Micro- and nano-structures of cellulose from eggplant plant (Solanum melongena L) agricultural residue

Fabrication of cellulose nanofibers/epigallocatechin gallate complexes: Insights into structure, antioxidant properties and enhanced emulsion performance

In this work, cellulose nanofiber/epigallocatechin gallate (CNF/EGCG) complexes at different ratio were fabricated and the effects on characteristics and stability of emulsions under different oil phase fraction (φ) were investigated. The results of functional groups indicated the formation of CNF/EGCG complexes via hydrogen bond interaction, leading to enhanced antioxidant activity as the proportion of EGCG increased. The complexes exhibited more fragments but pure CNF were more homogenously dispersed in the aqueous phase. Enhancing the EGCG content reduced the droplet size of emulsions firstly before increased, while the apparent viscosity and viscoelastic properties displayed a contrary trend. Emulsion gels with smaller droplet size, higher apparent viscosity, excellent viscoelastic properties and physical stability could be formed at φ = 0.5 while emulsions at φ = 0.3 exhibited slight creaming. The emulsions at lower CNF/EGCG ratio presented better oxidative stability, which was ascribed to the higher antioxidant activity of the complexes and the thicker interfacial film. Results suggest that EGCG could be combined with CNF to improve the emulsion performance and be applied in extending the shelf-life of the emulsion-based products.

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.

Nanocellulose: A comprehensive review investigating its potential as an innovative material for water remediation

Rapid growth in industrialization sectors, the wastewater treatment plants become exhausted and potentially not able to give desirable discharge standards. Many industries discharge the untreated effluent into the water bodies which affects the aquatic diversity and human health. The effective disposal of industrial effluents thus has been an imperative requirement. For decades nanocellulose based materials gained immense attraction towards application in wastewater remediation and emerged out as a new biobased nanomaterial. It is light weighted, cost effective, mechanically strong and easily available. Large surface area, versatile surface functionality, biodegradability, high aspect ratio etc., make them suitable candidate in this field. Majorly cellulose based nanomaterials are used in the form of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), or bacterial nanocellulose (BNC). This review specifically describes about a variety of extraction methods to produced nanocellulose and also discusses the modification of nanocellulose by adding functionalities in its surface chemistry. We majorly focus on the utilization of nanocellulose based materials in water remediation for the removal of different contaminants such as dyes, heavy metals, oil, microbial colony etc. This review mainly emphasizes in ray of hope towards nanocellulose materials to achieve more advancement in the water remediation fields.

Structure and thermal properties of cellulose nanofibrils extracted from alkali-ultrasound treated windmill palm fibers

Windmill palm, a tree species that is native to China, has gained attention with regard to the production of substantial amounts of biomass fibers via yearly pruning. This study investigates the structure and thermal properties of cellulose nanofibrils (CNFs) obtained from windmill palm biomass, with the goal of promoting the usage of these CNFs. Alkali-ultrasound treatments are employed herein to prepare samples of the CNFs. The micromorphology of the prepared samples is observed using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. Furthermore, X-ray diffraction analysis is used to examine the aggregated structure of the samples, and thermogravimetric analysis is used to investigate their thermal properties. Results indicate that during alkali hydrolysis when obtaining CNFs, the fiber cell wall exhibits distinct spiral cracking. The diameter of the obtained nanocellulose is <90 nm. The removal of lignin and hemicellulose materials from the fiber cell enhances the crystallinity of CNFs to as high as 60 %, surpassing that of windmill palm single fibers. The thermal decomposition temperatures of the CNFs are found to be 469 °C and 246 °C for the crystalline and amorphous regions, respectively.

Cellulose microfiber extraction from leftover celery pulp: Chemomechanical treatments, structural, morphological, and thermal characterization

Based on the variety of attractive applicability and structural advantages, cellulose is suggested as a sustainable and environmentally-friendly replacement for petroleum-based materials. Therefore, the current study proposed two chemo-mechanical treatments including bleaching with sodium chlorite and sodium hypochlorite for pure cellulose extraction from leftover celery pulp (Apium graveolens var. dulce). The characterizations of the extracted cellulose fibers were measured and analyzed, by using FT-IR, XRD, optical microscopy, FE-SEM, and TGA analysis. FTIR analysis confirmed the successful removal of non-cellulosic and impurities materials by chemical treatments. Analyzing the X-ray diffraction showed that the proposed chemo-mechanical procedures did not have damaging impacts on the cellulose crystalline structure. Microscopies analysis within optical microscopy and FE-SEM indicated that the diameters of the untreated fibers generally ranged from 100 to 150 μm, while for the treated ones, they ranged from 10 to 15 μm. The TGA results illustrated the higher initial degradation temperatures for the treated samples which led to significant improvement in their thermal stabilities.

