Urea-Introduced Ionic Liquid for the Effective Extraction of Pt(IV) and Pd(II) Ions
Urea-Introduced Ionic Liquid for the Effective Extraction of Pt(IV) and Pd(II) Ions
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引入尿素的离子液体可有效萃取 Pt(IV) 和 Pd(II) 离子
DOI：
10.1021/acs.iecr.2c00304
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发表时间：
2022
影响因子：
4.2
通讯作者：
Hirochika Naganawa
中科院分区：
文献类型：
--
作者：
Yuki Ueda;Ayano Eguchi;Kohei Tokunaga;Kei Kikuchi;Tsuyoshi Sugita;Hiroyuki Okamura;Hirochika Naganawa
合成了一种引入尿素的咪唑基离子液体1-丁基-3-{3-（3-甲基-2H-咪唑-1-基）丙基}脲双（三氟甲基磺酰基）酰亚胺（L1），其对Pt（IV）和Pd（II）的选择性仅随pH值的变化而变化，并研究了其对Pt（IV）和Pd（II）的萃取行为。在传统的有机萃取体系中，在异辛烷中的具有脲基团的有机萃取剂1-丁基-3-（2-乙基己基）脲在相似的pH范围内萃取Pt（IV）和Pd（II），Pd（II）的萃取平衡半衰期（t1/2）为8.95 h。相反，在IL萃取系统中，Pt（IV）和Pd（II）分别在较低和较高pH区域中被萃取，表明Pt（IV）和Pd（II）通过pH变化相互分离。Pd（II）在离子液体萃取体系中的萃取平衡为0.18 h。用紫外-可见光谱和扩展X射线吸收光谱研究了离子液体萃取后Pt（IV）和Pd（II）的精细结构，确定了萃取机理。结果，Pt（IV）作为[PtCl 6]2-via阴离子交换（外层络合物）被萃取。另一方面，通过配体交换（球内络合）和阴离子交换的混合反应萃取Pd（II）。最后，IL萃取系统即使在负载高浓度Pt（IV）时也不产生第三相。
A urea-introduced imidazolium-based ionic liquid (IL), 1-butyl-3-{3-(3-methyl-2H-imidazol-1-yl)propyl}urea bis(trifluoromethylsulfonyl)imide (L1), whose selectivity to Pt(IV) and Pd(II) was changed only by a pH region, was synthesized, and its Pt(IV) and Pd(II) extraction behaviors were investigated. In the conventional organic extraction system, an organic extractant with a urea group, 1-butyl-3-(2-ethylhexyl)urea, in isooctane extracted Pt(IV) and Pd(II) in a similar pH range, the extraction equilibrium half-time (t1/2) of Pd(II) was 8.95 h. In contrast, in the IL extraction system, Pt(IV) and Pd(II) were extracted in the lower and higher pH regions, respectively, indicating the mutual separation of Pt(IV) and Pd(II) by pH-change. Furthermore, the extraction equilibriumt1/2of Pd(II) with the IL extraction system was 0.18 h. Ultraviolet–visible and extended X-ray absorption fine structure spectroscopies of Pt(IV) and Pd(II) after extraction using the IL were conducted to determine the extraction mechanism. As a result, Pt(IV) was extracted as [PtCl6]2–viaanion-exchange (outer-sphere complex). On the other hand, Pd(II) was extractedviaa mixed reaction of ligand-exchange (inner-sphere complex) and anion-exchange. Finally, the IL extraction system did not produce a third phase even when loaded with a high concentration of Pt(IV).