Physiochemically modified cellulose‐rich fibres from <scp> <i>Arbutus pavarii</i> </scp> for efficient adsorption of antihistamine (cyproheptadine hydrochloride): Models and mechanism of adsorption

Abstract The increasing presence of pharmaceutical residues in aquatic ecosystems poses significant environmental risks, necessitating effective and sustainable remediation strategies. This study evaluates the potential of Arbutus pavarii leaf fibre (APLF), an endemic Libyan biomass, as an economically viable biosorbent for eliminating the antihistamine cyproheptadine hydrochloride (CPH) from aqueous solutions. Cellulose‐rich fibres were isolated via dewaxing, delignification, and alkaline bleaching. Characterization using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis confirmed that chemical modification successfully removed lignin and hemicellulose, resulting in a fibrillated morphology with increased crystallinity and a specific surface area of 11.56 m 2 g −1 . Batch adsorption experiments revealed that CPH uptake was strongly influenced by solution pH, with maximum removal efficiency observed at pH 6.0 and a rapid equilibrium time of 25 min. Kinetic analysis provided that the Avrami fractional‐order kinetic model provides the most suitable description of the adsorption mechanism ( R 2 adj = 0.962), suggesting a complex physicochemical sorption mechanism involving multiple kinetic orders. The Sips isotherm model yielded the most accurate fit for the equilibrium data. ( R 2 adj = 0.975), predicting a maximum uptake capacity q m of 0.1225 mol kg −1 (39.7 mg g −1 ), which surpasses many previously studied agricultural by‐product adsorbents. Furthermore, regeneration studies demonstrated that APLF retained over 70% of its efficiency after two adsorption–desorption cycles. These findings demonstrate that Arbutus pavarii leaf fibre is an environmentally benign and highly effective sorbent for the removal of pharmaceutical pollutants from aqueous systems.