Sustainable Carbon Aerogels Derived from Nanofibrillated Cellulose as High‐Performance Absorption Materials

Abstract

contaminants owing to their chemical affi nity with these contaminants, large surface area, porous structure, and other remarkable physical properties. [ 1 ] Due to their superior hydrophobic and oleophilic characteristics, carbon aerogels can effectively absorb a variety of oils and organic solvents without water penetration. However, most of these carbon aerogels are synthesized from carbonaceous precursors, such as carbon-containing polymers, [ 2 ] carbon-containing fi bers, [ 3 ] carbon nanofi bers, [ 4 ] carbon nanotubes, [ 5 ] and graphene. [ 6 ] Problems of these expensive precursors and complex and energyconsuming process in the production of carbon aerogels restrict the practical use of carbon aerogels on a large-scale. In this regard, the utilization of renewable biomass as precursors, together with simple and low-energy treatment to fabricate sustainable carbon aerogels is strongly desired. [ 7 ] In this study, we employ nanofi brillated cellulose (NFC) as a sustainable and scalable precursor for producing carbon aerogels. The reason to choose NFC as the precursor is based on its unique structures and properties. First, cellulose is a good carbon source. Cellulose-containing woods have been used as the precursor of activated coals for many years. Second, comparing with traditional cellulosic pulps in the micrometer-scale, NFC produced by disintegration of pulps has much smaller diameters in nanometer-scale (typically <10 nm) as well as advantageous mechanical strength due to the extended chain crystals of cellulose and large specifi c surface areas. [ 8 ] Further, NFC is able to form porous aerogels with a microscopic network and a large specifi c surface area. Although the NFC aerogels are expected to use for absorbing or separating of oils and organic solvents from water, the separation effi ciency is low because of the strong hydrophilicity of cellulose. [ 9 ] To improve the absorbent performance, the surface of NFC aerogels was chemically modifi ed to be hydrophobic and oleophilic with TiO 2 coating [ 10 ] or vapor phase silanization. [ 11 ] However, these modifi ed NFC aerogels still showed a weak absorbent performance (<45 times of their own weight). Jiang and Hsieh synthesized a functionalized NFC aerogel by chemical vapor deposition of (triethoxyl(octyl) silane) which was able to absorb 139-356 times organic solvents or oils by weight. [ 12 ] Unfortunately, their NFC aerogel also absorbed water when it was immersed into water, Sustainable carbon aerogels with low density (≈7.8 mg cm −3 ), high porosity, high resiliency, excellent hydrophobicity, and oleophilic characteristics are synthesized by employing nanofi brillated cellulose as the precursor. The as-prepared carbon aerogels show a remarkable capacity for the absorption of a variety of oils and organic solvents with weight gains ranging from 7422 to 22356. Under extreme conditions (e.g., at severe temperatures and in corrosive liquids), these carbon aerogels still demonstrate a superior absorption performance. Furthermore, a device ...

Multifunctional Bionanocomposite Foams with a Chitosan Matrix Reinforced by Nanofibrillated Cellulose

“…[2,3] Carbonaceous foams have attracted enormousa ttentiona sh igh-performancea bsorbents. [4][5][6] However,s ome carbonaceous foams are synthesized from expensive or hazardous precursors of carbon nanotubes, [7][8][9] carbon nanofibers, [10,11] or graphenes, [12][13][14] and somea re made from nanocellulose aerogels, which are derived from high-price bacterial cellulose [15,16] or eco-friendly wooden resources [17] but need to be converted to carbonst hrough high-temperature pyrolyzation, which consumes al ot of energy.P etroleum-derived polymers have also been used to make functional foams to adaptf or variousa pplication fields. However,t aking into account the practical use for water purification in aw ide range of scenes, foam materials are required to have good handleability including inoffensiveness to humans and environmental acceptability such as biocompatiblity and biodegradability, which reduces the environmental ande conomic burdens for their disposal.…”

Aerogels Derived from Polymer Nanofibers and Their Applications

“…Owing to the robust network, HBCAs show good reusability (Figure b). The carbonized nanofiber aerogels can also act as oil absorbents due to their hydrophobicity and high porosity (Figure c) . Compared with the former absorbents, the carbonized ones can be efficiently recycled by direct combustion of the absorbed oil (Figure d) .…”

Wood‐Derived Ultrathin Carbon Nanofiber Aerogels

“…The key point was to partly exchange the water in Wood‐NFC hydrogel with tert ‐butyl alcohol (TBA) before freeze‐drying . For the freeze‐drying process with water, the large ice crystals grew and expelled the solute to their boundaries, leading to a sheet‐like aggregates (Supporting Information, Figure S7 b) . Differently, small‐sized needle‐shaped crystals were formed when the TBA‐containing solution was frozen, which avoided the formation of sheet‐like aggregate structure and finally resulting a highly porous 3D nanofibrous network structure.…”

“…Furthermore, to demonstrate the universality of the organic acid‐assisted pyrolysis method, another more economical and sustainable wood‐derived NFC that was produced in large‐scale from never‐dried wood pulp by a high pressure homogenizer without the use of harsh chemicals, was also employed as precursor successfully for preparing CNFs aerogels (Supporting Information, Figure S14).…”