Preparation and characterization of cellulose nanocrystal extracted from ramie fibers by sulfuric acid hydrolysis

Simple synthesis and excellent performance of the cow dung-based biodegradable liquid mulch for sustainable agriculture

The environmental pollution caused by the extensive use of plastic films in farmland and the discharge of large amounts of manure from animal husbandry has seriously affected the sustainable development of global agriculture and environment. In this study, using cow manure as raw material, a cow dung-based biodegradable liquid mulch (CD-BA) was synthesized through grafting polymerization and as an eco-friendly alternative to the traditional agricultural plastic film. By studying the effects of the proportion of cow manure raw materials and additives on the performance of liquid plastic film, the optimal CD-BA was synthesized with 48.36 wt% of cow dung, 26.77 wt% of glycerol and 2.08 wt% of quartz sand (red soil), respectively. The soil test results indicate that CD-BA has the capability to reduce soil water evaporation by 15%-42%, which is marginally lower than the 67% reduction observed with plastic mulch. Its temperature-increasing capacity ranges from 0.63 °C to 1.21 °C, which is comparable to the capacity of plastic mulch. Moreover, CD-BA achieves a soil degradation rate of 41.2%-69.5% within 120 days, significantly addressing the persistent non-degradability issue associated with traditional plastic mulch. In plant experiments, CD-BA demonstrated a 97.5% inhibition rate on weed seed germination, whereas CD-BA positively influenced crop growth and its drought resistance. This study provides a feasible resource utilization method for simultaneously solving the environmental pollution problems of animal breeding waste and farmland plastic film.

Multifunctional composite films with regenerated cellulose prepared via acid-catalytic degradation for in-situ growth of ZnO

Cellulose is extensively utilized as a natural polymer due to its actually natural piezoelectric properties as well as renewable properties, but suffers from processing difficulties and low piezoelectric constants (d33). Consequently, this work focuses on controlling the molecular weight of regenerated cellulose (RC) through pretreatment methods that promote the in-situ growth of ZnO to enhance its d33. Firstly, the acid-catalyzed pulp fibers (PFs) and zinc nitrate hexahydrate were added in NaOH/urea solvent to effectively prepare RC/ZnO composite film via regeneration and in-situ growth. The effects of the acid-catalytic degradation on the solubility of PFs, the structure of RC, and the RC/ZnO composite film were systematically discussed. It is found that 1.5 % - 6 h PFs formed a favorable three-dimensional network structure during the regeneration process, which is beneficial for the growth and dispersion of ZnO, and its d33 is up to 34.99 pm/V. The maximum open-circuit voltage of the piezoelectric generator (PEG) reaches 5 V. The composite film enables the development of portable an0d accurate piezoelectric sensing system as well as UV detection through the optical properties of ZnO. This work provides reference for the development and design of multifunctional cellulose and ZnO composites.

Active corrosion protection of epoxy coating filled with surface-engineered cellulose nanocrystals with polyaniline

Cellulose nanocrystal (CNC) grafted from polyaniline (PANI) doped with phosphate (PO43-) anion, designated here by C-pP, was employed as an active anticorrosive nanoparticle in epoxy (EP) coating at a concentration of 1 wt% for the mild-steel substrate. The presence of the phosphate agents on the backbone of PANI was confirmed by Fourier transform infrared spectroscopy (FT-IR) and further supported by thermogravimetric analysis (TGA). Electrochemical impedance spectroscopy (EIS) measurements for coatings with an artificial scratch revealed that EP/C-pP coating can provide an inhibition efficiency of up to ~69 %, about twice that of EP/PANI coating. Furthermore, the adhesion of the optimal sample was 3 MPa, more than those of EP/PANI and EP coatings. Additionally, the presence of C-pP drastically improved the hydrophobicity of the epoxy coating with an increase in its contact angle from 42.4 ̊ to 92.4 ̊. The superior anticorrosion property of EP/C-pP was attributed to the presence of CNC, which promoted the dispersion of PANI molecules within the EP matrix (confirmed by FE-SEM); resulting in 1) improved barrier effect against corrosive agents, and 2) self-healing property arising from the smart release of phosphate dopants from the PANI backbone under basic conditions and forming protective complexes at the infected areas.

Understanding nonwoody cellulose extractions, treatments, and properties for biomedical applications

Cellulose is a β1-4 glucan polymer that constitutes the most abundant polysaccharide on Earth. Recent advancements in its production have provided greater control and enabled the creation of functional celluloses with enhanced physical, mechanical, and chemical properties. With the increasing interest in polysaccharide materials, attention is now focused on alternative sources, particularly those derived from nonwoody plants such as jute, sisal, cotton, flax, or hemp. Compared to wood, nonwoody plants generally possess lower lignin content, shorter growing cycles with moderate irrigation requirements, high annual crops, and substantial annual cellulose yield. The discovery of nonwoody cellulose disintegration opens new avenues for environmentally friendly approaches, naturally paving the way for the exploration of new applications for this versatile material. Despite the broad range of potential applications, cellulose has primarily been utilized for industrial purposes, with only limited interest in the biomedical sector in the early stages. Therefore, this review focuses on nonwoody cellulose extraction and pretreatments while evaluating the compositions and properties of nonwoody plants, resulting in distinctive features beneficial for biomedical applications. This review aims to facilitate a deeper understanding of nonwoody cellulose and its prospects for biomedical applications.

Industrial by-products of tiger nut starch as a source of cellulose nanocrystals for biodegradable packaging materials

The development of eco-friendly, biodegradable nanomaterials is essential for promoting the sustainable utilization of industry by-products from tiger nut starch. This study focuses on the extraction of cellulose nanocrystals (TN-CNC) from tiger nut starch by-products through acid hydrolysis, as well as evaluation of their effects on the characteristics of starch-based biodegradable packaging. The TN-CNC was identified as having a rod-like morphology, exhibiting high crystallinity (CI = 87.2 ± 2.4 %), stable thermal properties (Tonset = 299.1 °C), an average length of 278.4 ± 91.6 nm, and a notable aspect ratio (23.1 ± 8.8). TN-CNC demonstrated compatibility with starch substrates and enhanced the microstructure of natural starch films through self-assembly and the formation of new hydrogen bonds. Incorporating 1.0 % TN-CNC improved the crystallinity of the starch films from 16.2 % to 23.7 %, and increased their thermal stability from 271.8 °C to 289.3 °C. This concentration also significantly increased tensile strength by up to 104.2 %. These findings advocate for the upcycling of tiger nut starch by-products, highlighting their potential in developing high-performance biodegradable packaging materials.

Plant-derived materials for biomedical applications

With exceptional biocompatibility and biodegradability, plant-derived materials have garnered significant interest for a myriad of biomedical applications. This mini-review presents a concise overview of prevalent plant-derived materials, encompassing polysaccharide-based polymers, protein-based polymers, extracellular vesicles, mucilage, decellularized scaffolds, and whole plant-based biomass. Through different processing techniques, these plant-derived materials can be tailored into a variety of forms, such as nanoparticles, nanofibers, and hydrogels, to address the nuanced requirements of biomedical applications. With the emphasis on wound healing, tissue engineering, and drug delivery, this review underscores the unique advantages of plant-derived materials, such as lower risk of endotoxin and virus contamination, reduced ethical concerns, scalability, and eco-friendly attributes. However, challenges such as the need for the development of standardized isolation methods of these materials, and further transition from preclinical to clinical applications still remain to be solved.

