Preparation of hydrophobic stearic acid-modified Fe3O4/graphite oxide/melamine sponge for oil-water separation

A fluorine-free strategy was developed for the hydrophobic modification of the melamine (MA) sponge, in which both the stearic acid-modified Fe3O4 nanoparticles (SA-Fe3O4) and the graphite oxide were immobilized on the MA sponge with the use of 3-aminopropyltriethoxysilane by a drop-coating method to prepare the SA-Fe3O4/GO/MA sponge for oil-water separation. The structure of the SA-Fe3O4/GO/MA sponge was investigated by FITR, WAXD, SEM, two-dimensional EDS mapping, TGA, and VSM. The contact angles of the SA-Fe3O4/GO/MA sponge prepared with different amounts of SA-Fe3O4 and GO were in the range of 140.2 degrees - 145.0 degrees, which confirmed the successful hydrophobic surface modification for the MA sponge. The demonstrations exhibited that the SA-Fe3O4/GO/MA sponge could separate the oil from the oil-water mixture by both direct absorption and gravity-driven filtration. Additionally, the SA-Fe3O4/GO/MA sponge possessed not only high absorption capacities for peanut oil, n-hexane, soybean oil, and diesel oil, but also good abilities of being able to recollect magnetically and reuse. The proposed preparation strategy and overall performance of SA-Fe3O4/GO/MA sponge were promising for the oil-water separation in the future.