Superhydrophobic behaviors of nanoSiO2 coating on stainless steel mesh and its application in oil/water separation

Abstract

With the rapid development of the world economy and the accelerating industrialization process, the industrial oily sewage faces multiple difficulties and severe challenges. It is difficult for the traditional oil–water separation methods to meet the processing requirements for a large amount of oily wastewater. Researchers have inspired by the superhydrophobic phenomenon on the surface of animals and plants in nature, and a variety of specific wetted oil–water separation materials to treat and purify of the oily sewage have been achieved. In this paper, an oleophilic hydrophobic silica sol is prepared by a sol–gel method, and a lipophilic hydrophobic coating is dip-coated onto a stainless steel mesh. The effects of sol ratio, impregnation times, and the heat treatment temperature on the hydrophobicity of the modified mesh coating were investigated. The hydrophobic properties, surface morphology, and the coating elements of the modified hydrophobic mesh were characterized by Optical Contact Angle meter, Focused Ion Beam Scanning Electron Microscope, Atomic Force Microscope, X-ray Photoelectron Spectroscopy, and Fourier Transform Infrared Spectroscopy. The durability of the mesh was examined by ultrasonic cleaning and acid–base immersion. Separation experiments were carried out on a variety of different oil–water mixtures. The results suggest that the modified mesh has better lipophilic hydrophobic properties. Consistent lipophilic hydrophobic properties were achieved under ultrasonic cleaning conditions and in solutions within different pH = 3–11. The modified mesh has good separation and reusability for different types of oil–water mixtures.