MULTISTATE SELF-CONSISTENT-FIELD THEORY FOR THE CALCULATION OF THE INTERFACE OF 2 IMMISCIBLE ELECTROLYTE-SOLUTIONS

A new theory is formulated for the calculation of the inter-face of tw o immiscible electrolyte solutions. The theory is based on the self-co nsistent field theory fur (chain) molecules in inhomogeneous systems d eveloped by Scheutjens and Fleer. Complexation equilibrium between ion s and carrier molecules is taken into account via the multistate chara cter of the segments. Electrostatic interactions are also included in the theory. The self-consistent equations are derived starting with th e optimization of the grand canonical partition function of the system . The set of equations is solved iteratively, giving the equilibrium d istributions of the components in the system. Calculations for a model system, consisting of a liquid-membrane phase doped with a carrier mo lecule in contact with a simple electrolyte solution, are performed to test the applicability of the new theory. These results show that the calculations presented in this paper can be used to interpret or pred ict important analytical features of ion-selective electrodes.