Accumulation of Surface-Active Solutes in the Aerosol Particles Generated by Ultrasound

We measured the composition of the droplets of the aerosols generated by ultrasound from aqueous solutions containing various concentrations of Triton X-100 (an octylphenyl ethoxylate nonionic surfactant) and d-glucose, the latter being a reference nonsurfactant solute. To prevent the sonochemical decomposition of the solutes, sonication was performed under the atmosphere of carbon dioxide. It was found that the concentration of the surfactant in the droplets of the ultrasonically generated aerosol was significantly (up to 10 times) higher than that in the solution being atomized, while the concentration of d-glucose in the droplets did not differ from its concentration in the bulk of the solution. The enrichment of the aerosol's droplets with the surfactant was found to increase with the decrease of the surfactant concentration in the solution being atomized. The observed effect is explained by the specific mechanism of the ultrasonic aerosol formation:  under the influence of ultrasound small droplets t...