Hierarchically porous hydrogels and aerogels based on reduced graphene oxide, montmorillonite and hyper-crosslinked resins for water and air remediation

A new sustainable solution to water and air pollution based on spontaneously adsorbent materials is presented in this work. For the first time, high surface area micro/mesoporous hyper-crosslinked resins (XDV) were engineered in hydrogels and aerogels based on reduced graphene oxide (rGO) and montmorillonite (MMT). Hydrogels and aerogels were obtained through a mild and environmental-friendly procedure based on graphene oxide (GO) reduction by vitamin C and eventual lyophilization. In all systems, the XDV specific surface area (SSA) is completely exposed and exploitable for adsorption application in water and air. rGO/XDV and rGO/MMT/XDV aerogels containing 50 wt% of XDV show hierarchical porosity and high SSA, reaching values of 1000–1200 m2/g. Hydrogels and aerogels show tuneable polar character on the basis of their composition, which is exploitable to develop customized adsorbents for water and air remediation from aromatic and polar pollutants. Indeed, while hydrogels containing MMT show high adsorption capacity towards cationic dyes such as rhodamine 6G, rGO and rGO/XDV systems show marked affinity for toluene. In all cases, the embedding of the hyper-crosslinked resins in the hydrogels and aerogels further enhances their adsorption capacity, with uptakes up to 482 mg/g of rhodamine 6G for rGO/MMT/XDV hydrogels and up to 500 mg/g of toluene vapours for rGO/XDV aerogels. Both systems show regenerable adsorption properties with efficiency higher than 96% over 5 adsorption/desorption cycles.