-[poly(ethylene glycol) phosphate] (PEGP) as a macromolecular, multisite, carrier of ions in an emulsion liquid membrane system. This polymer acts as a mobile carrier and surfactant-stabilizing W/O/W emulsion. The transport properties of PEGP have been checked for systems composed of (a) a feed phase containing Ni(II), Co(II) or Cu(II) ions; (b) an organic phase, i.e., PEGP dissolved in 1,2- dichloroethane; and (c) 1 M sulfuric acici as a receiving solution. Fast and effective membrane extraction of Ni(II) has been found for membranes with PEGP of molecular weight 22,000. It has been proved that the affinity of PEGP toward the studied ions is reversed in comparison with that for poly(ethylene glycol). The affinity order of PEGP toward the tested ions is Ni(II) > Co(II) > Cu(II).     

Separation of Silver(I) and Copper(II) from Aqueous Solutions by Transport through Polymer Inclusion Membranes with Cyanex 471X

In this work the selective transport of silver(I) and copper(II) ions from aqueous nitrate(V) solutions by transport through polymer inclusion membrane (PIM) has been studied. The membrane consisted of cellulose triacatate (CTA) as the polymeric support, o-nitrophenyl pentyl ether (ONPPE) as the plasticizer and Cyanex 471X (triisobutylphosphine sulphide) as the ion carrier. Ag(I) ions were effectively removed from the source phase by transport through PIM into 0.01 M Na₂S₂O₃ as the receiving phase. The influence of membrane composition on the transport of silver(I) ions has been evaluated.     

Studies on Cellulose Acetate/Low Cyclic Dimmer Polysulfone Blend Ultrafiltration Membranes and their Applications

Abstract

Flat sheet ultrafiltration membranes from cellulose acetate (CA)/low cyclic dimer polysulfone (LCD PSf) were prepared by a phase inversion method. N, N′‐Dimethyl formamide and different molecular weight of polyethylene glycol (PEG 200, PEG 400, and PEG 600) were used as solvent and pore‐forming additive, respectively. The membranes were characterized in terms of pure water flux, water content, porosity, membrane hydraulic resistance, and morphology. The pure water flux was found to reach the highest value of 181.82 Lm^?2h^?1 at 5 wt.% PEG of 600 molecular weight and 10 wt.% LCD PSf content in the blended solution for membrane preparation. SEM micrographs indicated that the addition of PEG into the CA/LCD PSf solution changes the inner structure of the membrane. The influence of filtration time and applied pressure on membrane permeability was examined by copper/polyethylenimine complex rejection studies. With increase in filtration time, the rejection of the copper/polyethylenimine complex decreased and the results were discussed.     

Coupled transport of copper through different commercial supports containing LIX 984 as carrier

The coupled transport of copper(II) ions through a supported liquid membrane containing LIX 984 as the mobile carrier dissolved in kerosene has been studied. Many commercial membrane supports were investigated at different stirrer speeds in a permeation cell. An equation describing the permeation rate has been derived, taking into account stagnant layer aqueous diffusion and liquid membrane diffusion. By means of this treatment the copper overall transfer resistance and the experimental determination of the effective porosity factor (ε/τ), for each support have been performed. The Accurel^® 2E-PP membrane showed a relatively high value of ε/τ (0·91), which makes this membrane an adequate support when the transport properties of the supported liquid membrane are concerned. © 1998 SCI     

Analysis of Extraction of Cu(II) by Strip Dispersion Hybrid Liquid Membrane (SDHLM) using PMBP as Carrier

A liquid membrane system, denoted a strip dispersion hybrid liquid membrane (SDHLM) containing 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazolone –5 as carrier in xylene, was reported for the transport and separation of Cu(II) from Zn (II) ions. The effects of various factors on the transport of copper(II) ions through SDHLM were systematically investigated by orthogonal tests. The optimum transport conditions of copper ions were summarized. In the overall mass transfer process the mass transfer resistance due to the aqueous boundary layer diffusion and diffusion in the microporous membrane is dominant. The accumulation of the Cu(II)‐carrier coordination compound in the membrane shows that the transfer in SDHLM possesses the characteristic of nonequlibrium mass transfer in this study. The rheologic experiments verified that the organic phase in the SDHLM system was the non‐Newtonian fluid and the organic phase after transport of 6 hr was a system of thixotropy in our experimental conditions. The lag ring experiments proved that the thixotropy of the organic phase in the SDHLM system was relevant to the composition of the membrane. In the experimental comparison of two types of liquid membrane, SDHLM has superiority over SLM in respect of transport flux, permeability coefficient, recovery percentage or concentration of solute in the stripping solution, efficiency of uphill transport, loss of membrane solution, and the separation efficiency of the membrane.     

Copper removal from acidic wastewaters using 2-hydroxy-5-nonylbenzaldehyde oxime as ionophore in pseudo-emulsion membrane with strip dispersion (PEMSD) technology

Results on Cu(II) extraction from acidic media through pseudo-emulsion based membrane strip dispersion (PEMSD) containing Acorga M5640/Iberfluid as organic phase in the form of a pseudo-emulsion with H₂SO₄ were presented. The transport of Cu(II) is investigated as a function of several experimental variables: hydrodynamic conditions, feed solution pH, Acorga M5640 (salicylaldoxime derivative) concentration in the organic solution, and initial metal concentration in feed phase. In this membrane technology, pseudo-emulsion is an emulsion that is formed temporarily between organic and stripping solutions, both solutions are completely separated when mixing is stopped. The value of the overall mass transfer coefficient obtained under standard experimental conditions was 5.5 × 10^?3 cm/s, being the recovery of copper in the stripping solution around 80–85%. The influence of the membrane support, the selectivity of Acorga M5640/Inerfluid based PEMSD towards different metals (Fe(III), Ni(II), Co(II), Zn(II), Cr(III)) an the performance of the system Cu/Acorga M5640/Ibefluid against other commercially available salicylaldoximes (LIX 860, Acorga PT5050) were also examined.     

Transport of mercury(II) ion through a supported liquid membrane containing a triisobutylphosphine sulfide (Cyanex 471X) as a mobile carrier

Carrier‐facilitated transport of mercury(II) against its concentration gradient from aqueous 0.1 mol dm^?3 hydrochloric acid solution across a flat‐sheet supported liquid membrane (SLM) containing triisobutylphosphine sulfide (Cyanex 471X) as the mobile carrier in kerosene as diluent has been investigated. Dilute sodium thiocyanate solution (0.11 mol dm^?3) was the most efficient stripping agent among several aqueous reagents tested. Various parameters such as stirring rate, concentration of HCl in the feed solution, concentration of NaSCN in the strippant, concentration of Cyanex 471X in the membrane, and contact time were investigated. Under optimum conditions the transport of Hg(II) across the liquid membrane is about 100% after 6 h. The carrier, Cyanex 471X, selectively and efficiently transported Hg(II) ions in the presence of other associated metal ions. The method has been demonstrated to recover selectively mercury from waste samples and mercurochrome solution. © 2002 Society of Chemical Industry