Salt effects on single aqueous drops falling through an immiscible organic liquid

Chao Tai Chen, Jer Ru Maa, Yu Min Yang, Chien-Hsiang Chang

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Drop settling (or rising) is crucial to the breaking of liquid-liquid dispersions. Most of the empirical correlations for terminal velocity of drops are formulated based on experimental data for systems of dispersed organic phase and continuous aqueous phase using pure and nearly pure liquids. Because the presence of the various third components in one or both of the phases may affect the settling of the drops, the terminal velocity and the onset of oscillation of aqueous drops containing various concentrations of electrolytes falling through n-dodecane were studied in this work. The applicability of existing empirical correlations to these reversed systems of continuous organic phase and dispersed aqueous phase was also examined. Dissolved electrolytes have the effect of causing the terminal velocities and their peak velocities at the onset of drop oscillation to become faster and the peak diameters to become smaller when their concentrations are high enough to cause sufficient changes of physical properties. Existing correlations for drop terminal velocity in pure systems are shown to be adequate in the presence of electrolytes. For high interfacial tension systems, the Hu-Kinter correlation predicts the terminal velocity of organic drops in water and aqueous drops in organics equally well, independent of the presence of electrolytes. The criteria of Hu-Kintner can be used to estimate the peak velocities and peak diameters at the onset of oscillation within a deviation of 3.7%.

Original languageEnglish
Pages (from-to)1297-1313
Number of pages17
JournalChemical Engineering Communications
Issue number10
Publication statusPublished - 2002 Dec 1


All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

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