MWCNTs polyurethane sponges with enhanced super-hydrophobicity for selective oil–water separation

ABSTRACT

In this work, long-chain hexadecyl siloxane groups were introduced into hydroxylated multi-walled carbon nanotubes (MWCNTs-OH) to obtain modified carbon nanotubes (CNTs) with super-hydrophobic characteristics. A novel super-hydrophobic/super-oleophilic polyurethane sponge (SH-MWCNTs@PU sponges) was achieved by performing further surface-modification with the super-hydrophobic CNTs via the immersion-coating process. The results showed that SH-MWCNTs@PU sponges exhibited excellent super-hydrophobic properties, with a water contact angle of 157.4 ± 1.1°, and water droplets roll-off angle of only 6.7°. In addition, its mechanical strength was greatly improved by the introduction of CNTs. Significantly, it exhibits excellent adsorption capability for different oils and organic solvents. The initial oil adsorption capacity is still maintained with a contact angle of 152.2° after 10 oil adsorption cycles, demonstrating good reusability of the SH-MWCNTs@PU sponges. The low-cost (the used MWCNTs-OH are industrial-grade), durable, and super-hydrophobic sponge is a promising material for oil–water separation with high efficiency and selectivity.

GRAPHICAL ABSTRACT

KEYWORDS:

• Hydroxylated multi-walled carbon nanotubes
• polyurethane sponge
• super-hydrophobicity
• oil–water separation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

National Key R&D Program of China for “Research and development of key technologies for the preservation of marine wooden cultural relics” is greatly acknowledged for their financial support.