Adsorption of Most Common Drug Residues From Hospital Wastewater on Vermiculite Exchanged With Magnesium: A DFT Study

Significant amounts of effluents containing pharmaceuticals residues are released each year in the environment. These residues are responsible for the disruption of the metabolism of organisms. In this study, vermiculite, a low-cost and high specific area clay material, is a best and effective way to remove the micro-pollutants by adsorption. Thus, we investigate the adsorption of carbamazepine (CAR), aspirin (ASP), diazepam (DIA), diclofenac (DIC), paracetamol (PAR), and ibuprofen (IBU), the most common pharmaceutical pollutants encountered in wastewater, on the hydrated surface of vermiculite exchanged with magnesium using thermodynamic calculations and density functional theory (DFT). Our results indicate that DIC exhibits the highest affinity for the hydrated surface of vermiculite, followed by PAR, IBU, ASP, CAR, and DIA. Furthermore, it is possible to regenerate the adsorbent after use, just by heating the vermiculite to a temperature of 360 K. The adsorptions are all exothermic, with energies depending upon the structural configuration of the pollutant on the surface.