Graphene/Phenolic Nanosheet Aerogels with Hierarchical Porosity for Sustainable Wastewater Remediation

The development of efficient adsorptive materials is critically important for advanced wastewater purification and sustainable water environment remediation. However, traditional graphene-based aerogels suffer from problems such as severe layer stacking, unavailable active sites and poor cycling stability. Herein, we propose an innovative two-dimensional mesoporous polymer cross-linking strategy to develop novel graphene oxide composite aerogels as adsorbents for the separation and removal of pollutants from water. The aerogels are fabricated by mixing graphene oxide and ordered mesoporous phenolic nanosheets, followed by hydrothermal reaction, acid treatment and freeze-drying. The obtained aerogels feature three-dimensional cross-linked frameworks, hierarchical macro-meso porosity, high specific surface area (636.6 m2/g) and abundant functional sites. The adsorption behavior is consistent with the pseudo-second-order kinetic model, and high adsorption capacity (280.9 mg/g for methylene blue) is achieved governed mainly by electrostatic interaction. Meanwhile, the aerogels maintain stress after compression for 1000 cycles thanks to the cross-linked structure, favoring efficient removal of methylene blue during adsorption and recycling. Moreover, the aerogels can be further carbonized for stable recovery of oils and organic solvents from wastewater with an ultrahigh adsorption capacity of 117–250 g/g. This work provides a new pathway for designing aerogels with high adsorption performance and stability for water remediation and resource recovery.