Innovative cellulose-lactone hybrid material for efficient rhodamine 6G dye adsorption: Synthesis and characterization

This study uses a simple solvent casting technique to offer an innovative, cost-effective synthesis of a cellulose-lactone hybrid material for Rhodamine 6G dye adsorption. The modified cellulose revealed superior adsorption competencies, triumphing a maximum dye removal efficiency of 97.8 % under neutral pH. Adsorption isotherms were best defined by the Langmuir model (R2 = 0.999), signifying monolayer adsorption, while the Freundlich model (R2 = 0.9714) suggested the existence of heterogeneous adsorption sites. Characterization methods, including FTIR, TGA, DSC, and SEM, confirmed the structural, thermal, and morphological changes induced by lactone modification, which enhanced the material's mechanical properties and adsorption efficiency. The hybrid material demonstrated excellent long-term stability, recyclability, and potential for large-scale water treatment applications. These findings emphasize the material's potential as a sustainable solution for removing organic pollutants from wastewater.

Enhancing the quantum yield and electrochemical properties of carbon quantum dots via optimized hydrothermal treatment using cellulose nanocrystals as precursors

Carbon quantum dots (CQDs) are receiving increasing attention due to their tunable redox activity, abundant surface functional groups, and excellent aqueous dispersion. However, their low quantum yield remains a significant impediment to their synthesis and practical application. In the present work, cellulose nanocrystals (CNCs) were utilized as precursors for the optimized hydrothermal synthesis of CQDs. Subsequently, the synthesized CQDs were electrodeposited onto a carbon-coated surface. The influence of hydrothermal temperature and time on the quantum yield and electrochemical properties of CQDs was systematically explored. The successfully synthesized CQDs exhibited an average particle size of approximately 5 nm. The quantum yield was enhanced from 14.35 % to 23.7 % as the hydrothermal temperature increased from 180 °C to 230 °C. Additionally, the electrochemical properties of the composite films were investigated. Electrochemical assessments demonstrated an increase in specific capacitance from 60.4 mF·cm-2 to 65.2 mF·cm-2 with an elevation in temperature from 180 °C to 210 °C. Remarkably, the CQDs displayed higher energy density (8.819 mWh·cm-2) and power density (1800 mW·cm-2) at 210 °C for 8 h. This work offers a scalable approach for the efficient production of high-performance CQDs, showcasing their substantial potential for supercapacitor applications.

Bacterial Cellulose In Vitro Uptake by Macrophages, Epithelial Cells, and a Triculture Model of the Gastrointestinal Tract

Bacterial cellulose (BC) has a long-standing human consumption history in different geographies without any report of adverse effects. Despite its unique textural and functional properties, the use of BC in food products in Europe is still restricted due to concerns over its nanosize. Here, we evaluated the potential uptake of celluloses (from plant and microbial sources, processed using different blenders) by macrophages (differentiated THP-1 cells) and human intestinal epithelial cells (Caco-2 and HT29-MTX cells) without (coculture) or with (triculture) Raji-B cells. A carbohydrate-binding module coupled to a green fluorescent protein was employed to observe cellulose in the cell cultures by confocal laser scanning microscopy and stimulated emission depletion microscopy. The methodology demonstrated excellent sensitivity, allowing detection of single nanocrystals within cells. All celluloses were taken up by the macrophages, without significantly compromising the cell's metabolic viability. The viability of the cocultures was also not affected. Furthermore, no internalization was observed in the triculture cell model that was exposed 24 h to BC and Avicel LM310. When (rarely) detected, cellulose particles were found on the apical side of the membrane. Overall, the obtained results suggest that BC should not be absorbed into the human gut.

Nanocellulose-based conductive composites: A review of systems for electromagnetic interference shielding applications

Electronic systems and telecommunications have grown in popularity, leading to increasing electromagnetic (EM) radiation pollution. Environmental protection from EM radiation demands the use of environmentally friendly products. The design of EM interference (EMI) shielding materials using resources like nanocellulose (NC) is gaining traction. Cellulose, owing to its biocompatibility, biodegradability, and excellent mechanical and thermal properties, has attracted significant interest for developing EMI shielding materials. Recent advancements in cellulose-based EMI shielding materials, particularly modified cellulosic composites, are highlighted in this study. By incorporating metallic coatings compounded with conductive fillers and modified with inherently conductive elements, conductivity and effectiveness of EMI shielding can be significantly improved. This review discusses the introduction of EMI shields, cellulose, and NC, assessing environmentally friendly EMI shield options and diverse NC-based composite EMI shields considering their low reflectivity. The study offers new insights into designing advanced NC-based conductive composites for EMI shielding applications.

Emerging nanocellulose from agricultural waste: Recent advances in preparation and applications in biobased food packaging

With the increasing emphasis on sustainability and eco-friendliness, a novel biodegradable packaging materials has received unprecedented attention. Nanocellulose, owing to its high crystallinity, degradability, minimal toxicity, and outstanding biocompatibility, has gained considerable interest in the field of sustainable packaging. This review provided a comprehensive perspective about the recent advances and future development of cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs). We first introduced the utilization of agricultural waste for nanocellulose production, such as straw, bagasse, fruit byproducts, and shells. Next, we discussed the preparation process of nanocellulose from various agricultural wastes and expounded the advantages and shortcomings of different methods. Subsequently, this review offered an in-depth investigation on the application of nanocellulose in food packaging, especially the function and packaged form of nanocellulose on food preservation. Finally, the safety evaluation of nanocellulose in food packaging is conducted to enlighten and promote the perfection of relevant regulatory documents. In short, this review provided valuable insights for potential research on the biobased materials utilized in future food packaging.

Lignin-containing cellulose nanocrystals enhanced electrospun polylactic acid-based nanofibrous mats: Strengthen and toughen

Biodegradable polylactic acid (PLA) nanofibrous mats prepared by electrospinning serve as suitable packaging materials. However, their practical applications are limited by their weak mechanical properties, poor thermal stability, and high cost. In this study, green and low-cost lignin-containing cellulose nanocrystals (LCNCs) with different lignin contents were developed and employed as reinforced materials to synergistically enhance the thermal, mechanical, and hydrophobic properties of PLA electrospun nanofibrous mats. The presence of moderate lignin improved the interfacial compatibility between the LCNCs and PLA, resulting in excellent mechanical properties of the nanofibrous mats. Compared to pure PLA mats, the tensile strength of the composites reached up to 21.0 MPa, representing a 6.6-fold increase. Its toughness was synchronously enhanced by 16 times, reaching a maximum of 3.6 MJ/m3. The maximum decomposition temperature of PLA/LCNCs electrospun nanofibrous mats increased from 339 °C to 365 °C. Furthermore, the increase in lignin in the LCNCs positively contributed to improving the hydrophobicity of the PLA/LCNCs electrospun nanofibrous mats. This bio-based strategy of LCNCs employed in the enhancement of fully bio-based PLA nanofibrous mats offers a viable approach for the advancement of packaging films.

