Micro- and nano-celluloses derived from hemp stalks and their effect as polymer reinforcing materials

Extraction of microcrystalline cellulose from Ficus benghalensis leaf and its characterization

Microcrystalline cellulose (MCC) is a crucial component in various industries, including pharmaceuticals, culinary, and cosmetics. The growing demand for MCC has spurred research into extraction methods. This study focused on extracting MCC from Ficus benghalensis using acid hydrolysis to convert the alpha-cellulose content of its leaves into MCC. The solvent used in this process was recyclable for further use. The extracted MCC was characterized by its physicochemical properties, including density, yield percentage, and structural characteristics. The yield was approximately 39.68 %, and the density was low at 1.518 g/cm3, making it suitable for filler applications. Fourier transform spectroscopy and UV-visible analysis identified functional groups of cellulose. X-ray diffraction analysis revealed a crystallite size of 1.560 nm and a crystallinity index of 66.43 %, indicating suitability for related applications. ImageJ determined a mean particle size of 36.545 μm, while scanning electron microscopy showed distinct surface orientations. Atomic force microscopy revealed surface roughness, root mean square, ten-point average roughness, skewness, and kurtosis. Elemental analysis indicated high concentrations of carbon (20.1 %) and oxygen (34 %). Based on these physicochemical features, the extracted MCC could be a valuable source for applications such as filler in reinforcement technology and coating material in pharmaceutical products.

Nanocellulose from agro-industrial wastes: A review on sources, production, applications, and current challenges

Significant volumes of agricultural and industrial waste are produced annually. With the global focus shifting towards sustainable and environmentally friendly practices, there is growing emphasis on recycling and utilizing materials derived from such waste, such as cellulose and lignin. In response to this imperative situation, nanocellulose materials have surfaced attracting heightened attention and research interest owing to their superior properties in terms of strength, stiffness, biodegradability, and water resistance. The current manuscript provided a comprehensive review encompassing the resources of nanocellulose, detailed pretreatment and extraction methods, and present applications of nanocellulose. More importantly, it highlighted the challenges related to its processing and utilization, along with potential solutions. After evaluating the benefits and drawbacks of different methods for producing nanocellulose, ultrasound combined with acid hydrolysis emerges as the most promising approach for large-scale production. While nanocellulose has established applications in water treatment, its potential within the food industry appears even more encouraging. Despite the numerous potential applications across various sectors, challenges persist regarding its modification, characterization, industrial-scale manufacturing, and regulatory policies. Overcoming these obstacles requires the development of new technologies and assessment tools aligned with policy. In essence, nanocellulose presents itself as an eco-friendly material with extensive application possibilities, prompting the need for additional research into its extraction, application suitability, and performance enhancement. This review focused on the wide application scenarios of nanocellulose, the challenges of nanocellulose application, and the possible solutions.

Phosphorylating Tannin in Urea System: A Simple Approach for Enhanced Methylene Blue Removal from Aqueous Media

Tannin, after lignin, is one of the most abundant sources of natural aromatic biomolecules. It has been used and chemically modified during the past few decades to create novel biobased materials. This work intended to functionalize for the first time quebracho Tannin (T) through a simple phosphorylation process in a urea system. The phosphorylation of tannin was studied by Fourier transform infrared spectroscopy (FTIR), NMR, inductively coupled plasma optical emission spectroscopy (ICP-OES), and X-ray fluorescence spectrometry (XRF), while further characterization was performed by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) and thermogravimetric analysis (TGA) to investigate the morphology, composition, structure, and thermal degradation of the phosphorylated material. Results indicated the occurrence of phosphorylation, suggesting the insertion of phosphate-containing groups into the tannin structure, revealing a high content of phosphate for modified tannin (PT). This elevated phosphorus content serves as evidence for the successful incorporation of phosphate groups through the functionalization process. The corresponding PT and T were employed as adsorbents for methylene blue (MB) removal from aqueous solutions. The results revealed that the Langmuir isotherm model effectively represents the adsorption isotherms. Additionally, the pseudo-second-order model indicates that chemisorption predominantly controls the adsorption mechanism. This finding also supports the fact that the introduced phosphate groups via the phosphorylation process significantly contributed to the improved adsorption capacity. Under neutral pH conditions and at room temperature, the material achieved an impressive adsorption capacity of 339.26 mg·g-1 in about 2 h.

Nanocellulose reinforced polyvinyl alcohol-based bio-nanocomposite films: improved mechanical, UV-light barrier, and thermal properties

This study reported the development and characterisation of bio-nanocomposite films based on the polyvinyl alcohol (PVA) reinforced with cellulose nanofibres (CNFs) of different concentrations (1-5 wt%), isolated from pineapple leaf fibre via high-shear homogenisation and ultrasonication. The PVA film and bio-nanocomposite were prepared using a solution casting method. The PVA film and bio-nanocomposite samples were characterized using FE-SEM, XRD, FTIR spectroscopy, UV-vis spectroscopy in transmission mode, TGA, and DTG. Mechanical properties (tensile strength and strain at break) were also determined and statistical analysis was applied as well. With the incorporation of CNFs, the mechanical properties of the bio-nanocomposite were found to be significant (p ≤ 0.05), particularly the 4 wt% CNF bio-nanocomposite showed optimum properties. The tensile strength, CI, and thermal stability of this film were 28.9 MPa (increased by 28.2%), 78.7% (increased by 5.2%), and 341.8 °C (increased by 1.6%), respectively, compared to the pure PVA film. These characteristics imply that the bio-nanocomposite film has prospects as a promising material for biopackaging.

