Interfacial Chemistry: Surface Tension, Adsorption, Electrokinetics

This lecture covers the concepts of surface tension, adsorption on solids, and electrokinetics. It includes discussions on the gas/liquid interface, thermodynamics of adsorption, charged interfaces, DLVO theory, dynamic electrochemistry, and measurements of surface tension. The lecture also delves into the Kelvin equation, contact angle, Wilhelmy plate, Langmuir isotherm, and the BET isotherm for multilayer adsorption. Furthermore, it explores the theory of the diffuse double layer, electrokinetic phenomena like electrophoresis and electro-osmosis, and the DLVO theory of colloid coagulation. The sedimentation potential, streaming potential, and the DLVO theory's critical concentration of coagulation are also discussed.

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Related concepts (53)

CH-341: Physical chemistry of interfaces

Acquire an understanding of interfacial phenomena, micro-heterogeneous colloidal solution systems and dynamic electrochemistry.

Electrokinetic phenomena

Electrokinetic phenomena are a family of several different effects that occur in heterogeneous fluids, or in porous bodies filled with fluid, or in a fast flow over a flat surface. The term heterogeneous here means a fluid containing particles. Particles can be solid, liquid or gas bubbles with sizes on the scale of a micrometer or nanometer. There is a common source of all these effects—the so-called interfacial 'double layer' of charges. Influence of an external force on the diffuse layer generates tangential motion of a fluid with respect to an adjacent charged surface.

Streaming current

A streaming current and streaming potential are two interrelated electrokinetic phenomena studied in the areas of surface chemistry and electrochemistry. They are an electric current or potential which originates when an electrolyte is driven by a pressure gradient through a channel or porous plug with charged walls. The first observation of the streaming potential is generally attributed to the German physicist Georg Hermann Quincke in 1859.

Double layer (surface science)

In surface science, a double layer (DL, also called an electrical double layer, EDL) is a structure that appears on the surface of an object when it is exposed to a fluid. The object might be a solid particle, a gas bubble, a liquid droplet, or a porous body. The DL refers to two parallel layers of charge surrounding the object. The first layer, the surface charge (either positive or negative), consists of ions which are adsorbed onto the object due to chemical interactions.

Gel electrophoresis

Gel electrophoresis is a method for separation and analysis of biomacromolecules (DNA, RNA, proteins, etc.) and their fragments, based on their size and charge. It is used in clinical chemistry to separate proteins by charge or size (IEF agarose, essentially size independent) and in biochemistry and molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge.

Coagulation (water treatment)

In water treatment, coagulation and flocculation involve the addition of compounds that promote the clumping of fine floc into larger floc so that they can be more easily separated from the water. Coagulation is a chemical process that involves neutralization of charge whereas flocculation is a physical process and does not involve neutralization of charge. The coagulation-flocculation process can be used as a preliminary or intermediary step between other water or wastewater treatment processes like filtration and sedimentation.