Tailoring ZSM-5 zeolite surfaces for enhanced adsorption of organic pollutants: a molecular dynamics and MM-PBSA approach

Abstract

The efficient removal of organic pollutants from wastewater remains a major environmental challenge. Zeolite ZSM-5, known for its tunable physicochemical properties, is a promising adsorbent for contaminant removal. This study investigates the adsorption behavior of dimethyl phthalate (DMP), phthalic acid (PHA), and phenethylamine (PEA) on pristine and aminosilane-functionalized ZSM-5 using molecular dynamics simulations, emphasizing the underexplored role of functionalization in such systems. Results show that functionalization significantly enhances adsorption performance. The diffusion coefficient of DMP decreases from 0.01238 × 10− 5 cm2/s in pristine ZSM-5 to 0.0028 × 10− 5 cm2/s after functionalization, indicating a 77% reduction in mobility and stronger adsorbent–adsorbate interactions. Mean square displacement analysis reveals faster equilibration and improved adsorption efficiency, with DMP adsorption time reduced by 30%. Radial distribution function results confirm stronger and more selective adsorption, with sharper peaks indicating preferential localization near functional groups. MM-PBSA calculations demonstrate that enhanced binding arises from combined van der Waals, electrostatic, and hydrogen bonding interactions. Metadynamics simulations further show reduced free energy in functionalized systems, with minima of − 248.17 kJ/mol for ZSM-5/PEA and − 473.93 kJ/mol for ZSM-5/DMP, indicating more favorable adsorption. Energy barriers are overcome, leading to stable adsorption states. Overall, this study clarifies the molecular mechanisms governing adsorption and highlights functionalized ZSM-5 as an effective material for wastewater treatment. The combined computational approach provides insights for designing advanced zeolite-based adsorbents and optimizing functionalization strategies for real-world applications.