Robust and Versatile Cellulose Aerogel with a Self-Wettable Surface for Efficient Dual Separations of Oil-in-Water and Water-in-Oil Emulsions

Separation materials with unique surface wettability have been regarded as promising candidates for oily sewage treatment. However, simple and facile fabrication of superwettable materials integrating robust and tunable surface features is still a challenge. Inspired by the unique molecular structure of cellulose with a rigid skeleton and abundant hydroxyl groups, this work proposed high-strength, superhydrophilic, and underwater superoleophobic cellulose aerogels prepared via facile chemical cross-linking without any surface modification. Benefiting from the superporous microstructure and unique surface wettability, the cellulose aerogels exhibited on-demand separation performances for oil-in-water (O/W), water-in-oil (W/O) emulsions, and crude oil. The superior separation flux of 19,602 L/(m2 h) and a rejection of 99.5% were acquired for O/W emulsion, while 5158 L/(m2 h) of flux and 98.9% of rejection were acquired for W/O emulsions. Importantly, the cellulose aerogels show an outstanding efficiency for crude oil/water emulsions with flux from 7815 to 26,648 L/(m2 h) based on water content. Moreover, owing to the rigid skeleton and cross-linked cellular architecture, the aerogels displayed significant flexibility and toughness with tiny deformation of 0.15% after 60 cycles underwater, endowing it with excellent reusability. Thereby, this proposed cellulose aerogel with unique advantages of a robust, superhydrophilic, and underwater superoleophobic surface exhibits a promising application in versatile and efficient dual oil/water separation.