Selective and Efficient Liquid Membrane Transport of Thallium (III) Ion by Potassium‐dicyclohexyl‐18‐crown‐6 as Specific Carrier

Abstract

Potassium‐dicyclohexyl‐18‐crown‐6 was used as a selective and efficient carrier for the uphill transport of thallium (III) ion as [TlCl₄]^? complex ion through a chloroform bulk liquid membrane. By using oxalate anion as a metal ion acceptor in the receiving phase, the amount of thallium (III) transported across the liquid membrane after 120 min was 96±2%. The selectivity and efficiencies of thallium transport from aqueous solutions containing Cu²⁺, Zn²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Co³⁺, Mn²⁺ _, Cr³⁺, Mg²⁺, Ca²⁺, K⁺, Na⁺, and Fe³⁺ ions were investigated. In the presence of Na₃PO₄ (0.01 M) at pH=3 as a suitable precipitation agent in the source phase, the interfering effect of Pb²⁺ ion were diminished drastically.     

Highly Efficient Cooperative Membrane Transport of Lead(II) Ions by Aza-18-crown-6 and Palmitic Acid

Abstract

A chloroform membrane system containing a given mixture of aza-18-crown-6 and palmitic acid was applied for the uphill transport of Pb²⁺ ions. In the presence of P₂O₇ ^4? ion as a suitable metal ion acceptor in the receiving phase, the amount of lead ion transported across the liquid membrane after 100 minutes is 89.1 ± 1.3%. The selectivity and efficiency of lead transport from aqueous solutions containing other cations such as Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, Fe²⁺, Pd²⁺, and Ag⁺ ions were investigated. In the presence of S₂O₃ ^2? ion as a proper masking agent in the source phase, the interfering effects of Cu²⁺ ion were diminished drastically.     

A selective uphill transport of copper through bulk liquid membrane using Janus Green as an anion carrier

A bulk liquid membrane consisted of 1.8×10⁻⁴ M Janus Green in chloroform that placed between an aqueous source phase containing 0.5 M sodium thiocyanate at pH 7 and an aqueous receiving phase with 0.1 5 M histidine at pH 7 results in an uphill transport of copper from the source phase to the receiving phase. The amount of copper transport through the liquid membrane after 180 min was 97.0±1.7%. The presence of other metals such as Cd²⁺, Zn²⁺, Hg²⁺, Mg²⁺, Ag¹⁺, Ni²⁺, Pb²⁺, Fe³⁺, K¹⁺, Co²⁺ doesn't change the efficiency of copper transport.     

Selective Transport of Copper(I,II), Cadmium(II), and Zinc(II) Ions through a Supported Liquid Membrane Containing Bathocuproine,Neocuproine, or Bathophenanthroline

Abstract

Some selective transport systems for heavy metallic ions through a supported liquid membrane (SLM) containing a 2,2′-dipyridyl derivative ligand, 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline (bathocuproine), 2,9-dimethyl-1,10-phenanthro-line (neocuproine), or 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline), were investigated. The transport of copper(I, II), cadmium(II), zinc(II), lead(II), and cobalt(II) ions was accomplished with a halogen ion such as chloride, bromide, or iodide ion as a pairing ion species for any SLM. The ranking of the permeability of the metallic ions was Cu^+,2+, Zn²⁺, Cd²⁺ ? Pb²⁺, Co²⁺. When the oxidation-reduction potential gradient was used as a driving force for metallic ions, the transport of Cu⁺ ion was higher than those of Cd²⁺ and Zn²⁺ ions for any SLM containing bathocuproine, neocuproine, or bathophenanthroline. On the other hand, in the transport system which used the concentration gradient of pairing ion species, the permeability of the Cu²⁺ ion decreased whereas that of the Cd²⁺ ion increased. Moreover, it was found that the different selectivity for the transport of metallic ions is produced by using various pairing ion species.     

Macrocycle-Mediated Transport in a Bulk 1.5 M HNO3-CHCI3-0.01 M HNO3 Membrane System of Pd2+ and Mn+ from Pd2+Mn+ Mixtures

Abstract

Pd²⁺ has been transported using sulfur substituted macrocycles as carriers and several Mⁿ⁺ (Mⁿ⁺ = Lⁱ⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ag⁺, TL⁺, Cd²⁺, and Pb²⁺) have been transported using 18-crown-6 (18C6) and sulfur substituted macrocycles as carriers in a 1.5M HN0₃/CHCL₃3/0.01M HNO₃ bulk liquid membrane system. Competitive Pd²⁺-Mⁿ⁺ transport studies have also been carried out for the same systems. The cyclic polyether 18C6 transports Mⁿ⁺ selectively over Pd²⁺ for all Mⁿ⁺ except Li⁺, Mg²⁺, and Cd²⁺. In the cases of these three cations, no transport was found for either Pd²⁺ or Mⁿ⁺. Generally, the sulfur substituted macrocycles transport Pd²⁺ selectively over Mⁿ⁺.     

