Response surface optimization, kinetic and thermodynamic studies for effective removal of rhodamine B by magnetic AC/CeO₂ nanocomposite

The activated carbon (AC) was obtained from waste scrap tires and modified by bimetallic Fe and Ce nanoparticles in order to combine both the high surface area and the active sites for enhanced adsorption of the dye. The produced nanocomposite was used as a novel cost-effective magnetic in rhodamine B (RhB) removal from aqueous solutions. The FT-IR, SEM, EDX, TEM, and surface area analysis methods were implemented to characterize the morphological, chemical, thermal and surface properties of the developed adsorbent. The optimum batch experimental conditions were found under the response surface methodology. The adsorption equilibrium data were well fitted by the Langmuir isotherm model. The adsorption capacity was 324.6 mg g⁻¹. The kinetic and thermodynamics studies were also carried out to understand the adsorption mechanism. The study indicated that RhB adsorption by the AC/Fe/Ce magnetic adsorbent has an endothermic character and followed the pseudo-second-order kinetics model. By using ethanol solution, RhB was desorbed at high efficiency and the prepared material could be recycled for up to ten cycles. Thus, the magnetic nanocomposite is an effective and promising adsorbent for the cleaning treatment of RhB ions from wastewater by a large scale designed adsorption system.