Synthesis of structured adsorbents for PFAs capture monitored by 19F NMR

November 20, 2025

Poly- and perfluoroalkyl substances, commonly known as PFAs, are synthetic pollutants with unique properties, such as water repellency, making them valuable for various applications, including non-stick cookware, food packaging, firefighting foams and cosmetics. However, PFAs are hazardous and linked to health risks, including cancer. The extreme chemical stability of PFAs allows them to persist in the environment and within living beings, resisting degradation. A lot of effort has been made recently to develop methods for removing and destroying PFAs. The primary goal of this study is to explore the application of 19F NMR as a faster alternative to LC-MS/MS for detecting and quantifying four PFAs: perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorobutanoic acid (PFBA) and perfluorobutanesulfonic acid (PFBS). Improvements in spectra acquisition and data mathematical treatment enabled the detection of all PFAs, but accurate quantification was achieved only for the long-chain PFAs, such as PFOA. Additionally, the study focuses on the development of a specific material for PFAs adsorption in aqueous media, using as support an amorphous silica and two beta zeolites. The materials characterisation by FTIR, N2 physisorption, TGA and solid-state 29Si and 13C NMR demonstrated that the syntheses proceeded as expected. The materials were subjected to batch adsorption tests to assess the amount of active sites suitable for PFOA and PFBA adsorption, as well as the respective capacities. The beta zeolite with the highest amount of silicon (Si/Al = 128) exhibited the best performance, indicating that a microporous crystalline structure with high silicon contents favours PFAs adsorption.

Authors in the community:

• 

  M

  Margarida Maria Gonçalves de Jesus

  ist1100423

Supervisors of this institution:

• 

  M

  Moisés Luzia Gonçalves Pinto

  ist416959

chemical-engineering - Chemical engineering

por - Portuguese

Instituto Superior Técnico