三维石墨烯-碳纳米管磁性气凝胶的制备及其染料吸附性能

Preparation of 3D graphene-carbon nanotube-magnetic hybrid aerogels for dye adsorption

  • 摘要: 将ZnCl2、NiCl2·6H2O、FeCl2·4H2O和FeCl3·6H2O分别加入氧化石墨烯和碳纳米管的悬浮液中,在碱性条件下共沉淀和水中与聚乙烯醇交联后,冷冻干燥制备气凝胶。制备的气凝胶由磁性Ni0.5Zn0.5Fe2O4纳米粒子、氧化石墨烯、碳纳米管和聚乙烯醇组成,不仅具有吸附染料分子的活性位点,而且可通过外加磁场从水中分离。在最佳质量比下,制备的气凝胶对亚甲基蓝具有高的吸附容量(qe=71.03 mg g−1)和中等磁性强度(MS=3.519 emu g−1)。在染料浓度为0.025 mg mL−1的条件下,气凝胶对亚甲基蓝、甲基橙、结晶紫及其相等质量的混合物的去除效率分别为70.1%、4.2%、8.9%和11.1%。该气凝胶重复使用3次后,再生效率仍超过82%。此外,它对生物体无毒,有望用作处理工业废水的吸附剂。

     

    Abstract: Novel hybrid aerogels were prepared by adding ZnCl2, NiCl2·6H2O, FeCl2·4H2O and FeCl3·6H2O to a suspension of equal weights of graphene oxide and oxidized carbon nanotubes, followed by co-precipitation under basic conditions. The aerogels were then crosslinked with polyvinyl alcohol in water and freeze-dried. They consisted of magnetic Ni0.5Zn0.5Fe2O4 nanoparticles, graphene oxide, carbon nanotubes and polyvinyl alcohol, which have active sites that attract dye molecules and could be extracted from water by applying a magnetic field. Using optimum mass ratios of ZnCl2/NiCl2·6H2O/FeCl2·4H2O/FeCl3·6H2O/(graphene oxide+oxidized carbon nanotube) at 6∶6∶12∶12∶1, the hybrid aerogel has a high adsorption capacity of 71.03 mg g−1 for methylene blue and a moderate magnetic strength of MS = 3.519 emu g−1. Its removal efficiencies for methylene blue, methyl orange, crystal violet and a mixture of equal masses of the three were 70.1%, 4.2%, 8.9% and 11.1%, respectively for the same dye concentration of 0.025 mg mL−1. It could be used for 3 regeneration cycles with a regeneration efficiency of over 82%. It was also not toxic to the living organisms, suggesting that it is a promising adsorbent for treating industrial wastewater.

     

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