Preparation of magnetic, superhydrophobic/superoleophilic polyurethane sponge: Separation of oil/water mixture and demulsification

Regular problems faced due to chemical leaks and oil spills have caused tremendous threats to lakes and sea water. Therefore, there is an urgent need to develop efficient strategies to remove oil and organic pollutants from water surfaces. The aim of this study is to develop a high performance magnetic, superhydrophobic/superoleophilic three-dimensional porous composite material for efficient and selective adsorption of organic pollutants from water. The composite material was fabricated by simple immersion of a commercially available polyurethane (PU) sponge into a solution of high-density polyethylene (HDPE) containing pre-synthesized magnetic (Fe₃O₄) nanoparticles. The composite material exhibited a water contact of ~155° and an oil contact angle of ~0°. The presence of the Fe₃O₄ particles allowed magnetic-controlled elimination of underwater oil, while the superhydrophobic character of the functionalized PU sponge permitted efficient separation of oil/water mixtures and demulsification of toluene/water emulsions. Moreover, the HDPE coating not only firmly immobilized the magnetic particles, but also contributed to the excellent stability of the composite sponge which withstood acid, base, salts, seawater or temperature variation from −20 °C to 105 °C. In addition, the composite material maintained its oil adsorption ability over 10 cycles. The ease of fabrication of the magnetic super wetting 3D material sponge along with its durability and reusability makes it an interesting material with potential for practical applications.