MIL-53 (Al) nanostructure for non-steroidal anti-inflammatory drug adsorption in wastewater treatment: Molecular simulation and experimental insights

Pharmaceuticals are prevalent in the environment, especially the nanostructures of non-steroidal anti-inflammatory drugs (NSAIDs) in water, which can harm human health and the environment. Adsorption processes are effective and energy efficient for removing contaminants. In this study, a new adsorbent, MIL-53 (Al), was used to remove pharmaceutical pollutants, including diclofenac (DIC), ketoprofen (KET), indomethacin (IND), and mefenamic acid (MFA), from wastewater. This study employed a combination of quantum mechanical (QM) calculations, Monte Carlo (MC) simulations, and molecular dynamics (MD) simulations to understand the adsorption behaviors of these contaminants. This study first analyzed the structures of the contaminants and the adsorbent using various techniques, such as electrostatic potential, reduced density gradients, and Hirshfeld surfaces. Then, we investigated the adsorption affinity of pharmaceutical pollutants on MIL-53 (Al) using the COSMO sigma profile and HOMO-LUMO energies. The simulation results revealed that HBs, electrostatic interactions, and 7C-7C stacking primarily contribute to the adsorption mechanism. Laboratory tests confirmed the synthesis of MIL-53 using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and wide-angle X-ray diffraction (WAXD). Ultraviolet-visible (UV-Vis) spectroscopy was performed to analyze the adsorption of the targeted drugs, and the experimental results agreed well with the modeling results. This study concluded that MIL-53 (Al) has the potential to serve as an effective adsorbent for the removal of pharmaceutical pollutants from wastewater because of its strong adsorption properties.