The polarization of a nanoparticle surrounded by a thick electric double layer

In contrast to the case of the thin electric double layer, the particle with the thick double layer exhibits only high-frequency dispersion. The polarization of a charged, dielectric, nanoparticle enveloped by a thick electric double layer and subjected to a uniform, alternating electric field is st...

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Published inJournal of colloid and interface science Vol. 333; no. 2; pp. 663 - 671
Main Authors Zhao, Hui, Bau, Haim H.
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier Inc 15.05.2009
Elsevier
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ISSN0021-9797
1095-7103
1095-7103
DOI10.1016/j.jcis.2009.01.056

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Summary:In contrast to the case of the thin electric double layer, the particle with the thick double layer exhibits only high-frequency dispersion. The polarization of a charged, dielectric, nanoparticle enveloped by a thick electric double layer and subjected to a uniform, alternating electric field is studied theoretically with the standard model (the Poisson–Nernst–Planck PNP equations). The dipole coefficient ( f) is calculated as a function of the electric field's frequency and the double layer's thickness ( λ D ) . For a weakly charged particle with a small zeta potential ζ, an approximate, analytic expression for the dipole moment coefficient, accurate within O ( ζ 2 ) , is derived. Two processes contribute to the dipole moment: the ion transport in the electric double layer under the action of the electric field and the particle's electrophoretic motion. As the thickness of the electric double layer increases so does the importance of the latter. In contrast to the case of the thin electric double layer, the particle with the thick double layer exhibits only high-frequency dispersion. The theoretical predictions are compared and favorably agree with experimental data, leading one to conclude that the standard, PNP based-model adequately represents the behavior of nanoparticles subject to electric fields.
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ISSN:0021-9797
1095-7103
1095-7103
DOI:10.1016/j.jcis.2009.01.056