Surfactant recovery from water using foam fractionation

Abstract

The purpose of this study was to investigate the use of foam fractionation to recover surfactant present at low concentrations in aqueous streams. A simple continuous mode foam fractionation was used and three surfactants were chosen for this study : sodium dodecyl sulfate, cetylpyridinium chloride, and sodium n-hexadecyl diphenyloxide disulfonate. In a previous study, the effect of surfactant concentration, air flow rate, liquid and vapor phase heights, and sparger type were investigated for these surfactants. Here, the effect of temperature and added salt were studied. It was found that the foam flowrate and enrichment ratio increase whereas the foam wetness and the rate of surfactant recovery decrease with increasing temperature. Increasing the concentration of added salt decreases the CMC of the surfactants. The foam flowrate, foam wetness and the rate of surfactant recovery increase while the enrichment ratio decreases with increasing concentration of salt.