Preparation and characterization of nanocrystalline cellulose/Eucommia ulmoides gum nanocomposite film

Efficient extraction of Eucommia ulmoides gum by a deep eutectic solvent-organic solvent biphasic recyclable system

Eucommia ulmoides gum (EUG) with high purity was extracted directly from the Eucommia ulmoides pericarp using a biphasic solvent system consisting of deep eutectic solvent (DES) and petroleum ether. The addition of DES enabled the deconstruction of lignocellulose and the exposure of EUG, leading to the efficient dissolution of EUG in petroleum ether. The extraction rate of EUG was 22.986 %, and the purity of EUG was 98.01 %. The chemical structure of EUG was confirmed by FTIR and NMR characterization. XRD and DSC analysis reviewed the partial destruction of crystal structure and the decline of β-crystal phase of EUG during the extraction process. Moreover, the extracted EUG exhibited high tensile strength of 10.360 MPa, excellent elongation at break of 78.663 % ascribed to the unique crystallinity that enhanced the flexibility of molecular chains. In addition, the recycling performance of DES and petroleum ether was verified, and the recovery rate were up to 94.04 % and 82.60 %, respectively, indicating that this method is expected to replace the traditional pretreatment method for extracting EUG.

Development of active chitosan film containing bacterial cellulose nanofibers and silver nanoparticles for bread packaging

The objective was to develop an active chitosan-based coating and to evaluate its effect on the shelf life and microbial safety of bread. Bacterial cellulose nanofibers (BCNF) and various levels (0.5%, 1%, and 2%) of silver nanoparticles (AgNPs) were in the chitosan (CS) film. Characterization of films was determined by analyzing WVP, ultraviolet barrier, and opacity as well as FTIR, XRD, DSC, TGA, and SEM. The water vapor permeability (WVP) of CS was remarkably (p < .05) decreased from 3.75 × 10-10 to 0.85 × 10-10 g/smPa when filled with BCNF and 2% AgNPs. Thermal and structural properties were enhanced in nanoparticle-included films. Applying CS/BCNF/AgNPs coatings for bread samples demonstrated a significant improvement in moisture retention and a decrease in the hardness (from 10.2 to 7.05 N for CS and CS/BCNF/1% AgNPs coated samples, respectively). Moreover, microbial shelf life of bread sample increased from 5 to 38 days after packaging with CS/BCNF/2% AgNPs film. After a storage period of 15 days at 25°C, no fungal growth was detected in bread samples which were coated with nanocomposite suspensions containing 1% and 2% AgNPs. However, at the same condition, yeast and mold counts was 7.91 log CFU/g for control sample. In conclusion, the CS/BCNF/2% AgNPs film might have the potential for use as active packaging of bread.

Advances in Eucommia ulmoides polysaccharides: extraction, purification, structure, bioactivities and applications

Eucommia ulmoides (EU) is a precious tree species native to China originating during the ice age. This species has important economic value and comprehensive development potential, particularly in medicinal applications. The medicinal parts of EU are its bark (Eucommiae cortex) and leaves (Eucommiae folium) which have been successively used as a traditional Chinese medicine to treat diseases since the first century BC. During the last 2 decades, as natural polysaccharides have become of increasing interest in pharmacology, biomedicine, cosmetic and food applications, more and more scholars have begun to study polysaccharides derived from EU as well. EU polysaccharides have been found to have a variety of biological functions both in vivo and in vitro, including immunomodulatory, antioxidant, anti-inflammatory, anticomplementary, antifatigue, and hepatoprotective activities. This review aims to summarize these recent advances in extraction, purification, structural characteristics, pharmacological activities and applications in different fields of EU bark and leaf polysaccharides. It was found that both Eucommiae folium polysaccharides and Eucommiae cortex polysaccharides were suitable for medicinal use. Eucommiae folium may potentially be used to substitute for Eucommiae cortex in terms of immunomodulation and antioxidant activities. This study serves as a valuable reference for improving the comprehensive utilization of EU polysaccharides and further promoting the application of EU polysaccharides.

Characterization of active films based on chitosan/polyvinyl alcohol integrated with ginger essential oil-loaded bacterial cellulose and application in sea bass (Lateolabrax japonicas) packaging

The poor mechanical properties, low water-resistance, and limited antimicrobial activity of chitosan (CS)/polyvinyl alcohol (PVA) based film limited its application in aquatic product preservation. Herein, bacterial cellulose (BC) was used to load ginger essential oil (GEO). The effects of the addition of BC and different concentrations of GEO on the physicochemical and antimicrobial activities of films were systematically evaluated. Finally, the application of sea bass fillets was investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD) analysis indicated dense networks were formed, which was verified by enhanced physical properties. The mechanical properties, barrier properties, and antimicrobial activities enhanced as GEO concentration increased. CPB0.8 (0.8 % GEO) film had better tensile strength (TS) and barrier performance, improved the quality, and extended the shelf-life of sea bass for another 6 days at least. Overall, active films are potential packaging materials for aquatic products.

