Electrical Double Layer in Polar and Nonpolar Media in the Presence of Surfactants
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Authors
Khademi, Mahmoud
Date
Type
thesis
Language
eng
Keyword
Electrical Double Layer (EDL) , Electrical Impedance Spectroscopy (EIS) , Dielectric Relaxation Spectroscopy (DRS) , Permittivity , Zeta Potential , Surfactants , Micelles
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Abstract
The objective of this thesis is to improve our understanding of the concept of electrical double layer (EDL). The EDL is the basis of all electrokinetic phenomena. Despite numerous studies in the span of over a century, our perception of this concept is far from complete owing to its complex nature. In this work, we revisit the structure and properties of EDL in polar and nonpolar media. First, we investigate the change of the zeta potential of a representative polymeric particle in the presence of various types of surfactants using electrophoretic light scattering. This study allows us to comprehend the tuning of the zeta potential of a polymeric substrate as well as the adsorption mechanisms of the different types of surfactants. Second, we use dielectric relaxation spectroscopy (DRS) to understand the EDL formation around the micelles in an aqueous medium. This method can be implemented for determining the surface conductivity as well as the zeta potential of the dispersed species in an opaque sample. Third, electrical impedance spectroscopy (EIS) is used to resolve the structure of an EDL in aqueous electrolyte and surfactant solutions. This study allows us to infer the dominance of the compact layer in determining the equivalent capacitance of the EDL as well as the change in the permittivity of the medium within this compact layer. Finally, the EIS measurements are also conducted in a nonpolar medium in the presence of a nonionic surfactant. The electric charge formation and the emergence of the EDL are explored and compared to the charge formation mechanisms proposed in the literature.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.