Capturing Rare-Earth Elements by Synthetic Aluminosilicate MCM-22: Mechanistic Understanding of Yb(III) Capture

Area of Science:

• Materials Science
• Environmental Chemistry
• Geochemistry

Background:

• Heavy rare-earth elements (HREEs) are critical for modern technologies.
• Efficient adsorption methods are needed for HREE recovery from acidic solutions.
• Aluminosilicate materials, like zeolites, show promise for HREE adsorption.

Purpose of the Study:

• To elucidate the adsorption mechanism of Ytterbium (a HREE) onto MCM-22 zeolite.
• To investigate the role of surface properties and solution chemistry in HREE adsorption.
• To establish MCM-22 zeolite as a platform for studying HREE adsorption on aluminosilicates.

Main Methods:

• Solid-phase adsorption experiments using MCM-22 zeolite and Ytterbium.
• Solution pH adjustment to study surface charge effects.
• Spectroscopic analysis (e.g., FTIR, XPS) to identify adsorption sites.
• Theoretical calculations to support experimental findings.

Main Results:

• Yb(III) adsorption is primarily driven by electrostatic interactions between Yb(III) ions and surface sites.
• Solution pH significantly influences Yb adsorption, indicating the importance of surface charge.
• Framework aluminum content in MCM-22 zeolite correlates with the involvement of Brønsted acid sites (BAS) in Yb adsorption.

Conclusions:

• The adsorption mechanism of HREEs on MCM-22 zeolite involves both electrostatic attraction and interactions with Brønsted acid sites.
• MCM-22 zeolite effectively adsorbs Yb(III) from acidic solutions.
• Understanding these surface interactions is key for developing effective HREE separation and recovery technologies.