Rare earth elements (REE) have wide high-tech applications in permanent magnets, luminescent materials, catalysts and other fields. Because no decisive substitutes of REE have been found, the REE shortage will emerge which will hinder the development of industry fields involved.
On the other hand, mining, extraction and roasting stages for REE production involve high energy consumption and have detrimental environmental impacts such as acidification and eco-toxicity. Besides, discarding REE-containing wastes is wasteful. REE recovery could help recycling the valuable REE resources, relieving their high environmental burden and easing the potential supply crisis.
Prof. FENG Meiling from Prof. HUANG Xiaoying’s research group in Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, cooperates closely with Prof. Mercouri G. Kanatzidis from Northwestern University, USA. They recently reported the first chalcogenide example as a superior REE ion-exchange material from very complex aqueous solutions, namely [Me2NH2]4/3[Me3NH]2/3Sn3S7·1.25H2O (FJSM-SnS).
The advantages of this material are in the following: Rapid kinetics. It exhibits a faster adsorption ability with short equilibrium times (<5 min). High exchange capacity. It has high adsorption capacity (139 mg/g for Eu, 147 mg/g for Tb, 126 mg/g for Nd) than those of Al2O3/EG, clay minerals, zeolite and activated carbon. High selectivity. The largest distribution coefficient (Kd) value of FJSM-SnS is 6.5 × 106 mL/g, with good selectivity against Al3+, Fe3+ and Na+ ions. High recovery rates. The recovery rates can be kept around 99.99% in low concentration (0.59 ~ 1.14 ppm) during processing of 6024 bed volumes of solution in ion-exchange column experiments. Efficient Elution. It is important to note that the REE in the exchanged products could be recovered with a cost-affordable and environmentally friendly method, i.e. by elution with concentrated KCl solution.
This work distinguishes the crystalline microporous sulfide ion-exchangers as a new type of effective media for REE recovery and recycling, and points to unconventional paths of inquiry in the search for elective sorbent for REE.
These results entitled “Layered A2Sn3S7·1.25H2O (A = Organic Cation) as Efficient Ion-Exchanger for Rare Earth Element Recovery” have been published in J. Am. Chem. Soc.
Rare earth element recovery by layered FJSM-SnS as ion-exchanger (Image by Prof. HUANG’s Group)
Contact:
Prof. HUANG Xiaoying
Fujian Institute of Research on the Structure of Matter
Chinese Academy of Sciences
Email: xyhuang@fjirsm.ac.cn
