Experimental study and theoretical modelling based on DFT of the elimination of ceftriaxone by an activated carbon...

An activated carbon (AC) developed from grape seeds waste was characterized using various physico-chemical techniques to assess its structural and textural properties, then used for the removal of ceftriaxone (CFTX), an emerging pollutant, from aqueous solutions. Batch adsorption experiments were conducted, coupled with a theoretical study based on DFT (density functional theory) study , performed at the B3LYP level with a 6-311G (d,p) base , in order to study molecular geometries, electronic properties and molecular electrostatic potentials, to clarify the adsorption mechanism of CFTX on AC. The results revealed that the prepared AC had a well-established porosity offering a large exchange surface. Adsorption studies revealed that kinetic data aligned well with the PSO model, while equilibrium data were best described by the Freundlich isotherm and the multilayer STAT₁ model. Thermodynamic analysis indicated endothermal and favorable adsorption, mainly controlled by chemical interactions. Moreover, the regeneration studies showed the difficult desorption of CFTX, supporting a chemisorption mechanism. The results of DFT calculations indicated that the adsorption of CFTX is favorable on AC functionalized with -CHO and -COOH-OH-CHO, with adsorption energies of - [Formula: see text] and - [Formula: see text], respectively. AIM (atoms in molecules), NCI (non-covalent interactions) and RDG (reduced density gradient) analyses revealed that strong hydrogen-bond interactions mainly govern the adsorption mechanism. According to the obtained results, the produced AC is considered as a high-performance alternative material for the removal of CFTX from aqueous environments. In addition, a thorough understanding of the adsorption process resulted from integrating theoretical and experimental approaches.