TWL+Electrical+Double+Layer

Electrical Double Layer


 * 1) A phenomenon, which plays a fundamental role in the mechanism of the electrostatic stabilization of colloids.
 * 2) It has a combination of charged surface.
 * 3) Unequal distribution of co-ions and counter-ions near the surface.
 * 4) Colloidal particles gain negative electric charge when negatively charged ions of the dispersion medium are adsorbed on the particles surface.
 * 5) A negatively charged particle attracts the positive counter-ions surrounding the particle.
 * 6) ===== Electric Double Layer is the layer surrounding a particle of the dispersed phase and including the ions adsorbed on the particle surface and a film of the counter-charged dispersion medium

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 * 1) The Electric Double Layer is electrically neutral.

It consists of three parts:


 * 1) Surface charge - charged ions (commonly negative) adsorbed on the particle surface
 * 2) Stern layer – counter-ions (charged opposite to the surface charge) attracted to the particle surface and closely attached to it by the electrostatic force.
 * 3) Diffuse layer - a film of the dispersion medium (solvent) adjacent to the particle. Diffuse layer contains free ions with a higher concentration of the counter-ions. The ions of the diffuse layer are affected by the electrostatic force of the charged particle.

It is sensitive to electrolytes and temperature.


 * 1) The electrical potential within the Electric Double Layer has the maximum value on the particle surface (Stern layer).
 * 2) The potential drops with the increase of distance from the surface and reaches 0 at the boundary of the Electric Double Layer.
 * 3) When a colloidal particle moves in the dispersion medium, a layer of the surrounding liquid remains attached to the particle.
 * 4) The boundary of this layer is called slipping plane (shear plane).
 * 5) The value of the electric potential at the slipping plane is called Zeta potential, which is very important parameter in the theory of interaction of colloidal particles