Facile Fabrication of a Robust Superhydrophilic/Underwater Superoleophobic Material for Oil-Fouling Expulsion

Abstract

The reduction of oil fouling in pipes and tanks is essential for the oil storage and transportation industry. In this study, a superhydrophilic/underwater superoleophobic surface (SUSS) with high wearability, weatherability, and durability was developed using a facile two-step synthesis method and used to expel fouled oil from the surface using water without a surfactant. Some typical oils, including kerosene and white oil, can be spontaneously expelled by static water; however, rapeseed oil requires motive water for expulsion because of its high affinity for the SUSS. Different occurrences can be estimated based on a correlated parameter, φ(<i>P</i>_e), which is calculated using an introduced dimensionless number, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>P</mml:mi></mml:mrow><mml:mrow><mml:mi>e</mml:mi></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:msub><mml:mrow><mml:mi>σ</mml:mi></mml:mrow><mml:mrow><mml:mi>L</mml:mi><mml:mi>V</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mi>u</mml:mi><mml:mi>μ</mml:mi></mml:mrow></mml:mfrac></mml:math>. A positive value of φ indicates the occurrence of fouled-oil expulsion by water replacement, whereas a negative value indicates no occurrence of this phenomenon. This study provides a facile strategy for the rapid cleansing of oil-fouled pipes and tanks without using a detergent, thereby lowering costs and environmental risks.