Development of PLA-Waste Paper Biocomposites with High Cellulose Content

In this study, the integration of paper industry waste with high cellulose content into biocomposites of polylactic acid (PLA), a widely used biobased polymer material, was investigated. The PLA/waste biocomposite samples (0-25 wt.%) were manufactured using the extrusion and injection moulding techniques. The mechanical test results showed improvements in terms of tensile properties and a decrease in impact strength as the percentage of residue increased. The melting temperature decreased, and the crystallinity increased in all biocomposites according to the Differential Scanning Calorimetry (DSC) analysis. Water absorption increased proportionally with the percentage of residue, attributed to the higher cellulose content in the biocomposites, determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques. The scanning electron microscopy (SEM) fracture analysis demonstrated effective reinforcement-matrix cohesion, supporting the previously observed behaviour of the analysed materials. This work highlights the potential of using waste from the paper industry as reinforcement in PLA matrices, opening new perspectives for sustainable applications in the framework of the manufacture of composite materials.

Sustainable microcrystalline cellulose extracted from biowaste Albezia lebeck L. leaves: Biomass exfoliation and physicochemical characterization

There is a focus on sustainability when manufacturing materials. Utilizing biobased materials and replacing fossil-based products is the main research focus. Bio-composite materials are applied to packaging, filler coatings, and pharmaceuticals. Here, we used the leaves of the agro-waste plant Albizia lebeck L. to extract cellulose. Chemical treatment causing strong acid hydrolysis successfully extracted the cellulose content from the leaves. The cellulose obtained was then strengthened with polylactic acid to make a biobased film for future applications. Fourier transform spectroscopy, scanning electron microscopy, thermal analysis, particle size analysis, visible UV and elemental analysis were all used to characterize the extracted cellulose. SEM and mechanical property analysis were used to check and describe the quality of the reinforced biofilm. The greatest cellulose yield from this raw material was 50.2%. The crystallinity index and crystallite size (CI 70.3% and CS 11.29 nm) were high in the extracted cellulose. The TG (DTG) curve analysis derivative revealed cellulose particle breakdown was initiated around 305.2°C and can endure temperatures up to 600°C. Biofilms reinforced with polylactic acid cellulose (1, 2, 3, and 5% by weight %) exhibited a smooth and parallel surface. As the filler concentration increased, minor agglomeration occurred. The tensile strength of pure polylactic acid (PLA) (34.72 MPa) was extended up to 38.91 MPa for 5% filler. Similarly, Young's modulus also increased to 5.24 MPa. However, the elongation break decreases with the increase of filler content, and the least value of decrease is 7.5 MPa. Concerning prospective implementations, it is expected that the biobased film and cellulose particles will prove to be more functional.

Characterization of Cellulosic Pulps Isolated from Two Widespread Agricultural Wastes: Cotton and Sunflower Stalks

Globally, huge amounts of cotton and sunflower stalks are generated annually. These wastes are being underutilized since they are mostly burned in the fields. So, in this work, we proposed a three-step method consisting of acid pre-treatment, alkaline hydrolysis, and bleaching for the extraction of cellulose pulps. These pulps were characterized to assess their morpho-structural and thermal properties. The design of experiments and response surface methodology were used for the optimization of the acid pre-treatment in order to achieve maximum removal of non-cellulosic compounds and obtain pulps enriched in cellulose. For cotton stalks, optimal conditions were identified as a reaction time of 190 min, a reaction temperature of 96.2 °C, and an acid (nitric acid) concentration of 6.3%. For sunflower stalks, the optimized time, temperature, and acid concentration were 130 min, 73.8 °C, and 8.7%, respectively. The pulps obtained after bleaching contained more than 90% cellulose. However, special care must be taken during the process, especially in the acid pre-treatment, as it causes the solubilization of a great amount of material. The characterization revealed that the extraction process led to cellulose pulps with around 69-70% crystallinity and thermal stability in the range of 340-350 °C, ready to be used for their conversion into derivatives for industrial applications.

Comprehensive characterization of microcrystalline cellulose from lemon grass (Cymbopogan citratus) oil extraction agro-industrial waste for cementitious composites applications

Presently, the construction industry demands components that are exceptionally strong and long-lasting. The initial important construction material is concrete, which contains between 1 % and 2 % of air voids. The structural damage caused by water that enters through the air spaces are improved with filler material. Chemical filler materials are environmentally harmful; therefore, eco-friendly materials are selected for this study. The environmentally benign character of agro-waste byproduct usage is a driving factor in the field of research. Numerous uses can be found for waste materials, especially after they have been repurposed. We used a byproduct of an essential oil extraction company, an extract made from the leaves of lemon grass (Cymbopogan citrus), in our research. Alkalization, slow pyrolysis, acid hydrolysis, and bleaching are only some of the chemical treatments that could be used to easily extract microcrystalline cellulose from the discarded waste material. In our study the chemicals used are mild harmful to the environment and a surface reactant (linear alkyl benzene sulfonic acid) is utilised to bleach and purify the microcrystalline cellulose. Thermal analysis, scanning electron microscopy, transmission electron microscopy and Fourier transform spectroscopy were all used to learn more about the cellulose that had been extracted. The extracted cellulose powder comprises a high crystallinity index (68.14 %) and low crystallite size (5.13 nm) found using X-ray diffraction analysis. The smooth and porous surface is observable in scanning electron microscope analysis. The Differential scanning calorimeter curve shows the highest degradation temperature at 218.16 °C. The micro sized particles mostly range between 100 and 120 μm and are found using ImageJ. The surface roughness and permissible skewness of cellulose particles were examined using atomic force microscopy. The density of extracted cellulose is 1.092 g/cm3. The microcrystalline cellulose yield % was notably maximum (40.45 %). This cellulose was introduced in a M30 grade cement concrete as fillers up to 5 % by the weight of cement. The fresh and mechanical properties of the concrete was found to get improved with the addition of cellulose up to 3 %. As a result, the characteristics of cellulose boost its utility within the construction sector.

