Mussel inspired stable underwater superoleophobic cotton fabric combined with carbon nanotubes for efficient oil/water separation and dye adsorption

Currently reported biobased superwetting cotton fabrics (CF) for wastewater purification were limited because they can only separate oil/water mixtures but cannot remove other pollutants such as dyes from wastewater. In this study, we reported a superhydrophilic and underwater superoleophobic cotton fabric (SUSCF) which was fabricated via a facile two-step method, i.e., dip-coating in poly(sodium 4-styrenesulfonate) (PSS) wrapped carbon nanotube (CNT) dispersion and subsequent in-situ deposition of polydopamine (PDA). The deposited PDA particles and coated CNT endowed CF with superhydrophilicity and underwater superoleophobicity by improving surface roughness and hydrophilicity. The obtained SUSCF showed an underwater oil contact angle of 160°, which made it an attractive water-removing material for oil/water separation with separation efficiency and water flux of higher than 99.8% and 10,834 L m-2h−1, respectively. The combination of CNT, PSS, and PDA endowed the SUSCF with outstanding cationic dye adsorption capacity, especially leading to a maximum removal ratio of 97% toward methylene blue. In addition, the SUSCF exhibited excellent stability to survive after exposure to sandpaper abrasion, boiling water, organic solvents, salt solution, and acidic/alkali erosion, due to the strong hydrogen bonds and mussel-inspired adhesion between coated components and fabric surface. The stable biobased underwater superoleophobic cotton fabric with integrated excellent oil/water separation performance and dye adsorption capacity shows great potential in wastewater purification even under some harsh conditions.