Tailoring nanofiltration membranes with MOF 303 modified support layer for enhanced PFAS and heavy metal separation

Abstract

Per- and polyfluoroalkyl substances (PFAS) are persistent synthetic chemicals extensively used in industrial and consumer products, posing significant environmental and health concerns. The PFAS and metal-contaminated water serve as a primary source of human exposure, necessitating effective remediation strategies. In this study, we developed a nanofiltration (NF) membrane by integrating an aluminum-based metal-organic framework (MOF 303) into a polyethersulfone (PES) support layer, followed by the fabrication of a selective polyamide layer, and tested its performance for PFOS, PFOA, As(V), and Cr(VI). The resulting PES-MOF 303-TFC membrane exhibited excellent performance, achieving pure water permeance of 11.68 ± 1.34 LMH bar^-1, approximately 1.5 times higher than the pristine PES-TFC membrane and a Na₂SO₄ salt rejection of 87.16 ± 3.14 %. It demonstrated robust rejection rates of ∼92 % for PFOA and 93 % for PFOS in simulated groundwater, alongside the effective removal of As(V): ∼97 % and Cr(VI): ∼86 % in a cross-flow mode of operation. The membrane maintained over 92 % rejection of PFOA and PFOS in a simulated secondary-treated wastewater matrix. These results highlight the dual electrostatic repulsion and size exclusion mechanisms of the PES-MOF 303-TFC membrane, offering a versatile, high-performance solution for remediating groundwater contaminated with PFAS and heavy metals. Our findings emphasize the promise of NF membranes with tailored properties for addressing emerging water contamination challenges.