The demand for rare earth elements (REEs), a group of 17 elements including scandium, yttrium, and lanthanides, has skyrocketed due to their vital role in cutting-edge technologies like wind turbines and electric vehicles. Addressing the pressing need for sustainable and efficient REE separation, Professor Gisele Azimi’s co-authored research, Separation of Praseodymium and Neodymium from Heavy Rare Earth Elements Using Extractant-Impregnated Surfaces Loaded with 2-Ethylhexyl Phosphonic Acid-mono-2-ethylhexyl Ester (PC88A), published in the August 2023 issue of Industrial & Engineering Chemistry Research, introduces a groundbreaking method with potential implications for both the environment and modern industries.
REEs, often essential in advanced green products, have become increasingly critical, driving a surge in demand. The United States Geological Survey reports a 25% increase in the import value of rare earth compounds in 2022, reaching $200 million, while global production reached 300,000 tons of REO equivalent, marking a 7% rise from the previous year.
Among REEs, praseodymium (Pr) and neodymium (Nd) have gained special attention due to their role in renewable energy technologies. These elements are used in permanent magnets like neodymium iron boron (NdFeB), which power wind turbines, electric vehicle motors, and more, contributing to energy-efficient systems.
Traditionally, separating REEs presents numerous challenges due to their similar properties. Conventional methods, such as solvent extraction, come with drawbacks like high solvent consumption, waste production, and complex processes. Professor Azimi’s new technique, supported-liquid extraction (SLE), offers a greener solution.
The heart of the breakthrough is the extractant-impregnated surface (EIS) – a hydrophobic microtextured silicon substrate coated with a compound called 2-Ethylhexyl Phosphonic Acid-mono-2-ethylhexyl Ester (PC88A). This remarkable surface selectively separates praseodymium and neodymium from heavy rare earth elements with impressive efficiency.
EIS demonstrates promising advantages over traditional methods, substantially reducing organic solvent consumption and hazardous waste generation. In initial tests, a feed containing various REEs showed promising results, achieving a remarkable 92% purity of praseodymium and neodymium with a 96% yield and a separation factor comparable to solvent extraction.
Beyond the technical advancements, this breakthrough has the potential to reshape the rare earth industry, aligning it with greener principles and more sustainable practices. By offering an efficient and environmentally-friendly separation technique, this research accelerates the transition towards a low-carbon era and reinforces the role of rare earth elements in a cleaner, more advanced future.