Quantitative analysis of electrostatic interactions in nanofiltration for charged organic molecules removal

Abstract Charged organic molecules (COMs) are widely used but persistent contaminants that pose risks to ecosystems and human health. Nanofiltration (NF) offers a promising solution, yet existing membranes often fall short in effectively removing COMs due to limited quantitative understanding of electrostatic interactions in the separation mechanism. In this study, a physics‐based electrostatic interaction model was developed by integrating Coulomb's law to quantify interaction forces, Gauss's law to describe the electric field of charged membranes, and the Henderson–Hasselbalch equation to relate the ionization of surface groups and solutes to their charge densities. The model quantitatively links membrane and solute charge states to electrostatic interaction strength and was validated through rejection experiments, yielding a correlation coefficient of −0.857. It demonstrates robust predictive capability for NF performance and guides membrane charge design to enhance targeted COM removal.