ABSTRACT
This chapter discusses briefly several charging mechanisms of particles in aqueous solutions, the electric double layer, which is an ion atmosphere formed around a charged particle and the zeta potential of a particle, which is a measure of its surface charge density. It describes electrophoresis, where charged particles migrate under an external electric field, and several theories that link the electrophoretic mobility with the zeta potential. The number of electrons in the material with a lower Fermi level increases, resulting in electrification to negative charge. As a matter of course, the other material is electrified to positive charge. The electrification of a nonconductive material is complicated, however, for metal–insulator contacts, the charge transfer can often be explained by a concept similar to that of the metal-to-metal electron transfer. The electric charge of particles after breakage is represented by a normal distribution with zero mean. Electrification through breakage is caused by the unequal partition of positive or negative charges.
