Effective removal and concentration of perfluoroalkyl substances (PFAS) using asymmetric membrane capacitive deionization with stop–flow operation

Abstract

The effective removal and concentration of perfluoroalkyl substances (PFAS) from aquatic environments has emerged as a critical challenge owing to their persistence, widespread occurrence, and potential human health risks. This study investigated the feasibility of using an asymmetric membrane capacitive deionization (ACDI) system for PFAS adsorption and concentration under various operational conditions. The results demonstrated that the ACDI system effectively adsorbed short-chain PFAS, even at low concentrations. Additionally, by employing a stop-flow operation during the desorption phase, the concentration factor was enhanced by 1.4 to 2.8 times compared to that achieved under a continuous-flow operation. The effects of key operational parameters, including initial concentration, applied voltage, flow rate, and desorption time, were systematically evaluated, in which the maximum concentration factor also reached 6.15 times. The performance of the system was further assessed using single-component, multi-component, and simulated semiconductor wastewater solutions containing various types of PFAS. Notably, even in simulated semiconductor wastewater containing high levels of competing ions and organic matter, the ACDI system maintained superior adsorption and concentration performance for short-chain PFAS, particularly trifluoroacetic acid (TFA). Overall, this study provides valuable insights into the applicability and operational factors associated with implementing ACDI systems for PFAS treatment scenarios, highlighting their effectiveness in the removal and concentration of short-chain PFAS. © 2025 The Author(s)