Abstract
As an essential environmental issue, the chemisorption/physisorption adsorption of non-steroidal anti-inflammatory drugs (NSAIDs) on solid adsorbents is one of the promising procedures to remove these drugs, especially from household water and wastewater treatment plants (WWTPs). This study presented the first available simulation of the interactions of four NSAIDs, namely Ketoprofen (KETO), Ibuprofen (IBU), Diclofenac sodium salt (DIC), and Naproxen (NAP) with a model of nanographene (NG) surface. Density Functional Theory (DFT) calculations at the B3LYP-D/6-311G(d) level were applied to investigate NG platelets' potential to adsorb such drugs. The electronic, electrostatic properties and some important quantum chemical parameters of the free drug molecules were calculated and compared. The systems' binding energies and thermodynamic parameters composed of drug adsorbed on the NG surface formed from optimized geometries obtained free from any structural restrictions were calculated and discussed. Among the four systems, the DIC@NG system showed the largest binding energy, totally agreed with the experimental finding. Computed negative free energies changes (ΔGads) matched the negative experimental values, the DIC@NG, the most stable adsorbed system and the system with the highest % removal value shows the most negative ΔGads. The spontaneity of the adsorption process was advent from the negative values of the thermodynamic parameters.