The concentrative isolation of metal traces from aqueous solutions is of vital importance for environmental and industrial processes. Developing reliable systems of nanoscale that can be fine-tuned to effectively isolate these metals remains an intriguing aim which can potentially beget economic benefits and mitigate major environmental concerns. Here we demonstrate a conceptual metal extraction system where magnetic multi-wall carbon nanotubes (M-MWCNTs) are surface-equipped with a molecular network of polyethylenimine (PEI) to serve as a reusable nano-ionic exchanger, referred to as “M-MWCNTs-PEI”. The designed nano-ionic exchanger forms readily stable suspensions with the metal-bearing aqueous solutions eliminating the need for vigorous agitation. Besides, it can be magnetically manipulated and separated in/from the solution. To exemplify its potential for the isolation of metal traces, the M-MWCNTs-PEI was tested with the uranium trace ions in aqueous media. The M-MWCNTs-PEI featured distinct sorption capacity of ~488 mg/g at pH 6, with moderate, but stable, binding affinity toward uranium ions. As such, excellent isolation performance is demonstrated while bound uranium ions are effectively concentrated and recovered from the interfacial PEI molecular network. This was efficiently achieved by exposing the loaded M-MWCNTs-PEI to solutions of small volumes and specific chemistry. Such combined qualities of large capacity and reusability have not been observed with the previously reported ion exchange systems. Altogether, our observations here demonstrate how functional systems of nanoscale can be adapted for industrial applications while this concept can be extended to address other important resources such as rare-earth and lanthanide elements.

从水溶液中富集分离金属痕迹对于环境和工业过程至关重要。开发可以进行微调以有效隔离这些金属的可靠的纳米级系统，仍然是一个吸引人的目标，可以潜在地获得经济利益并减轻主要的环境问题。在这里，我们演示了一种概念性的金属提取系统，其中磁性多壁碳纳米管（M-MWCNT）表面配备有聚乙烯亚胺（PEI）的分子网络，以用作可重复使用的纳米离子交换剂，称为“ M-MWCNT” -PEI”。设计的纳米离子交换剂可与含金属的水溶液形成易于稳定的悬浮液，而无需进行剧烈搅拌。此外，它可以被磁性操纵并与溶液分离。为了证明其分离痕量金属的潜力，在含水介质中用铀痕量离子测试了M-MWCNTs-PEI。M-MWCNTs-PEI在pH值为6时具有约488 mg / g的独特吸附能力，对铀离子具有中等但稳定的结合亲和力。这样，当结合的铀离子被有效地浓缩并从界面PEI分子网络中回收时，证明了出色的隔离性能。通过将加载的M-MWCNTs-PEI暴露于小体积和特定化学溶液中，可以有效地实现这一目标。在先前报道的离子交换系统中还没有观察到这种大容量和可重复使用的综合质量。共，