GAS SCAVENGING OF SOLUBLE AND INSOLUBLE ORGANIC VAPORS BY LEVITATED WATER DROPS

Three-millimeter-diameter drops of water were levitated with a standing acoustic wave centered in the jet of a small wind tunnel and the volume changes as the drop evaporates in the presence of 1-propanol vapor were measured. The results are compared with a steady-state continuum evaporation model based on nonideal solution theory. Because the thermodynamic parameters for the 1-propanol-water system are well known, this system provides a test for our model. Good overall agreement between model and experimental results means that small discrepancies can be used to establish limits for dynamic effects. An immiscible liquids version of this model, which accounts for gas scavenging of methyl salicylate, is used to predict the amount of insoluble material scavenged by a drop of water evaporating to dryness. This model predicts that the volume of organic liquid left behind increases slightly as the relative humidity approaches 100%.