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Double layer forces occur between charged objects across liquids, typically water. This force acts over distances that are comparable to the Debye length, which is on the order of one to a few tenths of nanometers. The strength of these forces increases with the magnitude of the surface charge density (or the electrical surface potential). For ...
DLVO theory is the combined effect of van der Waals and double layer force. For the derivation, different conditions must be taken into account and different equations can be obtained. [13] But some useful assumptions can effectively simplify the process, which are suitable for ordinary conditions.
Electroosmotic flow is caused by the Coulomb force induced by an electric field on net mobile electric charge in a solution. Because the chemical equilibrium between a solid surface and an electrolyte solution typically leads to the interface acquiring a net fixed electrical charge, a layer of mobile ions, known as an electrical double layer or Debye layer, forms in the region near the interface.
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.
Upon the application of pressure on a test solution, liquid starts to flow and to generate an electric potential. This streaming potential is related to the pressure gradient between the ends of either a single flow channel (for samples with a flat surface) or the porous plug (for fibers and granular media) to calculate the surface zeta potential.
The equation above is usually referred to as the Helmholtz–Smoluchowski equation. The above equations assume that: the double layer is not too large compared to the pores or capillaries (i.e., κ a ≫ 1 {\displaystyle \kappa a\gg 1} ), where κ is the reciprocal of the Debye length
The Poisson–Boltzmann equation describes a model proposed independently by Louis Georges Gouy and David Leonard Chapman in 1910 and 1913, respectively. [3] In the Gouy-Chapman model, a charged solid comes into contact with an ionic solution, creating a layer of surface charges and counter-ions or double layer. [4]
The interfacial (surface) tension, St, (dyne cm −1), can be calculated by applying the equation of capillary rise method (when the contact angle Ө → 0): = where: h (cm) is the height of Hg column above the Hg meniscus in the capillary; r (cm) is the radius of capillary