PFAS Replacement Chemistry: A Moving Target for Water Treatment
As regulators phase out PFOA, PFOS, and GenX, manufacturers have developed yet newer PFAS replacement compounds. ADONA (perfluoro(3,6-dioxaoctanoic acid)) and F-53B (6:2 chlorinated polyfluoroether sulfonate, used in China’s chrome plating industry) represent the expanding frontier of novel PFAS creating new treatment challenges.
ADONA’s Structural Novelty and Treatment Implications
ADONA contains ether linkages in its backbone that distinguish it structurally from linear PFAS. This structural difference affects its adsorption behavior on activated carbon—ether PFAS generally show reduced adsorption compared to all-carbon chain analogs of the same length. Studies of ADONA removal on GAC find removal efficiencies of 50–70%, substantially below PFOA removal under the same conditions.
F-53B: Chrome Plating’s Global Contamination Legacy
F-53B has contaminated water supplies near electroplating facilities throughout Asia and has been detected in European water supplies from imported goods. Its large molecular size and complex structure create variable GAC adsorption behavior, with removal efficiencies that depend heavily on competing ions, organic matter, and operating conditions. Standard GAC systems optimized for PFOA do not reliably remove F-53B.
The Regrettable Substitution Cycle
Each generation of PFAS replacement creates a new treatment challenge just as water utilities are adapting to the previous generation. ADONA was introduced as a safer PFOA alternative and is now itself under regulatory scrutiny. This cycle of regrettable substitution means treatment technologies that focus only on currently regulated compounds are perpetually behind the contamination curve.