Antiscaling Pickering Emulsions Enabled by Amphiphilic Hairy Cellulose Nanocrystals

Nucleation and growth of sparingly soluble salts, referred to as scaling, has posed substantial challenges in industrial processes that deal with multiphase flows, including enhanced oil recovery (EOR). During crude oil extraction/recovery, seawater is injected into oil reservoirs and yields water-in-oil (W/O) emulsions that may undergo calcium carbonate (CaCO3) scaling. Common antiscaling macromolecules and nanoparticles have adverse environmental impacts and/or are limited to functioning only in single-phase aqueous media. Here, we develop a novel antiscaling cellulose-based nanoparticle that enables scale-resistant Pickering emulsions. Cellulose fibrils are rationally nanoengineered to yield amphiphilic hairy cellulose nanocrystals (AmHCNC), bearing hydrophilic dicarboxylate groups and hydrophobic alkyl chains on disordered cellulose chains (hairs) protruding from nanocrystal ends. The unique chemical and structural properties of AmHCNC render them the first dual functional antiscaling and emulsion stabilizing nanoparticle. AmHCNC stabilize W/O Pickering emulsions at a concentration of 1.00 wt % for 1 week while inhibiting CaCO3 scale formation up to 70% by mass at a supersaturation degree of ∼101 compared with the synthetic surfactant Span 80. To the best of our knowledge, this study presents the first biopolymer-based solution for the long-lasting scaling challenge in multiphase media, which may set the stage for developing sustainable scale-resistant multiphase flows in a broad spectrum of industrial sectors.

Green and efficient synthesis of cellulose nanocrystals from Hamelia patens leftover via hydrolysis of microwave assisted-ionic liquid (MWAIL) pretreated microcrystalline cellulose

The efficient bioconversion of the lignocellulosic agro-waste has immense importance in biorefinery processing in extracting the cellulose and saccharide fractions. To achieve this, a series of chemical pretreatments is employed, thus concerning environmental threats limit its use. Therefore, an ionic liquid is employed for pretreatment before sustainable extractions owing to its safe manipulation, recycling, and reusability. Specifically, microwave-assisted ionic liquid (MWAIL) pretreatment has significant importance in extracting high cellulose yield at less thermal power consumption. In this study, the leftover stalks of Hamelia patens were subjected to MWAIL pretreatment at 60, 70, 80, and 90 °C to extract microcrystalline cellulose (MCC). Subsequently, the MCC was fabricated into cellulose nanocrystals (CNC) through hydrolytic treatment using acidic and ionic liquids and denoted as CNC-AH and CNC-ILH. Thus obtained CNC was characterized by FTIR, FESEM, XRD, and TGA to investigate the influence of solvent on its morphology, crystallinity, and thermal stability of CNC. The results support that the CNC-ILH has comparatively more thermal and dispersal stability with a reduced crystallinity index than CNC-AH. The surprising results of CNC-ILH signify its utilization in diverse applications in the food and industrial sectors.

Extraction, characterization and properties evaluation of pineapple leaf fibers from Azores pineapple

Pineapple leaves can provide competitive and high-quality fibers for textile purposes. Despite pineapple being cultivated in the Portugues islands there is still a technology gap for the extraction and treatment of Pineapple Leaf Fibers (PALF) in Europe. Since Azorean Pineapple differs significantly from other plants in the bromeliad family, the properties and characterization of its leaf fibers were explored for the first time. Long fibers have been extracted by hand scraping and compared to biological retting at 25 °C for different time periods. It was explored the properties of PALF from plants of different ages (11- and 18-months) and from different zones of the leaves (beginning, middle, and tip). Physical-mechanical properties of Azores PALF were determined, including diameter, linear density, strength, Young's modulus, and elongation at break and characterized by ATR-FTIR, XRD, TGA/DTG, and FESEM to understand their chemical and morphological characteristics. While slight differences were observed between different ages, variations in physical-mechanical properties were notable among fibers extracted from different leaf positions. Extraction of Azores PALF through 25 °C biological retting for 14 days effectively eliminated non-fibrous matter and produced the thinnest and strongest fibers. These fibers ranged between 34.9 and 168.3 μm in diameter, 1.39 and 7.07 tex in linear mass density, 37-993 MPa in tensile strength, 1.0-3.9 % in elongation at break, and 2.4-21.8 GPa in Young's modulus.

Synthesis, characterization, and cytotoxicity studies of nanocellulose extracted from okra (Abelmoschus Esculentus) fiber

Nanocellulose, especially originating from a natural source, has already shown immense potential to be considered in various fields, namely packaging, papermaking, composites, biomedical engineering, flame retardant, and thermal insulating materials, etc. due to its environmental friendliness and novel functionalities. Thus, a thorough characterization of nanocellulose is a hot research topic of research communities in a view to judge its suitability to be used in a specific area. In this work, a kind of green and environment-friendly nanocellulose was successfully prepared from okra fiber through a series of multi-step chemical treatments, specifically, scouring, alkali treatment, sodium chlorite bleaching, and sulfuric acid hydrolysis. Several characterization techniques were adopted to understand the morphology, structure, thermal behavior, crystallinity, and toxicological effects of prepared nanocellulose. Obtained data revealed the formation of rod-shaped nanocellulose and compared to raw okra fiber, their size distributions were significantly smaller. X-ray diffraction (XRD) patterns displayed that compared to the crystalline region, the amorphous region in raw fiber is notably larger, and in obtained nanocellulose, the crystallinity index increased significantly. Moreover, variations in the Fourier transform infrared spectroscopy (FTIR) peaks depicted the successful removal of amorphous regions, namely, lignin and hemicelluloses from the surface of fiber. Thermostability of synthesized nanocellulose was confirmed by both Differential Scanning Calorimetry (DSC) analysis, and thermogravimetric analysis (TGA). Cytotoxicity assessment showed that the okra fiber-derived nanocellulose exhibited lower to moderate cellular toxicity in a dose-dependent manner where the LD50 value was 60.60 μg/ml.

Evaluation of steam explosion pretreatment on the cellulose nanocrystals (CNCs) yield from poplar wood

The high sulfuric acid concentration used in the hydrolysis of cellulose to isolate cellulose nanocrystals (CNCs) leads to low yields due to the dissolution of both amorphous and semi-crystalline cellulose. The present study explored the use of steam explosion pretreatment before acid hydrolysis to enhance the crystallization of semi-crystalline/ non-crystalline cellulose and generating new CNC precursors with poplar wood as feedstock. The crystallinity of steam exploded poplar wood increased 1.3-fold compared to untreated poplar wood. Consequently, the overall yield of CNCs of steam exploded poplar wood increased 2.5-fold compared to untreated poplar wood. Moreover, the steam explosion pretreatment did not affect the quality of the CNCs with regard to the crystal size, crystallinity, and colloidal stability. Whereas the thermal stability of the CNCs increased due to the steam explosion pretreatment. This study demonstrates a simple and scalable pretreatment step that can significantly improve the CNCs yield from the acid hydrolysis step thereby improving the overall economics and commercial viability.

