Efficient removal of regorafenib from aqueous solutions using KOH-activated hazelnut husk-derived activated carbon: adsorption mechanism, kinetics, isotherms and thermodynamics
摘要
In this study, activated carbon was produced from hazelnut husks, an agricultural biomass waste, by chemical activation and thermal carbonization, and the performance of the resulting adsorbent in removing Regorafenib from aqueous solutions was investigated. The textural properties of the produced activated carbon were examined by BET analysis; it was determined that the specific surface area was 441.72 m² g− 1 and the total pore volume was 0.2490 cm³ g− 1. Pore structure analyses revealed that the adsorbent predominantly exhibited microporous characteristics. In addition, surface morphology, elemental composition, and functional groups were evaluated with SEM-EDX and FTIR analyses. In adsorption experiments, the effects of basic parameters such as solution pH, adsorbent dose, initial Regorafenib concentration, contact time, and temperature were systematically investigated. Optimum adsorption conditions were determined; The adsorbent dose was determined as 10 mg/50 mL, pH 7, initial concentration of 30 mg L− 1, and contact time of 120 min, under which approximately 97% removal efficiency was obtained. Isotherm model analysis of the equilibrium data revealed that the Langmuir model showed the best fit with the experimental data, and the maximum adsorption capacity was determined to be 283.47 mg/g. Kinetic analyses showed that the Pseudo Second Order kinetic model yielded a higher correlation coefficient. Thermodynamic analyses demonstrated that the adsorption process is endothermic and spontaneous. These results indicate that activated carbon produced from hazelnut husks can be considered an effective and sustainable adsorbent.