4-nitrophenol (4-NP) is a highly toxic pollutant for aquatic ecosystem and human life. Therefore, the catalytic reduction of 4-NP into useful 4-aminophenol (4-AP) is of interest. In this regard, two heterogeneous nanocatalysts, including Ag@HNTs-ILs and Co@HNTs-ILs were prepared by grafting imidazolium-based ionic liquids (ILs) onto the halloysite nanotubes (HNTs), followed by immobilization of Ag and Co nanoparticles (NPs), and characterized by means of FT-IR, SEM, EDX, TEM and XRD. The catalytic activity of the prepared nanocatalysts was evaluated for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) under environmentally friendly condition. A set of time, temperature, nanocatalyst amount and NaBH₄/4-NP molar ratios was screened. The reusability experiments demonstrated that Ag@HNTs-ILs and Co@HNTs-ILs were highly reusable, up to five reduction cycles without considerable changes in the reaction time. As the synthesized hybrid nanocatalysts could be re-collected and reused for various catalytic runs without any significant loss in their catalytic activity, they could be considered very promising nanomaterials from sustainability point of view.

中文翻译：

---

离子液体功能化埃洛石纳米管上固定银钴纳米粒子的合成及在水溶液中还原4-硝基苯酚中的应用

4-硝基苯酚（4-NP）是一种对水生生态系统和人类生命具有剧毒的污染物。因此，将 4-NP 催化还原为有用的 4-氨基苯酚 (4-AP) 是令人感兴趣的。在这方面，通过将咪唑基离子液体（ILs）接枝到埃洛石纳米管（HNTs）上，然后固定Ag和Co纳米颗粒（NPs），制备了两种非均相纳米催化剂，包括Ag@HNTs-ILs和Co@HNTs-ILs。 )，并通过 FT-IR、SEM、EDX、TEM 和 XRD 进行表征。评价了制备的纳米催化剂在环境友好条件下将 4-硝基苯酚 (4-NP) 还原为 4-氨基苯酚 (4-AP) 的催化活性。一组时间、温度、纳米催化剂用量和NaBH ₄筛选了 /4-NP 摩尔比。可重复使用性实验表明，Ag@HNTs-ILs 和 Co@HNTs-ILs 具有高度可重复使用性，最多可重复使用五个还原循环，而反应时间没有显着变化。由于合成的杂化纳米催化剂可以被重新收集并重新用于各种催化运行而不会显着降低其催化活性，因此从可持续性的角度来看，它们可以被认为是非常有前途的纳米材料。