Superhydrophobic PDMS@PEI-cCNTs wood with Joule heat and demulsification capability for oil-water emulsion separation

• Published in: Progress in organic coatings Vol. 185; p. 107960
• Main Authors: Chen, Zhuohan, Su, Xiaojing, Li, Kunquan, Chen, Rongxuan, Lai, Zhixuan, Li, Xuanjun, Chen, Shengye, Wu, Wenjian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2023
• Subjects: Compressibility; Demulsification; Joule heat; Superhydrophobic wood; Water-in-crude oil emulsion separation; Water-in-crude oil emulsion separation; Superhydrophobic wood; Joule heat; Compressibility; Demulsification
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2023.107960

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.