Graphene-Based Aerogels for Adsorption of Organic Contaminants: Synthesis Methods, Classification, and Property–Performance Relationships

Graphene-based aerogels (GAs) exhibit outstanding performance in the adsorption of organic contaminants. Consequently, numerous studies have investigated the use of GAs for this purpose. In this work, the synthesis methods commonly used to produce GAs are first briefly described, and their key characteristics are summarized. Subsequently, GAs are classified according to the modifications applied to improve their adsorption properties toward organic pollutants. Furthermore, the quantitative relationships between surface area, density, surface chemistry, and adsorption performance for organic contaminants are systematically reviewed. The analysis revealed that the adsorption of two representative organic contaminants, toluene and methylene blue, is not dependent on the surface area of GAs. In contrast, GAs with lower density exhibit an improved adsorption capacity for toluene. Additionally, the relationship between the surface chemistry of GAs and their adsorption capacity toward methylene blue was analyzed considering the concentration of carboxylic sites. The available data suggests a potential correlation between the concentration of carboxylic groups on the surface of GAs and their adsorption capacity for methylene blue. This observation is supported by the analysis of methylene blue species in aqueous solution and the pH at the point of zero charge of GAs, which indicate that the interaction occurs mainly through electrostatic attractions resulting from the deprotonation of acidic surface sites. Finally, several opportunity areas and future research directions regarding the use of GAs for pollutant adsorption are discussed.