Reducing surface fouling against emulsified oils using CuO nanostructured surfaces

Abstract

Surface fouling by oil is a significant engineering issue by degrading the performance of various energy systems. Recently, it has been shown that nanostructured surfaces with the proper wettability can mitigate surface fouling against various types of organic or inorganic matter in aqueous environments. However, their effectiveness in suppressing surface fouling is questionable against low surface tension bio-oils, particularly when they are present in the form of emulsified oils. Here, we show that a surface fouling on the metallic substrate can be mitigated by nanostructuring the substrate, followed by additional surface treatment. With hydrophobization of nanostructured substrate, oil-fouling is reduced up to similar to 48 % due to the reduced surface energy, although emulsified oil still sticks to the surface. Furthermore, with additional infusion of low surface tension lubricants, oil-fouling is significantly suppressed up to similar to 88 % due to non-sticking property of the lubricant-infused substrate even to emulsified oils. Also, it is found that surface fouling is strongly dependent on the temperature due to the change of emulsion property with the temperature, which should be taken into account in practical settings. By proposing a practical solution to minimizing surface fouling by emulsified bio-oils, we believe that our results can help address a critical fouling issue in energy systems utilizing bio-oils.