Equation oriented mixed micellization modeling based on asymmetric Margules-type formulations

•The proposed method obtains the composition of micelles on mixed micellar systems.•It assumes that Gexc can be properly approximated by a Taylor series.•The differentiation of Gexc is analytical, complying with the Gibbs–Duhem relation.•Global minimization of total free energy of micellization gives unique parameters.•It is based in analytical differentiation, so it requires few experimental values. The determination of the composition of mixed micellar systems is a major problem since only the composition of the total micellar solution is accessible to the experimenter. A new approach is introduced in the present work based on Equation Oriented Optimization and Margules asymmetric formulations which is not restricted to the number of components and guarantees the applicability of the Gibbs–Duhem relation. The method is validated through its application to systems from literature and the quality of the solutions is tested with already published data and by comparison with other approaches. We do also show how excess properties can be predicted and that the excess entropy is not zero as assumed by the original regular and sub-regular solution theories.