Abstract
An aqueous solution of dodecyl-benzenesulfonic acid sodium salt was ultrasonically atomized and liquid particles which were rich in surfactant were collected. Effects of surfactant concentration and KCl addition on the behavior of surfactant enrichment were examined. Interfacial tension was also observed at static conditions to discuss the trend of enrichment ratio in view of interfacial properties. For a mixture of the surfactant and de-ionized water, a high enrichment ratio was observed at lower concentration and the ratio dropped with increasing the surfactant concentration. Addition of KCl led to a significant enhancement of the enrichment ratio, and the ratio went through a peak on the plot against KCl concentration. The enhancement is interpreted as a result of an increase of surfactant adsorption due to charge neutralization of surfactant anions at gas-liquid interface. The salt addition lowers the cmc of the surfactant and micelles formation leads to a decrease in surfactant enrichment ratio.