Hemp cellulose nanocrystals for functional chitosan/polyvinyl alcohol-based films for food packaging applications

Hemp is known for its swift growth and remarkable sustainability, requiring significantly less water, an adaptable cultivation to a wide range of climates when compared to other fibers sources, making it a practical and environmentally friendly choice for packaging materials. The current research seeks to extract cellulose nanocrystals (CNCs) from hemp fibers using alkali treatment followed by acid hydrolysis and assess their reinforcing capacity in polyvinyl alcohol (PVA) and chitosan (CS) films. AFM analysis confirmed the existence of elongated, uniquely nanosized CNC fibers. The length of the isolated CNCs was approximately 277.76 ± 61 nm, diameter was 6.38 ± 1.27 nm and its aspect ratio was 44.69 ± 11.08. The FTIR and SEM analysis indicated the successful removal of non-cellulosic compounds. Furthermore, the study explored the impact of adding CNCs at varying weight percentages (0, 0.5, 1, 2.5, and 5 wt%) as a strengthening agent on the chemical composition, structure, tensile characteristics, transparency, and water solubility of the bionanocomposite films. Adding CNCs to the CS/PVA film, up to 5 wt%, resulted in an improvement in both the Young's modulus and tensile strength of the bionanocomposite film, which are measured at (412.46 ± 10.49 MPa) and (18.60 ± 3.42 MPa), respectively, in contrast to the control films with values of (202.32 ± 22.50 MPa) and (13.72 ± 2.61 MPa), respectively. The scanning electron microscopy (SEM) images reveal the creation of a CS/PVA/CNC film that appears smooth, with no signs of clumping or clustering. The blending and introduction of CNCs have yielded transparent and biodegradable CS/PVA films. This incorporation has led to a reduction in the gas transmission rate (from 7.013 to 4.159 cm3 (m2 day·0.1 MPa))-1, a decrease in transparency (from 90.23% to 82.47%), and a lowered water solubility (from 48% to 33%). This study is the inaugural effort to propose the utilization of hemp-derived CNC as a strengthening component in the development of mechanically robust and transparent CS/PVA-CNC bio-nanocomposite films, holding substantial potential for application in the field of food packaging.

Pomelo peel derived nanocellulose as Pickering stabilizers: Fabrication of Pickering emulsions and their potential as sustained-release delivery systems for lycopene

Two kinds of nanocellulose (cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were synthesized from pomelo peels via a facile approach of TEMPO oxidation and sulfuric acid treatment respectively. The FTIR results illustrated that hemicelluloses and lignin were completely removed from the pomelo peel cellulose substrate. The obtained CNFs and CNCs possessed a uniform morphology and nanoscale particle size. The stability of CNF-based Pickering emulsions was higher than that of emulsions stabilized with CNCs, due to the formation of gel structure induced by the CNFs' longer fibrils. Increased oil fractions enhanced the viscoelasticity of CNF-based Pickering emulsions. The in vitro digestion results suggested that increased oil fractions decreased the lipolysis degree, as a result of the larger droplet size and higher viscoelasticity of emulsion. The release of lycopene showed a trend similar to that of FFA release, suggesting that higher oil fractions were beneficial for controlling lycopene release during gastrointestinal digestion.

