Dual-functional adsorptive membranes for PFAS removal: Mechanism, CFD simulation, and selective enrichment

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Emerging water contaminants like per- and polyfluoroalkyl substances (PFAS) are difficult to remove due to their stability and the presence of other substances.
• Conventional methods often struggle with efficient and selective removal of these persistent pollutants.

Purpose of the Study:

• To design and evaluate dual-functional adsorptive membranes for selective removal of PFAS in the presence of organic competitors.
• To investigate the performance, reusability, and underlying mechanisms of these novel membranes for water remediation.

Main Methods:

• Fabrication of dual-functional adsorptive membranes with hydrophobic backbone and quaternary ammonium moieties.
• Performance testing for perfluorooctanoic acid (PFOA) removal, including reuse cycles and capacity assessment.
• Characterization of removal mechanisms using enrichment factors, permeability measurements, and computational fluid dynamics (CFD) modeling.

Main Results:

• Achieved 96.8% PFOA removal, with sustained >90% removal over five reuse cycles and a total capacity of 650 L m^-2.
• Demonstrated synergistic electrostatic attraction and hydrophobic interactions, yielding a PFOA enrichment factor of 18.5 and high permeability (34.6 L m^-2 h^-1 bar^-1).
• CFD modeling indicated efficient mass transfer control, with residence time as the most significant parameter.

Conclusions:

• Dual-functional adsorptive membranes show high efficacy and selectivity for PFAS removal, even with competing substances.
• The membranes exhibit excellent regeneration and reusability, highlighting their practical potential for large-scale water treatment.
• This study presents a promising adsorptive membrane technology for addressing the challenge of PFAS contamination in water resources.