Resistance of water and oil soluble surfactant mixtures to oxygen transfer

Effectiveness of the following mixed surfactant system in minimising oxygen transfer at surfaces was investigated: oil soluble ethoxylated (6) nonylph enol (NP6EO), water soluble ethoxylated (9) nonylphenol (NP9EO) and the alk ylbenzyldimethylammonium chloride, (ABDAC). The surfactants were incorporat ed with a liquid paraffin and water to form an O/W type emulsion. The type of emulsion formed was characterized by optical microscopy and drying tests . In this study the effect of synergism in interfacial behavior was investi gated for the following surfactant pairs: NP9EO/ABDAC in the aqueous phase; NP6EO/NP9EO and NP6EO/ABDAC in the oil/water binary phase system. The resu lts were used to interpret the transfer rate of oxygen through the emulsion and the oil phase of the dehydrated emulsion. Typical S shaped profiles wi th an initial lag time is observed in the transfer of oxygen through the oi l phase. Duration of the lag depends on the structure of the air/oil surfac e. Corrosion tests performed on carbon steel according to G60-79 ASTM metho d showed that there is an inverse relationship between the lag time and the rate of corrosion. (C) 1999 Elsevier Science B.V. All rights reserved.