Effect of Temperature and Other Variables on the Optimum Formulation of Anionic Extended Surfactant–Alkane–Brine Systems

Abstract

Abstract Anionic extended surfactants of the alkyl polypropylene oxide sulfate type are found to obey the linear correlation lnS = k ACN for optimum formulation (three‐phase behavior) of ionic surfactant–oil–water systems, with a k value essentially the same as for n ‐alkyl sulfates. The addition of n ‐pentanol produces a shift in optimum formulation without significant change in k . An increase in temperature is found to produce a decrease in surfactant hydrophilicity, which is opposite to the expected behavior of anionic species. This trend, which is typical of nonionic surfactant behavior, is probably due to the partial hydration of the very first propylene oxide units which are located close to the anionic head group.