Extraction Sauter mean drop diameter

Industrial liquid-liquid extraction most often involves processing two immiscible or partially miscible liquids in the form of a dispersion of droplets of one liquid (the dispersed phase) suspended in the other liquid (the continuous phase). The dispersion will exhibit a distribution of drop diameters d, often characterized by the volume to surface area average diameter or Sauter mean drop diameter. The term emulsion generally refers to a liquid-liquid dispersion with a dispersed-phase mean drop diameter on the order of 1 pm or less. 

Interfacial Area The mass-transfer efficiency of most extraction devices is proportional to the area available for mass transfer (neglecting any axial mixing effects). As discussed in Liquid-Liquid Dispersion Fundamentals, for the general case where the dispersed phase travels through the column as drops, an average liquid-hquid interfacial area can be calculated from the Sauter mean drop diameter and dispersed-phase holdup ... 

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