With increasing environmental and ecological concerns due to the use of petroleum-based chemicals and products, the synthesis of fine chemicals and functional materials from natural resources is of great public value. Nanocellulose may prove to be one of the most promising green materials of modern times due to its intrinsic properties, renewability, and abundance. In this review, we present nanocellulose-based materials from sourcing, synthesis, and surface modification of nanocellulose, to materials formation and applications. Nanocellulose can be sourced from biomass, plants, or bacteria, relying on fairly simple, scalable, and efficient isolation techniques. Mechanical, chemical, and enzymatic treatments, or a combination of these, can be used to extract nanocellulose from natural sources. The properties of nanocellulose are dependent on the source, the isolation technique, and potential subsequent surface transformations. Nanocellulose surface modification techniques are typically used to introduce e...

/pdf/nanocellulose-a-versatile-green-platform-from-biosources-to-2lbk2f63rt.pdf

Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their Applications

Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

/pdf/nanocellulose-from-fundamentals-to-advanced-applications-ecdehj4ngu.pdf

Nanocellulose: From Fundamentals to Advanced Applications

The rapid development of modern industry and excessive consumption of petroleum-based polymers have triggered a double crisis presenting a shortage of nonrenewable resources and environmental pollution However, this has provided an opportunity to stimulate researchers to harness native biobased materials for novel advanced materials and applications Nanocellulose-based aerogels, using abundant and sustainable cellulose as raw material, present a third-generation of aerogels that combine traditional aerogels with high porosity and large specific surface area, as well as the excellent properties of cellulose itself Currently, nanocellulose aerogels provide a highly attention-catching platform for a wide range of functional applications in various fields, eg, adsorption, separation, energy storage, thermal insulation, electromagnetic interference shielding, and biomedical applications Here, the preparation methods, modification strategies, composite fabrications, and further applications of nanocellulose aerogels are summarized, with additional discussions regarding the prospects and potential challenges in future development

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.202005569

Recent Progress on Nanocellulose Aerogels: Preparation, Modification, Composite Fabrication, Applications

Tremendous efforts have been dedicated to developing effective and eco-friendly approaches for separation of oil–water mixtures Challenges remain in terms of complex processing, high material cost, low efficiency, and scale-up problems Inspired by the tubular porosity and hierarchical organization of wood, a strong, mesoporous, and hydrophobic three-dimensional wood structure is created for selective oil/water separation A delignified wood template with hydrophilic characteristics is obtained by removal of lignin The delignified wood template is further functionalized by a reactive epoxy–amine system This wood/epoxy biocomposite reveals hydrophobic/oleophilic functionality and shows oil absorption as high as 15 g/g The wood/epoxy biocomposite has a compression yield strength and modulus up to 18 and 263 MPa, respectively, at a solid volume fraction of only 12% This is more than 20 times that of cellulose-based foams/aerogels reconstructed from cellulose nanofibrils The favorable performance is asc

Wood Nanotechnology for Strong, Mesoporous, and Hydrophobic Biocomposites for Selective Separation of Oil/Water Mixtures

Functionalized Cellulose for Water Purification, Antimicrobial Applications, and Sensors

Heavy metal pollution is one of the most serious environmental problems, posing threats to human health. Here, we developed a magnetic hybrid aerogel by integrating nanocellulose and ferroferric oxide (Fe3O4) nanoparticles for effectively adsorbing heavy metal ions from water and realizing controllable recovery under magnetic condition. The magnetic behavior and adsorbing capacity of the hybrid aerogel on removal of heavy metal chromium (Cr)(VI) ion were examined. Results show that the ferroferric oxide nanoparticles physically adsorb the nanocellulose, each of which retains the original composition and structural characteristics. The magnetic hybrid aerogel possesses good ferromagnetic property with saturation magnetization value of 53.69 emu/g, enabling effective and controllable recovery of the aerogel under magnetic condition The adsorption efficiency of the hybrid aerogel on the Cr(VI) ion reaches the highest value of 2.2 mg/g when the mass ratio of the nanocellulose to ferroferric oxide nanoparticle is 1:1. Additionally, the hybrid aerogel presents similar adsorption behavior on plumbum (Pb)(II) and copper (Cu)(II) ions, suggesting extended applications of the hybrid aerogel on removal of heavy metal ions. Such strategy could provide new applications for the abundant nanocellulose resources and could be extended to integrate nanocellulose with other functional nanomaterials into novel hybrid aerogel for water purification.

