Mechanochemically Synthesized Covalent Organic Framework Effectively Captures PFAS Contaminants

Area of Science:

• Environmental Chemistry
• Materials Science
• Nanotechnology

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants linked to significant health risks.
• Developing effective removal methods and adsorbers for PFAS is a critical environmental challenge.
• Covalent organic frameworks (COFs) offer potential as stable, tunable, and metal-free adsorbers.

Purpose of the Study:

• To synthesize a highly crystalline covalent organic framework (COF) for PFAS removal.
• To investigate the adsorption efficiency and kinetics of the synthesized COF for common PFAS.
• To elucidate the interaction mechanisms between PFAS molecules and the COF structure.

Main Methods:

• Mechanochemical synthesis of a TAPB-TFB COF.
• Real-time monitoring of COF formation using in situ synchrotron X-ray diffraction.
• Adsorption experiments for PFAS removal from water, including PFOA and PFOS.
• Characterization using X-ray photoelectron spectroscopy, FTIR, and DFT calculations.

Main Results:

• A highly crystalline TAPB-TFB COF was successfully synthesized.
• The COF demonstrated efficient removal of PFAS, including PFOA and PFOS, from water.
• Rapid adsorption kinetics were observed, with most PFAS removed within 10 minutes.
• Molecular interactions between PFAS and the COF were elucidated.

Conclusions:

• The TAPB-TFB COF is a highly effective and rapid adsorbent for PFAS removal.
• This metal-free COF presents a promising material for advanced water treatment applications.
• The study provides insights into the mechanism of PFAS adsorption by COFs.