Polydimethylsiloxane-decorated magnetic cellulose nanofiber composite for highly efficient oil-water separation

Developing three-dimensional porous hydrophobic and oleophilic materials (3D-PHOMs) for efficient and selective oil-water separation is important to clean up oil spills and organic pollutants. However, 3D-PHOMs are still confined to lab-scale research due to several crucial drawbacks. Herein, a hydrophobic oil-water separation composite, containing cellulose nanofiber (delignificated porous wood, PW) substrate, magnetic nickel (Ni) layer and hydrophobic polydimethylsiloxane (PDMS) coating, is prepared using electroless deposition (ELD) and surface modification techniques. Owing to the porosity, hydrophobicity (>130° of water contact angle), lipophilicity, convenient magnetic collection and high cycle compressibility, the as-fabricated PDMS-Ni-PW exhibits excellent oil adsorption capacity (>60% of the volumetric absorption capacity) and outstanding cyclic stability (>80% of the adsorption capacity after 200 cycles). Thanks to the low surface energy and rough surface structure, the adsorbent demonstrates superior oil-retention ability (>80% at 200 rpm). Also, the oil-collecting apparatus is successfully designed to continuously separate various oils, e.g., n-hexane and dichloromethane, from water due to the unidirectional liquid transport of the adsorbent. These excellent properties make PDMS-modified cellulose nanofiber a promising candidate for oil-water separation.