Surfactant recovery from water using a multistage foam fractionator

Abstract

The purpose of this research was to investigate the recovery of surfactants from water using a multistage form fractionation process. The study was divided into two parts. In the first part, the effects of various operational parameters on the recovery of a cationic surfactant (cetylpyridinium chloride of CPC) were investigated. In the second part, the recovery of three different types of surfactants: cationic (CPC), anionic (sodium dodecyl sulfate, SDS) and nonionic (polyoxyethylene sorbitan monolaurate, Span80) was studied under various conditions. The performance of the multistage foam fractionator was reported in terms of enrichment ratio and surfactant removal fraction. The results obtained from the first part of the study clearly showed that CPC was recovered from water by the multistage foam fractionator used in this study much more effectively when compared to the single-stage foam fractionator. For the multistage foam fractionator, both enrichment ratio and surfactant removal fraction increased with increasing feed flow rate, foam height, and number of stages whereas they decreased with increasing surfactant feed concentration and air flow rate. In the second part of the study, CPC, the cationic surfactant, was found to be removed from water by the multistage foam fractionator much more effectively than SDS and Span80 which appears to be related to the foamability and foam stability of the surfactant. When comparing among the three surfactants studied, both foamability and foam stability of the CPC system were the lowest due to the lower repulsive force between pyridinium groups.