Scaling up cloud point extraction of. aromatic contaminants from wastewater in a continuous rotating disk contactor. II. Effect of operating temperature and added electrolyte

When a nonionic surfactant solution is heated above the cloud point, phase separation occurs. Two isotropic phases are formed: a micellar-rich or coacervate phase and a micellar-dilute phase. The organic contaminant dissolved in the wastewater tends to solubilize into the micelles and concentrate in the coacervate phase, resulting in a low concentration of contaminant in the dilute phase. In this work, this cloud point extraction (CPE) was scaled up from batch to continuous operation in a multistage rotating disk contactor to remove toluene from wastewater. The surfactant partition ratio, toluene partition ratio, and the concentration of surfactant and toluene in the coacervate phase increase with increasing temperature. The addition of NaCl shows corresponding results to an increase in temperature since NaCl can depress the cloud point. The overall volumetric mass transfer coefficient and the number of transfer unit increase, whereas the height of transfer unit decreases when temperature is raised or NaCl is added to solution.