Effect of Macrocycle Type on Pb2+ Transport through an Emulsion Liquid Membrane

Abstract

The relative effectiveness of 14 different macro-cycles in transporting Pb(NO₃)₂ has been determined at 25 °C using a water-toluene-water emulsion membrane system. The largest amount of Pb²⁺ transport was found with dideeyl-1,1O-diaza-18-crown-6 (91%), followed by dicyclohexano-18-crown-6 (81%), di-tert-butyl-dicyclohexano-l8-crown-6 (77%), 1,10-diaza-18-crown-6 (27%), and cryptand 2.2.1 (4,7,13,16,21,24-pentoxa-1,10-diazabicyclo(8, 8, 5)-tricosane) (16%). The use of the other macrocycles produced little Pb²⁺ transport. Analysis of the transport results shows that, for most effective transport, the macrocycle should distribute preferentially to the organic phase and the log K value for the binding of the macrocycle with Pb²⁺ must be large enough for quantitative extraction of the Pb2 + into the membrane. However, this log K value must be sufficiently smaller than that for interaction of Pb²⁺ with P₂O₇ ^4?, the receiving phase complexing agent, to allow a large Pb²⁺ concentration gradient to be established. These features provide information which should be useful in designing systems for cation separations using emulsion membranes.     

Effect of Macrocycle Type on the Extraction into Toluene of Ag+, Pb2+, and Cd2+ Using a Combination of a Macrocycle and Di(2-ethylhexyl)phosphoric Acid as Extractants

Abstract

The nitrate salts of Ag⁺ and Pb²⁺ are extracted into toluene solutions of one of the following macrocycles: dicyclohexano-18-crown-6 (DC18C6); 1,10-dithia-18-crown-6 (DT18C6); 1,10-diaza-18-crown-6 (2.2); hexathia-18-crown-6 (HT18C6); or cryptand 2.2.1. In addition, the nitrate salt of Cd²⁺ is extracted into toluene solutions of DC18C6 or DT18C6. Ag⁺, Pb²⁺, and Cd²⁺ are also extracted into toluene containing di(2-ethylhexyl)phosphoric acid (HDEHP) and toluene containing a combination of HDEHP and one of the macrocycles. Metal ion extraction is synergistic for the systems containing HDEHP and DC18C6, 2.2, or 2.2.1, but is antagonistic for the systems containing HDEHP and DT18C6 or HT18C6.     

Effect of Receiving Phase Anion on Macrocycle-Mediated Cation Transport Rates and Selectivities in Water—Toluene—Water Emulsion Membranes

Abstract

Relative transport rates of metal nitrates (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, T1⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Zn²⁺, and Pb²⁺) were measured alone and in combination with either Pb²⁺, Ag⁺, or T1⁺ in a water-toluene-water emulsion membrane system. The toluene phase contained the surfactant Span 80 and the crown ether dicyclohexano-18-crown-6 (DC18C6). The aqueous receiving phase contained the lithium salt of one of the following anions: pyrophosphate, thiosulfate, hydroxide, chloride, formate, nitrate. In the case of the metal combinations, chloride and formate ions were not studied. Unless significant complexation occurred both between the transported cation and the anion in the receiving phase and between the cation and DC18C6 in the membrane phase, there was little or no transport of the cation from the source phase to the receiving phase. Selective removal of Pb²⁺ and of Ag⁺ from binary mixtures of these cations with each of the cations listed was demonstrated using the emulsion membrane.     