Promising Energetic Polymers from Nanostructured Bacterial Cellulose

This study investigated the nitration of nanostructured bacterial cellulose (NBC). The NBC, obtained using symbiotic Medusomyces gisevii Sa-12 as the microbial producer and then freeze-dried, was nitrated herein by two methods, the first using mixed sulphuric-nitric acids (MA) and the second using concentrated nitric acid in the presence of methylene chloride (NA+MC). The synthesized samples of NBC nitrates (NBCNs) exhibited 11.77-12.27% nitrogen content, a viscosity of 1086 mPa·s or higher, 0.7-14.5% solubility in an alcohol-ester mixture, and 0.002% ash. Scanning electron microscopy showed that the nitration compacted the NBC structure, with the original reticulate pattern of the structure being preserved in full. Infrared spectroscopy for the presence of functional nitro groups at 1658-1659, 1280, 838-840, 749-751 and 693-694 cm^-1 confirmed the synthesis of cellulose nitrates in particular. Thermogravimetric and differential thermal analyses showed the resultant NBCNs to have a high purity and high specific heats of decomposition of 6.94-7.08 kJ/g. The NBCN samples differ conceptually from plant-based cellulose nitrates by having a viscosity above 1086 mPa·s and a unique 3D reticulate structure that is retained during the nitration. The findings suggest that the NBCNs can be considered for use in novel high-tech materials and science-driven fields distinct from the application fields of plant-based cellulose nitrates. The NBCN sample obtained with NA+MC has the ability to generate an organogel when it is dissolved in acetone. Because of the said property, this NBCN sample can find use as a classical adhesive scaffold and an energetic gel matrix for creating promising energetic polymers.

Novel Double Cross-Linked Acrylic Acid/Bagasse Cellulose Porous Hydrogel for Controlled Release of Citral and Bacteriostatic Effects

In this study, double cross-linked acrylic acid/bagasse cellulose (AA/BC) porous hydrogels were first prepared using cold plasma (CP) technology instead of chemical initiators. The structure and properties of porous hydrogels, as well as the controlled release and bacteriostatic application as functional carriers, were investigated. Results showed that a novel double cross-linked hydrogel had been successfully synthesized by utilizing ^•OH and H⁺ produced during plasma discharge. The acrylic acid (AA) monomers were successfully grafted onto the main chains of bagasse cellulose (BC), forming a porous three-dimensional network structure. The AA/BC porous hydrogels showed excellent swelling levels and intelligent responses. The release of citral in hydrogel inclusion compounds embedded with citral was controlled by adjusting the pH, and the slow release period was about 2 days. The inclusion compounds presented strong bacteriostatic effects against Escherichia coli and Staphylococcus aureus, extending the shelf life of fruits for about 4 days. Therefore, it can be concluded that CP technology is considered to be an efficient and environmental-friendly initiation technology for preparing hydrogels. The potential application of hydrogel inclusion compounds in the food field is expanded.

Challenges associated with cellulose composite material: Facet engineering and prospective

Cellulose is the most abundant polysaccharide on earth. It has a large number of desirable properties. Its low toxicity makes it more useful for a variety of applications. Nowadays, its composites are used in most engineering fields. Composite consists of a polymer matrix and use as a reinforcing material. By reducing the cost of traditional fibers, it has an increasing demand for environment-friendly purposes. The use of these types of composites is inherent in moisture absorption with hindered natural fibers. This determines the reduction of polymer composite material. By appropriate chemical surface treatment of cellulose composite materials, the effect could be diminished. The most modern and advanced techniques and methods for the preparation of cellulose and polymer composites are discussed here. Cellulosic composites show a reinforcing effect on the polymer matrix as pointed out by mechanical characterization. Researchers tried their hard work to study different ways of converting various agricultural by-products into useful eco-friendly polymer composites for sustainable production. Cellulose plays building blocks, that are critical for polymer products and their engineering applications. The most common method used to prepare composites is in-situ polymerization. This help to increase the yields of cellulosic composites with a significant enhancement in thermal stability and mechanical properties. Recently, cellulose composites used as enhancing the incorporation of inorganic materials in multi-functional properties. Furthermore, we have summarized in this review the potential applications of cellulose composites in different fields like packaging, aerogels, hydrogels, and fibers.