Obtaining of a rich-cellulose material from black wattle (Acacia mearnsii De Wild.) bark residues

Black wattle (Acacia mearnsii De Wild.) barks are residues produced by tannin industries in huge quantities, which are normally discharged on environmental or used for energy production. Therefore, this study aimed to evaluate the use of black wattle bark residues as a raw material on obtaining of a rich-cellulose material by alkaline (MET1), acetosolv (MET2), and organosolv (MET3) procedures. The results obtained indicated that the alkaline methodology, followed by a bleaching step (MET1), promoted klason lignin and hemicellulose removals more efficiently. It was possible to observe that better results were achieved using NaOH concentration of 6% (wt%), at 65 °C for 2.5 h, presenting a yield of 63.24 ± 1.25%, and a reduction on klason lignin content of almost 90.45%. Regarding the bleaching step, it was possible to obtain a material free of non-cellulosic compounds with a yield of 78.28 ± 1.48%. Thermogravimetric analysis indicated the removal of lignin and hemicellulose as well as an increase in cellulose degradation temperature, due to changes in crystalline phases. According to X-ray diffraction (XRD), the procedures employed have led to an increase in crystallinity from 66.27 to 91.78% due to the removal of non-cellulosic compounds. Scanning electron microscopy (SEM) showed morphological alterations in accordance with the removal of non-cellulosic compounds.

Synthesis, Properties, Applications, and Future Prospective of Cellulose Nanocrystals

The exploration of nanocellulose has been aided by rapid nanotechnology and material science breakthroughs, resulting in their emergence as desired biomaterials. Nanocellulose has been thoroughly studied in various disciplines, including renewable energy, electronics, environment, food production, biomedicine, healthcare, and so on. Cellulose nanocrystal (CNC) is a part of the organic crystallization of macromolecular compounds found in bacteria's capsular polysaccharides and plant fibers. Owing to numerous reactive chemical groups on its surface, physical adsorption, surface grating, and chemical vapor deposition can all be used to increase its performance, which is the key reason for its wide range of applications. Cellulose nanocrystals (CNCs) have much potential as suitable matrices and advanced materials, and they have been utilized so far, both in terms of modifying and inventing uses for them. This work reviews CNC's synthesis, properties and various industrial applications. This review has also discussed the widespread applications of CNC as sensor, acoustic insulator, and fire retardant material.

Emerging trends in the appliance of ultrasonic technology for valorization of agricultural residue into versatile products

The utilization of agricultural residues to obtain biocompounds of high-added value has significantly increased in the past decades. The conversion of agro-based residues into valuable products appears to be an economically efficient, environment-friendly, and protracted waste management practice. The implementation of ultrasonic technologies in the conversion of value-added goods from agricultural waste materials through pre-treatment and valorization processes has imparted many advantageous effects including rapid processing, effective process performance, minimization of processing steps, minimal dependency on harmful chemicals, and an increased yield and properties of bio-products. To further enliven the literature and inspire new research investigations, this review covers the comprehensive work including theoretical principles, processes, and potential benefits of ultrasonic treatment technologies to assist the production of bio-products which emphasize the extraction yield and the characteristic of the end-product extracted from agriculture residues. A detailed evaluation of these methods and key aspects impacting their performance as well as the features and shortcomings of each ultrasound-assisted approach is also discussed. This review also addressed some of the challenges associated with using ultrasonic irradiation and proposed several potential techniques to maximize productivity. Understanding the concept of ultrasonication technique allow the academician and industrial practitioners to explore the possibility of applying a greener and sustainable approach of biomass extraction to be translated into higher scale production of commercial products.

Oxidized Cellulose Nanocrystals from Durian Peel Waste by Ammonium Persulfate Oxidation

Cellulose nanocrystals (CNCs) have gained much attention due to their biodegradable, renewable, nontoxic, and inexpensive nanomaterials with some remarkable properties. In this study, cellulose nanocrystals from durian peel waste were isolated by chemical oxidation. This process involved two stages of a chemical process, namely, bleaching followed by oxidation of ammonium persulfate (APS). The impact of process parameters (APS concentrations and oxidation temperatures) on the oxidized CNC was assessed. The properties of CNC were investigated by attenuated total reflection-infrared (ATR-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). ATR-IR results showed that the structure of cellulose did not change during APS oxidation. XRD results indicated that APS oxidation improved the crystallinity index by 103% due to the removal of the amorphous components. The resulting CNC was needlelike in shape and had an average width range of 5.00-7.81 nm, a length range of 114.52-126.83 nm, and an aspect ratio range of 16.76-24.20. From the TGA analysis, the thermal stability was found to increase with increasing oxidation temperature. The optimum conditions for a maximum crystallinity index and the highest thermal stability were obtained at 80°C oxidation with 1 M APS. Therefore, APS oxidation was a remarkable method for increasing the value of durian peel waste into high-value nanocellulose.

Recent advances in qualitative and quantitative characterization of nanocellulose-reinforced nanocomposites: A review

Nanocellulose has received immense consideration owing to its valuable inherent traits and impressive physicochemical properties such as biocompatibility, thermal stability, non-toxicity, and tunable surface chemistry. These features have inspired researchers to deploy nanocellulose as nanoscale reinforcement materials for bio-based polymers. A simple yet efficient characterization method is often required to gain insights into the effectiveness of various types of nanocellulose. Despite a decade of continuous research and booming growth in scientific publications, nanocellulose research lacks a measuring tool that can characterize its features with acceptable speed and reliability. Implementing reliable characterization techniques is critical to monitor the specifications of nanocellulose alone or in the final product. Many techniques have been developed aiming to measure the nano-reinforcement mechanisms of nanocellulose in polymer composites. This review gives a full account of the scientific underpinnings of techniques that can characterize the shape and arrangement of nanocellulose. This review aims to deliver consolidated details on the properties and characteristics of nanocellulose in biopolymer composite materials to improve various structural, mechanical, barrier and thermal properties. We also present a comprehensive description of the safety features of nanocellulose before and after being loaded within biopolymeric matrices.

Biodegradable Polylactic Acid and Its Composites: Characteristics, Processing, and Sustainable Applications in Sports

Polylactic acid (PLA) is a biodegradable polyester polymer that is produced from renewable resources, such as corn or other carbohydrate sources. However, its poor toughness limits its commercialization. PLA composites can meet the growing performance needs of various fields, but limited research has focused on their sustainable applications in sports. This paper reviews the latest research on PLA and its composites by describing the characteristics, production, degradation process, and the latest modification methods of PLA. Then, it discusses the inherent advantages of PLA composites and expounds on different biodegradable materials and their relationship with the properties of PLA composites. Finally, the importance and application prospects of PLA composites in the field of sports are emphasized. Although PLA composites mixed with natural biomass materials have not been mass produced, they are expected to be sustainable materials used in various industries because of their simple process, nontoxicity, biodegradability, and low cost.

