Interfacial activity of dinonylnaphthalene sulphonic acid in the presence of modifiers possessing an hydroxyl group

Abstract The interfacial activity of dinonylnaphthalene sulphonic acid (HDNNS) and modifiers such as isodecanol or p -nonylphenol (both denoted ROH) is investigated at the n-decane/0.1 M HCl interface, at 25°C. In particular, it is shown that the addition of isodecanol or p -nonylphenol significantly decreases the interfacial activity of dinonylnaphthalene sulphonic acid. Such behaviour is quantitatively explained by the formation of non-surface-active extractant-modifier complexes; namely, (HDNNS) 3 (ROH) 1 and (HDNNS) 3 (ROH) 3 , for isodecanol and p -nonylphenol, respectively.