Starch biocomposites based on cellulose microfibers and nanocrystals extracted from alfa fibers (Stipa tenacissima)

Cellulose-based biopolymers have emerged as one of the most promising components to produce sustainable composites as a potential substitutes to fossil-based materials. Herein, the aim of this study is to investigate the reinforcing effect of cellulose microfibers (CMFs) and cellulose nanocrystals (CNCs), extracted from alfa fibers (Stipa tenacissima), on the properties of starch biopolymer extracted from potato. The as-extracted CMFs (D = 5.94 ± 0.96 μm), CNCs (D = 14.29 ± 2.53 nm) and starch were firstly characterized in terms of their physicochemical properties. Afterwards, CMFs and CNCs were separately dispersed in starch at different concentrations, and their reinforcing effects as well as the chemical, thermal, transparency and mechanical properties of the resulted starch-based films were evaluated. Thus, CMFs and CNCs incorporation into starch resulted in a minor impact on the films thermal stability, while a considerable impact on the transparency property was observed. In terms of mechanical properties, the addition of up to 20 wt% CMFs reduced the film's elongation but drastically increased its stiffness by 300 %. On the other hand, in the case of CNCs, a loading of 10 wt% was found to be the most effective in increasing film stiffness (by 57 %), while increasing the loading up to 20 wt% CNCs enhanced the film's ductility (strain-to-failure) by 52 %. This study showed that introduction of cellulosic fibers having different sizes into starch can produce biocomposite materials with a wide range of properties for food packaging application.

Extraction of high-quality grade cellulose and cellulose nanocrystals from different lignocellulosic agri-food wastes

Introduction

Prompted by the increasing need for an intensified valorization of agri-food waste, in this work a three-step chemical procedure was used to extract high-purity cellulose from garlic stalk, corncob, and giant cane cut-up by a sequential removal of hemicellulose, lignin, ash, and organic compounds. Cellulose nanocrystals of potential interest for nanocomposite applications were then obtained through acid hydrolysis.

Methods

The purity of the cellulose was determined employing Nuclear Magnetic Resonance and infrared spectroscopy, whereas dynamic light scattering, optical, atomic force microscopy, and transmission electron microscopy were used for morphological characterization. The high purity and crystallinity of cellulose was confirmed by comparison with the ultra-pure bacterial cellulose originating from K. sucrofermentans, irrespective of the waste used.

Results and discussion

At the end of the extraction procedure, cellulose yields of 35.73, 37.15, and 39.10%, for garlic stalk, corncob, and giant cane cut-up, respectively, were achieved. Dynamic light scattering and atomic force microscopy analyses showed that the length of the whisker-like nanocrystals depended on the raw material (from ~100 nm up to &gt; 2μm), while the final yield was ~40–50% for all three wastes. The versatility and effectiveness of the method here proposed can be profitably used for a wide range of agro-waste feedstocks.

Isolation of Cellulose Nanocrystals from Banana Peel Using One-Pot Microwave and Mild Oxidative Hydrolysis System

The current investigation deals with the application of a one-pot system to facilitate the production of cellulose nanocrystals (CNCs) from banana peel by a combination of microwave pre-treatment and mild oxidative hydrolysis with hydrogen peroxide (H₂O₂, 0-30 wt%) and sulfuric acid (H₂SO₄, 0-10%). H₂O₂ causes decolorization of the banana peel suspension from dark brown to light yellow, while further treatment with H₂SO₄ produces a white suspension, indicating successful removal of the non-cellulosic components from the banana peel. This finding was further supported by Fourier Transform Infrared (FTIR) spectroscopic analysis, which showed the gradual disappearance of lignin and hemicellulose peaks with increasing H₂O₂ and H₂SO₄ concentrations. The CNCs has considerably high crystallinity, with the highest crystallinity (~85%) being obtained at 6% H₂SO₄. Therefore, CNCs obtained at 6% H₂SO₄ were selected for further characterization. Scanning Electron Microscope (SEM) analysis confirmed the disintegration of the cellulose fibres into small fragments after hydrolysis. Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM) analyses revealed the spherical shape of the CNCs with an average size of approximately 20 nm. The CNCs have good stability with zeta potential of -42.9 mV. Findings from this study suggest that the combination of microwave pre-treatment and oxidative hydrolysis with 30 wt% H₂O₂ and 6% H₂SO₄, which is about 11 times lower than the commonly used H₂SO₄ concentration, is proven effective for the isolation of CNCs from banana peel. These observations are expected to provide insight into a facile and environmentally benign alternative to the conventional CNCs isolation method, using abundant and underutilized agricultural waste as feedstock.

