Brief History of Defoaming by Ultrasound

3 DEFOAMINC USING ULTRASOUND 7.3.1 Brief History of Defoaming by Ultrasound 

FIGURE 7.17 Schematic diagram of arrangement used by Sandor and Stein to study effect of ultrasound on foam generated in bubble column from a submicellar aqueous solution of SDS. (From Sandor, N., Stein, H.N., J. Colloid Interface ScL, 161, 265,1993.) 

Komarov et al. [61] have also studied the effect of acoustic pressure on the residence time of gas in foam generated by nitrogen sparging a bubble column containing highly viscous glycerin-water solutions (of viscosity 100 mPa s). The residence time of gas in the foam in a bubble column is of course the foaminess, Ebik of Bikerman [62]. It is measmed in the case where continuous injection of gas results in the formation of a foam of a steady height at which the rate of bubble rupture 

FIGURE 7.19 Residence time of gas in foam (foaminess, Sb,k) of a bubble column as function of acoustic pressure and frequency. Solutions of 85 15 volume ratio glycerin-water , v = 90 Hz , v = 289 Hz A, v = 465 Hz. Solutions of 90 10 volume ratio glycerin-water , v = 90Hz O, v = 289 Hz A, v = 465 Hz. (Reprinted from Ultrason. Sonochem., 7, Komarov, S.V., Kuwabara, M., Sano, M., 193. Copyright 2000, with permission from Elsevier.) 

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