Purification of water through oil–water separation is essential for preserving the ecosystem and protecting human health. Although a conventional polypropylene depth filter can effectively purify water, modifying the wettability of a filter for oil–water separation is difficult owing to its low reactivity. In this study, we developed a superhydrophilic polypropylene filter with a hydrogel layer that could enable effective oil–water separation by using plasma treatment and dip coating, which enabled an even distribution of the coating solution across the filter. The fabricated filter was superhydrophilic with a water contact angle of 0o. It showed a high repulsive force with oil in water with an underwater oil contact angle of 142.9o. When such filter was applied to an oil–water separation device, it effectively purified water with low oil content (< 15 ppm) at a flow rate of 300 mL/min. These results demonstrate potential applications of such filters in areas such as wastewater treatment and oil spill cleanup.

In this study, aluminum, used throughout the industry and actively studied for surface modification, is selected as the test subject. Micro-structured through acid etching, nano-structured through alkali treatment to maximize surface roughness, and the superhydrophilic surfaces were fabricated by forming the surface chemicals into aluminum hydroxide (Al(OH)₃). The superhydrophobic surfaces were fabricated through the self-assembled monolayer coating on the surface, and the surface structure and components were analyzed. The superhydrophilicity and superhydrophobicity were applied on the aluminum surface at the bottom of the low speed water vehicle. For the superhydrophilic and superhydrophobic surfaces, the reasons for the drag reduction performance on the bare surface and the difference in the amount of reduction were analyzed. A coating material that strong bonds with the surface are selected for anti-corrosive performance under NaCl solution. To verify that, the contact angle was measured by exposing each prepared aluminum surface to a 3.5% NaCl solution for 14 days. Additionally, we analyzed why the superhydrophobic surfaces were robust against the NaCl solution.

A study of super-hydrophobic surface originated from the analysis of lotus leaf in the nature and fabrication method of super-hydrophobic surface on copper substrate has been researched for, showed functional surfaces with anti-corrosion. However, since copper nanowires decomposed during thiol coating, it is necessary to reseach on the relation with morphology of copper nanowires and thiol coating time. In this study, the research is all about the effect of thiol coating time on wettability of copper nanowires surface. Copper hydroxide nanowires were made up by oxidation using dipping method and a polymer layer was formed on nanowires using thiol coating. Surface characteristics were assessed using scanning electron microscopy and liquid contact angles. The conclusion showed relation for wettability of thiol coated copper hydroxide nanowires with thiol coating time and proposed method would be favorable for anti-corrosion functional surface.