Cellulose from Annual Plants and Its Use for the Production of the Films Hydrophobized with Tetrafluoroethylene Telomers

Cellulose HogC was produced by the modified traditional method with 35% yield from the stem of Sosnovsky hogweed and was characterized by elemental analysis, infrared (IR) spectroscopy, powder X-ray diffractometry, differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). For HogC, the degree of crystallinity (approximately 70%) and the glass transition temperature (105–108 °C) were determined. It was found that the whiteness characteristic in the case of HogC was 92% and this significate was obtained without a bleaching procedure using chlorine-containing reagents. In this paper, the possibility of hydrophobization of HogC films by treatment with radiation-synthesized telomers of tetrafluoroethylene is shown. It was found that the contact angle of the telomer-treated cellulose film surface depended on the properties of the telomers (the chemical nature of the solvent, and the initial concentration of tetrafluoroethylene) and could reach 140 degrees.

Simultaneous quantification of cellulose and pectin in tobacco using a robust solid-state NMR method

Cellulose and pectin are the important components of tobacco (Nicotiana tabacum L.) cell wall, which affect the formation of undesirable compounds. Their contents are closely related to the harmfulness of tobacco. But the simultaneous quantitative analysis of cellulose and pectin is hard to be achieved for traditional analytical methods. A solid-state ¹³C cross-polarization by multiple contact periods (multiCP) NMR method was developed for the simultaneous quantification of cellulose and pectin in tobacco. The multiCP spectrum at optimal parameters agreed well with the direct polarization (DP) spectrum within one-thirtieth of the measurement time and provided satisfactory signal to noise ratio (SNR). After three simple procedures of sample preparation and spectra deconvolution, simultaneous quantification of cellulose and pectin extracted from tobacco was effectively achieved. Compared with the chemical method, this interesting method was rapid, practicable, and very promising, which provided the technical support for the simultaneous quantification of cell wall substances in biological sample.

Source of Nanocellulose and Its Application in Nanocomposite Packaging Material: A Review

Food packaging nowadays is not only essential to preserve food from being contaminated and damaged, but also to comply with science develop and technology advances. New functional packaging materials with degradable features will become a hot spot in the future. By far, plastic is the most common packaging material, but plastic waste has caused immeasurable damage to the environment. Cellulose known as a kind of material with large output, wide range sources, and biodegradable features has gotten more and more attention. Cellulose-based materials possess better degradability compared with traditional packaging materials. With such advantages above, cellulose was gradually introduced into packaging field. It is vital to make packaging materials achieve protection, storage, transportation, market, and other functions in the circulation process. In addition, it satisfied the practical value such as convenient sale and environmental protection, reduced cost and maximized sales profit. This review introduces the cellulose resource and its application in composite packaging materials, antibacterial active packaging materials, and intelligent packaging materials. Subsequently, sustainable packaging and its improvement for packaging applications were introduced. Finally, the future challenges and possible solution were provided for future development of cellulose-based composite packaging materials.

Enhanced Photocatalytic Degradation with Sustainable CaO Nanorods Doped with Ce and Cellulose Nanocrystals: In Silico Molecular Docking Studies

This research work intends to evaluate the photoactivity of calcium oxide (CaO) nanorods (NRs) doped with cellulose nanocrystals (CNCs) and cerium (Ce). CNC-doped CaO and Ce/CNC codoped CaO were synthesized via the sol-gel technique. Structural, optical, morphological, physiochemical, phase constitution, and functional group evaluations were performed. The photodegradation of the prepared nanostructures was analyzed by observing photodegradation of a mixture of methylene blue and ciprofloxacin dye under light irradiation. The photocatalytic activity of the dye was drastically enhanced upon codoping in CaO. For both Escherichia coli and Staphylococcus aureus, statistically significant inhibitory zones (p < 0.05) were achieved in the case of CNCs and pristine and codoped CaO. Furthermore, in silico molecular docking studies (MDS) were accomplished against DNA gyrase from nucleic acid biosynthesis and enoyl-[acyl-carrier-protein] reductase (FabI) from the fatty acid biosynthetic pathway to rationalize the possible mechanism behind these antibacterial activities.

