Recovery of Cerium(III) from aqueous solutions via selective adsorption using a three-layer bio-based composite

As the demand for critical rare earth elements increases, their recovery from e-waste has become a sustainable alternative to traditional mining. Cerium, widely used in strategic technologies, remains challenging to recover efficiently. In this study, a three-layer bio-based composite adsorbent containing of cellulose, phosphorylated cellulose, and electrospun chitosan nanofibers was developed to selectively adsorb and recover Ce³⁺ ions from aqueous solutions. The composite’s composition strongly influenced its adsorption performance: phosphorylated cellulose introduced phosphate groups that enhanced Ce³⁺ binding through electrostatic interactions, while chitosan nanofibers provided amino and hydroxyl sites that improved chelation, porosity, and mechanical integrity. The optimized combination of these components achieved a balance between functionality, permeability, and stability. Characterization (e.g., scanning electron microscopy, energy-dispersive X-ray spectroscopy, image analysis) confirmed the uniform distribution of active layers and the presence of functional groups responsible for adsorption. Batch adsorption tests revealed a high capacity of over 64 mg/g within 60 minutes, following a pseudo-first-order kinetic model and Langmuir isotherm behavior. Thermodynamic analysis indicated an exothermic process, and the composite exhibited selectivity toward Ce³⁺ and Nd³⁺ over Cu²⁺. Cerium was effectively desorbed and recovered, and the material maintained over 83% of its performance after four cycles, demonstrating its strong potential for sustainable rare earth recovery in line with circular economy principles.