Oil–water separation has recently become an important subject due to the increasing incidence of oil spills. Materials with underwater superoleophobic properties have aroused considerable interest due to their cost-effectiveness, environmental friendliness and anti-fouling properties. This paper presents a robust salt-tolerant superoleophobic aerogel inspired by seaweed used without any further chemical modification for oil–seawater separation. The green aerogel is prepared by freeze-drying of sodium alginate (SA)–nanofibrillated cellulose (NFC) using Ca²⁺ ions as the crosslinking agent. The three-dimensional (3D) interconnected network structure of the developed aerogel ensures its high mechanical strength and good flexibility. The natural hydrophilicity of the polysaccharides contained in the aerogel ensures its excellent underwater superoleophobicity, antifouling and salt-tolerance properties. More impressively, the as-prepared aerogel can even keep its underwater superoleophobicity and high hydrophilicity after being immersed in seawater for 30 days, indicating its good stability in marine environments. Furthermore, the aerogel could separate oil–seawater mixtures with a high separation efficiency (of up to 99.65%) and good reusability (at least 40 cycles). The facile and green fabrication process combined with the excellent separation performance and good reusability makes it possible to develop engineering materials for oil–water separation in marine environments.

Oil-water separation has recently become a worldwide concern because of the increasing oil spill accidents and industrial oily wastewater generation. Herein, a facile method with the combined superhydrophobic coating and adhesive was used to fabricate superhydrophobic TiO₂ NPs coated cellulose sponge. The developed materials exhibited excellent superhydrophobicity (WCA = 171°) and superoleophilicity (OCA = 0°), which can separate a variety of oil-water mixtures, including chloroform, toluene, kerosene and other contaminations. A high separation efficiency up to 98.5% for chloroform-water mixture was achieved when used for gravity-driven oil/water separation test. More importantly, the as-prepared samples exhibited excellent chemical stability and mechanical abrasion resistance even towards various corrosive oil/water mixtures (such as strong acid, alkali solution and salt-water environment) or a strong abrasion by aluminium oxide sandpaper of 600 mesh. In addition, the separation efficiency remained above 93% even after 40 scratch cycles, and the materials could be reused with a stable hydrophobicity, indicating a strong potential for industrial application.

Marine pollution caused by frequent oil spill accidents has brought about tremendous damages to marine ecological environment. Therefore, the facile large-scale preparation of three-dimensional (3D) porous functional materials with special wettability is in urgent demand. In this study, we report a low-cost and salt-tolerant superoleophobic aerogel for efficient oil/seawater separation. The aerogel is prepared through incorporating graphene oxide (GO) into alginate (ALG) matrix by using a facile combined freeze-drying and ionic cross-linking method. The 3D structure interconnected by ALG and GO ensures the high mechanical strength and good flexibility of the developed aerogel. The rough microstructure combined with the hydrophilicity of the aerogel ensures its excellent underwater superoleophobic and antifouling properties. High-content polysaccharides contained in the aerogel guarantees its excellent salt-tolerant property. More impressively, the developed aerogel can retain its underwater superoleophobicity even after 30 days of immersion in seawater, indicating its good stability in marine environments. Furthermore, the aerogel could separate various oil/water mixtures with high separation efficiency (>99%) and good reusability (at least 40 cycles). The facile fabrication process combined with the excellent separation performance makes it promising for practical applications in marine environments.