Non-equilibrium surface forces of diffusion-electrical nature in

Non-equilibrium Surface Forces of Diffusion-Electrical Nature in Flotation 

As a result, an electric field must arise within the limits of the diffusion boundary layer which is associated with the dynamic adsorption layer of ionic surfactants. The electric field is caused by the deformation of the DL, i.e. by its slight deviation from electroneutrality. 

Deijaguin Samygin (1962) investigated the gravity deposition of galenite particles of different size on the mobile surface of a fixed bubble fi om a vertical flow of liquid. They found that the particles smaller than some critical size a do not reach the bubble surface. Using the 

Because of its large velocity, a freely rising bubble has a diffusion layer much thinner that in the described experiments. This effect can manifest itself only if the particles are small enough so that their thermal motion becomes significant. Thus, electro- and diffusiophoresis should be taken into account in describing the Brownian diffusion of sub-micron particles towards the bubble s mobile surface under the conditions of a sufficiently low electrolyte concentration. The influence of diffusiophoretic transport to the surface of a rising bubble through its diffusion layer is theoretically proved by Zholkovsky et al. (1983). 

When drops or bubbles approach each other their diffusion layers overlap. This leads to local changes in the surface concentration and surface tension which causes liquid to flow into or out of the thick liquid interlayer. The dynamic adsorption layer and its diffusion layer deviate from electroneutrality and contain charges of opposite sign. The charged dynamic adsorption layer and the oppositely charges diffusion layer as a whole are electroneutral. This ensemble can be called the secondary electrical double layer. 

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