Interaction parameter binary surfactant mixtures

Table I. Values of the Net Interaction Parameter 3 for Some Binary Surfactant Mixtures (from Ref. 3) ...

The Interaction Parameter in Binary Surfactant Mixtures of a Chelating Surfactant and a Foaming Agent... 

From the experimentally determined eme s of the binary surfactant mixtures, as well as the eme s of the individual surfactants, the p parameter was calculated.[4] The p parameter reflects the net interaction between two surfactants, and the stronger the attraction, the more negative is the p parameter. Here, surfactants with the same hydrophobic chain length have been studied, so the effects refer to the interactions between the head groups.[10] First, using the fact that ZxJ" = 1, the mole fraction of surfactant i in the micelle, was calculated by iteration... 

It is also worth noting that in the case of SAFT equations of state, the molecular basis of the theory means that it is possible to transfer binary-interaction parameters when studying mixtures within a homologous series very successfully. This idea has been used in numerous works to predict the phase behaviour of (alkanes - -water), (alkanes + perfluoroalkanes),(alkanes -I- carbon dioxide), (alkanes-I-hydrogen chloride) , and (alkanes-I-nitrogen), and aqueous solutions of surfactants, to name but a few. 

By extending regular solution theory for binary mixtures of AEg in aqueous solution to the adsorption of mixture components on the surface (3,4), it is possible to calculate the mole fraction of AEg, Xg, on the mixed surface layer at tt=20, the molecular interaction parameter, 6, the activity coefficients of AEg on the mixed surface layer, fqg and f2s and mole concentration of surfactant solution, CTf=20 3t surface pressure tt=20 mn-m l (254p.l°C). The results from the following equations are shown in Table I and Table II. 

In most cases, the complex array of interactions at work within an actual surfactant-water mixture leads to variations of the surfactant parameter with surfactant dilution and temperature. In general then, the phase behaviour of a binary surfactant-water mixture follows a curved trajectory through the local/global domain plotted in Fig. 4.11. If these variations in molecular conformation are small, the phase progression with water dilution is expected to follow a nearly-vertical line in the plot if the molecular architecture is sensitive to these external parameters, die succession of phases with water dilution is more nearly horizontal. 

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