Summary
The mechanism of demulsification of 30% Nujol-70 % water emulsions with various surfactants has been studied using a Coulter Counter to monitor the particle size at various depths in the cream layer as a function of time of centrifugation. It was found that the cream layer is stratified with varying sizes of oil globules along the centrifuge cell. Coalescence of the oil globules occurs throughout the body of the cream as well as at the bulk oil-cream interface at high concentrations of Tween 80, and Sponto 221 emulsions whereas the bulk oil-cream interface is found to be the major site of coalescence at lower concentrations of Tween 80 and Gantrez AN 119 emulsions. The globule size at the bulk oil-cream interface reaches a plateau (“steady state” particle size), and subsequently the rate of oil separation decreases considerably in all cases. The “steady state” particle size is a function of the concentration of Tween 80, the particle size increasing with increase in concentration of Tween 80.
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Hahn, A.U., Mittal, K.L. Mechanism of demulsification of oil-in-water emulsion in the centrifuge. Colloid & Polymer Sci 257, 959–967 (1979). https://doi.org/10.1007/BF01520721
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DOI: https://doi.org/10.1007/BF01520721