Biowaste Valorization of Palm Tree Phoenix dactylifera L. for Nanocellulose Production

The desire to reduce reliance on oil resources arises from the concerns about carbon footprint and nonrenewability. Conversely, the global presence of over 100 million palm trees poses a significant challenge due to the substantial amount of biowaste generated annually. Additionally, the use of nanocellulose (NC) as a cost-effective material is steadily gaining recognition for its growing adaptability over time. The main goal of this study is to biosynthesized NC from Iraqi date palm Phoenix dactylifera leaves waste with low-concentration acid-alkali treatment. The date palm leaves waste yields 20 g of NC from 100 g of leaves before acid hydrolysis treatment. The chemical components of biosynthesized NC were 47.90%, 26.78%, and 24.67% for α-cellulose, hemicellulose, and lignin, respectively. In order to study their properties, NC from raw date palm leaves was studied by microscopic techniques such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and atomic force microscope (AFM). SEM results revealed rod-like structured NC as well as combined long-fine fibrous structures rather than compacted bundles with sizes ranging between 31 and 74 nm. With EDX, all spectra exhibit the peaks of carbon and oxygen as the main elements with 63.8% and 10.44%, respectively, in their compositions, which relate to the typical composition of cellulose. The 3D image of AFM NC with a tapping mode presented a highly uniform distribution of NC with a size of ∼15 nm. The statistical roughness analysis shows that the obtained roughness average is 7.20 nm with the root-mean-square roughness value of 21.56 nm, which corresponded relatively with the micrographs of SEM. The results of this study demonstrate the promise of using date palm waste as raw material to produce NC as green nanocomposite from biodegradable nanomaterials for water purification and sustained drug delivery for biomedical applications. In this regard and because of the insufficient reports about the extraction of NC from palm tree leaves waste, the objective of this study was designed to fabricate NC biologically from fibers sourced from the waste of Iraqi date palm P. dactylifera leaves that left in agricultural lands or burned, which can be an ecological and health problem as a bionanocomposites in the medical and industrial field and as alternative resources of wood materials.

Process-structure-property relationships of cellulose nanocrystals derived from Juncus effusus stems on ҡ-carrageenan-based bio-nanocomposite films

This study investigates the potential of Juncus plant fibers as a renewable source for producing cellulose nanocrystals (CNs) to reinforce polymers. Cellulose microfibers (CMFs) were extracted with a 0.43 ± 0.2 μm diameter and 69 % crystallinity through alkaline and bleaching treatments, then subjected to sulfuric acid hydrolysis, yielding four CN types (CN10, CN15, CN20 and CN30) with distinct physico-chemical properties and aspect ratios (47, 55, 57, and 60). The study assessed the influence of cellulose nanocrystals (CNs), incorporated at different weight percentages (3 %, 5 %, and 8 %), on thermal, transparency, and mechanical properties in k-carrageenan (CA) biocomposite films. The results indicate significant enhancements in these characteristics, highlighting good compatibility between CNs and CA matrix. Particularly noteworthy is the observed substantial improvement in tensile strength at an 8 wt% loading, with values of 23.43 ± 0.83 MPa for neat CA, 33.53 ± 0.83 MPa for CA-CN10, 36.67 ± 0.71 MPa for CA-CN15, 37.65 ± 0.56 MPa for CA-CN20, and 39.89 ± 0.77 MPa for CA-CN30 composites. Furthermore, the research explores the connection between the duration of hydrolysis and the properties of cellulose nanocrystals (CNs), unveiling their influence on the characteristics of nanocomposite films. Prolonged hydrolysis enhances CN crystallinity (CrI), aspect ratio, and surface charge content, consequently enhancing mechanical features like strength and flexibility in these films. These findings demonstrate the potential of Juncus plant fibers as a natural and eco-friendly resource for producing CNs that effectively reinforce polymers, making them an attractive option for diverse applications in the field.

Utilizing the Potential of Waste Hemp Reinforcement: Investigating Mechanical and Thermal Properties of Polypropylene and Polylactic Acid Biocomposites

Hemp has gained significant popularity for its diverse applications; however, this study explores the untapped potential of waste hemp (wH) as a cost-effective and sustainable bioadditive for the development of high-performance biocomposites. wH offers advantages such as low cost, easy availability, and suitability for extrusion. Polypropylene (PP) and poly(lactic acid) (PLA) served as polymer matrices for this investigation. In order to enhance the interaction between the wH and polymer matrices, alkaline and silane pretreatments were applied to the wHs of both matrices. At the same time, the MA-g-PP additive was used exclusively for the PP matrix. The resulting PP biocomposite demonstrated Young's modulus (2986 MPa) and flexural modulus (2490 MPa), surpassing those of neat PP by 109 and 77%, respectively. Similarly, wH40-PLA-A showed enhancements in the PLA biocomposite, with Young's modulus (6214 MPa) and flexural modulus (5970 MPa) representing an increase of 81 and 56% over that of neat PLA, respectively. The thermal properties and behaviors of the resulting biocomposites were minimally affected by the inclusion of wH as a bioadditive. This study contributes to the advancement of sustainable materials and provides valuable insights into the utilization of wH as a valuable resource for the development of high-performance biocomposites.

Lignin-functionalized cobalt for catalytic reductive degradation of organic dyes in simple and hybrid binary systems

To fulfill the unprecedented valorization approaches for lignocellulose, this work focuses on the potential of lignin-derived catalytic systems for bio-remediation, which are natural materials perceived to address the increased demand for eco-conscious catalyzed processes. A useful lignin-functionalized cobalt (Lig-Co) catalyst has been prepared, well-characterized and deployed for the catalyzed reducing decomposition of stable harmful organic pollutants such as methylene blue (MB) and methyl orange (MO), in simple and binary systems. The multifunctional character of lignin and the presence of various active sites can promote effectively loaded metal nanoparticles (NPs). Considerably, optimizing detoxification tests showed that the uncatalyzed use of NaBH4 as a reductive agent led to an incomplete reduction of organic contaminants over a long period of up to 65 min. Interestingly, Lig-Co catalyst exhibited a high reduction rate and turnover frequency of up to 99.23% and 24.12 min-1 for MB, respectively, while they reached 99.25% and 26.21 min-1 for MO at normal temperature. Kinetically quick catalytic reaction was also demonstrated for the hybrid system, in which the rate constant k was 0.175 s-1 and 0.165 s-1 for MB and MO, respectively, within a distinctly low reaction time of around 120 s. The reproducibility of the Lig-Co catalyst induces a desirable capacity to reduce stable dyes present simultaneously in the binary system, with 6 successive catalytic runs and over 80% of activity retained. Such robust findings underline the considerable interest in developing future lignin-mediated catalytic transformations and upscaling biomass-derived products, to meet the growing demand for sustainable and eco-friendly alternatives in various industries.

