Sustainable adsorption of pharmaceuticals from wastewater using clay and cuttlebone powder: a case study in Northern Tunisia

Abstract Carbamazepine (CBZ), ibuprofen (IBU), and naproxen (NAP) are pharmaceutical compounds frequently found in natural waters due to their persistence during wastewater treatment processes. Their removal is essential for improving future wastewater management globally. In this study, we evaluated the performance of two adsorbents, clay powder (CP) and cuttlefish bone powder (CFBP), for the removal of these pharmaceutical compounds (PhCs). Adsorption isotherms, kinetics, and thermodynamics were investigated at the laboratory scale. The concentrations of the PhCs were measured using a validated method that combined solid-phase extraction (SPE) with high-performance liquid chromatography coupled with an ultraviolet detector (HPLC-UV). The kinetic were well described by the Elovich model, while adsorption isotherms corresponded better with the Freundlich and Sips models, suggesting multilayer adsorption. Thermodynamic analysis revealed that the adsorption of these PhCs was endothermic, driven by physisorption. The adsorption process demonstrated significant potential for application in real wastewater effluents containing PhCs at low, environmentally relevant concentrations, with removal rates exceeding 70% for carbamazepine, while ibuprofen and naproxen removal rates reached 53% at pH = 4 and at 10 µg L -1 . An assessment of implementation factors and costs suggests that the adsorbents CP and CFBP are promising candidates for real-world applications in water treatment systems. These materials provide a sustainable solution for the remediation of pharmaceutical pollutants in wastewater.