Separation of Adjacent Light Rare Earth Elements Using Silica Gel Modified with Diglycolamic Acid

Area of Science:

• Analytical Chemistry
• Materials Science
• Inorganic Chemistry

Background:

• Rare earth elements (REEs) exhibit similar chemical properties, making their separation a significant challenge in various industrial applications.
• Developing efficient and cost-effective methods for REE separation is crucial for sustainable resource utilization.

Purpose of the Study:

• To investigate the efficacy of novel silica gel-based adsorbents modified with diglycolamic acid for separating adjacent rare earth elements.
• To evaluate the separation performance and recovery capabilities of a specific adsorbent, EDASiDGA, for critical REEs.

Main Methods:

• Synthesis and characterization of four types of silica gel adsorbents functionalized with diglycolamic acid derivatives.
• Adsorption studies of rare earth elements (La to Sm and heavier REEs) on the prepared adsorbents.
• Evaluation of separation factors, particularly for neodymium/praseodymium (Nd/Pr).
• Column chromatography experiments using an EDASiDGA-packed column for selective elution of Pr, Nd, and Sm.

Main Results:

• Adsorption ratios of REEs generally increased with atomic number from La to Sm, plateauing for heavier REEs.
• The EDASiDGA adsorbent demonstrated a high separation factor of 2.8 for Nd/Pr.
• Individual recovery of Pr, Nd, and Sm was achieved using the EDASiDGA-packed column, with selective elution using different concentrations of HCl (0.32 M for Pr/Nd, 1.0 M for Sm).

Conclusions:

• EDASiDGA exhibits excellent performance in separating adjacent rare earth elements, specifically Nd/Pr.
• The developed method allows for the selective recovery of Pr, Nd, and Sm without the need for chelating agents.
• The EDASiDGA-packed column presents a promising and practical solution for the separation and purification of rare earth elements.