CHAPTER 5. Lotus Effect-based Superhydrophobic Surfaces: Candle Soot as a Promising Class of Nanoparticles for Self-cleaning and Oil–Water Separation Applications

Candle soot consists of hydrophobic carbon nanoparticles (diameter ∼40 ± 10 nm) that can be chiefly collected from the candle flame. There is no other easier and cheaper way available to produce hydrophobic nanoparticles. The deposition of candle soot on any solid surface appears as a black layer with superhydrophobicity, however this layer is delicate and washed away with rolling water drops or by gentle finger touching. The sole use of hydrophobic candle soot nanoparticles could not achieve a durable as well as transparent coating. The candle soot is then used as a template as well as in combination with silica or polymers to achieve durable and transparent superhydrophobic coatings. Candle soot can prove to be an adequate precursor in the preparation of superhydrophobic coatings and oil–water separation sponges/meshes due to its easy availability for everyone. The researchers who are eager to jump into superhydrophobic surface research with a low level of funding can start with candle soot. Novel ideas and techniques should be adopted to fabricate candle soot based superhydrophobic surfaces. The use of candle soot nanoparticles in industrial products can reduce the price of the final product reasonably.