Simultaneous removal of organic and inorganic contaminants by micellar enhanced ultrafiltration with mixed surfactant

Micellar-enhanced ultrafiltration (MEUF)is a promising technology to separate organic and inorganic contaminants simultaneously under mild conditions. Organic compounds are solubilized into the core of micelle and inorganic pollutants can be bound on the surface of oppositely charged micelle. Trichloroethylene (TCE) and chromate were selected as an organic and inorganic contaminant, respectively. In this study, mixed surfactants were used to minimize the permeate surfactant concentration and enhance solubilization capacity. The feasibility of simultaneous removal of TCE and chromate by MEUF in the mixed surfactants was investigated, especially focused on the following aspects: the removal efficiency of each contaminant, the rejection of surfactants and relative flux. Cetylpyridinium chloride (CPC) as a cationic surfactant and Tween 80 as a nonionic surfactant were used to form mixed micelles. The removal of each pollutant was not hindered by co-presence of TCE and chromate, because the dominant removal mechanisms for each compound were different. Both CPC and Tween 80 were rejected effectively and the permeate concentration of each surfactant was maintained near the critical micelle concentration of the mixed surfactants system. The flux decline observed during filtration was mainly caused by the concentration polarization and high viscosity of Tween 80.