Extraction of cellulose nanocrystalline from Camellia oleifera Abel waste shell: Study of critical processes, properties and enhanced emulsion performance

Cellulose nanocrystals (CNCs) extracted from the waste shell of Camellia oleifera Abel (C. oleifera) are gaining attention as valuable materials. In this study, CNCs were extracted from the agricultural waste shell of C. oleifera through phosphoric acid and sulfuric acid hydrolysis, respectively. Firstly, we optimized the alkaline treatment process for cellulose isolation by using response surface methodology. Furthermore, the properties of CNCs were investigated by neutralizing them with NaOH and NH3·H2O, and by dialysis in water. In addition, the characterization methods including FT-IR, TGA, AFM and TEM were used to analysis the properties of the synthesized CNCs. Finally, CNCs were studied for their application in essential oil-based Pickering emulsions. CNCs obtained from sulfuric acid showed the smallest particle size and good dispersibility. Moreover, the release profiles of essential oils in the emulsions were followed by Peppa's kinetic release model. The antibacterial activity of the emulsions against E. coli and S. aureus showed that CNCs-stabilized emulsions enhanced the antibacterial activity of essential oils. Therefore, neutralization treatments may enhance the properties of CNCs, and CNCs stabilized Pickering emulsions can enhance antibacterial activity of essential oil. This study provides insight into the potential application of CNCs derived from C. oleifera waste shells.

In situ preparation and properties of polyvinyl alcohol/synthetic ribbon-like nanocellulose composites

This study presents a novel approach in which a dual network (DN) composite, comprising polyvinyl alcohol (PVA) and ribbon-like nanocellulose (RC), was synthesized in one step using the volume exclusion effect involved in enzyme-catalyzed cellulose synthesis. Additionally, the impact of PVA as a crowding reagent during enzymatic catalysis on the in situ formation of nanocellulose and its resulting aspect ratio was explored. In contrast, the other two composites were created by incorporating enzyme-catalyzed synthetic block cellulose (BC) and its acid-hydrolyzed regenerated disc-shaped cellulose (DC) into the PVA. Subsequently, the mechanism by which three distinct types of nanocellulose, varying in morphology and size, was explored to elucidate their contributions to enhancing the properties of PVA. The results demonstrated that PVA/RC outperformed PVA/BC and PVA/DC. The elevated aspect ratio and intricate network structure of RCs not only significantly bolster the mechanical robustness of PVA/RC, leading in an 86.40 % surge in tensile strength and a remarkable 277.03 % rise in tensile modulus in comparison to pure PVA, but also induce a slight enhancement in elongation at break. Moreover, the thermal stability and biodegradability of PVA/RC was enhanced. Collectively, this study introduces an innovative strategy for the efficient fabrication of biodegradable composites with enhanced properties.

Properties of sodium alginate-based nanocomposite films: Effects of aspect ratio and surface charge of cellulose nanocrystals

Three cellulose nanocrystals (CNCs) were prepared to reinforce sodium alginate (SA) films. This study investigated effects of aspect ratio (L/D) and surface charge of three CNCs (CCNC, MCNC, and WCNC) on the properties of films. At CNC concentrations ≤3 wt%, MCNC, with a medium L/D but the lowest surface charge density among the three CNCs, exhibited the highest efficiency in enhancing the Young's modulus and tensile strength of films. This indicated that, apart from L/D, CNC's surface charge density also affected its reinforcing effects in anionic SA-based films. Compared with other CNCs, MCNC with the lowest charge density exhibited weaker repulsion with SA, potentially contributing to stronger interfacial interactions between them. At concentrations >3 wt%, the reinforcing efficiency of MCNC was extremely close to that of WCNC, which had the highest L/D but medium charge density. This was possibly because, according to SEM results, MCNC with the lowest absolute value of zeta potential aggregated more severely than other CNCs. However, both MCNC and WCNC were consistently more efficient than CCNC. Moreover, FTIR results revealed that WCNC formed more hydrogen bonds with SA than other CNCs. Consequently, adding WCNC was more effective in reducing films' water vapor permeability and hydrophilicity.

Multifunctional composite films based on polyvinyl alcohol, quaternary ammonium salt modified cellulose nanofibers and tannic acid-iron ion coordination complexes for food packaging

The development of sustainable and well-performing food packaging materials takes on critical significance, whereas it is still challenging. To overcome the shortcomings of polyvinyl alcohol (PVA) as a degradable packaging material, in this work, hydrophobic quaternary ammonium salt (QAS) modified cellulose nanofibers (CNF) and tannic acid‑iron ion coordination complexes (TA-Fe) were adopted for the preparation of functional PVA films. The modified CNF (CNF-QAS) not only improved the mechanical properties and water resistance of PVA, but also endowed it with antibacterial ability. In addition, the synergistic antibacterial capability with CNF-QAS was achieved using TA-Fe with photothermal therapy. As a result, the modulus, elongation at break, tensile strength, and water contact angle of the prepared PVA films were examined as 88 MPa, 200 %, 11.7 MPa, and 94.8°, respectively. Furthermore, with the assistance of CNF-QAS and TA-Fe, the films inhibited the growth of E. coli and S. aureus by 99.8 % and 99.7 %, respectively, and they exhibited high cell viability of 90.5 % for L929 fibroblasts. Based on the above encouraging properties, the functional PVA films could significantly extend the shelf life of oranges for over two weeks, proving the excellent application prospects in the food packaging field.

