  The work reviews on a general level various modified Poisson-Boltzmann
equations and demonstrates their use on the specific system of charged
particles at an interface. This system is special, first, because it exhibits
the long-range interactions on account of an air-water interface, and two,
because the strength of these interactions depends on the structure of a
double-layer. Thus, this system is particularly sensitive to the type of the
modified Poisson-Boltzmann equation used.
