(180m) Determination of Dynamic Interfacial Tension in a Pulsed Disc and Doughnut Column

Interfacial tension is an essential physical property in liquid-liquid extraction. Under mass transfer conditions, the interfacial tension changes due to mass transfer and concentration variation. The measurement of dynamic interfacial tension in such condition is of vital importance to direct the design of extraction equipment. In previous study (Zhou at al., Chemical Engineering Science, 197, 172–183), we presented the quantitative relation between the droplet breakup frequency function and interfacial tension. In this work, the droplet breakup frequency function in mass transfer process is measured at four different heights of the pulsed column using the method developed in our previous work (Zhou at al., AIChE Journal, 63(9), 4188-4200). The dynamic interfacial tension at different height of the column is then calculated by regression method. With acetic acid – water as the dispersed phase and 5%TBP – kerosene as the continuous phase, the results show that the dynamic interfacial tension increases with height decreasing. Comparing the dynamic interfacial tension with the static interfacial tension of equilibrium liquid-liquid system, we have found that the former is smaller than the latter when the concentration of acetic acid in the continuous or dispersed phase is the same. This result indicates that interphase mass transfer leads to decreasing of the interfacial tension. The decreasing extent of the dynamic interfacial tension has a positive correlation with the mass transfer flux. Furthermore, under mass transfer conditions, binary breakage occupy the dominant position at different height and up to quintuple breakage can be observed.