Different nanocellulose morphologies (cellulose nanofibers, nanocrystals and nanospheres) extracted from Sunn hemp (Crotalaria Juncea)

Nanocellulose of different morphologies was extracted from Sunn Hemp (Crotalaria Juncea) using acid hydrolysis. The work focused on two objectives: first, to valorize the Sunn Hemp fibers for nanocellulose (NC) production, and second, to study the effects of acid concentration on different morphologies of NC and their properties. The study extracted nanocellulose at five different concentrations of H2SO4: 16 %, 32 %, 48 %, 64 %, and 72 %. Obtained nanocellulose was characterized by Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Thermogravimetric Analysis (TGA). AFM and FE-SEM confirmed the production of three different morphologies of nanocellulose. The NC-32 had a web-like structure typically observed for cellulose nanofibrils (CNF), whereas NC-48 and NC-64 were observed as cellulose nanocrystals (CNC) with rod-like and needle-like shapes, respectively, and NC-72 displayed spherical particles termed cellulose nanospheres (CNS). The total crystallinity index of NC was calculated using FTIR, and a similar trend of crystallinity was also observed from XRD analysis. NC-32 was obtained with the highest yield of 94.83 %, followed by 91.40 % and 81.70 % for NC-48 and NC-64, respectively, whereas NC-72 yielded the lowest yield of 12.03 %. NC-72 had the highest thermal stability among other NC morphologies.

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.

Isolation of cellulose nanofibers from rapeseed straw via chlorine-free purification method and its application as reinforcing agent in carboxymethyl cellulose-based films

In this study, cellulose nanofibers (CNFs) were successfully isolated from rapeseed straw (RS) whose valorization has been rarely investigated to date. A combined bleaching method without chlorine was applied for the purification of cellulose fibers, previously unexplored for RS. Chemical composition analysis and Fourier-transform infrared spectroscopy (FTIR) indicated that the purification method eliminated hemicellulose and reduced lignin content from 24.4 % to 1.8 %. The isolation of CNFs was performed using sulfuric acid hydrolysis under different acid concentrations (55 and 60 % v/v) and hydrolysis times (15, 30, and 45 min). The isolated CNFs were characterized by FTIR, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The formation of CNFs was confirmed by a significant increase in crystallinity index from 46.45 % of RS to >79.41 % of CNFs, depending on acid concentration and isolation duration. Carboxymethyl cellulose (CMC) films with different contents of CNFs were prepared by casting method. The mechanical properties and cytotoxicity of the prepared films were investigated. The CNFs obtained from RS via a chlorine-free purification method showed promising results for their usage as reinforcement in CMC matrix and film fabrication for various applications such as transdermal medicine and food packaging.

Obtaining Cellulose Nanocrystals from Olive Tree Pruning Waste and Evaluation of Their Influence as a Reinforcement on Biocomposites

The objective of this work is to improve the mechanical properties of polylactic acid (PLA) by incorporating cellulose nanocrystals (CNC) previously obtained from a cellulose pulp extracted from olive tree pruning (OTP) waste. Composites were manufactured by melt processing and injection moulding to evaluate the effect of the introduction of CNC with conventional manufacturing methods. This OTP-cellulose pulp was subjected to a further purification process by bleaching, thus bringing the cellulose content up to 86.1%wt. This highly purified cellulose was hydrolysed with sulfuric acid to obtain CNCs with an average length of 267 nm and a degradation temperature of 300 °C. The CNCs obtained were used in different percentages (1, 3, and 5%wt.) as reinforcement in the manufacture of PLA-based composites. The effect of incorporating CNC into PLA matrix on the mechanical, water absorption, thermal, structural, and morphological properties was studied. Maximum tensile stress and Young's modulus improved by 87 and 58%, respectively, by incorporating 3 and 5%wt. CNC. Charpy impact strength increased by 21% with 3%wt. These results were attributed to the good dispersion of CNCs in the matrix, which was corroborated by SEM images. Crystallinity index, glass transition, and melting temperatures were maintained.

Characterization of Cellulose Fiber Derived from Hemp and Polyvinyl Alcohol-Based Composite Hydrogel as a Scaffold Material

Cellulose nanocrystals (CNCs) were successfully extracted and purified from hemp using an alkaline treatment and bleaching process and subsequently used in conjunction with polyvinyl alcohol to form a composite hydrogel. Cellulose nanocrystals (1-10% (w/v)) were integrated into polyvinyl alcohol, and sodium tetraborate (borax) was employed as a crosslinking agent. Due to the small number of cellulose nanocrystals, no significant peak change was observed in the FT-IR spectra compared to pristine polyvinyl alcohol. The porosity was created upon the removal of the water molecules, and the material was thermally stable up to 200 °C. With the presence of cellulose nanocrystals, the melting temperature was slightly shifted to a higher temperature, while the glass transition temperature remained practically unchanged. The swelling behavior was examined for 180 min in deionized water and PBS solution (pH 7.4) at 37 °C. The degree of swelling of the composite with cellulose nanocrystals was found to be higher than that of pristine PVA hydrogel. The cell viability (%) of the prepared hydrogel with different proportions of cellulose nanocrystals was higher than that of pristine PVA hydrogel. Based on the results, the prepared composite hydrogels from cellulose nanocrystals extracted from hemp and polyvinyl alcohol were revealed to be an excellent candidate for scaffold material for medical usage.

Use of cellulose microfibers from olive pomace to reinforce green composites for sustainable packaging applications

To valorize abundant, unexploited, and low-cost agro-industrial by-products, olive pomace is proposed as a sustainable and renewable raw material for cellulose microfibers (CMFs) production. In this study, CMFs were extracted from olive pomace using alkaline and bleaching treatments and characterized in terms of morphological, structural, and thermal properties. Afterward, the reinforcing capability of microfibers was examined using carboxymethyl cellulose (CMC) as a polymer matrix by the solvent casting process. The effects of CMF loading (1%, 3%, 5%, and 10%) on the composites' mechanical, physical, morphological, and thermal properties were assessed. CMF incorporation led to a decrease in moisture content (MC), water solubility (WS), and water vapor permeability (WVP) and an increase in tensile strength (TS), stiffness and transparency values, and thermal stability of CMC films. Increasing CMF content to 5%, increased the TS and elasticity modulus by 54% and 79%, respectively, and reduced the WVP and light transmissivity at 280 nm, by 22% and 47%, respectively. The highest water, moisture, light barrier, and mechanical properties of composites were reached at 5% CMFs.

