Surface Properties of Mixed Adsorbed Surfactants Film of Tween 20 and Tween 80 on Liquid ? Air Interfacial

The surface properties of mixed adsorbed surfactants film of Tween 20 and Tween 80 on water Air have been investigated by surface tension measurements at 298 K. The critical micelle concentration (CMC), max (maximum surface excess), Amin (minimum surface area per molecule), cmc (surface tension at the CMC), PC20 (the negative log C20 where C20 is the surfactant molar concentration required to reduce the surface tention of the solvent by 20 mN/m), and CMC/C20 have been determined. The results show that the surface activity by pC20 values is in the order of TW-80 greater than TW-20 while the CMC/C20 values indicate the mixtures of 1 = 0.3 and 0.5 prefer adsorption at interface but other mixture preferred micelle formation. The results of the mixed systems were analyzed in the light of Rosens theory to evaluate the composition of the mixed adsorbed film and the corresponding interaction parameters (X1 and). The negative values of interaction parameters indicate the attractive interaction for certain systems. The existence of synergism in surfactant mixtures at the adsorbed film was examined.