Acrylic Acid-Functionalized Metal-Organic Frameworks for Sc(III) Selective Adsorption

Area of Science:

• Materials Science
• Inorganic Chemistry
• Environmental Science

Background:

• Rising demand for rare-earth elements (REEs) necessitates sustainable recovery and separation methods.
• High-tech applications drive the need for efficient separation of critical REEs.

Purpose of the Study:

• To develop and evaluate acrylic acid-functionalized metal-organic frameworks (y-AA-x@MIL-101s) for selective Sc(III) adsorption.
• To investigate the adsorption performance and selectivity of the synthesized materials for various REEs and other metal ions.

Main Methods:

• Synthesis and characterization of y-AA-x@MIL-101s using SEM, FTIR, XRD, N2 adsorption, XPS, and titration.
• Adsorption studies using Langmuir and pseudo-second-order models to analyze isotherm and kinetic data.
• Selective adsorption experiments in mixed REE systems and solutions containing coexisting metal ions.

Main Results:

• The y-AA-x@MIL-101s demonstrated high adsorption capacities for Sc(III) (90.21 mg g⁻¹), Nd(III) (104.59 mg g⁻¹), Gd(III) (58.29 mg g⁻¹), and Er(III) (74.94 mg g⁻¹).
• The adsorbent exhibited superior selectivity for Sc(III) recovery from a 16-REE mixture and solutions with Cu(II), Zn(II), Mn(II), Co(II), and Al(III).
• Selective affinity was observed for Nd(III) in light REE mixtures and Gd(III) in middle REE mixtures.

Conclusions:

• Acrylic acid-functionalized MIL-101 materials offer a promising new avenue for the selective separation and recovery of rare-earth elements.
• The developed adsorbent shows significant potential for practical applications in REE enrichment and purification.
• This work contributes a novel and sustainable approach to addressing the challenges in REE separation technology.