Functionalization of graphene with nitrogen-based groups for water purification via adsorption: A review

The use of graphene-based materials in water purification via adsorption processes has become attractive among the scientific community in the recent decades. Its high porosity, great surface area, and especially, the available functional groups on its surface and potential for modification with new functional groups make graphene a promising adsorbent. Among the possible modifications, the grafting on N-based functional groups in the surface of graphene has gained prominence in the production of adsorbents for water purification, since it results in a material with improved properties and high adsorption capacity towards a series of water contaminants. This review presents a comprehensive approach of the main N-based functionalization techniques, namely solvothermal, photoelectric reduction, in situ polymerization and direct compounding processes, as well as a description of a variety of characterization techniques that are commonly applied for these composites. Furthermore, an overview of the recent applications of N-functionalized graphene in water purification is presented accompanied by a discussion of the most important influential parameters, the main results in terms of adsorption efficiency and reusability as well as future perspectives for the development of this research field.