ABSTRACT
Surface-active compounds used in commercial applications typically consist of a mixture of surfactants because they can be produced at a cost relatively lower than that of pure surfactants. In addition, mixed surfactants generally provide better performance than a single pure surfactant in practical fields,
where the compositions and concentrations can be optimized for each practical application. Because different types of surfactants exist, various kinds of combinations are possible to produce different properties and application fields. Mixed aqueous solutions of nonionic and ionic surfactants have been intensively investigated during the last nearly two decades.
