Synthesis of Graphene Aerogel Adsorbents and Their Applications in Water Treatment

Graphene aerogels (GA) are three-dimensional (3D) graphene-based macrostructures with well-defined interconnected porous networks. Their excellent features, including large surface area, controllable porous structure, ability of electronic transmission and unique interconnected networks, make them an ideal material for water treatment. Up to now, there are many fabrication methods for preparing GA which differs in performance and structure. However, their methodology and relationships between different methods, structures and features haven't been reported systematically. This review aims to describe the fabrication methods for preparing GA absorbents as well as their applications in water treatment and perspective. Thus, the structural features of GA, especially those related to adsorption and relationships between structures and adsorption are analyzed. The methodology and key factors in preparing process which have an influence on structures of GA are also summarized. Based on the methodology, the synthesis methods for preparing GA can be classified to five types, namely template method, intercalation method, self-supporting method, substrate-casting method and gelation, which are described and exampled in detail. Applications as well as mechanisms in water treatment, including adsorption of organic pollutants and heavy metals, oil-water separation, photocatalysis and capacitive deionization are systematically reviewed. Finally, the problems in environmental applications and prospects of further research are discussed.