Abstract
Surfactants are widely found in many products such as detergent, cosmetics, shampoo and drugs. As environmental regulations tightened, there is increasing concern about reducing the surfactant concentration in effluent streams. Foam fractionation is the direct and continuous treatment which would allow for the reuse of both water and surfactant. In this study, two multi-stage foam fractionators with different tray spacing were set up to investigate the recovery of cetylpyridium chloride (CPC), a cationic surfactant, from aqueous solution. Effects of several important variables, including surfactant feed concentration and flow rate, air flow rate, foam height, number of trays and recycle position ratio, were systematically studied. It can be seen from the results that increasing air flow rate and surfactant concentration resulted in lowering enrichment ratio but increasingly % surfactant recovery. Effect of foam height on surfactant recovery was not as significant as it was on the enrichment ratio. With increasing feed flow rate, both enrichment ratio and surfactant recovery decreased. On a contrary, increasing number of trays was found to enhance both enrichment ratio and recovery. Lastly, changing recycle position was shown to have more impact on the column performance than changing the recycle ratio or tray spacing.
