Interaction Energies between Spherical Colloidal Particles in a Symmetric Electrolyte Solution

Derjaguin–Landau–Verwey–Overbeek (DLVO) theory is used to classically model the interaction energy between two colloidal particles in a dilute aqueous electrolyte solution. In its simplest form, DLVO theory defines the total interaction potential energy as the sum of the van der Waals attractive energy and the electrostatic double-layer repulsive energy . When the potential barrier , the maximum value of , is near or below 0, particle aggregation is inevitable and for all practical purposes irreversible as evidenced by the deep potential well (primary minimum) to the left of the barrier. However, when is high, the colloidal suspension will be energetically stable. Under certain conditions, a "dip" (secondary minimum ) will occur in the energy curve to the right of the energy barrier that is deeper than the thermal energy of the system. This dip is a potential well where flocculation occurs. Flocculation is an aggregation of particles that can easily be redispersed by mixing or shaking the solution.