The Short and the Long of It
Electrochemistry-based system removes 90 percent of both ultra-short and long-chain PFAS from water
Credit: Lehava Center Qiryat Gat
The ongoing battle against per- and polyfluoroalkyl substances (PFAS) – the group of pollutants famed for their persistence and toxicity – has been bolstered by the development of a new electrochemical system capable of tackling ultra-short to long-chain compounds simultaneously.
The system, known as redox-polymer redox-electrodialysis (ED), developed by a team at the University of Illinois Urbana-Champaign, USA, uses a water-soluble redox polymer integrated with nanofiltration membranes (NFs). These membranes allow selective removal of PFAS by size and charge while resisting material build up on the membrane’s surface (fouling) – an issue commonly encountered in PFAS treatment. The method enables the simultaneous removal of both ultra-short-chain PFAS, which are particularly challenging due to their high mobility, and long-chain PFAS, which tend to persist in environmental systems.
The team employs a combination of electrodialysis and electrosorption; short-chain PFAS were up-concentrated through electrodialysis; whereas longer-chain PFAS are removed through electrosorption. In practice, the system removed approximately 90 percent of various PFAS chain lengths from water, while concurrently reducing salts to potable levels, addressing both PFAS contamination and desalination in a single step.
Further analyses using Fourier transform infrared (FTIR) spectroscopy and energy-dispersive X-ray spectroscopy (EDS) confirmed that the system minimized membrane fouling. Unlike conventional anion-exchange membranes (AEMs), the cellulose-based nanofiltration membranes retained their functionality throughout repeated cycles.
Once PFAS were removed from water, the team incorporated electrochemical defluorination to break down the fluorinated compounds, achieving mineralization levels between 76 percent and 100 percent. This highlighted the potential for the redox-polymer ED system to go beyond mere PFAS separation, integrating both removal and degradation within a scalable electrochemical framework.
Looking to the future, the team intends to scale up their process outside of lab conditions, for on-site integration into industrial wastewater streams. "This work is very timely due to interest from the US government, wastewater treatment facilities, and the semiconductor industry," said lead author Xiao Su in a recent press release. "Semiconductor production is expected to rise over the coming years, and PFAS abatement for sustainable production will become a major issue moving forward."
Deputy Editor of The Analytical Scientist