Plant Fibers as Composite Reinforcements for Biomedical Applications

Plant fibers possess high strength, high fracture toughness and elasticity, and have proven useful because of their diversity, versatility, renewability, and sustainability. For biomedical applications, these natural fibers have been used as reinforcement for biocomposites to infer these hybrid biomaterials mechanical characteristics, such as stiffness, strength, and durability. The reinforced hybrid composites have been tested in structural and semi-structural biodevices for potential applications in orthopedics, prosthesis, tissue engineering, and wound dressings. This review introduces plant fibers, their properties and factors impacting them, in addition to their applications. Then, it discusses different methodologies used to prepare hybrid composites based on these widespread, renewable fibers and the unique properties that the obtained biomaterials possess. It also examines several examples of hybrid composites and their biomedical applications. Finally, the findings are summed up and some thoughts for future developments are provided. Overall, the focus of the present review lies in analyzing the design, requirements, and performance, and future developments of hybrid composites based on plant fibers.

Cellulose nanocrystals from agricultural residues (Eichhornia crassipes): Extraction and characterization

Extraction of cellulose nanocrystals (CNCs) from agro-residues has received much attention, not only for their unique properties supporting a wide range of potential applications, but also their limited risk to global climate change. This research was conducted to assess Nile roses (Eichhornia crassipes) fibers as a natural biomass to extract CNCs through an acid hydrolysis approach. Nile roses fibers (NRFs) were initially subjected to alkaline (pulping) and bleaching pretreatments. Microcrystalline cellulose (MCC) was used as control in comparison to Nile rose based samples. All samples underwent acid hydrolysis process at a mild temperature (45 °C). The impact of extraction durations ranging from 5 to 30 min on the morphology structure and crystallinity index of the prepared CNCs was investigated. The prepared CNCs were subjected to various characterization techniques, namely: X-ray diffraction (XRD), FT-IR analysis, Transmission electron microscopy (TEM), and X-ray Photoelectron spectroscopy (XPS). The outcomes obtained by XRD showed that the crystallinity index increased as the duration of acid hydrolysis was prolonged up to 10 min, and then decreased, indicating optimal conditions for the dissolution of amorphous zones of cellulose before eroding the crystallized domains. These data were confirmed by FT-IR spectroscopy. However, a minor effect of hydrolysis duration on the degree of crystallinity was noticed for MCC based samples. TEM images illustrated that a spherical morphology of CNCs was formed as a result of 30 min acid hydrolysis, highlighting the optimal 20 min acid hydrolysis to obtain a fibrillar structure. The XPS study demonstrated that the main constituents of extracted CNCs were carbon and oxygen.

Preparation and characterization of starch-based composite films reinforced by quinoa (Chenopodium quinoa Willd.) straw cellulose nanocrystals

The development of green and biodegradable nanomaterials is significant for the sustainable utilization of renewable lignocellulosic biomass. This work aimed to obtain the cellulose nanocrystals from quinoa straws (QCNCs) by acid hydrolysis. The optimal extraction conditions were investigated by response surface methodology, and the physicochemical properties of QCNCs were evaluated. The maximum yield of QCNCs (36.58 ± 1.42 %) was obtained under the optimal extraction conditions of 60 % (w/w) sulfuric acid concentration, 50 °C reaction temperature, and 130 min reaction time. The characterization results of QCNCs showed that it is a rod-like material with an average length of 190.29 ± 125.25 nm, an average width of 20.34 ± 4.69 nm, excellent crystallinity (83.47 %), good water dispersibility (Zeta potential = -31.34 mV) and thermal stability (over 200 °C). The addition of 4-6 wt% QCNCs could significantly improve the elongation at break and water resistance of high-amylose corn starch films. This study will pave the route for improving the economic value of quinoa straw, and provide relevant proof of QCNCs for the preliminary application in starch-based composite films with the best performance.

Nanotechnology Applied to Cellulosic Materials

In recent years, nanocellulosic materials have attracted special attention because of their performance in different advanced applications, biodegradability, availability, and biocompatibility. Nanocellulosic materials can assume three distinct morphologies, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial cellulose (BC). This review consists of two main parts related to obtaining and applying nanocelluloses in advanced materials. In the first part, the mechanical, chemical, and enzymatic treatments necessary for the production of nanocelluloses are discussed. Among chemical pretreatments, the most common approaches are described, such as acid- and alkali-catalyzed organosolvation, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, ammonium persulfate (APS) and sodium persulfate (SPS) oxidative treatments, ozone, extraction with ionic liquids, and acid hydrolysis. As for mechanical/physical treatments, methods reviewed include refining, high-pressure homogenization, microfluidization, grinding, cryogenic crushing, steam blasting, ultrasound, extrusion, aqueous counter collision, and electrospinning. The application of nanocellulose focused, in particular, on triboelectric nanogenerators (TENGs) with CNC, CNF, and BC. With the development of TENGs, an unparalleled revolution is expected; there will be self-powered sensors, wearable and implantable electronic components, and a series of other innovative applications. In the future new era of TENGs, nanocellulose will certainly be a promising material in their constitution.

Synthesis, characterization and adsorption behavior of modified cellulose nanocrystals towards different cationic dyes

Green and efficient removal of polluted materials are essential for the sustainability of a clean and green environment. Nanomaterials, particularly cellulose nanocrystals (CNCs), are abundant in nature and can be extracted from various sources, including cotton, rice, wheat, and plants. CNCs are renewable biomass materials with a high concentration of polar functional groups. This study used succinic anhydride to modify the surface of native cellulose nanocrystals (NCNCs). Succinic anhydride has been frequently used in adhesives and sealant chemicals for a long time, and here, it is evaluated for dye removal performance. The morphology and modification of CNCs studied using FTIR, TGA & DTG, XRD, SEM, AFM, and TEM. The ability of modified cellulose nanocrystals (MCNCs) to adsorb cationic golden yellow dye and methylene blue dye was investigated. The MCNCs exhibited high adsorption affinity for the two different cationic dyes. The maximum adsorption efficiency of NCNCs and MCNCs towards the cationic dye was 0.009 and 0.156 wt%. The investigation for adhesive properties is based on the strength and toughness of MCNCs. MCNCs demonstrated improved tensile strength (2350 MPa) and modulus (13.9 MPa) using E-51 epoxy system and a curing agent compared to 3 wt% composites. This research lays the groundwork for environmentally friendly fabrication and consumption in the industrial sector.

