The relative permittivity of the ternary 1,2-ethanediol + 2-methoxyethanol + water solvent system

For many multicomponent cosolvent systems which can be important in electrochemical studies as far as in practical applications, the relative permittivity (epsilon) is a continuous but nonlinear function of the solvent composition. Rational functions were applied to the 1,2-ethanediol (1)+2-methoxyethanol (2)+water (3) ternary mixtures data at various temperatures (50 less-than-or-equal-to t/degrees-C less-than-or-equal-to 80) instead of the more conventional polynomial regressions for epsilon=epsilon(X(i)). These rational functions seem to be more adequate than the other polynomials, being reduced the number of required adjustable coefficients; in fact only a first power dependence on mole fraction (X(i)) is necessary, and a computational simplicity in reproducing reliable epsilon values over the total mole fraction 0 less-than-or-equal-to X1/X2/X3 less-than-or-equal-to 1 range is achieved. Furthermore, the calculated excess function (epsilon(E))is always negative, confirming the existence of rather strong interaction between components, probably via hydrogen bonding networks. Changes with temperature in epsilon(E) for these ternary mixtures seem to be very useful in order to depict and differentiate the experimental trend in three well distincted regions (namely M(I),M(II),M(III)) which are likely characterized by different specific interactions between like and/or unlike species. Nevertheless, no evidence for a three component adduct was obtained.