Article

Streaming potential and streaming current measurements at planar solid/liquid interfaces for simultaneous determination of zeta potential and surface conductivity

Leibniz Institute of Polymer Research Dresden, Dresden, Saxony, Germany
Colloids and Surfaces A Physicochemical and Engineering Aspects (Impact Factor: 2.75). 11/2001; 192(1-3):205-213. DOI: 10.1016/S0927-7757(01)00725-7

ABSTRACT

Strongly encouraged and supported by Stanislav S. Dukhin the authors of this article recently designed, built and tested a new device for the simultaneous determination of zeta potential and surface conductivity from streaming potential and streaming current measurements across rectangular slit channels formed between two planar samples. In this Microslit Electrokinetic Set-up (MES) the planar samples are adjusted in parallel to form a channel of variable height which can become as narrow as about 1 μm. Due to this key feature of the device electrokinetic measurements can be performed at conditions where surface conductivity can be neglected and at conditions where surface conductivity provides a substantial part of the total channel conductivity. Utilizing the novel set-up, zeta potential and surface conductivity data can be obtained for a wide variety of materials which can be prepared as thin films on top of planar, macroscopic glass carriers. In order to demonstrate the potentialities of the advanced experimental technique of electrokinetic surface characterization we discuss three examples reflecting different levels of complexity of the analysed solid/liquid interface: (1) The charge formation at unpolar polymers without dissociating surface functions is studied referring to an inert, plasma-deposited fluoropolymer layer (PDFP) in simple electrolyte solutions. An extended evaluation of the experimental data of zeta potential and surface conductivity is given; (2) Further, grafted polypetide chains bearing dissociating side groups (polyglutamic acid and polylysine) were characterized with regard to the pH-depended variation of zeta potential and surface conductivity to provide new insights into the interrelation of charge density and conformation; (3) Finally, adsorbed fibrinogen on top of plasma-deposited fluoropolymer was studied by zeta potential and surface conductivity measurements as an example for highly hydrated macromolecular adsorption layers.

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    • "The direction of the resultant streaming potential relates to the positive or negative charges of a diffuse layer on colloidal surfaces. The measurement of streaming potential has been extensively used in the characterization of surface electric properties, of which the zeta potential is one of the most commonly referred and widely demanded information (Childress and Elimelech, 1996; Deshiikan et al., 1998; Deshmukh and Childress, 2001; Elimelech et al., 1994; Huisman and Trägårdh, 1999; Werner et al., 2001). Despite these investigations, streaming potential still remains to be regarded as a tool or indicator for colloidal characterizations instead of an influencing factor for solute transport through capillary porous media. "
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    ABSTRACT: Pollutant migration in dense clay barriers appears to be strongly influenced by the electric double layer of colloidal surfaces. Osmosis that resulted from chemical potential or electric potential difference across the clay membrane has been successively described in a number of theoretical works. Streaming potential (SP) which is present in charged porous medium under hydraulic gradient has been recognized as a significant factor governing the mass migration in compacted clays. However, few studies have been carried out in geo-environmental area with regard to this physical phenomenon. A coupled model was proposed to account for the effects of electrical, chemical and fluidic fields on solute transport in porous medium in this study. The electrical field deals with both the streaming potential and the externally applied electrical potential. The coupled nonlinear partial differential equations are numerically simulated by finite element method. Both the steady state solution and the time-dependent solution were investigated with the consideration of a series of influential factors. The streaming potential coefficient and the electro-osmotic coefficient were found to control the solute transport process. The potential application of the materials with tendency of producing SP was discussed. With appropriate selection of materials and parameters, optimum barring effect could be obtained for soil barriers in waste containment applications.
    Full-text · Article · Nov 2014 · Applied Clay Science
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    • "The direction of the resultant streaming potential relates to the positive or negative charges of a diffuse layer on colloidal surfaces. The measurement of streaming potential has been extensively used in the characterization of surface electric properties, of which the zeta potential is one of the most commonly referred and widely demanded information (Childress and Elimelech, 1996; Deshiikan et al., 1998; Deshmukh and Childress, 2001; Elimelech et al., 1994; Huisman and Trägårdh, 1999; Werner et al., 2001). Despite these investigations, streaming potential still remains to be regarded as a tool or indicator for colloidal characterizations instead of an influencing factor for solute transport through capillary porous media. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Pollutant migration in dense clay barriers appears to be strongly influenced by the electric double layer of colloidal surfaces. Osmosis that is resulted from chemical potential or electric potential difference across the clay membrane has been successively described in a number of theoretical works. Streaming potential (SP) which is present in charged porous medium under hydraulic gradient has been recognized as a significant factor governing the mass migration in compacted clays. However, few studies have been carried out in geo-environmental area with regard to this physical phenomenon. A coupled model was proposed to account for the effects of electrical, chemical and fluidic fields on solute transport in porous medium in this study. The electrical field deals with both the streaming potential and the externally applied electrical potential. The coupled nonlinear partial differential equations are numerically simulated by finite element method. Both the steady state solution and the time-dependent solution were investigated with the consideration of a series of influential factors. The streaming potential coefficient and the electro-osmotic coefficient were found to control the solute transport process. The potential application of the materials with tendency of producing SP was discussed. With appropriate selection of materials and parameters, optimum barring effect could be obtained for soil barriers in waste containment applications.
    Full-text · Article · Oct 2014 · Applied Clay Science
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    • "The movement of the electrolyte on the solid surface creates a streaming potential, having a direct relationship with the zeta potential by the Helmholtz– Smoluchowski equation [15] [17] [18]. "
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    ABSTRACT: The controlled adsorption of surfactants on ultrafiltration (UF) membranes can modify their surface properties by increasing the fields of applicability. In this context, the understanding of the phenomena involved in the adsorption process of the surfactants is very important. The latter may be accomplished through measurements of the electrokinetic properties of the modified membranes under different conditions. Thus, this work is focused on the study of the streaming current and the zeta potential of polyethersulfone (PES) UF membranes modified with the anionic surfactant sodium dodecyl sulfate (SDS). The study was performed by measuring of the streaming current at the first contact between the membrane and the surfactant. The results obtained show that there are two zones of behavior, for the concentrations under and above the critical micelle concentration (CMC). In the first case a positive current was observed, meanwhile for the concentrations higher than the CMC the current observed was negative. Measurements of zeta potential of the modified membrane showed that the saturation of the membrane was reached at lower concentrations of SDS, and that the adsorption of the surfactant is taking place only on the membrane surface.
    Full-text · Article · Jan 2014 · Desalination and water treatment
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