title: Electrophoresis and stability of nano-colloids: history, theory and experimental examples.
abstract: The paper contains an extended historical overview of research activities focused on determining interfacial potential and charge of dispersed particles from electrophoretic and coagulation dynamic measurements. Particular attention is paid to nano-suspensions for which application of Standard Electrokinetic Model (SEM) to analysis of experimental data encounters difficulties, especially, when the solutions contain more than two ions, the particle charge depends on the solution composition and zeta-potentials are high. Detailed statements of Standard Electrokinetic and DLVO Models are given in the forms that are capable of addressing electrophoresis and interaction of particles for arbitrary ratios of the particle to Debye radius, interfacial potentials and electrolyte compositions. The experimental part of the study consists of two groups of measurements conducted for Pt/C nano-suspensions, namely, the electrophoretic and coagulation dynamic studies, with various electrolyte compositions. The obtained experimental data are processed by using numerical algorithms based on the formulated models for obtaining interfacial potential and charge. While analyzing the dependencies of interfacial potential and charge on the electrolyte compositions, conclusions are made regarding the mechanisms of charge formation. It is established that the behavior of system stability is in a qualitative agreement with the results computed from the electrophoretic data. The verification of quantitative applicability of the employed models is conducted by calculating the Hamaker constant from experimental data. It is proposed how to explain the observed variations of predicted Hamaker constant and its unusually high value.
authors.affiliation: South African Institute for Advanced Materials Chemistry (SAIAMC), University of the Western Cape, Modderdam Road, Bellville 7535, Cape Town, South Africa.
authors.forename: C
authors.initials: C
authors.lastname: Felix
authors.affiliation: ICREA and Department d'Enginyeria Química (EQ) Universitat Politècnica de Catalunya Av. Diagonal, 647, Edifici H, 4a planta, 08028, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Yaroshchuk
authors.affiliation: South African Institute for Advanced Materials Chemistry (SAIAMC), University of the Western Cape, Modderdam Road, Bellville 7535, Cape Town, South Africa.
authors.forename: S
authors.initials: S
authors.lastname: Pasupathi
authors.affiliation: South African Institute for Advanced Materials Chemistry (SAIAMC), University of the Western Cape, Modderdam Road, Bellville 7535, Cape Town, South Africa.
authors.forename: B G
authors.initials: BG
authors.lastname: Pollet
authors.affiliation: Institute of Biocolloid Chemistry of Ukrainian Academy of Sciences, Vernadskogo, 42, 03142 Kiev, Ukraine.
authors.forename: M P
authors.initials: MP
authors.lastname: Bondarenko
authors.affiliation: Institute of Biocolloid Chemistry of Ukrainian Academy of Sciences, Vernadskogo, 42, 03142 Kiev, Ukraine. Electronic address: vladim@koval.kiev.ua.
authors.forename: V I
authors.initials: VI
authors.lastname: Kovalchuk
authors.affiliation: Institute of Biocolloid Chemistry of Ukrainian Academy of Sciences, Vernadskogo, 42, 03142 Kiev, Ukraine.
authors.forename: E K
authors.initials: EK
authors.lastname: Zholkovskiy
mesh_terms: D000268:Adhesiveness; D000465:Algorithms; D002627:Chemistry, Physical / Q000379:methods / Q000639:trends; D003102:Colloids; D004586:Electrophoresis / Q000379:methods; D007700:Kinetics; D008956:Models, Chemical; D053761:Nanocomposites / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000639:trends; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D003102:Colloids
keywords: Coagulation dynamics; DLVO theory; Electrophoresis; Nano-suspensions; Standard Electrokinetic Model