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Recently, the membrane separation materials show promising applications in the fields of crude oil removal because of their low energy consumption and less secondary pollution. However, the membrane separation materials suffer problem of low separation efficiency due to the high viscosity of crude oil. Here, a superhydrophobic material with Joule heat and photothermal effect was prepared by decorating the delignified wood with reduced graphene oxide (GSH) and vinyl terminated polydimethylsiloxane (V-PDMS) through thiol-ene click reaction. The prepared PDMS@GSH wood exhibited stable superhydrophobicity with a water contact angle of 156°. Meanwhile, the GSH layer provided promising electrothermal effect that endowed the PDMS@GSH wood with excellent crude oil/water separation capability under the Joule heat with a surface temperature of 139 °C and separation rate of 1.78 × 105 kg m−3 h−1. Besides, the PDMS@GSH wood displayed a good photothermal effect that assisted with the Joule heat to heat the wood for crude oil removal to save energy. More importantly, the PDMS was crosslinked with GSH on the wood via thiol-ene click reaction, leading to the stable superhydrophobicity and electrical conductivity in strong acid or alkali environment. This material has broad application prospects in crude oil clean-up due to its high separation speed and easy large-scale production. [Display omitted] • A new strategy for fabricating superhydrophobic wood with heating property is proposed. • The wood presents stable superhydrophobicity and electrical conductivity. • The wood shows excellent Joule heat and photothermal effect. • The wood exhibits high separation rate for viscous crude oil wastewater. [ABSTRACT FROM AUTHOR]

Superhydrophobic materials possess prospective applications of oily wastewater treatment due to their high efficiency and easy operation. Nevertheless, most superhydrophobic materials are difficult to separate oil-water emulsion, especially for highly viscous water-in-crude oil emulsion. Herein, a superhydrophobic wood with excellent Joule heat and demulsification was proposed by chemically treating the natural wood and subsequent coating of the carboxyl-modified carbon nanotubes (cCNTs) for providing conductive pathways, polyethylenimide (PEI) for supporting demulsification and polydimethylsiloxane (PDMS) for hydrophobic modification. The fabricated superhydrophobic PDMS@PEI-cCNTs wood displayed a water contact angle of 155o and great compression property with a nearly undamaged structure at a strain of 40 % after 50 compression tests, which could separate and recover oil from the oil-water mixture via absorption-extrusion process. Besides, due to the filtration and electrostatic interaction of the PDMS@PEI-cCNTs wood, the water-in-oil emulsion was demulsified quickly with a separation efficiency greater than 99.7 %. Meanwhile, the PDMS@PEI-cCNTs wood showed a good Joule heat capability, and the surface temperature reached 160 °C at 35 V of voltage within 120 s, which largely reduced the viscosity of water-in-crude oil emulsion. Thus, the PDMS@PEI-cCNTs wood was successful in separating the water-in-crude oil emulsion via Joule heat capability with a separation rate of 4.33 × 104 kg·m−3·h−1 and a separation efficiency of 93.4 %. The material developed in this study has wide range of applications in treating the stable crude oil-water emulsion with high viscosity. [Display omitted] • A new strategy for fabricating superhydrophobic wood for various oil-water emulsions separation is proposed. • The wood presents stable superhydrophobicity and good electrical conductivity. • The wood shows excellent demulsification capability via charge action, absorption and gathering. • The wood exhibits great Joule heat to promote separating viscous water-in-crude oil emulsion. [ABSTRACT FROM AUTHOR]