Recyclable porous polyurethane sponge for highly efficient oil–water separation

Oil spills and chemical leakages have caused severe environmental problems. Physical absorption of the spilled oils and chemical reagents by absorbing materials is an efficient and economical approach to solve these problems. Herein, we have prepared a porous thermoplastic polyurethane (TPU) sponge by combining the thermally induced phase separation method with the selective dissolution of water-soluble PEG components. The selective removal of PEG components from the walls of TPU sponges could increase the intensities of free volume holes and surface areas of TPU sponges. The content of free volume holes and surface areas of TPU sponge reached its maximum with the TPU/PEG ratio of 1:1. The increased roughness could improve the absorption capacities of TPU sponges for various oils/organic solvents. Moreover, due to its excellent compressibility, this TPU sponge could be reused 20 times with little loss of saturated absorption capacity. In addition, this TPU sponge exhibited excellent separation ability for the toluene from the toluene/water mixture and emulsion. In all, we have developed a facile method to prepare TPU sponge absorbent with excellent absorption performance, which holds great potential in the application of large-scale oil/water separation.