Rare-earth elements (REEs) are a group of 17 chemical elements in the periodic table, namely scandium (Sc), Yttrium (Y), and 15 lanthanides. The term “rare earths” name was first used in 1827 by Swedish chemist, Carl Axel Arrhenius, but the elements themselves were not discovered until late 18-19th century.
The name “rare-earth elements” was given due to their rarity in the Earths crust and difficulty in their access. However, recently, due to the rapid advancements in mining technology, these elements have become more accessible and thus are making their mark in everyday life.
REEs are increasingly used in various industrial, medical, and technological applications. For example, they are used in lamps and television tubes to generate white light, x-ray tubes to generate x-rays, high-strength magnets, and many other beneficial products.
The REEs are widely utilized in modern technologies such as powertrains, turbines, air conditioning systems, wind turbines, aerospace, and energy storage. REEs are also essential components in many of the modern gadgets such as smartphones, laptops and tablets, where they are used in displays and various other components.
REEs play a significant role in the wastewater treatment industry where they are used for a process known as ion exchange chromatography. Through this process, specific ions are clumped together or placed together and isolated from other ions or molecules.
In addition to their applications in technology, REEs are also used in many medical applications. For example, they are used to make bone-strengthening isotopes for cancer treatment, radioisotopes for diagnostic imaging, and mask materials used in fluoroscopes.
REEs are highly reactive elements and their separation from other elements requires use of some advanced techniques such as selective ion exchange, solvent extraction, centrifugal separation, ion chromatography and precipitation. Most of these separation methods rely on one or more physical characteristics of the REEs, such as their solubility, volatility, and extraction with certain solvents, to separate them from the other elements.
In the recent decades, the importance of these elements has arisen, and with that the need for accurate and reliable methods for their separation and extraction is becoming more urgent. The main challenge in the separation and extraction of REEs is the presence of other strongly related elements such as gallium, indium and boron.
The colorimetric layer separation method has been employed with good success in REE separations. This technique relies on the ability of the REEs to interact with each other via transition metal group elements. This interaction leads to the formation of colored complexes between the metal ions and the chromogenic material present in the separation layer.
The separation layer consists of a chromogenic material such as tannic acid or sodium silicate and a precipitant, such as sodium chloride or ammonium chloride. These components are dissolved in an appropriate solvent, typically water, and placed in an appropriate layer of the separation medium.
The chromogenic material absorbs the energy from light which supplies the energy necessary for the REE ions to form the colored complexes responsible for their separation. The color of each of the complexes is used to differentiate between the different REEs.
The efficiency of the separation process depends on the appropriate selection of materials for the separation layer, the correct setup of the separation procedure and its optimization for the specific separation needs. The optimized colorimetric layer separation method is a very reliable technique for the separation of heavy and rare-earth elements.
The development of efficient and convenient methods for the separation and extraction of REEs is essential for the advancement of technology and medicine. The colorimetric layer separation method is an established technique in the field of rare-earth element separations and has shown great promise.