Rapid Separation of Tl+ and Pb2+ from Various Binary Cation Mixtures Using Dicyclohexano-18-crown-6 Incorporated into Emulsion Membranes

Abstract

Relative transport rates of metal cation nitrates (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Tl⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺) in a water-toluene-water emulsion membrane system were measured. The toluene component contained the surfactant Span 80 and the crown ether dicyclohexano-18-crown-6. The aqueous receiving phase contained Li₄P2O₇. When each metal cation was individually present in the aqueous source phase, metal extraction was complete within 10 min with the order of extraction being Tl⁺ > Cs⁺ > Ag⁺ > Rb⁺ > K⁺ ≥m Na⁺ and Pb⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺ for uni-and bivalent cations, respectively. Significant extraction was found for all cations except Na⁺, K⁺, and Ba²⁺. Some metal ions were concentrated nearly 10-fold in a 10-min period. Relative transport rates were determined when binary cation mixtures of either Tl⁺ or Pb²⁺ were present at equal concentrations with each of the remaining metal ions in the source phase. Tl⁺, when present with either Na⁺, Cs⁺, or Rb⁺, was selectively extracted from the source phase. Complete and nearly exclusive extraction of Pb²⁺ was observed in the presence of all cations including Tl⁺. The enrichment ratios of Pb²⁺ in the binary mixtures were approximately 10 while those of the second cation were less than 0.5 except for Sr²⁺ which was 0.86. Corresponding separation factors for Pb²⁺ ranged from 1000 to > 6000.     

Coupled transport of Pb2+ through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membranes

Transport of Pb²⁺ was carried from acidic solution into alkaline stripping phase through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membrane. The transport of Pb²⁺ through the membrane was studied by varying the concentration of Pb²⁺ and HNO₃ in feed solution, NaOH concentration in strip solution and TOA concentration in membrane phase. The flux data obtained has been used to study the stoichiometry of complex Pb(NO₃)_n+2(HNR₃)_n. The supported liquid membrane (SLM) has been found stable for 10 runs with 24 h between each run. This SLM has been used effectively to extract lead ions along with chromium, copper and zinc ions from aqueous acidic leached solution of paint and industrial effluents. © 2012 Canadian Society for Chemical Engineering     

Cation Transport at 25°C from Binary Cd2+–Mn+ Mixtures in a H2O-CHCl3–H2O Liquid Membrane System Containing a Series of Macrocyclic Carriers[1]

Macrocycle-mediated fluxes of Cd(NO₃)₂ and of several binary mixtures of Cd(NO₃)₂ with the nitrate salt of either Na⁺, K⁺, Rb⁺ Cs⁺, Ag⁺, Ca²⁺, Sr²⁺, Pb²⁺, Zn²⁺, or Cu²⁺ have been determined in a H₂O-CHCl₃–H₂O liquid membrane system. Of the macrocycles studied, 2.2 and 2.2DD most successfully transported Cd²⁺ In the Cd²⁺–Mⁿ⁺ mixtures, Cd²⁺ was transported selectively with 2.2 when Mⁿ⁺ was either an alkali or an alkaline earth cation. However, when Mⁿ⁺ was either Ag⁺, Pb²⁺, or Cu²⁺ the Cd²⁺ flux was reduced sharply. Generally, cation flux was greater for 2.2DD than for 2.2 with selectivity for Cd²⁺ being altered also in several cases. Relative fluxes from binary cation mixtures depend on metal cation radius, macrocycle cavity diameter, ligand ring substituent and log K for metal ion-macrocycle interaction.     

Metal Separations Using Emulsion Liquid Membranes

Abstract

Emulsion membrane systems consisting of an aqueous metal salt source phase, a toluene membrane containing the macrocyclic ligand dicyclohexano-18-crown-6 (DC18C6) (0.02 M) and the surfactant sorbitan monooleate (3% v/v), and an aqueous 0.05 M Li₄P₂O₇ receiving phase were studied with respect to the disappearance of metal from the source phase as a function of time. The salts Pb(NO₃)₂, Sr(NO₃)₂, TINO₃, and LiNO₃ were studied both singly and in mixtures of Pb(NO₃)₂ with each of the other salts. In all mixtures studied, Pb²⁺ was transported first, followed by the second cation (except Li⁺ which was not transported). An excess of a second salt with a common anion enhanced the transport of Pb²⁺. Modeling of these systems was discussed. Source phases containing basic (pH 11) K[Al(OH)₄] solutions were studied using the same membrane and a 0.15 M H₃PO₄ receiving phase. K⁺ and Al(III) (as aluminate anion) were both found to transport in this system, but no transport of Al(III) and little transport of K⁺ were detected when DC18C6 was absent.     

