Surface activity of mixtures of oxyethylated methyl dodecanoate and sodium dodecylbenzenesulfonate |
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Authors: | Danuta Makowska Wieslaw Hreczuch Jolanta Zimoch Mariusz B. Bogacki Jan Szymanowski |
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Affiliation: | (1) Institute of Heavy Organic Synthesis, 47-215 Kędzierzyn-Koźle, Poland;(2) Institute of Chemical Technology and Engineering, Poznań University of Technology, Pl. Skłodowskiej-Curie 2, 50-965 Poznań, Poland |
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Abstract: | Surface and interfacial tension and detergency of mixtures containing oxyethylated methyl dodecanoate and sodium dodecylbenzenesulfonate were determined. Synergism in the surface tension reduction was not observed. The competition for adsorption at the air/water interface between oxyethylated methyl dodecanoate and sodium dodecylbenzenesulfonate depended on the considered surface tension, the weight ratio of surfactants in the aqueous phase, and the hydrophile-lipophile balance of the nonionic surfactant. Generally, coverage of the interface with oxyethylated methyl dodecanoate increased when surface tension decreased. Nonionics were the dominant species at the interface in the important region of surface activity, i.e., for surface tensions below 40 mN m−1. The mole fraction of the hydrophobic nonionic at the interface was higher than the contribution of hydrophilic oxyethylates. An increase of the surfactant ratio in the bulk phase affects the interfacial ratio of surfactants in the same way. The lowest interfacial tension (1.5 mN m−1) at the hexadecane/water interface was observed for oxyethylated methyl dodecanoate having an average degree of oxyethylation equal to 8 and 10. Nearly 5 min was needed to achieve equilibrium value. Mixtures with sodium dodecylbenzenesulfonate decreased the interfacial tension somewhat less efficiently but the equilibrium was rapidly established. The standard washing powders containing oxyethylated methyl dodecanoates exhibited washing ability similar to that obtained for the powder with traditional alcohol oxyethylate. |
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Keywords: | Co-adsorption detergency interfacial tension oxyethylated methyl dodecanoate sodium dodecylbenzenesulfonate surface tension |
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