Donnan Effects in the Steady-State Diffusion of Metal Ions through Charged Thin Films

Yezek, Lee P.; Leeuwen, Herman P. van

doi:10.1021/la050159v

Cited by 40 publications

(51 citation statements)

References 27 publications

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“…From consideration of Eqns 4 and 5 it appears that at these low ionic strengths the Donnan potential resulting from the gel charge is not negligible. [44] Sangi et al [45] had earlier used bis gels (0.8 g of bis and 30 g of acrylamide in 3. Schematic diagram of the concentration gradients of a cation at steady-state through a diffusive gradients in thin films (DGT) device when the gel is negatively charged, assuming that the filter membrane is not charged.…”

Section: Inert Diffusive Gel?mentioning

confidence: 99%

“…Adapted from Yesek and van Leeuwen. [44] (DBL, diffusive boundary layer.) 100 mL of gel solution) in DGT to measure metals in situ in a stream with a very low ionic strength.…”

Section: Inert Diffusive Gel?mentioning

confidence: 99%

“…[41] Several papers authored by van de Veeken and van Leeuwen [46][47][48] state that there is a negative charge on the APA gel, but they refer to their measurements made using bis gels. [43,44] Even for their bis gels they found it difficult to measure a Donnan potential at I ¼ 1 mM. The restricted gel that has been used in DGT is a bis crosslinked gel of a different composition (0.8 g of crosslinker and 15 g of monomer).…”

Section: Inert Diffusive Gel?mentioning

confidence: 99%

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Progress in understanding the use of diffusive gradients in thin films (DGT) – back to basics

2012

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Environmental context. It is now nearly 20 years since the introduction of the technique of diffusive gradients in thin films, which can provide information on solute concentrations and dynamics in sediments, soils and water. The interpretation of these measurements in terms of concentrations relies on simple equations and associated assumptions. This review examines how well they have stood the test of time.Abstract. Diffusive gradients in thin films (DGT) is now widely used to measure a range of determinands in waters, soils and sediments. In most cases the mass accumulated is interpreted in terms of a labile form of the component being measured using a simple equation that applies to steady-state conditions. During the past decade several publications have revealed phenomena that question some of the assumptions necessary for use of the simple equation. This review systematically examines the available evidence relating to appropriate geometry, possible charge effects, binding of solutes and ligands to the diffusive gel and filter, the rate of reaction with the binding layer, the effects of solution complexation and kinetic limitation, necessary time for deployment and the measurement of nanoparticles. DGT emerges as a robust monitoring tool for labile components in solution. Although there is evidence, for some conditions, of binding of metals and, more moderately, humic substances to the diffusive gel and filter membrane, this is unlikely to affect DGT measurement in natural waters for deployment times exceeding a few days. Detailed speciation and kinetic studies require a more thorough interpretation of the mass accumulated by DGT. A coherent theory has emerged for relatively simple solutions, but systems with complex heterogeneous ligands, as is the case for natural waters, are challenging. The size discrimination of DGT is still poorly known. Systematic measurements with well characterised nanoparticles are required to define the distribution of pore sizes in the gels and to establish the contribution of natural colloids to the DGT measurement.

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Section: Inert Diffusive Gel?mentioning

confidence: 99%

“…Adapted from Yesek and van Leeuwen. [44] (DBL, diffusive boundary layer.) 100 mL of gel solution) in DGT to measure metals in situ in a stream with a very low ionic strength.…”

Section: Inert Diffusive Gel?mentioning

confidence: 99%

Section: Inert Diffusive Gel?mentioning

confidence: 99%

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Progress in understanding the use of diffusive gradients in thin films (DGT) – back to basics

2012

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“…It must be noted however that ligand or metal interactions with the gel may drastically influence the values of the diffusion coefficients, as well as ion concentrations inside the gel and in turn the metal flux. These interactions include [21] chemical reactions as well as electrostatic effects, at ionic strength 61 mM, due either to non-homogeneous electric field inside the gel or Donnan potential between the gel and the solution, These effects should then be considered carefully, as discussed in [21,30]. (3) Finally, this works also points out two important practical results for in situ environmental monitoring.…”

