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: 2.35). 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.
    Applied Clay Science 11/2014; 101. DOI:10.1016/j.clay.2014.09.017 · 2.70 Impact Factor
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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.
    Applied Clay Science 10/2014; · 2.70 Impact Factor
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    • "Among methods used for flocculation control by chemical coagulant dosage, are mathematical model, on-site test equipment simulation, stream current measurement, aggregates equivalent diameter detection , etc. (Li and Wilkinson, 2005; Werner et al., 2001); and many apparatus such as zeta potentiometer, stream current detector, photometric dispersion analyzer , particle size analyzer, etc. (Chakraborti et al., 2003; Huang, 2005; Rossi et al., 2002; Swift et al., 2004) were applied. However, the development tendency of flocculation control is presently focused on the aggregates characteristic parameter method and the digital image analysis technology. "
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    ABSTRACT: A study on flocculation control based on fractal theory was carried out. Optimization test of chemical coagulant dosage confirmed that the fractal dimension could reflect the flocculation degree and settling characteristics of aggregates and the good correlation with the turbidity of settled effluent. So that the fractal dimension can be used as the major parameter for flocculation system control and achieve self-acting adjustment of chemical coagulant dosage. The fractal dimension flocculation control system was used for further study carried out on the effects of various flocculation parameters, among which are the dependency relationship among aggregates fractal dimension, chemical coagulant dosage, and turbidity of settled effluent under the conditions of variable water quality and quantity. And basic experimental data were obtained for establishing the chemical coagulant dosage control model mainly based on aggregates fractal dimension.
    Journal of Zhejiang University SCIENCE B 11/2005; 6(10):1038-44. DOI:10.1631/jzus.2005.B1038 · 1.29 Impact Factor
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