ELECTRICAL-PROPERTIES OF A CHARGED SURFACE IN A GENERAL ELECTROLYTE SOLUTION

The electrical properties of a planar charged surface in a general ele ctrolyte solution are examined. Analytical expressions for the electri cal potential, surface excess of co-ions, double-layer free energy, an d entropy are derived. A perturbation method is proposed for the resol ution of the Poisson-Boltzmann equation governing the electrical poten tial distribution. The analysis extends the classic Gouy-Chapman's res ult to an arbitrary a:b electrolyte solution. The present approach yie lds a system of linear ordinary differential equations, which can be s olved to an arbitrary order, in principle. The performance of the pres ent perturbation solution is satisfactory for conditions normally enco untered in practice. For example, if the second-order solution is adop ted, deviations in the electrical potential and thermodynamic properti es examined are less than 5%. (C) 1998 Elsevier Science B.V. All right s reserved.