Exploration of multifunctional properties of garlic skin derived cellulose nanocrystals and extracts incorporated chitosan biocomposite films for active packaging application

For many years, garlic has been used as a condiment in food and traditional medicine. However, the garlic skin, which accounts for 25% of the garlic bulk, is considered agricultural waste. In this study, cellulose nanocrystals (CNCs) and garlic extract (GE) from garlic skin were isolated and used as fillers to manufacture biocomposite films. The films were characterized in terms of UV barrier, thermal, mechanical, biodegradability, and antimicrobial activity. The chitosan-containing films and CNCs have significantly improved the films' tensile strength, Young's modulus, and elongation but decreased the film transparency compared to chitosan films. The combination of the CNCs and GE, on the other hand, slightly reduced the mechanical properties. The addition of CNCs slightly decreased the film transparency, while the addition of GE significantly improved the UV barrier properties. Thermal studies revealed that the incorporation of CNC and GE had minimal effect on the thermal stability of the chitosan films. The degradability rate of the chitosan composite films was found to be higher than that of the neat chitosan films. The antimicrobial properties of films were studied against Escherichia coli, Streptomyces griseorubens, Streptomyces alboviridis, and Staphylococcus aureus, observing that their growth was considerably inhibited by the addition of GE in composite films. Films incorporating both CNCs and GE from garlic skin hold more promise for active food packaging applications due to a combination of enhanced physical characteristics and antibacterial activity.

Structure modification and property improvement of plant cellulose: Based on emerging and sustainable nonthermal processing technologies

Cellulose has attracted high attention due to its advantages of abundant resources, renewable and biodegradable. Modification of natural plant cellulose has become a hot topic worldwide. Conventional chemical modification methods commonly cause great damage to the environment. The current review presents the effects of innovative, eco-friendly and sustainable nonthermal processing technologies on cellulose structure and properties. Typical techniques include high pressure processing, cold plasma, ultrasonic and irradiation treatment. Their superiorities in the modification of cellulose are highlighted, and the advantages and limitations of nonthermal processing technologies for plant cellulose modification are also discussed. Nonthermal processing technologies can improve cellulose functional properties by playing an important role in the chemical bonds of the molecular chains, crystalline regions or amorphous parts through energy or active particles generated in the process, or promoting the crosslinking and graft copolymerization of cellulose molecules. The development of modified cellulose functional materials will have wider applications.

Effect of oxalic acid and sulphuric acid hydrolysis on the preparation and properties of pineapple pomace derived cellulose nanofibers and nanopapers

Nanocellulose is the "green magnet" which attracts a wide spectrum of industries towards it due to its availability, biodegradability, and possible smart applications. For the first time, pineapple pomace was being explored as an economic precursor for cellulose nanofibers. Nanofiber isolation was accomplished using a chemo-mechanical method and solution casting was adopted for the development of nanopapers. Moreover, the study examines the structural, optical, crystalline, dimensional, and thermal features of nanofibers isolated using different acid hydrolysis (oxalic acid and sulphuric acid) methods. Fourier-transform infra-red spectroscopy, ¹³C solid-state nuclear magnetic resonance spectroscopy, and X-ray diffraction analysis indicated the presence of type I cellulose. The transmittance, crystallinity index, and thermal stability of PPNFS (sulphuric acid treated fiber) were greater than PPNFO (oxalic acid treated fiber). The transmission electron microscopy and dynamic light scattering analysis confirmed the nanodimension of PPNFO and PPNFS. While comparing the optical and mechanical properties of nanopapers, PPNFS outperforms PPNFO. The tensile strength of the prepared nanopapers (64 MPa (PPNFO) and 68 MPa (PPNFS)) was found to be high compared to similar works reported in the literature. The prepared nanopaper is proposed to be used for food packaging applications.

