Simple preparation of floating magnetic particles for oil recovery using the ferrite production process in the presence of long-carbon-chain surfactants

This study developed a simple, low-cost, and low-energy method for preparing floating magnetic particles (FMPs) for oil recovery, characterized the prepared FMPs, and evaluated their oil recovery performance. It has been established that the production of iron hydroxide in the presence of anionic surfactants with alkyl chains with 12 or more carbon atoms, e.g., sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium laurate, and sodium stearate, followed by the oxidation of the mixture in air at 20 ± 3 °C, facilitates the straightforward production of MPs that float on the surface of water, boasting a hydrophobic surface. The surfactant added to the Fe(II) solution is considered to be incorporated in the process of producing iron hydroxide precipitates (green rust) and endows the surface of the produced Fe₃O₄ with hydrophobicity. The produced water-FMPs were characterized by X-ray diffraction, Brunauer-Emmett-Teller, thermogravimetry, and water contact angle measurements. The water contact angle of the MPs prepared using sodium stearate was 138°, indicating a higher hydrophobicity than that of magnetite (120°). The recovery rate of the FMPs in water was high for all the surfactants, and the amount of heavy oil A adsorbed per 1.0 g of stearic acid-modified MPs was approximately 3.6 g. Furthermore, the FMPs can be reused by washing them in an organic solvent. The study findings present FMPs as a low-cost and environmentally friendly solution to oil pollution in aquatic systems.