具有优异循环性能的三维石墨烯气凝胶对有机染料的有效去除（英文）

Efficient removal of organic dyes using a three-dimensional graphene aerogel with excellent recycling stability

以聚乙烯醇(PVA)为交联剂,采用一步水热法和冷冻干燥法制备了氮掺杂石墨烯气凝胶(N-GA)。PVA的加入使GA的三维多孔结构更加稳定,提高了GA的循环性能。氮源的加入为染料的吸附提供了较多的的吸附位点。在pH=8和pH=2时,PVA-N/GA对亚甲基蓝(MB,98.39%)和甲基橙(MO,78.78%)表现出优异的吸附能力。MB和MO的吸附过程符合准二阶动力学模型,且遵循单层朗缪尔等温线模型和多层弗伦德里希等温线模型。此外,PVA-N/GA具有良好的可重复性。PVA-N/GA对染料的吸附主要归因于π-π键,氢键和静电相互作用。

The development of a renewable absorbent with a high adsorption efficiency is of great importance for the purification of dye wastewater. A nitrogen-doped graphene aerogel (N-GA) was prepared by a one-step hydrothermal and freeze-drying method using polyvinyl alcohol (PVA) as a cross-linking agent. Results indicated that the nitrogen doping provided more adsorption sites for the dyes. The PVA-N-GA showed excellent adsorption efficiencies for methylene blue (MB)(98.39% at pH=8) and methyl orange (MO)(78.78% at pH=2). The adsorption kinetic data of MB and MO on the PVA-N-GA were better fitted with a pseudo-second-order kinetic model than a pseudo-first-order kinetic model while the adsorption isotherms of MB and MO were better described by the monolayer Langmuir model and the multilayer Freundlich model, respectively. The PVA-N-GA showed excellent recycling stability with a negligible decay of adsorption efficiency after five cycles, which was ascribed to PVA making the three-dimensional (3D) pore structure of the N-GA more stable. The adsorption of the PVA-N-GA for dyes was mainly attributed to the π-π bonds, hydrogen bonds and electrostatic interactions.