Superhydrophobic Stainless-Steel Mesh with Excellent Electrothermal Properties for Efficient Separation of Highly Viscous Water-in-Crude Oil Emulsions

The separation of tiny water droplets from viscous crude oil is urgently needed and still remains a substantial challenge because of severe membrane fouling resulting from the high viscosity and adhesive property of crude oil. To solve this issue, the electrothermal effect, for the first time, was utilized to heat the water-in-crude oil emulsion using electrical current as an energy source to extremely reduce the viscosity of the water-in-crude oil emulsion and thus to realize efficient viscous emulsion separation. A silicone-modified stainless-steel mesh (SSM) was fabricated via coating silicone on the SSM and transient heating. The as-prepared silicone-modified SSM allows for an outstanding integration of superhydrophobic/superoleophilic properties from the partial thermal degradation of the silicone coating and superior electrothermal capability from SSM. Thanks to the excellent electrothermal capability, the silicone-modified SSM achieved a high electrothermal power density of 3.43 W cm–2 at a low input voltage of 5 V. The resulting Joule heating, superhydrophobicity, and micropore structure enabled the silicone-modified SSM to efficiently separate a viscous water-in-crude oil emulsion (2.6 × 104 mPa s at 20 °C) with high separation efficiency (98.9%) and separation flux (314 L m–2 h–1). Moreover, the silicone-modified SSM presented optimal reusability and stability after six cycles for the viscous water-in-crude oil emulsion. This electrothermal-assisted viscous emulsion separation strategy can provide some new perspectives for viscous oil/water emulsion separation.