▎ 摘　　要

NOVELTY - Preparing nitrogen-doped graphene airgel involves dispersing oxidized graphene in deionized water for 10-30 minutes, adding urea, and stirring for 15 minutes. The mixture is poured in into a hydrothermal reactor and heated in a muffle furnace to a reaction temperature of 180 degrees C for 12 hours. The obtained product is immersed in distilled water for 2 to 3 days and freeze-dried to obtain nitrogen-doped graphene airgel material. USE - Method for preparing nitrogen-doped graphene airgel for removing mercuric ions from waste water (claimed). ADVANTAGE - The method enables to remove iron ions from water effectively with high efficiency in simple and cost-effective manner. DETAILED DESCRIPTION - Preparing nitrogen-doped graphene airgel involves dispersing oxidized graphene in deionized water for 10-30 minutes, adding urea, and stirring for 15 minutes. The mixture is poured in into a hydrothermal reactor and heated in a muffle furnace to a reaction temperature of 180 degrees C for 12 hours. The obtained product is immersed in distilled water for 2 to 3 days and freeze-dried to obtain nitrogen-doped graphene airgel material. The nitrogen-doped graphene airgel paper electrode is prepared by mixing nitrogen doped graphene airgel with a pre-formulated polyvinyl alcohol solution to form a paste-like dispersion. The 0.1-0.4ml dispersion is uniformly coated on the hard paper which is freeze-dried to obtain a nitrogen-doped graphene airgel paper electrode. The heavy metal solution is prepared and placed in an electric adsorption vessel for performing mercuric-ion adsorption on the nitrogen-doped graphene airgel paper electrode. The three-electrode system is used to study the mercuric-ion adsorption. The paper electrode is used as the working electrode, platinum electrode as counter electrode and the calomel electrode as reference electrode. The conductivity meter is used to monitor the change of solution conductivity. The electrode desorption regeneration is performed.