Effects Of Surfactants On Acoustic Cavitation Bubble Dynamics

Acoustic cavitation bubble is a kind of bubble in liquid,which is closely related to the nature of gas-liquid interface.Surfactants can change the mechanical,thermal and chemical properties of gas-liquid interface,so the dynamic behavior of acoustic cavitation bubble is sensitive to surfactants.Surfactants are often added into the acoustic cavitation liquid to improve the effects of acoustic cavitation.However,the effects of surfactants on the dynamics of a single cavitation bubble are rarely reported.The effects of surfactants on acoustic cavitation bubble dynamics have been investigated experimentally and theoretically.There are many kinds of surfactants,sodium dodecyl sulfate(SDS)is a common and important surfactant.In this paper,the time evolution of single cavitation bubble radius in SDS aqueous solution driven by ultrasonic wave and its correlation with SDS concentration are measured.The bubble pulsation is measured by a phase-locked integrated imaging technique,and the ambient radius is obtained by fitting the numerical calculation based on Rayleigh-Plesset bubble dynamics model to the experimental data.The results show that,under the same driving condition,the anbient radius of the cavitation bubble decreases correspondingly with the increase of SDS concentration within the critical micelle concentration,while the compression ratio of the radius increases,which indicates that the addition of SDS decreases the internal molecular number of the cavitation bubble and increase the power capability of the cavitation bubble.In addition,bubble oscillation increases the concentration of the surfactant molecules on the bubble wall,so that the effect of SDS on single cavitation bubble is reduced when the SDS concentration is greater than 0.8mM.