DFT-Based Study of the Removal Mechanism of Pollutant Metronidazole from Water Using a Polypyrrole Adsorbent

Quantum chemical analysis using the density functional theory (DFT) was used to characterize the adsorption mechanism of metronidazole on the surface of polypyrrole (PPy). Researchers have established the electrophilic character of metronidazole and the nucleophilicity of PPy, as well as the electrophilic and nucleophilic zones responsible for non-covalent interaction in the processes of physical sorption of metronidazole on PPy as part of the decontamination of water using a drug. The adsorption mechanism of metronidazole on PPy is mainly governed by physical interactions (water bonds) between the adsorbate and adsorbent, and also the energy and structure results indicate that physically the process is sorption. These structural and energetic procedures match well with experimental results. The changes in thermochemical enthalpy and entropy showed the non-negotiable and exothermic phenomenon of physical adsorption. Thus, PPy can be considered an environmentally friendly and effective adsorbent material for the removal of metronidazole and, possibly, other pharmaceutical pollutants from pharmaceutical and municipal wastewater.