Facile construction of superhydrophobic/superoleophilic melamine sponges with durability and antifouling for selective oil absorption and effective oil/water separation

The manufacturing techniques of superhydrophobic/superoleophilic materials typically involve complicated processes. To address the issue, tannic acid, 3–aminopropyltriethoxysilane, and hexadecyltrimethoxysilane were used as primary ingredients to construct 3D superhydrophobic/superoleophilic melamine sponges by a facile one–step biomimetic method. The surface morphologies and functional composition of the modified 3D melamine sponges were characterized by scanning electron microscope, energy dispersive spectrometer, Fourier transform infrared spectroscopy, and X–ray photoelectron spectroscopy, respectively. The wetting performance of the modified 3D melamine sponge was estimated by measuring the water contact angle and oil contact angle. The water and oil contact angle were determined to be 155.4° and 0°, suggesting that the modified sponge showed superhydrophobic/superoleophilic performance. The modified sponge also presented remarkable self-cleaning and antifouling performance. As a result of porous skeleton and resilience of the melamine sponge, the superhydrophobic/superoleophilic sponge possessed outstanding oil absorption capacity and recycling durability. The modified sponge exhibited absorption capacities ranging from 38.43 g/g to 194.62 g/g for the chosen absorbents. The recycling absorption capacity for diesel and chloroform remained at 94.32% and 97.76% of their initial absorption capacity after 20 cycles. In addition, the modified sponge could also be used to separate oil and water continuously. The continuous separation efficiency for the mixture of diesel/water and chloroform/water could reach 98.52% and 99.42%, respectively. Therefore, the modified sponge shows considerable potential for practical application in oil/water separation.