STUDY ON MICELLIZATION AND INTERFACIAL ADSORPTION OF POLYOXYETHYLENE (30) LAURYL ETHER (C12E30) IN 0.01 M NACL AT AIR-WATER INTERFACE
The surface properties of a polyoxyethylated octyl phenol [C8H17-O(CH2CH2O)30-H] has been studied through surface tension measurements. The surface excess (Γ) and the corresponding interfacial parameters have been computed. The Gibbs free energy, enthalpy and entropy of micellization (ΔGm 0, ΔHm 0, ΔSm 0) and of adsorption at air-water interface (ΔGad 0, ΔHad 0, ΔSad 0) have also been evaluated. An enthalpy- entropy compensation effect has been examined with an isostructural temperature of 292 K for both the micellization and interfacial adsorption processes. Like the micellization process, the adsorption at the air-water interface has been found to be also endothermic. The endothermic character of micellization and adsorption are specific to the surfactant, the additive and the temperature. The minimum area per surfactant molecule and critical micellar concentration divulge that both hydrophobicity and steric constraints of the surfactant play a pivotal role in micelle formation.
PRAGNESH N. DAVE, NARSIDAS J. PARMAR AND SHAKIL S. SAIT