Features of the Electrical Double Layer Around Spherical Particles. The Poisson–Helmholtz–Boltzmann Model

The Poisson–Helmholtz–Boltzmann model is used to study the properties of an electrical double layer formed near an individual weakly charged spherical particle surrounded by a 1 : 1 electrolyte solution. Dividing into Coulomb and non-Coulomb (specified by the Yukawa potential) interactions between ions in the solution, as well as between ions and the particle, mathematical expressions are obtained for the profiles of the corresponding potentials near the particle as functions of the main parameters of the model. When varying the values of key parameters, we find both monotonic and nonmonotonic profiles of the electrostatic potential, and we observe a change in the sign of the potential, resulting in the phenomena of inversion and reversal of charge. The conditions, under which the inversion and reversal of the particle potential sign occur, are determined. The dependences of the zero charge potential on the particle size, the concentration of the 1 : 1 electrolyte solution, and the surface density of a non-Coulomb force source are considered.