Extraction of Technetium and Rhenium with Ionic Liquid

doi:10.13209/j.0479-8023.2017.074

Abstract

Abstract:

The extraction of ReO₄^- and TcO₄^- by ionic liquids (ILs) were investigated systematically. The results indicated that imidazolium and quaternary ammonium ILs could extract ReO₄^- and TcO₄^- efficiently via anion-exchange mechanism. Compared with NTf₂-based ILs, PF₆-based ILs had a higher extraction efficiency towards ReO₄^-and TcO₄^-. With respect to the ILs with an identical anion, the extraction efficiency increased with the increase of the chain length of IL’s cations. The addition of HNO₃ and IL’s anion in aqueous phase decreased the extraction efficiency, while the increase of the concentration of IL’s cation led to an opposite effect. At a lower concentration of nitric acid, ReO₄^- ions were selectively extracted by either [N_6,444][NTf₂] or [C₈mim][PF₆] from simulated liquid waste. KPF₆and LiNTf₂aqueous solutions can strip ReO₄^- effectively from [C₈mim][PF₆] and [N_6,444][NTf₂], respectively.

Key words: ionic liquid, ReO₄^-, TcO₄^-, extraction selectivity, extraction mechanism

摘要：

系统地研究离子液体对ReO₄^-和TcO₄^-的萃取。结果发现, 咪唑类和季铵盐类离子液体可通过阴离子交换机理高效萃取ReO₄^-和TcO₄^-。其中, PF₆^-类离子液体对ReO₄^-和TcO₄^-的萃取效率明显高于NTf₂^-类离子液体。当阴离子相同时, 离子液体阳离子侧链增长, 萃取效率增大。增加水相HNO₃浓度或在水相中加入相应离子液体的阴离子可以抑制ReO₄^-和TcO₄^-的萃取。水相中加入相应离子液体的阳离子则可以促进萃取反应进行。在低酸度下, 己基三丁基铵双三氟甲烷磺酰亚胺[N_6,444][NTf₂]和1-辛基-3-甲基咪唑六氟磷酸盐[C₈mim][PF₆]对模拟废液中的ReO₄^-均具有很好的萃取选择性。LiNTf₂和KPF₆水溶液可以分别实现对[N_6,444][NTf₂]和[C₈mim][PF₆]中ReO₄^-的有效反萃。

关键词: 离子液体, ReO₄^-, TcO₄^-, 萃取选择性, 萃取机理

Yue SONG, Taoxiang SUN, Qingde CHEN, Xinghai SHEN. Extraction of Technetium and Rhenium with Ionic Liquid[J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 2017, 53(5): 810-816.

宋岳, 孙涛祥, 陈庆德, 沈兴海. 离子液体萃取锝和铼的研究[J]. 北京大学学报自然科学版, 2017, 53(5): 810-816.

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URL: https://xbna.pku.edu.cn/EN/10.13209/j.0479-8023.2017.074

https://xbna.pku.edu.cn/EN/Y2017/V53/I5/810

Figures/Tables 8

Table 1 Compositions of simulated liquid waste (SLW)[19]

元素	浓度/(g ∙ L^-1)	元素	浓度/(g ∙ L^-1)
Sr	0.54	Ru	0.38
Cs	0.54	Ni	0.17
Zr	0.68	Nd	1.00
Cr	0.34	U	2.38
Re	0.15

Fig. 1 Extraction efficiencies of 0.01 mol/L ReO4- and tracer amount of TcO4- using different ILs

Fig. 2 Effect of HNO3 (solid) and LiNO3 (hollow) on the extraction of 0.01 mol/L ReO4- (▲ and △) and tracer amount of TcO4- (▼) by [N6,444][NTf2], and on the extraction of 0.01 mol/L ReO4- (■ and □), tracer amount of TcO4- (●) by [C8mim][PF6]

Fig. 3 Effects of [N6,444]Cl (■) and LiNTf2 (●) on the extraction of 0.01 mol/L ReO4- by [N6,444][NTf2], and effects of [C8mim]Cl (▲) and KPF6 (▼) on the extraction of 0.01 mol/L ReO4- by [C8mim][PF6]

Fig. 4 ESI-MS spectra of IL phase after extracting0.1 mol/L ReO4- by [C8mim][PF6]

Table 2 Peak positions associated in the ESI-MS spectra of IL phase after extracting 0.1 mol/L ReO4- with [C8mim][PF6]

模式	峰的归属	m/z
阴离子谱	[3C₈mim⁺+3PF₆^-+ReO₄^-]^-	1271.3
	[3C₈mim⁺+4PF₆^-]^-	1165.4
	[2C₈mim⁺+2PF₆^-+ReO₄^-]^-	931.2
	[2C₈mim⁺+3PF₆^-]^-	825.2
	[C₈mim⁺+2PF₆^-]^-	485.1
	ReO₄^-	250.9
阳离子谱	[5C₈mim⁺+4PF₆^-]⁺	1555.8
	[2C₈mim⁺+PF₆^-]⁺	535.3
	C₈mim⁺	195.2

Fig. 5 Effects of HNO3 on the extraction of different elements in SLW by [C8mim][PF6] (a) and [N6,444][NTf2] (b), respectively

Fig. 6 Dependence of the total stripping efficiency of ReO4- in [N6,444][NTf2] (●) and [C8mim][PF6] (▲) on the number of stripping (the stripping agents were LiNTf2 and KPF6 aqueous solutions, respectively)

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