Electro-EnhancedPolyacrylonitrile Membrane Separationfor Pharmaceutical Wastewater: Mechanism Study via Molecular DynamicsSimulation

Advanced membrane separation technology is essential for green chemical processes in pharmaceutical wastewater treatment. Electric field-assisted separation effectively blocks charged molecules and ion transmembrane migration, but a detailed molecular-scale model of these mechanisms is still needed. Herein, we present a molecular dynamics study investigating the effects of electric field strength and water content on the separation process of pharmaceutical wastewater within various polyacrylonitrile membranes. Under an external electric field, the repulsion of anions and attraction of cations, especially in the mixed membrane system, were significantly enhanced. Within the range of 0 to 15 Å, the cumulative distribution intensity of cefuroxime^– decreased by 2.1 to 15.1%, while the intensity of Na⁺ increased by 28.8 to 51.3%. The concentration disparity of charged particles on the membrane surface was mainly attributed to electrically enhanced adsorption/desorption and the Donnan effect, rather than electrophoretic motion. Additionally, both Na⁺ and cefuroxime^– diffusion increased with rising water content and electric field strength. These findings propose a mechanism for the electrically enhanced separation of pharmaceutical wastewater, offering guidance for selecting and modifying membranes prior to experiments through molecular dynamics simulation.