Multifunctional nano-cellulose aerogel for efficient oil–water separation: Vital roles of magnetic exfoliated bentonite and polyethyleneimine

Discharge of oily wastewater have caused serious environmental pollution and resources waste. Due to the characteristics of hydrophobic and porous, aerogel has been proved to be a kind of promising oil-adsorbing materials for oil adsorption and recovery. However, dissatisfactory adsorption properties and recovery ability of aerogel for oil pollution treatment were still critical issues hindering aerogel applications. Magnetic exfoliated bentonite (MBTex) possesses good magnetic separation property, anti-mold ability and anti-extruding strength. Meanwhile, Polyethyleneimine (PEI) can cross-link with nano-cellulose to form sponge-like structure and prevent the corrosion of magnetic media. Basing on the above-mentioned characteristics of MB and PEI, a new carboxy cellulose nanofibers/polyethyleneimine/magnetic exfoliated bentonite (CNF-C/PEI/MBTex) aerogel was synthesized using simple hydrothermal and chemical vapor deposition (CVD) methods, and the adsorption and recovery ability of different oil on samples were investigated. The results showed that CNF-C/PEI/MBTex aerogel exhibited superhydrophobic properties (contact angle 151°), excellent mechanical properties (full recovery at 80% pressure), anti-mold properties (the anti-mold efficiency was more than 90%) and magnetic responsivity. Furthermore, CNF-C/PEI/MBTex aerogel exhibited high oil adsorption capacity (24.6 ∼ 77.8 times higher than its original weight) and can recover the adsorbed oil by simple hand squeezing (the adsorption capacity still exceeds 90% after 20 cycles). In summary, the present work provides a valuable reference for the synthesis of high-performance adsorbent materials for oil–water separation using cost-effective clays combined with polymers.