Superhydrophobic and magnetic Fe3O4/RGO/SA composite membranes for oil-water separation

The iron tetroxide/reduced graphene oxide/stearic acid (Fe3O4/RGO/SA) composite membrane with a micro-nano-graded rough structure is fabricated on cotton cloth. Surface morphology, crystal structure, infrared spectra, and contact angle are tested to analyze the microstructure and wettability properties of the composite membrane. Compared with the original cotton, the composite membrane is changed from superhydrophilic to superhydrophobic, the water contact angle reached 156.1°, and it has stable superhydrophobicity at different pH values (pH = 5, 6, 7, 8, 9). A series of oil-water separation experiments show that the separation efficiency of composite membrane for four oil-water mixtures is higher than 98.4%, the results of the cycle separation test show that the separation efficiency and flux test for 10 cycles did not appear measurably fluctuations, the separation efficiency has always been maintained above 98%. In addition, the membrane can absorb oil slick on the water surface by magnetic drive, which provides a new idea for contactless manipulation of oil removal.