Efficient recovery of Ce(III) ions from acidic solutions using oxalic acid crosslinked chitosan

Cerium (Ce) is widely utilized in several industrial applications and may pose health risks owing to environmental overexposure. The oxalic acid crosslinked chitosan (CHOA) adsorbent was fabricated via an eco-friendly two-step technique and employed for the Ce(III) ions adsorption from a water-based solution. The CHOA was defined by quantitative and spectroscopic examinations. The results indicate that the inclusion of oxalic acid as a cross-linking agent improved the adsorption and stability of chitosan under acidic conditions. Furthermore, it was noted that the CHOA comprised carboxylic groups, which function as functional groups for the Ce(III) ion adsorption. The maximal adsorptive ability for Ce(III) ions was ascertained to be 408.71 mg g⁻¹ at optimum investigational settings based on the Langmuir equation. The settings comprised a solution pH of 4, a CHOA dosage of 0.01 g, a steadiness time of 30 min, and a temperature of 300 K. Kinetic and isotherm analyses specified that the Ce(III) ions adsorption onto CHOA is most accurately designated by the pseudo-second-order and Freundlich models. Thermodynamical analysis reveals that the adsorption method was endothermic and spontaneous. The desorption percentage of Ce-loaded CHOA was approximately 40% when subjected to strong acids like HCl and HNO₃. This indicates a chemical reaction between the Ce(III) cations and the functional groups on the adsorbent's surface. The primary adsorption mechanisms suggested were chelation and ion exchange. The CHOA adsorbent exhibits substantial potential for the recovery of Ce(III) cations due to its elevated adsorption potential and swift adsorption kinetics.