A comparative study of the effect of ready-made and in situ-formed surfactants on interfacial tension measured by drop volume tensiometry

Interfacial tension between paraffin oil and water was investigated in the presence of surface-active additives using drop volume tensiometry, Two systems in particular were compared, In the first, sodium linoleate, a ready-made surfactant, was added to the aqueous phase, In the other, the oil phase was acidified with linoleic acid and sodium hydroxide was dissolved in the aqueous phase in order that the same surfactant be formed in situ via an interfacial reaction, The dynamic interfacial tension trends exhibited by the two systems were qualitatively comparable, Under similar conditions in terms of effective surfactant concentration and salinity, the equilibrium interfacial tensions observed were also of a similar magnitude. (C) 1996 Academic Press, Inc.