Removal of Perfluorooctanoic Acid and Perfluorooctane Sulfonate from Wastewater by Ion Exchange

Recent studies have demonstrated that fully fluorinated surfactant molecules have a tendency to accumulate in biological tissues. As a result, the Environmental Protection Agency has sought to reduce the usage of these chemicals and limit their discharge into the environment. Perfluorooctanoic acid (PFOA) is used in the manufacture of fluoropolymers and fluoroelastomers and is present as a component of some top-antireflective coating (TARC) materials. Perfluorooctane sulfonate (PFOS) is a component of some TARCs and photoacid generators used by the semiconductor industry in its fabrication processes. The purpose of this study is to determine effective and economically feasible methods to treat PFOA/PFOS contaminated process wastewater. A treatment screening study was performed investigating activated carbon adsorption, adsorption onto calcium fluoride solids, evaporation, ion exchange, and liquid-liquid extraction. Ion exchange was determined to be the best technology for treatment of PFOA/PFOS wastewater. Batch equilibrium isotherm experiments and a continuous-flow column study were performed to determine a feasible design. In addition, a model based upon equilibrium multicomponent chromatography theory was employed for prediction of column breakthrough curves.