Superelastic, ultralight aramid fibre/tannic acid/graphene nanohybrid aerogel constructed using a cross–scale strengthening strategy for rapid and high–flux oil–water separation

Graphene-based aerogels are efficient oil–water separation materials with enormous potential, but their poor mechanical strength and cycling stability limit their applications. A cross-scale strengthening strategy was used to construct aramid fibre (A)/tannic acid (T)/graphene (G) (ATG) aerogel using an in situ electrostatic self-assembly and freeze-drying process. At 95 % of the ultimate compressive strain, the ATG aerogel could withstand a stress of up to 147 kPa and can rebound quickly. The mechanism for the high mechanical strength of the ATG aerogel was explored by structure characterisation and density functional theory (DFT) calculation. A superhydrophobic aerogel (named H-ATG) was prepared by a hydrophobic modification of ATG using a vapor deposition reaction method. The H-ATG aerogel exhibited excellent superoleophilicity/superhydrophobicity with the oil and water contact angles of 0° and 152.48°, respectively. The hydrophobicity of the H-ATG aerogel was stable over the pH range of 1–13 and the temperature range of -80–600 °C. In addition, the aerogel had an ultra-fast absorption speed and excellent absorption capability, rapidly absorbing various oil-based organic solvents up to 101 times its own weight within 5 s. After the absorption of oil or solvents, it could be easily recovered by combustion, distillation or extrusion, and the performance remained relatively unchanged after 10 cycles. When H-ATG was used as a filter to achieve fast and efficient oil–water separation with a high flux of 20,371.83 L·h−1·g−1. Therefore, the H-ATG aerogel has excellent potential for applications in the oil–water separation and the purification of oily wastewater.