Morphological, Spectroscopic and Thermal Analysis of Cellulose Nanocrystals Extracted from Waste Jute Fiber by Acid Hydrolysis

Natural cellulose, a sustainable bioresource, is highly abundant in nature. Cellulosic materials, particularly those that explore and employ such materials for industrial use, have recently attracted significant global attention in the field of material science because of the unique properties of cellulose. The hydroxyl groups enable the formation of intra- and inter-molecular hydrogen bonding and the arrangement of cellulose chains in a highly ordered crystalline zone, with the remaining disordered structure referred to as an amorphous region. The crystalline areas of cellulose are well-known as cellulose nanocrystals (CNCs). In the present study, we extracted CNCs from pure cellulose isolated from waste jute fibers by sulfuric acid hydrolysis, followed by characterization. Pure cellulose was isolated from jute fibers by treating with sodium hydroxide (20% w/w) and anthraquinone (0.5%) solution at 170 °C for 2 h, followed by bleaching with chlorine dioxide and hydrogen peroxide solution. CNCs were isolated from pure cellulose by treating with different concentrations (58% to 62%) of sulfuric acid at different time intervals (20 min to 45 min). The FTIR study of the CNCs reveals no peak at 1738 cm^-1, which confirms the absence of hemicellulose in the samples. The CNCs obtained after 45 min of acid hydrolysis are rod-shaped, having an average length of 800 ± 100 nm and width of 55 ± 10 nm, with a high crystallinity index (90%). Zeta potential significantly increased due to the attachment of SO₄^2- ions on the surface of CNC from -1.0 mV to about -30 mV, with the increment of the reaction time from 20 min to 45 min, which proved the higher stability of CNC suspension. Crystallinity increased from 80% to 90% when the reaction time was increased from 20 to 45 min, respectively, while a crystallite size from 2.705 to 4.56 nm was obtained with an increment of the acid concentration. Acid hydrolysis enhanced crystallinity but attenuated the temperature corresponding to major decomposition (Tmax) at 260 °C and the beginning of degradation (Ti) at 200 °C due to the attachment of SO₄^2- ions on the surface, which decreased the thermal stability of CNC. The second degradation at 360 °C indicated the stable crystal structure of CNC. The endothermic peak at 255 °C in the DTA study provided evidence of sulfated nanocrystal decomposition and the recrystallization of cellulose I to cellulose II, the most stable structure among the other four celluloses. The proposed easy-to-reproduce method can successfully and efficiently produce CNCs from waste jute fibers in a straightforward way.

Preparation of microcrystalline cellulose from agricultural residues and their application as polylactic acid/microcrystalline cellulose composite films for the preservation of Lanzhou lily

Microcrystalline celluloses were isolated from four agricultural residues, including sweet sorghum stalk, Jerusalem artichoke stalk, grains stillage, and Chinese herb residue, and characterized in terms of physicochemical and structural properties. The obtained microcrystalline celluloses were composited with polylactic acid as a packing film for the preservation of Lanzhou lily. All the agricultural residues-derived microcrystalline celluloses were in cellulose I_β structure with high purity and good thermal stability. Microcrystalline celluloses from sweet sorghum stalk had a higher degree of polymerization (327) and crystallinity (70.52 %) than others. The preservation effect of lily bulbs packaged by films were significantly improved indicated by the lessened weight loss rate and the meliorative hardness and whiteness, which ascribe to the repressed oxidation reactions. Polylactic acid/microcrystalline cellulose composite films prepared from sweet sorghum straw have been proved the most effective. This work could offer a value-added outlet for agricultural residues to produce microcrystalline celluloses-based biocompatible films for preservation of Lanzhou lily.

Banana Peel Waste: An Emerging Cellulosic Material to Extract Nanocrystalline Cellulose

Nanocrystalline cellulose (NCC) has gained attention due to its versatile properties such as biocompatibility, sustainability, high aspect ratio, and abundance of -OH groups that favor modifications of NCC. The objective of this paper is to develop NCC by extracting and characterizing NCC prepared from banana peel powder (BPP). BPP was subjected to alkali and bleaching treatment to remove lignin and hemicellulose and then subjected to acid hydrolysis to prepare NCC. Under optimal conditions (200 mL of sulfuric acid 55% v/v at 50 °C for 60 min), the NCC yield was found to be 29.9%. The particle size and zeta potential of the NCC were found to be 209 nm and -43 mV, respectively. Attenuated total reflectance Fourier transform infrared spectroscopy showed successful removal of lignin and hemicellulose from BPP after the alkali treatment, bleaching, and acid hydrolysis. Field emission scanning electron microscopy showed needle-shaped crystals and transmission electron microscopy showed particles in the nano range. X-ray diffraction analysis showed that the crystallinity index of NCC was 64.12% while keeping the cellulose I crystal structure intact. Thermogravimetric analysis showed good stability which paves way for NCC to be explored for various applications. All the parameters evaluated indicated that NCC was successfully prepared from BPP using alkali treatment, bleaching, and acid hydrolysis.

Parametric optimization of the production of cellulose nanocrystals (CNCs) from South African corncobs via an empirical modelling approach

In this study, cellulose nanocrystals (CNCs) were obtained from South African corncobs using an acid hydrolysis process. The delignification of corncobs was carried out by using alkali and bleaching pretreatment. Furthermore, the Box-Behnken Design (BBD) was used as a design of experiment (DOE) for statistical experimentations that will result in logical data to develop a model that explains the effect of variables on the response (CNCs yield). The effects (main and interactive) of the treatment variables (time, temperature, and acid concentration) were investigated via the response methodology approach and the obtained model was used in optimizing the CNCs yield. Surface morphology, surface chemistry, and the crystallinity of the synthesized CNC were checked using scanning electron microscopy (SEM), a Fourier Transform Infra-red spectroscopy (FTIR), and an X-ray diffraction (XRD) analysis, respectively. The SEM image of the raw corncobs revealed a smooth and compact surface morphology. Results also revealed that CNCs have higher crystallinity (79.11%) than South African waste corncobs (57.67%). An optimum yield of 80.53% CNCs was obtained at a temperature of 30.18 °C, 30.13 min reaction time, and 46 wt% sulfuric acid concentration. These optimized conditions have been validated to confirm the precision. Hence, the synthesized CNCs may be suitable as filler in membranes for different applications.

The Encapsulation of Bioactive Plant Extracts into the Cellulose Microfiber Isolated from G. optiva Species for Biomedical Applications

Agricultural waste-based cellulose fibers have gained significant interest for a myriad of applications. Grewia optiva (G. optiva), a plant species, has been widely used for feeding animals, and the small branches' bark is used for making rope. Herein, we have extracted cellulose fibers from the bark of G. optiva species via chemical treatments (including an alkaline treatment and bleaching). The gravimetric analysis revealed that the bark of G. Optiva contains cellulose (63.13%), hemicellulose (13.52%), lignin (15.13%), and wax (2.8%). Cellulose microfibre (CMF) has been synthesized from raw fibre via chemical treatment methods. The obtained cellulose fibers were crosslinked and employed as the matrix to encapsulate the bioactive plant extracts derived from the root of Catharanthus roseus (C. roseus). The microscopic images, XRD, FTIR, and antibacterial/antioxidant activity confirmed the encapsulation of natural extracts in the cellulose microfiber. The microscopic images revealed that the encapsulation of the natural extracts slightly increased the fiber's diameter. The XRD pattern showed that the extracted cellulose microfiber had an average crystalline size of 2.53 nm with a crystalline index of 30.4% compared to the crystalline size of 2.49 nm with a crystalline index of 27.99% for the plant extract incorporated membrane. The water uptake efficiency of the synthesized membrane increased up to 250%. The antimicrobial activity of the composite (the CMF-E membrane) was studied via the zone inhibition against gram-positive and gram-negative bacteria, and the result indicated high antibacterial activity. This work highlighted G. optiva-derived cellulose microfiber as an optimum substrate for antimicrobial scaffolds. In addition, this paper first reports the antimicrobial/antioxidant behavior of the composite membrane of the C. roseus extract blended in the G. optiva microfiber. This work revealed the potential applications of CMF-E membranes for wound healing scaffolds.

