Molecular-level insights into naproxen sodium adsorption on activated carbons using advanced multilayer modeling

This study delves into the adsorption mechanism of Naproxen Sodium (NPXS), a relevant pharmaceutical pollutant found in wastewater, on three different commercial activated carbons (WG-12, F-300, ROW 08 Supra). An improved theoretical approach based on a multilayer adsorption model revealed that the total number of adsorption layers formed ranged from one to two in all systems. The number of NPXS molecules adsorbed per active site was quantified at 293, 303 and 313 K, resulting in 2.39, 2.16 and 1.95 for the ROW 08 Supra, 1.38, 2.64, 2.87 for WG-12 and 2.67, 2.06 and 1.82 for F-300. The magnitude of this parameter suggested comparable affinities across the different adsorbents. This behavior implies that the active sites exhibit similar interactions with NPXS molecules, possibly involving an aggregation process among adsorbed molecules. The correlation between the maximum adsorption capacities and adsorption energies revealed an endothermic behavior of the process, predominantly driven by physical interactions. A comparative analysis of the adsorbents' performance indicates that the materials evaluated in this study are competitive candidates for various adsorption-based applications and subsequent scale-up.