Abstract
Aqueous ecological environment is exacerbated by indiscriminate discharge of industrial and municipal wastewater, particularly oily contaminants. Janus materials with unique asymmetric wettability have been considered potential candidates for oil-water separation. Herein, we developed a novel approach to accomplish controllable construction of three-dimensional Janus all-cellulose aerogel with asymmetric wettability based on a similar phase self-assembling strategy. Significantly, the ratio of asymmetric structures could be controlled by tailoring thickness of hydrophobic/hydrophilic layers. Three-dimensional Janus all-cellulose aerogel had both super-hydrophilic/oleophilic and super-hydrophobic/oleophilic cellulose skeleton structures simultaneously. The adsorption capacity of the aerogel for oil reached up to 34.38 g/g. It could effectively separate a variety of oil-water mixtures and water-in-oil emulsions only driven by gravity, even surfactant-stabilized emulsions. The separation efficiency was more than 99% with the high separation flux. The ‘Trade-off’ effect in the field of membrane separation was avoided effectively. Three-dimensional Janus all-cellulose aerogel exhibited good stability and recyclability. Moreover, the demulsification and separation mechanism was analyzed in details. This work provided not only an environmental-friendly, facile and flexible approach to construct controllable three-dimensional asymmetric wettable Janus materials, but also a scientific understanding and development of the separation mechanism of three-dimensional Janus materials.
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