Characterization of a supported liquid membrane for macrocycle-mediated selective cation transport

Lamb, John D.; Bruening, Ronald L.; Izatt, Reed M.; Hirashima, Yoshiyuki; Tse, Pui-Kwan; Christensen, James J.

doi:10.1016/s0376-7388(00)85066-8

Cited by 50 publications

(21 citation statements)

References 27 publications

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“…Because the membrane was then placed in contact with aqueous donor and receiver solutions, it was vital that the organic solvent be immiscible in water. A comparison (18) indicates that phenylhexane is the solvent with the lowest water solubility, followed by decanol.…”

Section: Methodsmentioning

confidence: 99%

“…The membrane was impregnated with the crown ether dicyclohexano-18-crown-6 (DC18C6), which has a cavity size selective for lead (9,17,18). The lead-containing solution was introduced to the donor compartment of the membrane cell, and the receiver side was monitored for the appearance of transported lead.…”

Section: Characterization Of Transportmentioning

confidence: 99%

“…To calculate the amount of Pb in the sample present as Pb(NO 3 ) 2 , an iterative approach to the systematic treatment of equilibrium was taken. Using the β (log stepwise formation constant) values (18) for the formation of PbNO 3 + and Pb(NO 3 ) 2 (2.14 and 2.15, respectively) and the sample concentration of 1000 mg L -1 for the total amount of Pb, it was possible to compute [Pb 2+ ] from the mass balance equation for lead. This value for [Pb 2+ ] was used, along with the appropriate β value and the concentration of unbound NO 3 -in solution, to obtain the concentration of Pb(NO 3 ) 2 .…”

Section: Mechanism Of Transport and Calculationsmentioning

confidence: 99%

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Comparison of supported liquid membranes and solid-phase extraction for quantitative removal of lead from aqueous solutions

Yourd¹,

Tyson²

2003

Can. J. Chem.

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The selective transport of a target metal ion across a membrane from a donor to an acceptor solution is an attractive concept for preconcentration or separation in a flow injection (FI) system. However, we found that the transport of lead across a supported liquid membrane consisting of dicyclohexano-18-crown-6 in decanol embedded in Celgard 2400 was too slow to be practical for an FI atomic spectrometry system. On the other hand, the same chemistry in an on-line, solid-phase reactor (a mini-column containing Pb-Spec resin) gave a satisfactory performance. In an attempt to understand the kinetics of the system, we have calculated the rate of transport across the membrane. As flux is proportional to concentration on the donor side -which decreases with time -we performed a series of numerical simulations involving fixed time intervals of decreasing values. These calculations show that for the sizes of membranes in a typical FI system, transport is very slow compared with the adsorption of lead by the Pb-Spec resin: it takes about 100 min for the concentration in a 0.06 mL donor solution to decrease by a factor of 1000. The time required for the same decrease in concentration for a membrane having the same surface area and ligand concentration as the Pb-Spec column was calculated as approximately 9 s.Key words: supported liquid membrane, solid-phase extraction, flow-injection, lead. Résumé :Le transport sélectif d'un ion métallique cible à travers une membrane à partir d'un donneur vers une solution accepteuse est un concept attrayant pour la préconcentration ou la séparation dans un système à injection continue (IC). Cependant, nous avons trouvé que le transport du plomb à travers une membrane liquide incrustée dans un support, cette membrane est constituée de dicyclohexano-18-couronne-6 dans le décanol incorporé dans du Celgard 2400, est trop lent pour être pratique dans un système de spectrométrie atomique à injection continue (IC). Par ailleurs la même chimie en continu dans un réacteur en phase solide (une mini colonne contenant une résine Pb-Spec), a donné une performance satisfaisante. Dans une tentative pour comprendre la cinétique du système, nous avons calculé la vitesse de transport à travers la membrane. Comme le flux est proportionnel à la concentration du côté du donneur, laquelle diminue avec le temps, nous avons réalisé une série de simulations numériques impliquant des intervalles de temps fixes de valeurs décroissantes. Ces calculs montrent que, compte tenu des dimensions des membranes dans un système typique à injection continue, le transport est très lent comparativement à l'adsorption du plomb par la résine Pb-Spec; il faut environ 100 minutes pour que la concentration dans 0,06 mL d'une solution donneuse décroisse d'un facteur de 1000. Le temps requis pour la même diminution de concentration dans le cas d'une membrane ayant la même superficie et la même concentration de ligand dans une colonne de Pb-Spec est selon les calculs approximativement de 9 s.

