Colloids

 Elecro-osmosis is the flow of liquid due to influence of an applied electric field. Assume an electric field , it follows that

(42)

(Diagram Here)

Using (9) to replace ), we find

(43)

or

(44)

where y = 0,

(45)

Particle Electrophoresis

Particle electrophoresis is the movement of charged particles in an electric field. For thin double layer (),

(46)

which may be restated in terms of the electrophoretic mobility,   (velocity for unit field) as

(47)

This is known as the Smoluchowski equation.

For small particles with , the viscous drag must be balanced by the Coulomb force, i.e.

where equation (27) is used for total charge and .

It then follows that

(48)

which is known as the Huckel equation. More generally, then

(49)

where varies from 1 to 1.5 for varying between 0 to .