Review on biopolymers and composites - Evolving material as adsorbents in removal of environmental pollutants

The presence of pollutants and toxic contaminants in water sources makes it unfit to run through. Though various conventional techniques are on deck, development of new technologies are vital for wastewater treatment and recycling. Polymers have been intensively utilized recently in many industries owing to their unique characteristics. Biopolymers resembles natural alternative to synthetic polymers that can be prepared by linking the monomeric units covalently. Despite the obvious advantages of biopolymers, few reviews have been conducted. This review focuses on biopolymers and composites as suitable adsorbent material for removing pollutants present in environment. The classification of biopolymers and their composites based on the sources, methods of preparation and their potential applications are discussed in detail. Biopolymers have the potentiality of substituting conventional adsorbents due to its unique characteristics. Biopolymer based membranes and effective methods of utilization of biopolymers as suitable adsorbent materials are also briefly elaborated. The mechanism of biopolymers and their membrane-based adsorption has been briefly reviewed. In addition, the methods of regeneration and reuse of used biopolymer based adsorbents are highlighted. The comprehensive content on fate of biopolymer after adsorption is given in brief. Finally, this review concludes the future investigations in recent trends in application of biopolymer in various fields in view of eco-friendly and economic perspectives.

Nanocellulose-based membrane as a potential material for high performance biodegradable aerosol respirators for SARS-CoV-2 prevention: a review

The controversy surrounding the transmission of COVID-19 in 2020 has revealed the need to better understand the airborne transmission route of respiratory viruses to establish appropriate strategies to limit their transmission. The effectiveness in protecting against COVID-19 has led to a high demand for face masks. This includes the single-use of non-degradable masks and Filtering Facepiece Respirators by a large proportion of the public, leading to environmental concerns related to waste management. Thus, nanocellulose-based membranes are a promising environmental solution for aerosol filtration due to their biodegradability, renewability, biocompatibility, high specific surface area, non-toxicity, ease of functionalization and worldwide availability. Although the technology for producing high-performance aerosol filter membranes from cellulose-based materials is still in its initial stage, several promising results show the prospects of the use of this kind of materials. This review focuses on the overview of nanocellulose-based filter media, including its processing, desirable characteristics and recent developments regarding filtration, functionalization, biodegradability, and mechanical behavior. The porosity control, surface wettability and surface functional groups resulting from the silylation treatment to improve the filtration capacity of the nanocellulose-based membrane is discussed. Future research trends in this area are planned to develop the air filter media by reinforcing the filter membrane structure of CNF with CNCs. In addition, the integration of sol-gel technology into the production of an air filter can tailor the pore size of the membrane for a viable physical screening solution in future studies.

Graphical abstract

Tracking Bacterial Nanocellulose in Animal Tissues by Fluorescence Microscopy

The potential of nanomaterials in food technology is nowadays well-established. However, their commercial use requires a careful risk assessment, in particular concerning the fate of nanomaterials in the human body. Bacterial nanocellulose (BNC), a nanofibrillar polysaccharide, has been used as a food product for many years in Asia. However, given its nano-character, several toxicological studies must be performed, according to the European Food Safety Agency’s guidance. Those should especially answer the question of whether nanoparticulate cellulose is absorbed in the gastrointestinal tract. This raises the need to develop a screening technique capable of detecting isolated nanosized particles in biological tissues. Herein, the potential of a cellulose-binding module fused to a green fluorescent protein (GFP–CBM) to detect single bacterial cellulose nanocrystals (BCNC) obtained by acid hydrolysis was assessed. Adsorption studies were performed to characterize the interaction of GFP–CBM with BNC and BCNC. Correlative electron light microscopy was used to demonstrate that isolated BCNC may be detected by fluorescence microscopy. The uptake of BCNC by macrophages was also assessed. Finally, an exploratory 21-day repeated-dose study was performed, wherein Wistar rats were fed daily with BNC. The presence of BNC or BCNC throughout the GIT was observed only in the intestinal lumen, suggesting that cellulose particles were not absorbed. While a more comprehensive toxicological study is necessary, these results strengthen the idea that BNC can be considered a safe food additive.

Flame Retardant Coatings: Additives, Binders, and Fillers

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.

Isolation and Properties of Cellulose Nanocrystals Fabricated by Ammonium Persulfate Oxidation from Sansevieria trifasciata Fibers

Cellulose nanocrystals (CNCs) were successfully prepared from Sansevieria trifasciata fibers (STFs) via ammonium persulfate (APS) oxidation in this study. The influences of the APS concentration (1.1, 1.5, and 1.9 M) and oxidation temperature (60, 70, and 80 °C) on the characteristics of CNCs were studied. The resulting CNCs were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The TEM observations revealed that the rod-like CNCs possessed average length and diameter ranges of 96 to 211 nm and 5 to 13 nm, respectively, which led to an aspect ratio range of 16–19. The optimum conditions for maximum crystallinity were achieved at an oxidation temperature of 70 °C, a reaction time of 16 h, and an APS concentration of 1.5 M. All CNCs exhibited lower thermal stability compared to the STFs. The CNCs could be produced from the STFs through the APS oxidation process and showed potential as nanocomposite reinforcement materials.

Hemp Stem Epidermis and Cuticle: From Waste to Starter in Bio-Based Material Development

Nowadays, hemp farmers are facing an urgent problem related to plant stem disposal after seed harvesting. In this work, the commonly discarded epidermis and cuticle of hemp stems were valorized, turning them towards a sustainable recycling and reuse, contributing to the circular economy concept. Cellulose deprived of amorphous regions was obtained by a green process consisting of an ethanolic ultrasound-assisted maceration followed by mild bleaching/hydrolysis. The obtained hemp cellulose was esterified with citric acid resulting in a 1.2-fold higher crystallinity index and 34 °C lower T_g value compared to the non-functionalized hemp cellulose. Green innovative biocomposite films were developed by embedding the modified cellulose into PLA by means of an extrusion process. The structural and morphological characterization of the obtained biocomposites highlighted the functionalization and further embedment of cellulose into the PLA matrix. Attenuated Total Reflectance–Fourier Transform Infrared spectroscopy (ATR-FTIR) results suggested physical and chemical interactions between PLA and the organic filler in the biofilms, observing a homogeneous composition by Field Emission-Scanning Electron Microscopy (FESEM). Moreover, some increase in thermal stability was found for biocomposites added with 5%wt of the hemp cellulose filler. The obtained results highlighted the feasible recovery of cellulose from hemp stem parts of disposal concern, adding value to this agro-waste, and its potential application for the development of novel biocomposite films to be used in different applications.

