Green synthesis of polyvinyl alcohol (PVA)–cellulose nanofibril (CNF) hybrid aerogels and their use as superabsorbents

Abstract

Cross-linked polyvinyl alcohol (PVA)–cellulose nanofibril (CNF) hybrid organic aerogels were prepared using an environmentally friendly freeze-drying process. The resulting PVA/CNF aerogel was rendered both superhydrophobic and superoleophilic after being treated with methyltrichlorosilane via a simple thermal chemical vapor deposition process. Successful silanization on the surface of the porous aerogel was confirmed by various techniques including scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements. The silane-treated, cross-linked PVA/CNF aerogels not only exhibited excellent absorption performance for various types of oils (e.g., crude oil) or organic solvents (with a typical weight gain ranging from 44 to 96 times of their own dry weight), but also showed a remarkable scavenging capability for several types of heavy metal ions tested (e.g., Pb²⁺, Hg²⁺), making them versatile absorbents for various potential applications including water purification. Furthermore, these PVA/CNF aerogels demonstrated excellent elasticity and mechanical durability after silane-treatment as evidenced by the cyclic compression tests.