MagneticallyDrivenFloatingFoamsforthe Removal of Oil Contaminants from Water

il and fuel spills released during industrial accidents or oil tankers and ships sinking are catastrophic for the marine and aquatic ecosystems. To avoid such environmental disasters, im- mediate polluted water purification and long-term water preservation are essential. These issues have inspired the recent sci- entific research in the field of materials science, with numerous studies aiming at the development of new materials for "wateroil separation". 1� 6 The large-scale application of this research area points to- ward highly efficient but, at the same time, low-cost systems. A common approach of the previous studies is the combined con- trol of the chemical and structural proper- ties of the developed materials in order to exhibit simultaneous superhydrophobicity and superoleophilicity. So far, superhydrophobic and superoleo- ABSTRACT In this study, we present a novel composite material based on commercially available polyurethane foams functionalized with colloidal super- paramagnetic iron oxide nanoparticles and submicrometer polytetrafluoroethy- lene particles, which can efficiently se- parate oil from water. Untreated foam surfaces are inherently hydrophobic and oleophobic, but they can be rendered water-repellent and oil-absorbing by a solvent-free, electrostatic polytetrafluoroethylene particle deposition technique. It was found that combined functionalization of the polytetra- fluoroethylene-treated foam surfaces with colloidal iron oxide nanoparticles significantly increases the speed of oil absorption. Detailed microscopic and wettability studies reveal that the combined effects of the surface morphology and of the chemistry of the functionalized foamsgreatlyaffecttheoil-absorptiondynamics.Inparticular,nanoparticlecappingmolecules are found to play a major role in this mechanism. In addition to the water-repellent and oil- absorbing capabilities, the functionalized foams exhibit also magnetic responsivity. Finally, duetotheirlightweight,they floateasilyonwater.Hence,bysimplymovingthemaroundoil- polluted waters using a magnet, they can absorb the floating oil from the polluted regions, thereby purifying the water underneath. This low-cost process can easily be scaled up toclean large-area oil spills in water.