Microwave-assisted deep eutectic solvent leaching for efficient and selective extraction of rare earth elements from...

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Rare earth elements (REEs) are critical for green energy technologies.
• Coal fly ash is a potential secondary source of REEs.
• Conventional REE extraction methods are inefficient and environmentally problematic.

Purpose of the Study:

• To develop an efficient and selective method for REE recovery from coal fly ash.
• To investigate the use of microwave-assisted deep eutectic solvents (DES) for REE leaching.
• To optimize DES composition and leaching conditions.

Main Methods:

• Synthesis of three DESs using choline chloride and different hydrogen bond donors (p-toluenesulfonic acid, lactic acid, formic acid).
• Microwave-assisted leaching of REEs from coal fly ash using the synthesized DESs.
• Optimization of leaching parameters and characterization of DES formation and leaching mechanism (FT-IR, ¹H NMR).

Main Results:

• The ChCl-PTSA DES showed the best leaching performance due to its acidity.
• Optimized conditions yielded an 89.16% REE leaching efficiency.
• DES formation is driven by hydrogen bonding; leaching involves protonation and coordination.

Conclusions:

• Microwave-assisted DES leaching is a highly efficient and rapid strategy for REE recovery from coal fly ash.
• This method offers a sustainable and promising alternative to conventional hydrometallurgical processes.
• The study highlights the potential of coal fly ash as a valuable secondary source for critical REEs.