Natural and synthetic superhydrophobic surfaces: A review of the fundamentals, structures, and applications

Self-cleaning surfaces are nature-inspired and based on the surface processes occurring on butterfly wings and lotus leaves. Owing to their unique characteristics, they are usable in a number of industrial applications, including the manufacture of solar panels and glass. In particular, they can be used for the separation of oil and water, which is highly relevant to petroleum technologies. Self-cleaning surfaces help to reduce the time and cost of keeping equipment clean while enhancing its durability, and they can be broadly categorized into hydrophilic and hydrophobic surfaces. On hydrophilic surfaces, water spreads considerably (sheeting of water), and therefore, it can transport contaminants and leave a clean surface. However, a hydrophobic surface is cleaned by the slipping of water droplets on it. Currently, water-repellent surfaces are used more widely in self-cleaning technologies. The selection and design of such surfaces require a thorough understanding of the underlying physical chemistry of the relevant process. This paper presents an in-depth discussion of self-cleaning surfaces, with an emphasis on their applications in the petroleum industry