Liu Wenhui, Wang Qi, Zheng Yan, Wang Shubin, Yan Yan, Yang Yanzhao
Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, PR China.
Dalton Trans. 2017 Jun 6;46(22):7210-7218. doi: 10.1039/c7dt01142c.
In this study, a method of one-step separation and recycling of high purity Pd(ii) and Pt(iv) using an ionic liquid, 1-butyl-3-benzimidazolium bromate ([HBBIm]Br), was investigated. The effects of [HBBIm]Br concentration, initial metal concentration, and loading capacity of [HBBIm]Br were examined in detail. It was observed that [HBBIm]Br was a very effective extractant for selectively extracting Pd(ii) and precipitating Pt(iv). Through selectively extracting Pd(ii) and precipitating Pt(iv), each metal with high purity was separately obtained from mixed Pd(ii) and Pt(iv) multi-metal solution. The method of one-step separation of Pd(ii) and Pt(iv) is simple and convenient. The anion exchange mechanism between [HBBIm]Br and Pt(iv) was proven through Job's method and FTIR and H NMR spectroscopies. The coordination mechanism between [HBBIm]Br and Pd(ii) was demonstrated via single X-ray diffraction and was found to be robust and distinct, as supported by the ab initio quantum-chemical studies. The crystals of the [PdBr ·2BBIm] complex were formed first. Moreover, the influence of the concentrations of hydrochloric acid, sodium chloride, and sodium nitrate on the precipitation of Pt(iv) and extraction of Pd(ii) was studied herein. It was found that only the concentration of H could inhibit the separation of Pt(iv) because H could attract the anion PtCl; thus, the exchange (anion exchange mechanism) between the anions PtCl and Br was prevented. However, both the concentration of H and Cl can obviously inhibit the extraction of Pd(ii) because H and Cl are the reaction products and increasing their concentration can inhibit the progress of the reaction (coordination mechanism).
在本研究中，研究了一种使用离子液体1-丁基-3-苯并咪唑溴酸盐（[HBBIm]Br）一步分离并回收高纯度钯（II）和铂（IV）的方法。详细考察了[HBBIm]Br浓度、初始金属浓度以及[HBBIm]Br的负载容量的影响。结果表明，[HBBIm]Br是一种非常有效的萃取剂，可选择性地萃取钯（II）并沉淀铂（IV）。通过选择性地萃取钯（II）和沉淀铂（IV），从混合的钯（II）和铂（IV）多金属溶液中分别获得了高纯度的每种金属。钯（II）和铂（IV）的一步分离方法简单便捷。通过乔布法、傅里叶变换红外光谱（FTIR）和核磁共振氢谱（H NMR）证实了[HBBIm]Br与铂（IV）之间的阴离子交换机理。通过单晶X射线衍射证明了[HBBIm]Br与钯（II）之间的配位机理，并且从头算量子化学研究表明该机理牢固且独特。首先形成了[PdBr·2BBIm]配合物的晶体。此外，本文还研究了盐酸、氯化钠和硝酸钠的浓度对铂（IV）沉淀和钯（II）萃取的影响。结果发现，只有氢离子浓度会抑制铂（IV）的分离，因为氢离子会吸引阴离子PtCl；因此，阻止了PtCl和Br之间的阴离子交换。然而，氢离子和氯离子浓度都会明显抑制钯（II）的萃取，因为氢离子和氯离子是反应产物，增加它们的浓度会抑制反应进程（配位机理）。
