Cellulose Nanomaterials as a Future, Sustainable and Renewable Material

Cellulose nanomaterials (CNs) are renewable, bio-derived materials that can address not only technological challenges but also social impacts. This ability results from their unique properties, for example, high mechanical strength, high degree of crystallinity, biodegradable, tunable shape, size, and functional surface chemistry. This minireview provides chemical and physical features of cellulose nanomaterials and recent developments as an adsorbent and an antimicrobial material generated from bio-renewable sources.

Nanocellulose enhances the dispersion and toxicity of ZnO NPs to green algae Eremosphaera viridis

The widespread cellulose nanomaterials from industrial production and natural plant degradation inevitably lead to the accumulation of nanocellulose in aquatic environment. However, the effect of nanocellulose on the fate, transport...

Dragon Fruit Foliage: An Agricultural Cellulosic Source to Extract Cellulose Nanomaterials

In this report, we focus our effort to extract cellulose nanomaterials (CNs) from an agricultural cellulosic waste, Dragon Fruit foliage (DFF). DFF was first pretreated by several mechanical treatments and then bleached by chemical treatment to obtain bleached DFF. CNs were then produced from the hydrolysis of the bleached DFF catalyzed by sulfuric acid. We obtained CNs with a small diameter (50 to 130 nm) and length (100 to 500 nm) and a height of 3 to 10 nm. The CNs have a high crystallinity (crystallinity index 84.8%), high −COOH content (0.74 mmol. g−1), good thermal stability and a good Cu (II) adsorption capacity with an adsorption maximum of ~103 mg. g−1. These findings demonstrated the great potential of converting many agricultural cellulosic wastes into valuable cellulose nanomaterials.

Production and Characterization of Cellulose Nanofiber Slurries and Sheets for Biomedical Applications

Cellulose nanomaterials are produced employing a multitude of methodologies including electrospinning, bacterial generation, acid digestion, and a variety of mechanical defibrillation techniques; the morphology of the nanomaterial produced is specific to the production process. Feedstocks range from various forms of woody biomass, to fungi, and have a great impact on the resulting product. The mechanical defibrillation technique, such as that employed in the present work, continuously breaks down cellulose fibers suspended in water via segmentation and defibrillation through grinding and refining. The process is typically operated until a desired level of fines is achieved in the resultant slurry of cellulose nanofiber (CNF), alternatively known as cellulose nanofibril. Mechanical defibrillation processes can be built to produce several liters in a small batch system or up to tons per day in a continuous pilot scale refiner system. In the present work a continuous system was developed with the capacity to produce 14 L of cellulose nanofiber slurry with consistent specifications and in a manner compliant with GMP/GLP protocols in order to be amenable to biomedical applications. The system was constructed within an ISO class 7 cleanroom and refining was performed on bleached softwood pulp suspension in purified water. This manuscript details the continuous grinding system, the processes employed to produce cellulose nanofiber, and characterizes the resultant cellulose nanofiber slurry and sheets formed from the slurry.

COMPARISON OF PROPERTIES OF CELLULOSE NANOMATERIALS OBTAINED FROM SUNFLOWER STALKS

This study aimed to investigate the usability of sunflower stalks, which is one of the most significant agricultural residues in Turkey, in the production of cellulose nanomaterials (CNMs). Cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were produced by using a grinding method and acid hydrolysis, respectively. The average width and length of CNCs were found as 13.91 ± 3.09 nm and 60.44 ± 21.06 nm, respectively. Besides, the average width of CNFs was determined as 15.03 ± 3.68 nm. The crystallinity index of CNFs and CNCs was determined as 82.64% and 83.09%, respectively. Although the main thermal degradation stage of CNCs started at higher temperature than that of CNFs, the latter were more stable than CNCs at high temperatures. Furthermore, the chemical bonds in the raw material, bleached fiber, CNCs and CNFs were investigated with FTIR analysis. Consequently, it was seen that sunflower stalks can be a suitable raw material for the production of CNMs.

CELLULOSE NANOMATERIALS IN TEXTILE APPLICATIONS

Nanocellulose (NCC) has attracted increasing attention for use in several applications owing to its impressive strength-to-weight ratio, ease of functionalization, and apparent biocompatibility. In the nanocomposite textile field, NCC has exhibited outstanding potential for reinforced fibers, especially fibers processed by solution spinning. Continuous NCC fibers with high modulus and strength can be obtained, while preserving the cellulose I crystal structure. Owing to the various possibilities of surface modification, NCC is an efficient adsorbent of cationic and anionic textile dyes, as it reaches maximum removal capacities comparable to those of commercial adsorbents. In dyeing, NCC contributes in improving dye fixation and reducing the consumption of chemicals and water. In this review, recent studies on the applications of NCC in the textile field are discussed. The main methods, advances and limitations, regarding the NCC applications for fiber reinforcement of water-soluble and insoluble materials, dye removal and textile finishing, are presented.

Getting Environmentally Friendly and High Added-Value Products from Lignocellulosic Waste

In recent years, alternatives have been sought for the reuse of lignocellulosic waste generated by agricultural and other industries because it is biodegradable and renewable. Lignocellulosic waste can be used for a wide variety of applications, depending on their composition and physical properties. In this chapter, we focus on the different treatments that are used for the extraction of natural cellulose fibers (chemical, physical, biological methods) for more sophisticated applications such as reinforcement in biocomposites. Due to the different morphologies that the cellulose can present, depending from sources, it is possible to obtain cellulose nanocrystals (CNCs), micro- nanofibrillated cellulose (MFC/NFC), and bacterial nanocellulose (BNC) with different applications in the industry. Among the different cellulose nanomaterials highlighted characteristics, we can find improved barrier properties for sound and moisture, the fact that they are environmentally friendly, increased tensile strength and decreased weight. These materials have the ability to replace metallic components, petroleum products, and nonrenewable materials. Potential applications of cellulose nanomaterials are present in the automotive, construction, aerospace industries, etc. Also, this chapter exhibits global market predictions of these new materials or products. In summary, lignocellulosic residues are a rich source of cellulose that can be extracted to obtain products with high value-added and eco-friendly characteristics.

Nano-Cellulosic Fibers from Agricultural Wastes

In recent years, the potential of agricultural wastes has received increasing attention from academia and industry. The aim has been to identify strategies for the conversion of low-value wastes into new materials and other value-added products. Cellulose is a naturally abundant polymer that is readily available in various agricultural wastes. It is a linear polymer consisting of β-D-glucopyranose units (disaccharides) joined by glycosidic β-1,4 bonds. Nanoparticles can be extracted from cellulose fibers using a top-down mechanically or chemically treatment. Cellulose nanomaterials have generated significant interest due to their intrinsic properties such as large surface-to-volume ratios, high tensile strength, stiffness, and flexibility in addition to good dynamic mechanical, electrical, and thermal properties. The use of nanocellulose for reinforcement in matrices improves thermo-mechanical properties, decreases the sensitivity of polymers to water, and preserves biodegradability. The mixing of nanocellulose with polysaccharides improves mechanical properties. Nano-sized cellulose fibers possess unique physical, chemical, and morphological characteristics. Hence, nano-sized cellulose fibers are considered versatile materials for addition to polymers, and application in high gas barriers and packaging materials. Other uses include electronic devices, foods, medicine, cosmetics, and health care. This chapter focuses on the cellulose nanofibers attained from banana, pineapple and corn-based agricultural wastes.