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Section: Methodsmentioning

confidence: 99%

Section: Characterization Of Transportmentioning

confidence: 99%

Section: Mechanism Of Transport and Calculationsmentioning

confidence: 99%

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Comparison of supported liquid membranes and solid-phase extraction for quantitative removal of lead from aqueous solutions

Yourd¹,

Tyson²

2003

Can. J. Chem.

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“…[18] Lamb et al also described facilitated transport through a liquid membrane of cyclohexyl phenyl ether as ion pairs. [19] In our previous studies, we assumed that cation-facilitated transport of salts through NPOE occurs as solvent-separated ions [15] as the polarity of the solvent is relatively high (e r 24) and the concentrations of salt in the membrane phase are relatively low.…”

mentioning

confidence: 99%

“…Competition experiments: The selectivity S for the transport of H 2 PO À 4 in the presence of Cl À is defined by Equation (19).…”

mentioning

confidence: 99%

Facilitated Transport of Salts by Neutral Anion Carriers

Chrisstoffels¹,

Jong²,

Reinhoudt³

2000

Chem. Eur. J.

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Partitioning of ions from water to the membrane solvent (NPOE) can be quantified by Gibbs free energies of transfer, deltaG(tr,NPOE)(ion). These were derived from transport studies of lipophilic salts through supported liquid membranes (SLMs) in the absence of the carrier. Partition coefficients Kp for various salts can now be calculated. The neutral anion receptors uranyl sal(oph)enes 1-5 transport Cl- and H2PO4- as tetrapropylammonium salts. The transport is diffusion-limited and can be described by two transport parameters Dm and K(ex). From the extraction constants K(ex) and the partition coefficients Kp of the transported salts, the association constants Ka of the anion receptors for Cl- and H2PO4- in NPOE were determined. Competitive transport with carriers 3 and 4 of NPr4H2PO4 and NPr4Cl demonstrated highly selective transport of H2PO4- even in the presence of excess of Cl-.

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Facilitated Transport of Salts by Neutral Anion Carriers

Chrisstoffels¹,

Jong²,

Reinhoudt³

2000

Chem. Eur. J.

View full text Add to dashboard Cite

Partitioning of ions from water to the membrane solvent (NPOE) can be quantified by Gibbs free energies of transfer, DG tr,NPOE (ion). These were derived from transport studies of lipophilic salts through supported liquid membranes (SLMs) in the absence of the carrier. Partition coefficients K p for various salts can now be calculated. The neutral anion receptors uranyl sal(oph)enes 1 ± 5 transport Cl À and H 2 PO À 4 as tetrapropylammonium salts. The transport is diffusion-limited and can be described by two transport pa-rameters D m and K ex . From the extraction constants K ex and the partition coefficients K p of the transported salts, the association constants K a of the anion receptors for Cl À and H 2 PO À 4 in NPOE were determined. Competitive transport with carriers 3 and 4 of NPr 4 H 2 PO 4 and NPr 4 Cl demonstrated highly selective transport of H 2 PO À 4 even in the presence of excess of Cl À .

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Characterization of a supported liquid membrane for macrocycle-mediated selective cation transport

Cited by 50 publications

References 27 publications

Comparison of supported liquid membranes and solid-phase extraction for quantitative removal of lead from aqueous solutions

Comparison of supported liquid membranes and solid-phase extraction for quantitative removal of lead from aqueous solutions

Facilitated Transport of Salts by Neutral Anion Carriers

Facilitated Transport of Salts by Neutral Anion Carriers

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