Superhydrophobic Cellulose Nanofiber-Assembled Aerogels for Highly Efficient Water-in-Oil Emulsions Separation

Here, we reported a facile strategy to create superhydrophobic aerogels via freeze-drying of silylated cellulose nanofibers and silica nanoparticles mixed suspensions. The as-prepared aerogels possessed a hierarchical porous structure with high roughness and low surface energy. The hierarchical rough structure and low surface energy endowed the resultant aerogels with superhydrophobicity (water contact angle up to 168.4°). Importantly, the composite aerogels could separate surfactant-stabilized water-in-oil emulsions without external pressure, with high separation efficiency (>99%) and high flux (1910 ± 60 L m–2 h–1). The aerogels were easily recyclable and showed great antifouling performance, which could meet the requirements for long-term use. We also assembled a simple device to collect oil directly from water-in-oil emulsions with the obtained aerogel and a self-priming pump. The fabrication of the composite aerogels in our work provides a versatile way to fabricate cellulose composite materials for water-in-oil emulsions separation.