Flexible and robust porous thermoplastic polyurethane/reduced graphene oxide monolith with special wettability for continuous oil/water separation in harsh environment

Abstract

With the increase of severe environmental problems caused by oil spill and chemical leakage, there is an urgent necessity for efficient and durable oil/water separation materials with high environmental suitability. Here we developed a hierarchical porous superelastic thermoplastic polyurethane/reduced graphene oxide (TPU/RGO) monolith with superhydrophobicity/superoleophilicity for the continuous absorption of oils or organic solvents. The morphology investigation indicated that the three-dimensional porous structure of composite monoliths was definitely perfected by adding 1.5 wt% RGO, significantly improving hydrophobicity (155°) and mechanical property (compression strength of 307 kPa). In consequence, the TPU/RGO monolith could efficiently absorb different oils/organic solvents with high saturation absorption capacity (6.5–44.5 g g−1) and fast absorption speed (attaining equilibration within 15 s). And it possessed stable superhydrophobicity and absorption capacity in various pH (1–14), high/low temperature (0–90 °C) and strongly turbulent conditions. Furthermore, the composite monolith exhibited outstanding reversible compressibility (80% strain) and fatigue resistance (1000 cycles), endowing it with superior reusability by simple manual squeezing. More importantly, the flexible and robust monolith was capable of continuously and efficiently separating at least 15,000 times its own weight of oils or organic solvents from water with a peristaltic pump, showing huge potential for the large-scale cleanup of oily wastewater.