Performance of oil sorbents based on reduced graphene oxide-silica composite aerogels

Clean-up of crude-oil spills ranks among the major environmental remediation issues and demands for sorbents with high and stable oleophilic and hydrophobic features. Here, aerogels with durable hydrophobicity are produced by incorporating reduced graphene oxide (rGO) in highly porous silica matrices. By a sol-gel protocol, high rGO loadings are achieved by exploiting highly dispersible hydrophilic graphene oxide as rGO precursor. Homogeneous rGO-silica composite monoliths are obtained with tunable loading up to 10 wt%, enabling a detailed analysis of the sorption behaviour towards oil spills. Composite aerogels demonstrate an excellent performance towards oil sorption with oil uptake from similar to 7 to similar to 10 times the aerogel mass. Although the sorption ability is lower than for plain hydrophobic silica, composites with a minimum loading of 5 wt% exhibit very high oil selectivity and show a durable and reliable behaviour over time, providing longer shelf-life than plain SiO2 aerogels. The synergetic effect of rGO towards long-term hydrophobicity and oil selectivity on silica composite aerogels allows for the implementation of such composite materials in real water remediation processes.