Measurement and Interpretation of Electrokinetic Phenomena (IUPAC Technical Report)

Abstract

Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the Measurement and interpretation of electrokinetic phenomena (IUPAC Technical Report)Abstract: In this report, the status quo and recent progress in electrokinetics are reviewed. Practical rules are recommended for performing electrokinetic measurements and interpreting their results in terms of well-defined quantities, the most familiar being the ζ-potential or electrokinetic potential. This potential is a property of charged interfaces, and it should be independent of the technique used for its determination. However, often the ζ-potential is not the only property electrokinetically characterizing the electrical state of the interfacial region; the excess conductivity of the stagnant layer is an additional parameter. The requirement to obtain the ζ-potential is that electrokinetic theories be correctly used and applied within their range of validity. Basic theories and their application ranges are discussed. A thorough description of the main electrokinetic methods is given; special attention is paid to their ranges of applicability as well as to the validity of the underlying theoretical models. Electrokinetic consistency tests are proposed in order to assess the validity of the ζ-potentials obtained. The recommendations given in the report apply mainly to smooth and homogeneous solid particles and plugs in aqueous systems; some attention is paid to nonaqueous media and less ideal surfaces.

Optimized nanoporous materials.

“…[60] If a tangential voltage drop is present along the surface, we assume that adsorbed ions do not move. While surface conductivity is important near glass or polymers in electrophoresis, [61] we have found very little on the topic in the literature for a metal surface.…”

Long-range attractive forces extending from the alumina’s nanolayer surface in aqueous solutions

“…Gouy [7] and Chapman [8] developed a diffuse layer (DL) theory. Stern extended that theory by proposing a model in which the interfacial layer is divided into two parts [9], the inner Helmholtz plane and the outer Helmholtz plane [10]. It has been shown [11] that the Stern model is applicable away from the surface, but cannot be taken literally near the surface.…”

Electrical and Physical Characteristics of Silica Nanoparticles in Aqueous Media Affected by Cations Na+, Ba2+and Al3+

“…The EDL around solid particles can be considered as a layer in which the distribution of ions differs from that in the bulk liquid far from particles (Delgado et al 2005;Hunter 1981Hunter , 1989Lyklema 1991Lyklema , 1995.…”

“…The main parameter of the slipping plane of EDL is electrophoretic potential (or zeta potential), which determines the electrophoretic mobility of particles in the external electrostatic field, as well as the distribution of counterions in the diffuse layer. The zeta potential of nanoparticles is one of the parameters governing the electrokinetic phenomena at the interfaces (Delgado et al 2005;Gun'ko et al 2014;Hunter 1981Hunter , 1989Tandon et al 2008).…”