An Advanced Pore Flow Model for Uncoding Micropollutant Transport in Nanofiltration Membranes

Effective removal of organic micropollutants (OMPs) is crucial for water safety. While nanofiltration (NF) membranes offer a promising strategy, their limited and unpredictable performance against diverse OMPs arises from complex and poorly understood transport mechanisms. Here, we develop the pore flow model incorporating intermolecular forces (PFIF), a mechanistic framework that explicitly integrates key molecular interactions, including hydrogen bonding and van der Waals forces, into the analysis of OMP transport through NF membranes. Validated against a comprehensive data set encompassing diverse OMPs across multiple NF membranes, PFIF demonstrates high prediction accuracy and mechanistic interpretability, capturing OMP-specific retention behaviors beyond traditional size- and charge-exclusion paradigms. Density functional theory (DFT) calculations reveal hydrogen bonding as a predominant OMP-membrane interaction, correlating strongly with OMP-membrane binding strength. Meanwhile, molecular dynamics (MD) simulations suggest van der Waals forces attract OMPs from bulk solutions, potentially facilitating the partitioning process. By combining these multiscale approaches with experimental results, we construct a robust mass transfer framework demonstrating how high adsorption capacity, coupled with strong OMP-membrane binding, raises the transport energy barrier. Overall, PFIF not only establishes a reliable platform for rational membrane design but also deepens our understanding of molecular transport, advancing selectivity and performance in water purification technologies.