Lecture

Colloidal Stability: Electrostatic Interactions & Aggregation Kinetics

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In course

MSE-326: Ceramic and colloidal processing

The course covers the production of ceramics and colloids from the basic scientific concepts and theories needed to understand the forming processes to the mechanisms and methods of sintering (firing) ceramics. Including the scientific principles behind th ...

Description

This lecture covers the interaction between charged surfaces, electrostatic forces, and colloidal stability using the DLVO model. It discusses the aggregation kinetics of colloidal suspensions, emphasizing the importance of surface charges, ion adsorption, and the stability of dispersions. The presentation delves into the mechanisms of surface charging, ion adsorption at interfaces, and the evaluation of colloidal stability. The lecture also explores the Poisson-Boltzmann equation, surface potential, and the formation of charged interfaces. Various factors influencing the stability of colloidal systems, such as attractive Van der Waals forces and repulsive electrostatic interactions, are analyzed.

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Instructors (2)

Paul Bowen

Dr. P. Bowen after gaining his BSc in Physics at Imperial College (UK), he obtained his Ph.D. in Physical Chemistry in the field of catalysis from the University of Cambridge, UK, in 1982, He then worked at the BP Research Centre, Sunbury, UK, for 4 years in applied surface sciences before moving to Switzerland and EPFL in 1987. He has been at the Powder Technology Laboratory, in the Materials Institute since its conception in 1988. He has over 190 publications and has written an undergraduate book on ceramic synthesis and processing. Education: 1976-1979 Imperial College of Science and Technology, University of London. B.Sc. Honours in Physics. 1979-1982 Department of Physical Chemistry, University of Cambridge. Certificate of Postgraduate Studies in Chemistry. Thesis: A Mössbauer Study of Some Clay Minerals and their Surfaces. Ph.D. in Physical Chemistry. Thesis: An Iron-57 and Tin-119 Mössbauer Spectroscopic Study of Some Graphite Intercalation Compounds and Carbon Supported Iron Catalysts. Professional Experience: 1983-1986 Research Scientist (Physical Chemist), New Technology Division, British Petroleum Company plc, BP Research Centre, Sunbury on Thames, Middlesex TW16 7LN, England. 1987-1988 Engineer, Ceramics Laboratory, Département des Matériaux, Ecole Polytechnique Fédérale de Lausanne, CH - 1015 Lausanne, Switzerland. 1988-2008 Research Associate/lecturer, Powder Technology Laboratory (Present) Institute des Matériaux, Ecole Polytechnique Fédérale de Lausanne, CH - 1015 Lausanne, Switzerland. 1988- 2015 Maitre DEnsiegnement et Recherche (Lecturer & Researcher), Powder Technology Laboratory, Institute des Matériaux, Ecole Polytechnique Fédérale de Lausanne,CH - 1015 Lausanne, Switzerland 2015 – present Adjunct Professor (Professeur Titulaire), Powder Technology Laboratory (LTP), Materials Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH - 1015 Lausanne, Switzerland

Andrea Testino

Expertise Ceramics synthesis and Processing; Nanomaterial synthesis; Nanomaterial characterization; Thermodynamic - Kinetic modeling; Powder synthesis scale-up. MER Dr. Andrea Testino received his master’s degree in Industrial Chemistry and PhD in Material Science from the University of Genoa (Italy). He did post-doctoral studies at EPFL (CH), University College London (UK), and University of Milan (I) working on nanoparticles synthesis and characterization. In 2007 he joined the company TDK-EPC (A) as Seni

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Related concepts (31)

DLVO theory

The DLVO theory (named after Boris Derjaguin and Lev Landau, Evert Verwey and Theodoor Overbeek) explains the aggregation and kinetic stability of aqueous dispersions quantitatively and describes the force between charged surfaces interacting through a liquid medium. It combines the effects of the van der Waals attraction and the electrostatic repulsion due to the so-called double layer of counterions.

Pi-interaction

In chemistry, π-effects or π-interactions are a type of non-covalent interaction that involves π systems. Just like in an electrostatic interaction where a region of negative charge interacts with a positive charge, the electron-rich π system can interact with a metal (cationic or neutral), an anion, another molecule and even another π system. Non-covalent interactions involving π systems are pivotal to biological events such as protein-ligand recognition.

Gaussian surface

A Gaussian surface is a closed surface in three-dimensional space through which the flux of a vector field is calculated; usually the gravitational field, electric field, or magnetic field. It is an arbitrary closed surface S = ∂V (the boundary of a 3-dimensional region V) used in conjunction with Gauss's law for the corresponding field (Gauss's law, Gauss's law for magnetism, or Gauss's law for gravity) by performing a surface integral, in order to calculate the total amount of the source quantity enclosed; e.

Intermolecular force

An intermolecular force (IMF) (or secondary force) is the force that mediates interaction between molecules, including the electromagnetic forces of attraction or repulsion which act between atoms and other types of neighbouring particles, e.g. atoms or ions. Intermolecular forces are weak relative to intramolecular forces – the forces which hold a molecule together. For example, the covalent bond, involving sharing electron pairs between atoms, is much stronger than the forces present between neighboring molecules.

Electrostatics

Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber, ἤλεκτρον (), was thus the source of the word 'electricity'. Electrostatic phenomena arise from the forces that electric charges exert on each other. Such forces are described by Coulomb's law.

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