Specific membrane transport of silver and copper as Ag(CN)3 and Cu(CN)4 ions through a supported liquid membrane using K-crown ether as a carrier

Facilitated transport of silver and copper from cyanide solutions through a supported liquid membrane (SLM) containing K⁺-crown ether as a carrier is described. The SLM used is a thin porous polypropylene (Celgard 2500, 2400) membrane impregnated with dibenzo-18-crown-6 (DB18C6), diaza-18-crown-6 (DA18C6), hexathia-18- crown-6 (HT18C6) and hexaaza-18-crown-6 (HA18C6) dissolved in a mixture of ethanol/chloroform (v/v). K₋⁺-crown ether showed a high efficiency to carry silver and copper as Ag(CN)₃²⁻ and Cu(CN)₄³⁻ species through the SLM. However, the mass flux of both silver and copper ions decreases when concentration of cyanide ions in the feed phase increases due to the difference in stability of the complexes M(CN)_nⁿ⁻(M=Ag, Cu) when n increases from 2 to 4. This was related to the partition of the species in the aqueous phase using a theoretical model.     

Synthesis of SPR Nanosensor using Gold Nanoparticles and its Application to Copper (II) Determination

This research describes a colorimetric assay for Cu (II) ions that is highly selective over other metal ions. It is based on the measurement of changes in the surface plasmon resonance absorbance (at 525 nm) of gold nanoparticles (Au NPs) modified with 1,7-diaza-15-crown-5 (Crown-Au NPs). The unique structure of crown ethers and presence of heteroatoms enable the crown-Au NPs to recognize very low concentrations of Cu (II) ions. After aggregation, the surface plasmon absorption band has a red shift so that the nanoparticle solution shows a violet color. The TEM images data show that this color change is a result of crown-Au NPs aggregation upon addition of Cu (II), In contrast, other metal ions Al³⁺, Ca²⁺, Cd²⁺, Co²⁺, Cr³⁺, Ag⁺, Fe²⁺, Fe³⁺, Hg²⁺, K⁺, Mg²⁺, Mn²⁺, Na⁺, Ni²⁺, Pb²⁺, and Zn²⁺ do not aggregate. The recognition mechanism is attributed to the formation of a sandwich (2+1) between the Cu (II) ion and two diaza-15-crown-5 moieties that are attached to separate nanoparticles. This simple and fast method can be used to determine the Cu (II) ions with a detection limit as low as 200 nM.     

Competitive Adsorption of Ag+, Pb2+, Ni2+, and Cd2+ Ions on Vermiculite

Competitive adsorption of Ag⁺, Pb²⁺, Ni²⁺, and Cd² ions on vermiuculite in a binary, ternary, and quaternary mixture was investigated in batch experiments. The effects of the presence of Ag⁺, Ni²⁺, and Cd²⁺ ions on the adsorption of Pb²⁺ ions were investigated in terms of the equilibrium isotherm. Experimental results indicated that Pb²⁺ ions always favorably adsorbed on vermiculite over Ag⁺, Ni²⁺, and Cd²⁺ ions. The adsorption equilibrium data of Pb²⁺ ions better fitted the Langmuir model than the Freundlich model. The results showed that the pseudo-second-order kinetics model was in good agreement with the experimental results for all metal ions, and the adsorption rate among the metal ions followed Ag⁺ > Pb²⁺ > Ni²⁺ > Cd²⁺. The desorption and regenration study indicated that vermiculite can be used repeatedly and be suitable for the design of a continuous process.     

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.     

Poly(2‐acrylamido glycolic acid‐co‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid): Synthesis,characterization, and retention properties for environmentally impacting metal ions

Poly(2‐acrylamido glycolic acid‐co‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) [P(AGA‐co‐APSA)] was synthesized by radical polymerization in an aqueous solution. The water‐soluble polymer, containing secondary amide, hydroxyl, carboxylic, and sulfonic acid groups, was investigated, in view of their metal‐ion‐binding properties, as a polychelatogen with the liquid‐phase polymer‐based retention technique under different experimental conditions. The investigated metal ions were Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, and Cr³⁺, and these were studied at pHs 3, 5, and 7. P(AGA‐co‐APSA) showed efficient retention of all metal ions at the pHs studied, with a minimum of 60% for Co(II) at pH 3 and a maximum close to 100% at pH 7 for all metal ions. The maximum retention capacity (n metal ion/n polymer) ranged from 0.22 for Cd²⁺ to 0.34 for Ag⁺. The antibacterial activity of Ag⁺, Cu²⁺, Zn²⁺, and Cd²⁺ polymer–metal complexes was studied, and P(AGA‐co‐APSA)–Cd²⁺ presented selective antibacterial activity for Staphylococcus aureus with a minimum inhibitory concentration of 2 μg/mL. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The competitive heavy metal removal by hydroxyethyl cellulose-g-poly(acrylic acid) copolymer and its sodium salt: The effect of copper content on the adsorption capacity

