Review on the Aerogel-Type Oil Sorbents Derived from Nanocellulose

Abstract

Because of the severe risk of oil pollution and increasing concerns about the sustainability of sorbent materials, there are considerable interests across the world to develop cost-effective, reusable, and environmentally friendly oil sorbents derived from renewable resources. Nanocellulose is a new family of promising cellulosic materials with a cellulose fibril width in the order of nanometer range (i.e., 2−100 nm). As a class of newly developed cellulose aerogels, nanocellulosederived ones combine intriguing interconnected three-dimensional porous characteristics of aerogel-type materials such as high porosity, large surface area, and low density with fascinating advantages related to naturally occurring nanocellulose: impressive mechanical properties, abundant sources, natural renewability, excellent biodegradability, and ease to surface modification. Therefore, nanocellulose-based aerogels are very ideal "green" oil sorbents after either appropriate hydrophobic modifications or carbonization. This present review summarizes the state-of-the-art in the aerogel-type oil sorbents derived from nanocellulose, including hydrophobized nanofibrillated cellulose (NFC)-based aerogels, hydrophobized bacterial cellulose (BC)-based ones, and the carbon ones prepared through the pyrolysis NFC or BC aerogels. Their respective preparation methods, structure, and oil-absorption performance are summarized. And the existing problems in the current research and the future development perspectives are also presented.

Cellulose Mineralization as a Route for Novel Functional Materials

“…Hierarchical morphology consists of a 3D network of entangled micro‐nanofibrils (Figure C). These aerogels have an advantage against the silica materials, which is the absence of brittleness . When being made from nanocellulose, they are obtained in transparent form as well …”

“…Its hydrophobization opens up novel areas of uses. Therefore, this field of research is flourishing . A comparison of various materials in ref.…”

“…A large number of silica precursors suggested for cellulose mineralization contain alkyl and fluoroalkyl radicals attached directly to silicon atoms (Table ). Cellulosic materials treated by them possess reduced surface energy, which is obvious from the high water contact angle (Figure C). If a material has a superhydrophobic character with a value that exceeds 150° and a sliding angle of less than 10°, the morphology with roughness at the microscale level should be tuned (Figure F) …”

“…Hydrophobization causes a notable stabilizing effect on cellulose. Mineralized paper, fabrics, and aerogels possess increasing resistance toward harsh environmental and operating conditions, such as high humidity, acidic and alkaline solutions, high temperature, washing, and mechanical abrasion . Additional benefits are gained by combining silica with titania.…”

“…Hydrophobized aerogels and paper possess flexibility, can change their shape, and demonstrate enhanced durability and good recyclability, which is crucial for industrial applications . Further improvement of the oil absorbing ability and mechanical properties, flexibility, and reusability of cellulose is afforded by its integration with graphene oxide and carbon nanotubes …”