DESTABILIZATION OF OIL-IN-WATER EMULSION WITH INORGANIC ELECTROLYTES IN THE ABSENCE AND IN THE PRESENCE OF SODIUM DODECYL SULFATE

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Abstract
The coagulation concentrations of Na+, Ba2+, and La3+ in the absence of SDS were analyzed in terms of the DLVO theory. The Hamaker constant obtained was larger by one order of magnitude than that available in the literature on the basis of the Lifshitz theory. An explanation of this discrepancy was given by taking into account the hydrophobic interaction between oil droplets in aqueous media. Coagulation of decane particles with Na in the presence of SDS (1 × 10−3M) was interpreted qualitatively in terms of the DLVO theory in which the adsorbed layer effect was taken into account. The critical adsorption density of SDS at which no coalescence of aml1sion takes place was found to be 3.3 × 10−10mol cm−2. Electrokinetic adsorption densities of SDS were found to be smaller than those obtained from the interfacial tension vs. concentration data.