Summary Crosslinked hydroxyethyl cellulose-g-poly(acrylic acid) (HEC-g-pAA) graft copolymer was prepared by grafting of acrylic acid (AA) onto hydroxyethyl cellulose (HEC) using [Ce(NH₄)₂(NO₃)₆]/HNO₃ initiator system in the presence of poly(ethyleneglycol diacrylate) (PEGDA) crosslinking agent in 1:1 (v/v) mixture of methanol and water at 30 °C. Carboxyl content of copolymer was determined by neutralization of –COOH groups with NaOH solution and sodium salt of copolymer (HEC-g-pAANa) was swelled in distilled water in order to determine the equilibrium swelling value of copolymer. Both dry HEC-g-pAA and swollen HEC-g-pAANa copolymers were used in the heavy metal ion removal from three different aqueous ion solutions as follows: a binary ion solution with equal molar contents of Pb²⁺and Cd²⁺, a triple ion solution with equal molar contents of Pb²⁺, Cu²⁺ and Cd²⁺, and a triple ion solution with twice Cu²⁺molar contents of Pb²⁺and Cd²⁺. Higher removal values on swollen HEC-g-pAANa were observed in comparison to those on dry polymer. The presence of Cu²⁺decreased the adsorption values for Pb²⁺ and Cd²⁺ ions on both types of HEC copolymer. However, with further increase in Cu²⁺ content both dry and swollen copolymers became apparently selective to Cu²⁺ removal and Cu²⁺ removal values exceeded the sum of adsorption values for Pb²⁺ and Cd²⁺. Maximum metal ion removal capacities were 1.79 and 0.85 mmol Me²⁺/g_polymer on swollen HEC-g-pAANa and dry HEC-g-pAA, respectively.     

Facilitated Transport of Cadmium Ions from Hydrochloric Acid Solutions through a Liquid Membrane Containing Dicyclohexyl‐18‐Crown‐6 as Extractant‐Carrier

Abstract

The transport of cadmium ions from hydrochloric acid solutions across a bulk liquid membrane by using dicyclohexyl‐18‐crown‐6 (DC18C6) dissolved in dichloromethane has been studied at 25°C. The effect of the fundamental parameters influencing the transport, e.g., hydrochloric acid concentration in the feed phase, DC18C6 concentration and the type of diluent used in the membrane and time of transport have been investigated. The transported amount of the cadmium ions (initial concentration 0.001 M) from a 6 M hydrochloric acid solution across a dichloromethane solution of DC18C6 (0.05 M) into distilled water (receiving phase) was found to be 98.3 (±1.8) percent after 6 h. The selectivity and efficiency of the method toward cadmium ions were tested by performing the competitive transport experiments on the mixtures containing Cd²⁺, Ni²⁺, Mn²⁺, Co²⁺, Zn²⁺, Pb²⁺, and Fe²⁺ ions. The best selectivity was found for the recovery of the cadmium ions from its mixture with Ni²⁺, Mn²⁺, Co²⁺, and Pb²⁺ ions. Thus, the method can be proposed for the application in cadmium recovery from the sources containing these ions such as spent rechargeable nickel‐cadmium batteries.     

Evaluation of a (E,E)‐Dioxime Containing Two 15‐Membered Dioxatrithiamacrocycles and its Mononuclear Ni(II) Complex as Ag+ Extractants

Abstract

A macrocyclic vic‐dioxime (1) and its mononuclear Ni(II) complex (2) were studied as extractant. The aqueous solutions of Ag⁺, Mn²⁺, Pb²⁺, Ni²⁺, Cu²⁺, Cd²⁺, and Zn²⁺ picrates were used for extraction experiments. The solutions of the ligands in two different organic solvents were used as organic phases. The metal picrate extractions were carried out at 25±0.1°C by using UV‐visible spectrometry. The most effective transport was observed for Ag⁺ picrate among the tested metal picrates. The effect of pH on the extraction of Ag⁺ picrate was evaluated with the ligands. The ratio of extracted Ag‐complex to chloroform phase was 2:1 (L:M) for (2). In other cases the ratios were 1:1 for both (1) and (2). Molar ratio method was also used to demonstrate the composition. The values of the extraction constants (log K_ex) were determined for the extracted Ag‐complexes.