Nanocellulose-based magnetic hybrid aerogel for adsorption of heavy metal ions from water

Nanocellulose is gaining evident interest from researchers and engineers because of its renewability, biocompatibility, biodegradability, high mechanical strength, abundant hydroxyl groups for potential functionality, and extensive raw materials. Versatile sources are accordingly explored like harvested wood, annual plants, and agricultural residues. However, an abundant shrub plant, Amorpha fruticosa Linn., has not yet been reported for isolating nanocellulose. We accordingly propose a green method with low energy consumption to extract nanocellulose from the vast shrub source via combined grinding and successive homogenization treatments. The derived nanocellulose possesses a fine structure with a diameter of ∼10 nm and an aspect ratio over 1000, high thermal stability with a maximum decomposition temperature of 337 °C, and similar composition with a hydroxyl group and a crystal I structure to that of natural cellulose. The demonstrated nanopaper presents visible light transmittance over 90% and haze be...

Nanocellulose Mechanically Isolated from Amorpha fruticosa Linn.

Solid wood materials and wood–plastic composites as two kinds of lightweight materials are attracting great interest from academia and industry due to their green and recycling nature. However, the relatively lower specific strength limits their wider applications. In particular, solid wood is vulnerable to moisture and decay fungi in nature, resulting in its poor durability for effectively long-term utilization. Inspired from the porous structure of wood, we propose a new design to build a wood-based nanocomposite with higher specific strength and satisfactory durability by in situ generation of organic–inorganic hybrid polymer within wood via a sol–gel method. The derived composite has 50–1200% improvement of impact toughness, 56–192% improvement of tensile strength, and 110–291% improvement of flexural strength over those of typical wood–plastic composites, respectively; and even 34% improvement of specific tensile strength than that of 36A steel; 208% enhancement of hardness; and 156% enhancement of c...

Wood-Based Nanocomposite Derived by in Situ Formation of Organic-Inorganic Hybrid Polymer within Wood via a Sol-Gel Method.

Cellulose-based materials are vulnerable to moisture and microorganisms and thus lose their original mechanical properties and durability; meanwhile, self-cleaning technique as a disruptive nanotechnology of waterproofing is attracting tremendous interest. Here, we develop a facile, cheap, and scalable “top-down” strategy to fabricate a transparent self-cleaning surface for cellulose-based materials by spray-coating a stable emulsion of nano-SiO2 particles. The nanoparticles are precisely synthesized at an average diameter of ∼110 nm via a sol–gel way and finely tailored with hydrophobic function by successive modification of poly(dimethylsiloxane) (PDMS) and (heptadecafluoro-1,1,2,2-tetradecyl)trimethoxysilane (17F). The modified nano-SiO2 particles well-distributed on the microscale rough surface of the cellulose-based materials by spray-coating to form a micro/nano two-tier structure to entrap air for water resistance, and thus build a superhydrophobic surface with static water contact angle (WCA) over...

Facile, Scalable Spray Coating of Stable Emulsion for Transparent Self-cleaning Surface of Cellulose-based Materials

Nanocellulose has many advantages, such as a wide range of sources of raw materials, renewability, biodegradability, high aspect ratio and large specific surface area. It can be potentially used in medicine, electronics, information technology, energy industry, aerospace and some other high-technological fields.  For preparation of nanocellulose, it is particularly important to separate nanocellulose from  raw materials by an environment-friendly method with environmental protection awareness. Consequently, we here report an effective and environmental friendly method to isolate nanocellulose from a shrub plant, i.e.,  Amorpha fruticosa Linn. Firstly, the plant fiber is pretreated with chemicals to remove lignin and hemicellulose; then the derived purified cellulose is pretreated with enzyme hydrolysis, followed by slight treatment of high-pressure homogenization. The results showed that with the assistance of enzyme pretreatment, effective isolation of nanocellulose could be achieved,  resulting in materials with a uniform diameter distribution and an average value of about 10 nm.  The aspect ratio of the derived nanocellulose is greater than 1000. Such results showed that the method was green and effective for nanocellulose isolation, and the derived biomaterial as a unique biocompatible and high-strength biomass nanomaterial could be used in biomedical, environmental protection and other fields.

https://www.udspub.com/ajj/public/index.php/aeb/article/download/420/pdf_1

Xiaoying Dong

Papers

Nanocellulose-based magnetic hybrid aerogel for adsorption of heavy metal ions from water

Nanocellulose Mechanically Isolated from Amorpha fruticosa Linn.

Wood-Based Nanocomposite Derived by in Situ Formation of Organic-Inorganic Hybrid Polymer within Wood via a Sol-Gel Method.

Facile, Scalable Spray Coating of Stable Emulsion for Transparent Self-cleaning Surface of Cellulose-based Materials

Nanocellulose isolation from Amorpha fruticosa by an enzyme-assisted pretreatment