Nd(III) and Gd(III) Sorption on Mesoporous Amine-Functionalized Polymer/SiO₂ Composite

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Growing demand for rare-earth elements (REEs) necessitates innovative recovery methods from low-grade ores and waste.
• Current methods for REE extraction face challenges in efficiency and selectivity.

Purpose of the Study:

• To develop and characterize a new functionalized mesoporous silica composite for efficient REE ion recovery.
• To evaluate the sorbent's capacity, kinetics, and selectivity for Nd(III) and Gd(III) ions.

Main Methods:

• Synthesis of diethylenetriamine-grafted mesoporous silica composite.
• Characterization using BET, TGA, elemental analysis, titration, FTIR, and XPS.
• Sorption experiments to determine capacity, kinetics, and selectivity at varying pH.

Main Results:

• The sorbent exhibits high amine group density (3.25-3.41 mmol N g⁻¹).
• Optimal sorption capacity reached 0.9 mmol Nd g⁻¹ and 1 mmol Gd g⁻¹ at pH 4.
• Pseudo-first-order kinetics observed with equilibrium in 30-40 minutes; high selectivity for REEs over alkali-earth elements at pH 4-5.

Conclusions:

• The developed sorbent shows high and fast sorption properties for REEs.
• Demonstrated efficient REE recovery from gibbsite ore leachates.
• The sorbent's recyclability and selectivity present a promising approach for REE valorization.