What is Zeta potential?

Particles dispersed in liquids (especially water) are due to the dissociation of surface dissociable groups, the selective adsorption of particles to ions in the liquid, the lattice substitution within the crystal particles, and the different electron affinities of the solid and liquid pairs. and other reasons, causing the particle surface to be charged. The solution around the charged particles will be enriched with ions with opposite signs (ie counter ions), and some of the counter ions are closely combined with the particle surface to form a fixed adsorption layer, or Stern layer. The remaining counterions are diffusely distributed around the particles in the solution due to the balance of electrostatic attraction and thermal diffusion. The so-called diffusion double layer is formed between the surface charge of the particles and the diffusely distributed counterions in the solution. If a DC electric field is applied to this solid/liquid dispersion system, the charged particles will move in a direction toward the opposite electrical electrode, which is called electrophoresis. If the particles cannot move, as in the case of a capillary filled with liquid, you will see directional movement of the liquid under the action of an electric field, which is called electroosmosis. Electrophoresis and electroosmosis are the two most common electrokinetic phenomena.

The potential difference between the charged particle surface and the inside of the solution is called the surface potential of the particle. When the particles perform electrophoretic movement, they will move with the fixed adsorption layer and some solvent molecules (closely combined with the particle surface), and between the particles and the liquid. A sliding surface is formed, and the potential difference between this sliding surface and the inside of the liquid is called the electromotive potential or Zate potential.