Design of mesoporous silica hybrid materials as sorbents for the selective recovery of rare earth metals

Abstract

The importance of rare earth metals in the global economy has increased significantly in recent years due to their essential role in advanced technologies in the electronics and biomedical industries. The recovery and purification of rare earth metals from waste products is therefore appealing, both in terms of the sustainability of rare earth resources and ecological environmental protection. We herein present the preparation of novel mesoporous silica materials modified by maleic anhydride, which can be used in the recovery of rare earth metals through extraction of their ions from an aqueous solution. Our novel maleic anhydride functional hybrid materials demonstrate enhanced selectivity for heavy rare earth metals, which vastly improves the separation process and reduces recovery costs. In addition, the directly modified hybrid materials have been found to exhibit higher distribution coefficients for rare earth elements compared to other materials. Adsorption kinetics studies were also carried out, and the adsorption followed a pseudo-second order model, with particularly rapid adsorption observed in the case of Gd³⁺. The resulting adsorption isotherms of the materials were better represented by the Langmuir model than the Freundlich model. The singly modified material exhibited a Gd³⁺ capture capacity of 76.89 mg g⁻¹. In addition, the proposed materials demonstrate a high degree of reusability over a number of cycles, thus enhancing their potential for application in rare earth metal recycling.