Green composites based on thermoplastic starch reinforced with micro- and nano-cellulose by melt blending - A review

Starch is a biodegradable biopolymer, a sustainable material that can replace conventional petrochemical-based plastics. However, starch has some limitations, as it must be processed by heating and treated mechanically with a plasticizer to become thermoplastic starch (TPS). Different variables such as mixing speeds, amount, and kind of plasticizers play a vital role in preparing TPS by melting. Despite this, the properties of the TPS are not comparable with those of traditional plastics. To overcome this limitation, microcellulose or nanocellulose is added to TPS by melt mixing, including the extrusion and internal mixing process, which enables large-scale production. This review aims to compile several studies that evaluate the effect of plasticizers, as well as the relevance of incorporating different cellulosic fillers of different dimensions on the properties of TPS obtained by melt mixing. Potential applications of these materials in food packaging, biomedical applications, and other opportunities are also described.

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.

Sustainable hemp-based bioplastics with tunable properties via reversible thermal crosslinking of cellulose

Modern bioplastics and biocomposites frequently contain non-biodegradable or non-sustainable components and require complex recycling routes. Sustainable materials require integrating bio-based, cheap, widely available, recycled, or waste components. In order to incorporate these concepts, we selected hemp stalk waste, the industrial byproducts glycerol and xylan (hemicellulose), and citric acid as key components. Hemp stalks were processed into cast papers using only mechanical processes and no chemical modifications or pre-treatments. Cast papers were impregnated with a crosslinking mixture of glycerol, xylan, citric acid, and the plasticizer polyethylene glycol (PEG). Thermal crosslinking was performed as a single-step reaction by curing materials at 140 °C. All prepared bioplastics were washed in water for 48 h and extensively tested for water resistance and water absorption. A recycling route with depolymerization (for pulp recovery) in sodium hydroxide is demonstrated. A comprehensive analysis of crosslinking reaction is provided via FTIR and rheology, supplemented by structure analysis via SEM. A 7-fold reduction in water uptake was achieved compared to cast hemp paper. Obtained bioplastics, after washing in water, show elastic modulus up to 2.9 GPa, tensile strength up to 70 MPa, and elongation up to 4.3 %. As a result of component ratio variation, bioplastics achieve a high tuneability of properties ranging from brittle to ductile. Dielectric analysis indicates that bioplastics have the potential for application in electric insulation. A three-layer laminate is demonstrated as a concept for potential application as an adhesive for bio-based composites.

Preparation of nanocellulose by a biological method from hemp stalk in contrast to the chemical method and its application on the electrospun composite film

In this study, CNFs were provided by an efficient, unmodified, and clean biological method with enzymes and a small amount of alkali, compared to the CNCs with the chemical method involving a strong acid. To provide an accurate targeted selection for future applications, we made the following comparison by analyzing the differences in the preparation method, performance, and application performance of the two nanocelluloses. The result of this study indicated that CNFs and CNCs exhibited a crystallinity index of 58.2 and 83.5%, respectively. CNFs had a mean length (L) of 192.3 nm and a diameter (D) of 1.9 nm, and the average L and D of CNCs reached 123.6 nm and 3.7 nm, respectively. The solution viscosity of CNFs and CNCs reached 7.46 Pa s and 1.91 Pa s, respectively. CNFs and CNCs exhibited zeta potential values of -88.26 mV and -26.40 mV, respectively. The electrospun composite film of PLA-CNFs and PLA-CNCs achieved water contact angles of 138.7 and 34.5°, and the water-oil contact angle reached 24.7 and 30.5°, respectively. The breaking strength of PLA-CNFs and PLA-CNCs reached 96.07 cN and 163.23 cN, and the break elongation followed an order of PLA-CNCs (32.16%) < PLA-CNFs (34.70%). In brief, CNFs can make the composite membrane hydrophobic and with superior extension, and CNCs can make the composite membrane hydrophilic and enhance its strength. Both the composite films conformed to the non-toxic standard, and the PLA-CNFs film more significantly contributed to the cell growth, which is expected to serve as a medical material.

Cellulose nanocrystalline from biomass wastes: An overview of extraction, functionalization and applications in drug delivery

Cellulose nanocrystals (CNC) have been extensively used in various fields due to their renewability, excellent biocompatibility, large specific surface area, and high tensile strength. Most biomass wastes contain significant amounts of cellulose, which forms the basis of CNC. Biomass wastes are generally made up of agricultural waste, and forest residues, etc. CNC can be produced from biomass wastes by removing the non-cellulosic components through acid hydrolysis, enzymatic hydrolysis, oxidation hydrolysis, and other mechanical methods. However, biomass wastes are generally disposed of or burned in a random manner, resulting in adverse environmental consequences. Hence, using biomass wastes to develop CNC-based carrier materials is an effective strategy to promote the high value-added application of biomass wastes. This review summarizes the advantages of CNC applications, the extraction process, and recent advances in CNC-based composites, such as aerogels, hydrogels, films, and metal complexes. Furthermore, the drug release characteristics of CNC-based material are discussed in detail. Additionally, we discuss some gaps in our understanding of the current state of knowledge and potential future directions of CNC-based materials.

