Superhydrophobic filter paper via an improved phase separation process for oil/water separation: study on surface morphology, composition and wettability

In this study, a novel method including the concurrent use of nanoparticles and non-solvent is proposed for surface modification of filter papers with the aim of achieving superhydrophobicity that can be used in oil/water separation applications. The effects of polymer, nanoparticle and non-solvent contents were investigated on the surface morphology, composition and wettability of the samples. A comparison was also made between the solution casting and dip-coating techniques. It was found that the dip-coating technique was not as efficient as solution casting because of the lower adsorption of polystyrene macromolecules onto the papers' surfaces. Scanning electron microscopy results demonstrated the role of non-solvent in the surface morphology of the coatings. In fact, in the absence of non-solvent, superhydrophobicity was not achieved. X-ray photoelectron spectroscopy results confirmed that the presence of non-solvent also changed the surface composition of the coatings significantly. The optimum composition was found to have promising potentials in the separation of oil from water because of the induced superhydrophobic and superoleophilic properties. The findings of this fundamental research could be exploited in other systems for more efficient oil/water separating devices.