EFFECTS OF SURFACE-ACTIVE AGENTS ON MASS-TRANSFER INSIDE DROPS

The transfer of iodine from a drop of carbon tetrachloride falling in water has been studied in the presence of two surface-active agents, Teepol and sodium dodecylsulfate. The presence of Teepol is found to decrease the drop's terminal velocity more than that of sodium dodecylsulfate, this effect being more pronounced for larger drops. Small amounts of these surfactants reduce the internal circulation and consequently the mass transfer rates. Efficiencies can even fall below those for rigid spheres when the surfactant concentration is high. The maximum reduction for the individual mass transfer coefficient is about 77% with both surface-active agents. Results are compared with the model of Vermeulen and the model of Calderbank and Korchinski. These results are also expressed using the Galileo number and diffusivity effective factor R. © 1979.