Surface and thermodynamic properties of p-alkylbenzene polyethoxylated and glycerated sulfonate derivative surfactants

The surface and thermodynamic properties of the 19 p- and n-alkylbenzene polyethoxylated and glycerated sulfonate derivatives as nonionic surfactants have been investigated. Surface tension as a function of concentration of the surfactants in aqueous solutions was measured at 25, 35, 45 and 55 degrees C using the spinning-drop technique. From these measurements, the critical micelle concentration (CMC), the surface pressure at CMC, the maximum surface excess concentration, Gamma(max), the minimum area per molecule at the aqueous solution-air interface, A(min), the effectiveness of surface tension reduction, Pi(CMC), and the efficiency, pC(20) were calculated. The thermodynamic parameters of micellization (Delta G(mic), Delta H-mic, Delta S-mic) and of adsorption (Delta G(ad), Delta H-ad, Delta S-ad) for these nonionic surfactants were also calculated. Structural effects on adsorption, micellization and the effectiveness of surface tension reduction are discussed in terms of these parameters. (C) 1998 Elsevier Science B.V.