Magnetic nanocomposites have emerged as promising materials for the recovery of metal ions owing to their distinctive physicochemical properties. In this study, a novel magnetic nanocomposite (Fe3O4@Bnt) was synthesized via coprecipitation by functionalizing bentonite clay with iron oxide nanoparticles. Comprehensive characterization was performed using XRD, FTIR, SEM, TGA, N2-BET surface analysis, and pHpzc measurements to evaluate the structural and surface features of the adsorbent. Furthermore, the efficiency of Fe3O4@Bnt for the adsorption of La(III) ions was evaluated under varying conditions, including pH, adsorbent dose, contact time, initial concentration, ionic strength, and temperature. The results showed that the adsorption efficiency could reach 97% after 20 min of contact, at a pH of 5.6, using 0.05 grams of adsorbent. The fitting of the experimental equilibrium data was investigated by different isothermal models, including Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin. The Langmuir model provided the best fit for the equilibrium data, with a maximum adsorption capacity of 62.32 ± 3.01 mg/g. Kinetic analysis conformed to the pseudo-second-order model, while thermodynamic parameters confirmed the spontaneous and endothermic nature of the process. Various possible mechanisms for the adsorption of La(III) on Fe3O4@Bnt, including electrostatic attraction, complexation, cation exchange, and pore filling, have been proposed. Regeneration tests demonstrated the reusability of Fe3O4@Bnt over three consecutive cycles with minimal efficiency loss. These findings highlight the potential of Fe3O4@Bnt as an effective and sustainable adsorbent for lanthanide ion recovery, aligning with circular economy principles and advances in environmental remediation technologies.
Ghitri et al. (Tue,) studied this question.