Efficient Covalent Organic Frameworks for Treating Pharmaceuticals in Water

The excessive use of antibiotics has resulted in severe water pollution, posing significant risks to human health. Therefore, effective antibiotic removal from water sources is urgently needed. Among various treatment methods, adsorption stands out as an ideal approach due to its cost-effectiveness, simplicity, and reusability. Mesoporous covalent organic frameworks (COFs) emerge as excellent adsorbents, offering high porosity, structural adaptability, and well-defined crystallinity. In this study, we investigated the adsorption behavior of two crystalline mesoporous covalent organic frameworks (COF-1 and COF-2) toward pharmaceutical pollutants, specifically diclofenac (DIC) and ketoprofen (KTP), in aqueous media. In addition, we explored their functionalized counterparts (F-COF1 and F-COF2) using molecular dynamics (MD) and metadynamics simulations to elucidate the underlying interaction mechanisms and assess their efficiency in capturing pharmaceutical contaminants. Our simulation results indicate that electrostatic and van der Waals hydrophobic forces play crucial roles in the interaction between antibiotics and COF substrates. Analysis of the obtained results reveals that the DIC/F-COF-1, DIC/F-COF-2, KTP/F-COF-1, and KTP/F-COF-2 systems exhibit remarkable stability, with total interaction energy values of −374.68, −639.71, −460.38, and −243.02 kJ mol–1, respectively, at a concentration of eight drug molecules per system. The energy analysis confirms that DIC and KTP show a good tendency for adsorption onto the COFs, and their functionalized versions demonstrate greater efficiency in adsorbing these pollutants from wastewater. The results demonstrated that the adsorption capacity (qe) increases with rising drug concentration across all systems, reflecting the typical adsorption behavior driven by the greater availability of drug molecules to occupy the accessible active sites. Furthermore, the results from the metadynamics simulations are supported by molecular dynamics analysis, showing that the KTP/F-COF system has an interaction energy of −275 kJ mol–1, while the DIC/F-COF systems exhibit interaction energies of approximately −300 kJ mol–1. This study emphasizes the potential of COF nanomaterials for water remediation, offering valuable insights for researchers exploring their use in antibiotic adsorption from aquatic environments.