Adsorption of cationic and anionic dyes onto coffee grounds cellulose/sodium alginate double-network hydrogel beads: Isotherm analysis and recyclability performance

This work describes the preparation of new eco-friendly adsorbents with a simple method. Gel beads of coffee grounds cellulose (CGC) and sodium alginate (SA) were prepared for wastewater treatment. Upon their synthesis, the physicochemical properties, performances and efficiency were analyzed by means of various structural and morphological characterizations. Kinetic and thermodynamic adsorption approaches evaluated the removal capacity of these beads which reached equilibrium in 20 min for Methylene Blue (MB) and Congo Red (CR). Also, the kinetics shows that the results can be explained by the pseudo-second-order model (PSO). Furthermore, the isotherm assessments showed that Langmuir-Freundlich can fit the adsorption data of both contaminants. Accordingly, the maximum adsorption capacities reached by the Langmuir-Freundlich model are 400.50 and 411.45 mg/g for MB and CR, respectively. It is interesting to note that the bio-adsorption capabilities of MB and CR on bead hydrogels decreased with temperature. Besides, the results of the thermodynamic study evidenced that the bio-adsorption processes are favorable, spontaneous and exothermic. The CGC/SA gel beads are therefore outstanding bio-adsorbents, offering a great adsorptive performance and regenerative abilities.

Strong, flexible and UV-shielding composite polyvinyl alcohol films with wood cellulose skeleton and lignin nanoparticles

The development of high-performance composite films using biomass materials have become a sought-after direction. Herein, a green method to fabricate strong, flexible and UV-shielding biological composite film from wood cellulose skeleton (WCS), lignin nanoparticles (LNPs) and polyvinyl alcohol (PVA) was described. In the work, WCS and LNPs were prepared by chemical treatment of wood veneer and Enzymatic lignin, respectively. Then, WCS was infiltrated with the LNPs/PVA mixtures and dried to obtain composite films. WCS enhanced the mechanical properties of the composite films, the tensile stress reached to 85.8 MPa and the tensile strain reached to 6.39 %. The composite films with LNPs blocked over 98 % of UV-light, the water absorption decreased by 30 %, and the thermal stabilities were also improved. These findings would provide some references for exploring high quality biological composite films.

Effects of direct sulfonation on the catalytic activity and recyclability of novel lignin-based solid acid catalysts from agri-food waste

Catalytic systems derived from lignin are emerging as quite efficient and profitable materials in many catalyzed transformations. However, these catalysts have been predominantly synthesized by carbonization. Alternatively, we prepared direct sulfonation lignin (DSL) and compared it to the carbonized-sulfonated lignin (CSL) catalyst, aiming to reveal the effects of direct functionalization of lignin on its catalytic performance and to simplify its preparation. Both catalysts were well characterized by several physicochemical techniques, and their catalytic activities were assessed by catalyzed esterification. Using CSL, the yield reached 94.11 % under the optimal conditions (60 °C, 4 h and 50 mg loading), while DSL yielded 93.97 % with only 2 h under the same conditions, which is attributed to the abundant catalytic active sites in DSL (0.62 mmol/g of SO₃H against 0.39 mmol/g for CSL). Furthermore, the activation energies were found to be 21 and 16 kJ mol^-1 for CSL and DSL, respectively, suggesting that esterification can occur with less energy input using DSL. Reusability showed that leaching of SO₃H groups and mass loss are inherently responsible for deactivation. However, both lignin-based catalysts show good stability and can be reused for 4 successive cycles. Direct lignin functionalization can be an alternative to conventional catalyst processing.

Extraction and surface modification of cellulose fibers and its reinforcement in starch-based film for packaging composites

BACKGROUND

Cellulose extraction from gloss art paper (GAP) waste is a recycling strategy for the abundance of gloss art paper waste. Here, a study was conducted on the impact of ultrasonic homogenization for cellulose extraction from GAP waste to improve the particle size, crystallinity, and thermal stability.

RESULTS

At treatment temperature of 75.8 °C, ultrasonic power level of 70.3% and 1.4 h duration, cellulose with properties of 516.4 nm particle size, 71.5% crystallinity, and thermal stability of 355.2 °C were extracted. Surface modification of cellulose GAP waste with H3PO4 hydrolysis and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation was done followed by starch reinforcement. Surface hydrophobicity and mechanical strength were increased for H3PO4 hydrolysis and TEMPO oxidation starch-cellulose. No reduction of thermal properties observed during the treatment, while increment of crystallinity index up to 47.65-59.6% was shown. Neat starch film was more transparent, followed by starch-TEMPO film and starch-H3PO4 film, due to better homogeneity.

CONCLUSIONS

The cellulose GAP reinforced starch film shows potential in developing packaging materials and simultaneously provide an alternative solution of GAP waste recycling.

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.

Enteromorpha cellulose micro-nanofibrils/poly(vinyl alcohol) based composite films with excellent hydrophilic, mechanical properties and improved thermal stability

This study presents the preparation of cellulose micro-nanofibrils (CMNFs) from Enteromorpha (EP) and the application in PVA/acetylated distarch phosphate (ADSP)/CMNFs composite films. The Micro-nano scale, hydrophilicity, and strong hydrogen bond characteristics of CMNFs prepared form EP by acid hydrolysis were confirmed through the granular statistics, XRD analysis and chemical structure analysis. With the addition of CMNFs, the ultimate tensile strength and elongation at break of composite films are increased by 42.4 % and 90.3 %. An original Weibull statistical analysis shows the impact of CMNFs' added amount on strength distribution and ultimate stress. SEM and polarizing microscope images show the CMNFs' dispersion state in that films is optimal, when their addition was to be 2 %-3 % of total dry weight of PVA/ADSP matrix， which is consistent with the results of Weibull modulus analysis. The main thermal weight-loss process of the composite film is divided into four stages, CMNFs can significantly increase the thermostability at 280 °C to 400 °C. The experiment of water contact angle and water vapor transmission rate of the composite films confirmed that CMNFs can improve films' hydrophilicity. This study provides basis for the preparation of hydrophilic CMNFs and mechanism of modification study PVA-based composites.

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.

