DYNAMIC INTER-FACIAL TENSION BEHAVIOR OF ACIDIFIED OIL SURFACTANT-ENHANCED ALKALINE SYSTEMS - 2 - THEORETICAL-STUDIES/

A mechanistic interpretation of the dynamic interfacial tension behavi or arising from the interactions between acidic oil and surfactant-alk aline systems has been developed. A physico-chemical model, based on N ernstian theory of convective diffusion, Langmuir theory of interfacia l sorption kinetics, and electrical interfacial phenomena, has been in voked to account for the dynamic nature of the interfacial tension. Th e results show that the interfacial tension arising from the interacti on of these chemical combinations with model acidic oil exhibits a mar ked dynamic behavior. The magnitude of interfacial tension variations changes not only with alkali concentration but also with surfactant co ncentration. The pertinent sorptive rate constants that characterize d ynamic behavior are precisely estimated by correlating experimental in terfacial tension data with the proposed model. A very good overall ag reement is obtained between the experimental values and those predicte d by the model. A better model of the interactions between acidic oil and alkaline solutions has been developed. The improvement is mainly r elated to a modification of the adsorption isotherms as well as the ki netic equations. These changes allow for the co-adsorption of the un-i onized acid along with the ionized acid at the interface. The extensio n of the acidic oil/alkaline model to incorporate an additional pre-fo rmed surfactant is also accomplished by a modification of the adsorpti on isotherms, of the micellar relationship and of the resulting equili bria. (C) 1998 Elsevier Science B.V.