Optimum detergency conditions with nonionic surfactants: II. Effect of hydrophobic additives

Abstract

Optimum detergent action for hydrocarbon soils in systems containing a mixture of two nonionic surfactants or one nonionic surfactant and a lipophilic additive occurs at a temperature approximately equal to a suitably chosen phase inversion temperature (PIT). When the amount of the aqueous bath containing the surfactant mixture or surfactant-additive mixture greatly exceeds the amount of soil, as in many practical situations, the PIT is that of a system whose surfactant films in the middle phase microemulsion have the same composition as that of the initial mixture. Enhanced videomicroscopy, phase equilibrium, and detergency experiments whose results lead to this conclusion are described.