Influence of photodegradation and surface modification on the graphene‐diclofenac physisorption process

The present study provides the theoretical investigation of the mutual interaction of diclofenac and its photodegradation product with carbon materials. Because of the known weak interaction between graphene and aromatic molecules, the analyzed material surfaces are modified in order to maximize the mutual material: drug attraction. It is shown that the Stone‐Wales defects and single boron‐nitride pair doping only slightly influence the drug attraction, but the strongest impact is noticed for the introduction of the functional carboxyl group to the graphene sheet that preferably contains moreover single or double vacancies. Here, the additional stabilization with respect to the pristine graphene sheet is on the order of 7 to 10 kcal mol−1. A comparison of the adsorption of neutral acidic diclofenac molecule with its ionized form frequently applied in medical formulations shows that the negative charge accumulated on the carboxylate anion significantly increases the attraction of the drug by the graphene oxide (interaction energy changes from −27.45 to −46.33 kcal mol−1 upon ionization). Symmetry‐adapted perturbation theory applied for the decomposition of the interaction energy into the physically justified components confirms that all the investigated structures are governed by dispersion forces. Supermolecular MP2‐coupled approach with improved dispersion description allows to conclude that common density functional theory (DFT) functionals, including double hybrids with spin‐component scaling and dispersionless Pernal and Podeszwa functional, perform qualitatively well in the case of (modified‐) graphene materials, however, need to be applied with care for their boron‐nitride analogs. Environmental and health‐safety concerns call for the design of new adsorbents that allow for the effective removal of nonsteroidal anti‐inflammatory drugs, as well as their metabolites, from soil and wastewaters. The present study presents a theoretical investigation of the mutual interaction of the commercially popular drug diclofenac, and its photodegradation products, with graphene‐based materials, modified to improve adsorption properties.