Removal and recovery of a cationic surfactant from its aqueous solution by foam fractionation

Abstract

Extensive use of the surfactants helps the development of many consumer products, but it contaminates water in many cases. Thus, the removal and recovery of these surfactants has become essential. In this study, a cationic surfactant (i.e., cetyltrimethylammonium bromide) was recovered from its aqueous solution by employing the foam fractionation method in batch mode in a cylindrical column. The surfactant concentration was five times its critical micellar concentration (i.e., 1822 mg dm–3). The effects of three salts (i.e., NaCl, CaCl2, and Na2SO4) and airflow rate on the surfactant recovery were studied. The salt concentration was varied from 10 to 100 mol m−3, and the airflow rate was varied from 0.4 to 1.6 dm3 min−1. About 60 % of the surfactant was recovered from the top of the column in the form of a semi-solid paste. The foam volume and surfactant recovery were reduced by the addition of salt. The stability of the foam played a very important role in surfactant recovery. The recovery of water was excellent.