Manufacturing of macroporous cellulose monolith from green macroalgae and its application for wastewater treatment

Enormous interest in using marine biomass as a sustainable resource for water treatment has been manifested over the past few decades. Herein, the objective was to investigate the possible use of green macroalgae (Codium tomentosum) for cellulose-based foam production through a versatile and convenient process. Macroporous cellulose monolith was prepared from cellulose hydrogel using freeze-drying process, resulting in a mechanically rigid monolith with a high swelling ratio. The as-produced spongy-like porous cellulosic material was used as bio-sorbent for wastewater treatment, particularly for removing methylene blue (MB) dye from concentrated aqueous solution. The adsorption capacity of MB was subsequently studied, and the effect of adsorption process parameters was determined in a controlled batch system. From the kinetic studies, it was found that the adsorption equilibrium was reached within 660 min. Furthermore, the analysis of the adsorption kinetics reveals that the data could be fitted by a pseudo-second order model, while the adsorption isotherm could be described by Langmuir isotherm model. The maximum adsorption capacity was found to be 454 mg/g. The findings suggested that the produced cellulose monolith could be used as a sustainable adsorbent for water treatment.

Chlorine-free extraction and structural characterization of cellulose nanofibers from waste husk of millet (Pennisetum glaucum)

This study aims to extract cellulose nanofibers (CNFs) from a sustainable source, millet husk, which is considered as an agro-waste worthy of consideration. Pre-treatments such as mercerisation, steam explosion, and peroxide bleaching (chlorine-free) were applied for the removal of non-cellulosic components. The bleached millet husk pulp was subjected to acid hydrolysis (5% oxalic acid) followed by homogenization to extract CNFs. The extracted CNFs were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Dynamic Light Scattering (DLS), Energy Dispersive X-ray Spectroscopy (EDX), Thermogravimetry (TG and DTG), Differential scanning calorimetry (DSC), and Solid state ¹³C nuclear magnetic resonance spectroscopy (solid state ¹³C NMR). The isolated CNFs show a typical cellulose type-I structure with a diameter of 10-12 nm and a crystallinity index of 58.5%. The appearance of the specific peak at 89.31 ppm in the solid state ¹³C NMR spectra validates the existence of the type-I cellulose phase in the prepared CNFs. The prepared CNFs had a maximum degradation temperature (T_max) of 341 °C, that was 31 °C greater than raw millet husk (RMH). The outcome of the study implies that the nanofibers are prominent alternatives for synthetic fibers for assorted potential applications, especially in manufacturing green composites.

Artemisia annua Stems a New Sustainable Source for Cellulosic Materials: Production and Characterization of Cellulose Microfibers and Nanocrystals

In this study, Artemisia annua stem waste was identified, for the first time, as a potential natural source to produce cellulose microfibers (CMF), as well as cellulose nanocrystals (CNC) with unique functionalities by using various organic acids. The CMF extraction was carried out using alkali and bleaching treatments, while the CNC were isolated under acid hydrolysis by using sulfuric acid (S-CNC), phosphoric acid (P-CNC), and hydrochloric acid / citric acid mixture (C-CNC). The CMF and CNC physicochemical, structural, morphological, dimensional, and thermal properties were characterized. CMF with a yield of 53%, diameter of 5 to 30 µm and crystallinity of 57% were successfully obtained. In contrast, CNC showed a rod-like shape with an aspect ratio of 53, 95, and 64 and a crystallinity index of 84, 79, and 72% for S-CNC, P-CNC, and C-CNC, respectively. Results suggested that the type of acid significantly influenced the structure, morphology, and thermal stability of CNCs. Based on these results, Artemisia annua stem waste is a great candidate source for cellulose derivatives with excellent characteristics.

Recent Advances on Lignocellulosic-Based Nanopesticides for Agricultural Applications

Controlled release systems of agrochemicals have been developed in recent years. However, the design of intelligent nanocarriers that can be manufactured with renewable and low-cost materials is still a challenge for agricultural applications. Lignocellulosic building blocks (cellulose, lignin, and hemicellulose) are ideal candidates to manufacture ecofriendly nanocarriers given their low-cost, abundancy and sustainability. Complexity and heterogeneity of biopolymers have posed challenges in the development of nanocarriers; however, the current engineering toolbox for biopolymer modification has increased remarkably, which enables better control over their properties and tuned interactions with cargoes and plant tissues. In this mini-review, we explore recent advances on lignocellulosic-based nanocarriers for the controlled release of agrochemicals. We also offer a critical discussion regarding the future challenges of potential bio-based nanocarrier for sustainable agricultural development.

