Benzimidazole-containing aramid nanofiber for naked-eye detection of heavy metal ions.

The rapid detection of heavy metal ions in wastewater has received significant attention in modern society. Herein, we report the exploration of benzimidazole-containing aramid fibers (B-ANF) for the naked-eye detection of heavy metal ions in aqueous solution. Firstly, B-ANF was prepared by hydroxylation from benzimidazole-containing aramid fiber. The unique benzimidazole unit endows the nanofiber with the ability to coordinate with multiple kinds of heavy metal ions. When B-ANF comes in contact with trace heavy metal ions in solution, the coordination interaction induces rapid aggregation, which can be detected by the naked eye within 2 minutes. Therefore, it provides an easy and time-saving strategy for the detection of heavy metal ions. In addition, B-ANF could be used for the rapid detection of total concentration of heavy metals ions in the presence of multiple kinds of heavy metal ions, which makes up for the shortage of traditional methods and shows prospects for broad application. Lastly, it was noticed that B-ANF, after the detection of heavy metal ions, could be readily recycled by an HCl/NaOH treatment, with the detection efficiency being completely preserved after the recycling process. It is believed that B-ANF integrates the advantages of low cost, easy transportation and naked-eye detection of heavy metal ions, and could be used as promising recyclable detector for heavy metal ions.