Section: Discussionmentioning

confidence: 99%

Factors affecting the flux of macromolecular, labile, metal complexes at consuming interfaces, in water and inside agarose gel: SSCP study and environmental implications

Noël¹,

Buffle²,

Fatin‐Rouge³

et al. 2006

Journal of Electroanalytical Chemistry

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“…Several studies have quantified KCl aq flux through hydrogels as well [98,123,124], and determined theoretical models for ion transport [125]. Capillary pore diffusion and solution-diffusion models were used to describe solute diffusion through PMMA and other materials used as dialysis membranes [126].…”

Section: Solute Diffusionmentioning

confidence: 99%

A Bio-inspired Excitable Cardiac Cell Membrane from Electroactive Polymers: Ion Transport Studies

Moored

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The heart is an incredibly efficient biological pump, which contracts as a whole from the coordinated effort of millions of excitable cells called cardiac myocytes. These cells are considered excitable since they possess the ability to respond to a threshold activation signal, but only if sufficient time has passed and they have recovered from their previous excitation. Excitable cells also have the capacity to propagate an activation signal to their neighboring cells, and collectively are referred to as an excitable medium. Numerous examples of excitable media exist in nature, including the heart, forest fires, the intestine, nerves, and certain kinds of chemical reactions. Engineered artificial excitable media, however, have never been developed before.The long-term goal of this project, therefore, is to develop the first such artificial excitable medium from an array of artificial excitable cells, called gel-cells. The conceptual design of the gel-cell consists of a thin electroactive ion-gating membrane (polypyrrole), sandwiched between two layers of hydrated polymer (hydrogel) loaded with different concentrations of potassium chloride (KCl aq ) electrolytes. The voltage controlled artificial membrane initially confines ions to the upper chamber of the gelcell, and releases them upon membrane opening into the lower chamber, a process similar to membrane activation in cardiac myocytes. Potassium sensing electrodes embedded throughout the gel-cell provide feedback on the location and concentration of ions within the gel-cell, becoming markers for its activation. The scope of the research presented here was to construct the biomimetic cell membrane portion of the gel-cell, and study ion transport through its assembly.First, the electrochemical response of polypyrrole (PPy) was characterized via cyclic voltammetry, and its membrane morphology and thickness were observed via scanning electron microscopy. Experimentally obtained membrane thickness values were then compared to model predictions, which were subsequently improved by updating membrane density and structure assumptions. Hydrogel pore size approximations were correlated to equilibrium water content calculations, and KCl aq concentrations were quantified using electrochemical impedance spectroscopy. Time-resolved KCl aq flux experiments were performed on PPy membranes in solution, providing real-time concentration profiles of KCl aq as it passes through the membrane. From the parameter space tested, the optimal membrane preparation and gating potentials were selected which produced the highest flux rates. Time-lapse flux experiments (providing piece-wise concentration profiles for KCl aq ) were then performed on PPy membranes in both solution and hydrogel. Ion transport through two nearly identical membranes produced under different deposition conditions (PPy a and PPy b ) were compared in solution. The slightly denser and thicker membrane (PPy b ) produced nearly an order of magnitude higher flux rates than PPy a , suggesting that an active comp...

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Donnan Effects in the Steady-State Diffusion of Metal Ions through Charged Thin Films

Cited by 40 publications

References 27 publications

Progress in understanding the use of diffusive gradients in thin films (DGT) – back to basics

Progress in understanding the use of diffusive gradients in thin films (DGT) – back to basics

Factors affecting the flux of macromolecular, labile, metal complexes at consuming interfaces, in water and inside agarose gel: SSCP study and environmental implications

A Bio-inspired Excitable Cardiac Cell Membrane from Electroactive Polymers: Ion Transport Studies

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