Analysis of the fluoride sorption mechanism
High fluoride concentration results in adverse environmental problems and a negative impact on human health. With increasing stringent mitigation measures to eliminate fluorine pollution, several technologies have been developed. Sorption technique has particularly attracted research attention owing to its generally low cost and operation ease. Sorbents used in fluoride removal are based on rare earth elements. However, the majority of presently available rare earth defluoridation adsorbents are based on Ce and La metals. With increasing interest in fluorine adsorption in rare earth metals, there is obvious need to extensively explore for new rare earth metals with high fluoride sorption performance.
In a recent paper published in the Science of The Total Environment journal, a group of scientists Professor Hualing Jiang, Xueqin Li, Dr. Lei Tian, Tao Wang, Qi Wang, Pingping Niu, Professor Pinghua Chen and Professor Xubiao Luo from Nanchang Hangkong University investigated Yttrium affinity towards fluoride. Concerning the high cost of pure Yttrium and previous studies on La and Ce defluoridation adsorbents, composites were prepared as a good alternative of improving its functionality and reducing the underling high cost of pure Yttrium. To this end, a laminated nanocomposite of Y-Zr-Al with a surface area of 256.6m2/g was synthesized and used to explore the defluoridation performance of Yttrium based sorbent.
The authors discovered that Yttrium, a rare earth element, has a high affinity toward fluoride. The laminated nanocomposite exhibited high fluoride sorption efficiency and anti-interference ability desirable in practical applications. Physical and chemical properties of the composite were characterized and the influence of factors such as pH investigated. The sorption was explored based on sorption kinetics and equilibrium sorption isothermal. Experimental results revealed the existence of three main sorption models: electronic interaction, ion exchange, and mesoporous diffusion sorption.
The composite of alumina (Al), Yttrium (Y), and Zirconium (Zr) proved to among the highly effective fluoride sorbents due to its high fluoride sorption performance. Both high maximum sorption ability and high sorption capacity were observed at low fluoride concentration. Additionally, it was capable of retaining high sorption capacity in the presence of many ions. The composite has a high potential for use in treatments of fluoride polluted water.
In summary, the discovery of the highly attractive nature of Yttrium towards fluoride contributed to the development of the first novel Y-Zr-Al tri-metal composite sorbent. The composite exhibited high fluoride sorption efficiency, anti-interference ability, and ability to keep high sorption capacity at the existence of many ions, which are desirable properties for practical applications. In view of the above results, Professor Hualing Jiang, first author in a statement to Advances in Engineering stated that the study will enable development of high-performance rare-earth-based defluoridation sorbents.
Jiang, H., Li, X., Tian, L., Wang, T., Wang, Q., Niu, P., Chen, P., & Luo, X. (2019). Defluoridation investigation of Yttrium by laminated Y-Zr-Al tri-metal nanocomposite and analysis of the fluoride sorption mechanism. Science of The Total Environment, 648, 1342-1353.