Synthesis Of Ammonium-type Bifunctional Ionic Liquid And Their Applications In Extraction Of Rare Earths

Ionic liquid (IL) is a kind of booming "designer solvents" for a multitude of applications. Their physicochemical properties can be easily tuned by changing combinations of cations and anions. The non-inflammability and non-volatility of ILs provided environment-friendly advantages for using them as replacement to volatile organic compounds (VOCs) in solvent extraction. Moreover, the extraction efficiencies of some IL-based extraction system are higher than those of VOC-based system. As the development of ILs, TSILs have emerged. The TSILs contain functional groups for task-specific purpose in their cation and/or anion, which can be "tailor-made" preparation for some separation processes.The common synthetic route of ILs is anion metathesis reaction, which is achieved by metathesis reactions between halide intermediates of ILs and appropriate acids or salts. However, ILs prepared by anion metathesis reaction are always contaminated by halide and alkali metals ions, the contamination is detrimental to biology, synthesis, electrochemistry, catalysis and spectroscopy. To get IL with desired quality, we report herein a simple strategy is acid/base neutralization method. Physicochemical properties of the bifunctional TSILs, i.e. density, water content, decomposition temperature, munal solubility, are also studied in this paper.As the development of ILs, TSILs containing functional groups come to be series of liquid functional materials. In view of extraction requirement, it is our purpose to design TSILs as high-efficient extractants. Synergistic effect in solvent extraction is attributed to combined coordinating/solvating abilities of two extractants are better than their simple sum of individual contributions. Recently, a series of ILs derived from tricaprylmethylammonium chloride (A336) have attracted attention. A336 was widely used as extractant in solvent extraction. To further enhance the extraction capacity of A336, we develop some novel Bif-ILEs by combining the cation of A336 with phosphonic acid group or carboxylic acid group as anions. The synergistic effect comes from both cations and anions of TSILs, we call it "inner synergistic effect". in this paper, we study [tricaprylmethylammonium][di-2-ethylhexylphosphinate] ([A336][P204]) as an extractant for Eu(III), which can be attributed to better stability and hydrophobicity of the complex formed by [A336][P204] with Eu(III).However, bigger viscosity of the TSIL is a disadvantage for its application in liquid-liquid extraction, which will result in lower rate of mass transfer, the loss of their cation and anion to aqueous phase. Solid-liquid extraction seems to be a more advisable method for its application in separation. [trialkylmethylammonium] [sec-nonylphenoxy acetate] ([A336][CA-100]) are impregnated on intermediate polaritied XAD-7 resin in this paper, and the prepared solvent impreganated resin (SIR) was studied for rare earths (REs) separation. Adsorption ability of the SIR is indicated to be obviously higher than that prepared by [A336][NO3] since the functional anion of [A336][CA-100]. Adsorption kinetics, adsorption isotherm, separation and desorption of the SIR are also studied in this paper.Ammonium-type ILs have attracted considerable attention because their costs are much cheaper than those of imidazolium-type IL. Moreover, the toxicity of ammonium-type IL is lower than those of imidazolium-type IL and organic solvents. In additional, some quaternary ammonium salts have well applied background in solvent extraction. In this paper, we study Cyanex925-[A336][NO3] system for REs separation. In compare to [Cgmim][PF6], the TSIL reveal many advantages for IL-based extraction, i.e., lower cost, lower toxicity, lower density than water, stability on acidic condition, solvating mechanism, easy to be stripped, regenerated and recycled.