Applications of Ionic LiquiDS IN Rare EarthS Mr. Hao Cui and Dr. Corby Anderson Kroll Institute for Extractive Metallurgy, The George S. Ansell Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden CO. 80401 Motivation Rare earth metals play a vital role in cutting-edge technologies. Due to their similar chemical and physical qualities, more attention has been paid on how to efficiently and selectively extract them. Ionic liquids, which are molten salts at room temperatures, have emerged since they have unique qualities . This review will summarize recent applications of ionic liquids in extraction and separation of rare earth. Type Ionic liquids Ligands/ solvents Extracted species Ref. Ammonium [A336][NO3] Cyanex925 Sc+3 Xiao S. et al.(2011) [A336][CA-12] [A336][CA-100] Sc+3, Y+3, Eu+3, Ce+3 Hualing Y. et al. (2011) [A336][P204] [A336][P507] Y+3, Eu+3, Gd+3, Ce+3, Tb+3 Phosphonium [Cnmim][PF6] Cyphos IL 104 Y+3, Dy+3, Yb+3, Ho+3 Yinghui L. et al. (2009) Cyphos IL 101 Sm+3, Nd+3 Tom V. H. et al. (2013) Objective List the representative examples of extraction of rare earth by ionic liquids Summarize the advantages and drawbacks of ionic liquids Ionic Liquid Extraction System Generally, there are three kinds of ionic liquids: imidazolium ILs, ammonium ILs and phosphonium ILs. Ligands are applied in order to form complexes with metal such as TBP, CMPO, DEHPA, etc. Some ionic liquids are immobilized in the resin to avoid the ion loss and increase the efficiency. The two main extraction mechanisms are cationic exchange and anionic exchange. Advantages and disadvantages Type Ionic liquids Ligands/ solvent Extracted species Ref. Imidazolium [bmim][Tf2N] Htta, 18C6/DC18C6 La+3 H. Okamura et al. (2010) [Cnmim][PF6] (n=2, 4) DEHPA Ce+3, Nd+3, Dy+3, Yb+3 Song J. Y. et al.(2010) bmimNTf2 CMPO-TBP Eu+3 Alok Rout et al. (2010) [C4mim][Tf2N] DODGAA Y+3, Eu+3 Fan Y. et al. (2013) Bmim[Tf2N] TTA/HFA, CO2 lanthanides Soufiane M et al.(2006) [Bmim][PF6] P507 Sc+3 Zhongwei P. et al. (2011) Ph2Et2, TPMDPO Ln+3 A. N. Turanov et al. (2008) Lariat crown ether omimNTf2 D2EHPA, HDEHDGA Alok Rout et al. (2011) [Cnmim][Tf2N] (n=2, 4, 6) TODGA K. Shimojo et al. (2008) Benzoyl acetone Advantage Disadvantage High selectivity Difficulty in stripping from loaded organic phase containing IL High efficiency Nonflammability Ion loss Low vapor pressure High cost Low toxicity High viscosity Difficulty of recovery Conclusion Ionic liquids are a promising technology that can be applied in extraction and separation of rare earth. The extractability and selectivity for the rare earth metals are generally better than those in conventional organic solvents. Reference 10. Kojiro Shimojo et al. Dalton Trans., 37, 5083(2008) Okamura H., N. Hirayama, K. Shimojo et al. Anal. Sci.,57, 607(2010) 11. Zhongwei Pan et al. Adv. Mat. Res., 335, 1428(2011) 12. Xiaoqi Sun et al. Separation and purification Tech., 81, 25(2008) Yoon, S. J., J. G. Lee et al. J. Ind. Eng. Chem., 16, 350(2010) Alok Rout, K. A. Venkatesan et al. Separation and Purification 13. Hualing Yang et al. Chin. J. Anal. Chem., 39, 1561(2011) Tech., 76, 238(2010) 14. Hualing Yang et al. J. Chem. Technol. Biotechnol., 87, 198(2012) 4. Fan Yang, et al. Journal of hazardous materials, 254, 79(2013) 5. Soufiane Mekki et al. Chem. Eur. J., 12, 1760(2006) 15. Yinghui Liu et al. Ind. Eng. Chem. Res., 48, 7308(2009) 6. Zhongwei P et al. Advanced Material research, 306, 1524(2011) 16. Tom Vander Hoogerstraete et al. Green Chem., 15, 919(2013) 7. A. N. Turanov et al. Russ. J. Inorg. Chem., 53, 970(2008) 8. A. N. Turanov et al. Russ. J. Inorg. Chem., 57, 292(2012) 9. Alok Rout, K. A. Venkatesan et al. Separation and Purification Tech., 81, 109(2011) Email:hcui@mymail.mines.edu Phone:1(303)-653-5825