Thermoplastic starch nanocomposites using cellulose-rich Chrysopogon zizanioides nanofibers

Green thermoplastic starch (TPS) nanocomposite films aided by cellulose nanofibers (CNFs) from Chrysopogon zizanioides roots were developed and characterized. When compared to other lignocellulosic fibers, Chrysopogon zizanioides roots revealed exceptionally high cellulose content (~48%). CNFs were separated using an environmentally friendly acid isolation technique that included three stages: (i) alkali treatment; (ii) bleaching; and (iii) mild acid hydrolysis using oxalic acid in an autoclave. Following that, green nanocomposite films were made from potato starch using the solution casting process, by which we used glycerol (30 wt%) to make thermoplastic starch. Then, cellulose nanofibers in different concentrations (0, 1, 2, 3, 4 wt%) were added to the thermoplastic starch matrix. The isolated CNFs had diameters in the range of 17-27 nm. Besides, these nanostructures presented a very high crystallinity index (~65%), thereby enhanced the thermal stability. TPS/CNF green nanocomposites containing 3 wt% CNFs had exceptional tensile strength (~161%), tensile modulus (~167%), thermal stability, and crystallinity. As a result, nanocomposite films made of starch and cellulose nanofibers (3 wt%) extracted from Chrysopogon zizanioides roots would be alternatives for sustainable packaging. It can be concluded that Chrysopogon zizanioides roots have high potential for polymer industry.

Synthesis and Physicochemical Properties of Poly(vinyl) Alcohol Nanocomposites Reinforced with Nanocrystalline Cellulose from Tea (Camellia sinensis) Waste

The purpose of this study was to utilize cellulose from tea waste as nanocrystalline cellulose (NCC), which is used as a filler in poly(vinyl) alcohol (PVA) nanocomposites. To obtain the NCC, a chemical process was conducted in the form of alkali treatment, followed by bleaching and hydrolysis. Nanocomposites were formed by mixing PVA with various NCC suspensions. With chemical treatment, lignin and hemicellulose can be removed from the tea waste to obtain NCC. This can be seen in the functional groups of cellulose and the increase in crystallinity. The NCC had a mean diameter of 6.99 ± 0.50 nm. Furthermore, the addition of NCC to the PVA nanocomposite influenced the properties of the nanocomposites. This can be seen in the general increase in opacity value, thermal and mechanical properties, and crystallinity, as well as the decrease in the value of the swelling ratio after adding NCC. This study has revealed that NCC from tea waste can be used to improve the physicochemical properties of PVA film.

P. S. AK, Oyekanmi AA, Gideon ON, Abdullah CK, Yahya EB, Alfatah T, Sabaruddin FA, Rahman AA. Cotton Wastes Functionalized Biomaterials from Micro to Nano: A Cleaner Approach for a Sustainable Environmental Application

The exponential increase in textile cotton wastes generation and the ineffective processing mechanism to mitigate its environmental impact by developing functional materials with unique properties for geotechnical applications, wastewater, packaging, and biomedical engineering have become emerging global concerns among researchers. A comprehensive study of a processed cotton fibres isolation technique and their applications are highlighted in this review. Surface modification of cotton wastes fibre increases the adsorption of dyes and heavy metals removal from wastewater. Cotton wastes fibres have demonstrated high adsorption capacity for the removal of recalcitrant pollutants in wastewater. Cotton wastes fibres have found remarkable application in slope amendments, reinforcement of expansive soils and building materials, and a proven source for isolation of cellulose nanocrystals (CNCs). Several research work on the use of cotton waste for functional application rather than disposal has been done. However, no review study has discussed the potentials of cotton wastes from source (Micro-Nano) to application. This review critically analyses novel isolation techniques of CNC from cotton wastes with an in-depth study of a parameter variation effect on their yield. Different pretreatment techniques and efficiency were discussed. From the analysis, chemical pretreatment is considered the most efficient extraction of CNCs from cotton wastes. The pretreatment strategies can suffer variation in process conditions, resulting in distortion in the extracted cellulose's crystallinity. Acid hydrolysis using sulfuric acid is the most used extraction process for cotton wastes-based CNC. A combined pretreatment process, such as sonication and hydrolysis, increases the crystallinity of cotton-based CNCs. The improvement of the reinforced matrix interface of textile fibres is required for improved packaging and biomedical applications for the sustainability of cotton-based CNCs.