Preparation of Cellulose Nanocrystals from Jujube Cores by Fractional Purification

Jujube cores are fiber-rich industrial waste. Dewaxing, alkali treatment, bleaching, and sulfuric acid hydrolysis were used to generate cellulose nanocrystals (CNCs) from the jujube cores in this study. The morphological, structural, crystallinity, and thermal properties of the fibers were investigated using FE-SEM, TEM, AFM, FT-IR, XRD, and TGA under various processes. CNCs’ zeta (ζ) potential and water contact angle (WAC) were also investigated. The findings demonstrate that non-fibrous components were effectively removed, and the fiber particles shrunk over time because of many activities. CNCs had a rod-like shape, with a length of 205.7 ± 52.4 nm and a 20.5 aspect ratio. The crystal structure of cellulose Iβ was preserved by the CNCs, and the crystallinity was 72.36%. The temperature of the fibers’ thermal degradation lowered during the operations, although CNCs still had outstanding thermal stability (>200 °C). Aside from the CNCs, the aqueous suspension of CNCs was slightly agglomerated; thus, the zeta (ζ) potential of the CNCs’ suspension was −23.72 ± 1.7 mV, and the powder had high hydrophilicity. This research will be valuable to individuals who want to explore the possibility for CNCs made of jujube cores.

An Innovative Preparation, Characterization, and Optimization of Nanocellulose Fibers (NCF) Using Ultrasonic Waves

Recently, environmental and ecological concerns have become a major issue owing to the shortage of resources, high cost, and so forth. In my research, I present an innovative, environmentally friendly, and economical way to prepare nanocellulose from grass wastes with a sodium hypochlorite (NaClO) solution of different concentrations (1−6% mol) at different times 10−80 min, washed with distilled water, and treated with ultrasonic waves. The optimum yield of the isolated cellulose was 95%, 90%, and 87% NaClO at 25 °C for 20 min and with NaOH and H2SO4 at 25 °C with 5% M, respectively. The obtained samples were characterized by dynamic light scattering (DLS), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). The effect of test temperature and reaction times on the crystallinity index (IC) of GNFC with different treated mediums was carried out and investigated. The IC was analyzed using the diffraction pattern and computed according to the Segal empirical method (method A), and the sum of the area under the crystalline adjusted peaks (method B) and their values proved that the effect of temperature is prominent. In both methods, GNFC/H2SO4 had the highest value followed by GNFC/NaOH, GNFC/NaClO and real sample nano fiber cellulose (RSNFC). The infrared spectral features showed no distinct changes of the four cellulose specimens at different conditions. The particle size distribution data proved that low acid concentration hydrolysis was not sufficient to obtain nano-sized cellulose particles. The Zeta potential was higher in accordance with (GNFC/H2SO4 > GNFC/NaOH > GNFC/NaClO), indicating the acid higher effect.

Recent advancement in isolation, processing, characterization and applications of emerging nanocellulose: A review

The emergence of nanocellulose from various natural resources as a promising nanomaterial has been gaining interest for a wide range application. Nanocellulose serves as an excellent candidate since it contributes numerous superior properties and functionalities. In this review, details of the three main nanocellulose categorised: cellulose nanocrystal (CNC), cellulose nanofibril (CNF), and bacterial nanocellulose (BNC) have been described. We focused on the preparation and isolation techniques to produce nanocellulose including alkaline pre-treatment, acid hydrolysis, TEMPO-mediated oxidation, and enzymatic hydrolysis. The surface modification of nanocellulose through esterification, silylation, amidation, phosphorylation, and carboxymethylation to improve the diverse applications has also been reviewed. Some invigorating perspectives on the applications, challenges, and future directions on the relevant issues regarding nanocellulose are also presented.

Emerging Developments on Nanocellulose as Liquid Crystals: A Biomimetic Approach

Biomimetics is the field of obtaining ideas from nature that can be applied in science, engineering, and medicine. The usefulness of cellulose nanocrystals (CNC) and their excellent characteristics in biomimetic applications are exciting and promising areas of present and future research. CNCs are bio-based nanostructured material that can be isolated from several natural biomasses. The CNCs are one-dimensional with a high aspect ratio. They possess high crystalline order and high chirality when they are allowed to assemble in concentrated dispersions. Recent studies have demonstrated that CNCs possess remarkable optical and chemical properties that can be used to fabricate liquid crystals. Research is present in the early stage to develop CNC-based solvent-free liquid crystals that behave like both crystalline solids and liquids and exhibit the phenomenon of birefringence in anisotropic media. All these characteristics are beneficial for several biomimetic applications. Moreover, the films of CNC show the property of iridescent colors, making it suitable for photonic applications in various devices, such as electro-optical devices and flat panel displays.

High-tensile regenerated cellulose films enabled by unexpected enhancement of cellulose dissolution in cryogenic aqueous phosphoric acid

We have demonstrated, for the first time, high-efficient non-destructive and non-derivative dissolution of cellulose could be achieved in cryogenic aqueous phosphoric acid. Cellulose from different sources and of varying degree of polymerization from 200 (MCC) to 2200 (cotton fabric) could be dissolved completely to afford solutions containing 5 wt%-18 wt% cellulose, from which ultra-strong and tough cellulose films of tensile strength as high as 707 MPa could be obtained using water as the coagulant. These solutions can be stored at -18 °C for extended time without noticeable degradation while desired degree of polymerization is also attainable by tuning the storage conditions. The findings of this work call for renewal attention on phosphoric acid as a promising cellulose solvent for being non-toxic, non-volatile, easy to handle, and cost-effective.

The Role of Eucalyptus Species on the Structural and Thermal Performance of Cellulose Nanocrystals (CNCs) Isolated by Acid Hydrolysis

Cellulose nanocrystals (CNCs) are attractive materials due to their renewable nature, high surface-to-volume ratio, crystallinity, biodegradability, anisotropic performance, or available hydroxyl groups. However, their source and obtaining pathway determine their subsequent performance. This work evaluates cellulose nanocrystals (CNCs) obtained from four different eucalyptus species by acid hydrolysis, i.e., E. benthamii, E. globulus, E. smithii, and the hybrid En × Eg. During preparation, CNCs incorporated sulphate groups to their structures, which highlighted dissimilar reactivities, as given by the calculated sulphate index (0.21, 0.97, 0.73 and 0.85, respectively). Although the impact of the incorporation of sulphate groups on the crystalline structure was committed, changes in the hydrophilicity and water retention ability or thermal stability were observed. These effects were also corroborated by the apparent activation energy during thermal decomposition obtained through kinetic analysis. Low-sulphated CNCs (E. benthamii) involved hints of a more crystalline structure along with less water retention ability, higher thermal stability, and greater average apparent activation energy (233 kJ·mol⁻¹) during decomposition. Conversely, the high-sulphated species (E. globulus) involved higher reactivity during preparation that endorsed a little greater water retention ability and lower thermal stability, with subsequently less average apparent activation energy (185 kJ·mol⁻¹). The E. smithii (212 kJ·mol⁻¹) and En × Eg (196 kJ·mol⁻¹) showed an intermediate behavior according to their sulphate index.