Recovery of nonionic surfactant from VOC-contaminated coacervate phase solutions by co-current vacuum stripping: Effect of surfactant concentration, temperature, and solute type

To make a cloud point extraction (CPE) process economically feasible, the used surfactant in the concentrated or coacervate phase should be recycled and reused. We have demonstrated a co-current vacuum stripping using a 30.5-cm long column packed with glass Raschig rings effectively removes as much as 90% of the toluene from a surfactant coacervate phase solution without flooding or plugging. It was found that the apparent Henry's law constant of the volatile organic compounds (VOCs) was significantly reduced due to solubilization of VOCs in surfactant micelles, but increased substantially with increasing temperature. In addition, it was observed that the increase in hydrophobicity of the VOCs results in higher micellar solubilization in the coacervate solution, leading to lower VOC removal efficiency. However, over 87% of all studied VOCs (benzene, toluene, ethylbenzene, 1,2 dichloroethane, trichloroethylene, and tetrachloroethylene) were removed from a coacervate solution within a single stage operation. The removal of VOCs increases with decreasing surfactant concentration and VOC hydrophobicity, and also increases with increasing system temperature.