Optimization of Hemp Bast Microfiber Production Using Response Surface Modelling

Non-wood biomass is particularly attractive as a cellulose source because of the lower lignin content. However, optimal cellulose extraction conditions are required as lignin content varies between plant sources. Further, the use of organic acids in place of harsh mineral acids is of interest in “greening” the cellulose production process. This study sought to establish optimum parameters for the extraction of cellulose microfibers (CMFs) from hemp (Cannabis sativa) biomass, using maleic and formic acids. Hemp fibers were pre-treated in NaOH (4 wt%) and aqueous chlorite in acetate buffer before ultrasonic treatment to break down bundles. The CMFs produced were compared with those generated from sulfuric acid hydrolysis. Response surface methodology (RSM) was used to determine combinations of three processing conditions, including acid concentration (45–64%), hydrolysis time (30–90 min), and temperature (45–65 °C). A central composite design (RSM-CCD) model with 21 experimental runs was optimized using MODDE 13.1 software. The model suitably described the data (R2 = 0.99; R2adj = 0.96). Microfibers with an average width of 6.91 µm, crystallinity range 40–75%, and good thermal stability were produced. Crystallinity was influenced by all three factors. The optimal crystallinity predicted by the model was 83.21%, which could be achieved using formic acid 62 wt% formic acid, 36 min hydrolysis time, and 47 °C hydrolysis temperature. These conditions resulted in a crystallinity degree of 82%. These data suggest formic acid can be used as an alternative to sulfuric acid for synthesis of cellulose microfibers from biodegradable hemp waste fibers.

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.

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.

Beneficiation of cactus fruit waste seeds for the production of cellulose nanostructures: Extraction and properties

Cactus fruit waste seeds (CWS) are a by-product of the cactus fruit processing industry. Until now, CWS are not recoverable in any sector. The valorization of these residues may reduce their volume in the environment and transform them into valuable products. In this work, CWS have been identified for the first time as a sustainable lignocellulosic source. Cellulose microfibers (CMFs) and nanocrystals (CNCs) were successfully produced via alkali and bleaching treatments followed by sulfuric acid hydrolysis. It was found that the extracted CMFs showed an average diameter of 11 μm, crystallinity of 72%, and a yield of 25%. The as-produced CNCs exhibited a needle-like shape with a diameter of 13 ± 3 nm and length of 419 ± 48 nm, giving rise to an aspect ratio of 30.7, with a zeta potential value of - 30 mV and a charge content of sulfate groups of 287.8 mmol·kg^-1. Herein, the obtained cellulosic derivatives with excellent properties from this underutilized waste can draw the attention of researchers towards CWS as a new type of biomass with virtually no hemicellulose, which could be of great interest to isolate and study the effects of how lignin interacts with cellulose.

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.

Extraction of cellulose nanocrystals from areca waste and its application in eco-friendly biocomposite film

Areca nut husk fibers are easily available and they are abundant agricultural waste, whose utilization to high value products needs more attention. The present study aims at the extraction of cellulose nanocrystals (CNCs) from areca nut husk fibers and the evaluation of its reinforcement capacity in polyvinyl alcohol (PVA) and chitosan (CS) film. The CNC showed rod-like structures, which were confirmed by TEM and AFM analysis. The diameter of the isolated CNC was 19 ± 3.3 nm; the length was about 195 ± 24 nm with an aspect ratio of 10.2 ± 6.8. The zeta potential of CNC was -15.3 ± 1.2 mV. Fourier Transform Infrared Spectroscopy analysis showed that the non-cellulosic compounds were effectively eliminated, and the X-ray diffraction results showed that CNC had higher crystallinity than the raw, alkali, and the bleached fibers. Thermogravimetric analysis revealed good thermal stability for the CNC. Moreover, the effects of the incorporation of CNC on the optical and tensile behaviours of the bionanocomposite film were investigated. The bionanocomposite film retained the same transparency as the PVA/CS film, indicating that the CNC was disseminated evenly in the film. The incorporation of CNC (3 wt%) to the PVA/CS film enhanced the tensile strength of the bionanocomposite film (9.46 ± 1.6 MPa) when compared to the control films (7.81 ± 1.4 MPa). Furthermore, the prepared nanobiocomposite film exhibited good antimicrobial activity against foodborne pathogenic bacteria and postharvest pathogenic fungi. These findings suggest that the bionanocomposite film might be suitable for food packaging applications.

The Effect of Varying the Amount of Short Hemp Fibers on Mechanical and Thermal Properties of Wood-Plastic Composites from Biobased Polyethylene Processed by Injection Molding

Biobased HDPE (bioHDPE) was melt-compounded with different percentages (2.5 to 40.0 wt.%) of short hemp fibers (HF) as a natural reinforcement to obtain environmentally friendly wood plastic composites (WPC). These WPC were melt-compounded using a twin-screw extrusion and shaped into standard samples by injection molding. To improve the poor compatibility between the high non-polar BioHDPE matrix and the highly hydrophilic lignocellulosic fibers, a malleated copolymer, namely, polyethylene-graft-maleic anhydride (PE-g-MA), was used. The addition of short hemp fibers provided a remarkable increase in the stiffness that, in combination with PE-g-MA, led to good mechanical performance. In particular, 40 wt.% HF drastically increased the Young’s modulus and impact strength of BioHDPE, reaching values of 5275 MPa and 3.6 kJ/m², respectively, which are very interesting values compared to neat bioHDPE of 826 MPa and 2.0 kJ/m². These results were corroborated by dynamic mechanical thermal analysis (DMTA) results, which revealed a clear increasing tendency on stiffness with increasing the fiber loading over the whole temperature range. The crystal structure was not altered by the introduction of the natural fibers as could be seen in the XRD patterns in which mainly the heights of the main peaks changed, and only small peaks associated with the presence of the fiber appeared. Analysis of the thermal properties of the composites showed that no differences in melting temperature occurred and the non-isothermal crystallization process was satisfactorily described from the combined Avrami and Ozawa model. As for the thermal degradation, the introduction of HF resulted in the polymer degradation taking place at a higher temperature. As for the change in color of the injected samples, it was observed that the increase in fiber generated a clear modification in the final shades of the pieces, reaching colors very similar to dark woods for percentages higher than 20% HF. Finally, the incorporation of an increasing percentage of fibers also increased water absorption due to its lignocellulosic nature in a linear way, which drastically improved the polarity of the composite.

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.