Bioinspired multiscale cellulose/lignin-silver composite films with robust mechanical, antioxidant and antibacterial properties for ultraviolet shielding

Constructing a high-performance ultraviolet shielding film is an effective way for addressing the growing problem of ultraviolet radiation. However, it is still a great challenge to achieve a combination of multifunctional, excellent mechanical properties and low cost. Here, inspired by the multiscale structure of biomaterials and features of lignin, a multifunctional composite film (CNF/CMF/Lig-Ag) is constructed via a facile vacuum-filtration method by introducing micron-sized cellulose fibers (CMF) and lignin-silver nanoparticles (Lig-Ag NPs) into the cellulose nanofibers (CNF) film network. In this composite film, the microfibers interweave with nanofibers to form a multiscale three-dimensional network, which ensures satisfactory mechanical properties of the composite film. Meanwhile, the Lig-Ag NPs are employed as a multifunctional filler to enhance the composite film's antioxidant, antibacterial and ultraviolet shielding abilities. As a result, the prepared CNF/CMF/Lig-Ag composite film demonstrates excellent mechanical properties (with tensile strength of 133.8 MPa and fracture strain of 7.4 %), good biocompatibility, high thermal stability, potent antioxidant and antibacterial properties. More importantly, such composite film achieves a high ultraviolet shielding rate of 98.2 % for ultraviolet radiation A (UVA) and 99.4 % for ultraviolet radiation B (UVB), respectively. Therefore, the prepared CNF/CMF/Lig-Ag composite film shows great potential in application of ultraviolet protection.

A review of "plant gold" Eucommia ulmoides Oliv.: A medicinal and food homologous plant with economic value and prospect

Eucommia ulmoides Oliv. is an ancient and precious plant that has been used as medicine in China for more than 2000 years. Because its bark, leaves, seeds, and male flowers can be used in medicine, it plays an important role in medicine, food, chemical industry, and other fields, so it is also called "plant gold". 246 compounds have been isolated from E. ulmoides, which endow E. ulmoides with many unique pharmacological effects and make it wide to study in the fields of osteoporosis, hypertension, liver protection, and so on. Besides, E. ulmoides also has significant medicinal effects on anti-inflammatory, antioxidant, immunomodulation, and neuroprotection, and is often used in clinical compound medicines of traditional Chinese medicine. In addition to updating its ethnobotany, phytochemistry, pharmacology, and toxicology information, the economic botany of leaves, seeds, and male flowers was also introduced. It hopes hoping to fully understand this economically important Chinese medicine and provide a scientific basis for further development and utilization of E. ulmoides.

Light-activated cellulose nanocrystals/fluorinated polyacrylate-based waterborne coating: Facile preparation, mechanical and self-healing behavior

The development of environmental-friendly self-healing nanocomposites has attracted much attention. In this paper, the light-activated cellulose nanocrystals/ fluorinated polyacrylate-based waterborne coating based on the reversible cycloaddition reaction of the coumarin groups was prepared via Pickering emulsion polymerization. The cellulose nanocrystals (CNCs) modified by the PDMAEMA-b-PGMA-b-P(HFBA-co-VBMC) copolymer were studied via FT-IR and TGA. In addition, the dispersity and interface behavior of CNCs before and after modification were investigated by DLS and interfacial tension measurements. Afterwards, we focused on the influence of modified CNCs, PDMAEMA-g-CNC-g- P(HFBA-co-VBMC) (MCNC) dosage on the Pickering emulsion, emulsion polymerization and properties of latex film. The droplet diameter of Pickering emulsion gradually reduced with the increase of MCNC dosage. The MCNC dosage for the minimum average size and optimum stability of latex particles was 1.0 wt%. Moreover, the latex film comprising 1.0 wt% MCNC presented not only high tensile stress (6.0 MPa), large elongation at break (567.70 %) and superior oil/water repellency but also excellent self-healing properties. The outstanding self-healing capability of latex film was attributed to the reversible light-activated dimerization of coumarin groups. The preparation method for the advanced performance waterborne cellulose nanocrystals/fluorinated polyacrylate will provide valuable guidance for the development of versatile materials.

A Study of Molecular Dynamic Simulation and Experimental Performance of the Eucommia Ulmoides Gum-Modified Asphalt

In recent years, eucommia ulmoides gum (EUG), also known as gutta-percha, has been extensively researched. Molecular dynamic simulations and experiments were used together to look at how well gutta-percha and asphalt work together and how gutta-percha-modified asphalt works. To investigate the gutta-percha and asphalt blending systems, the molecular models of asphalt and various dosages of gutta-percha-modified asphalt were set up using Materials Studio (MS), and the solubility parameters, intermolecular interaction energy, diffusion coefficient, and mechanical properties (including elastic modulus, bulk modulus, and shear modulus) of each system were calculated using molecular dynamic simulations at various temperatures. The findings indicate that EUG and asphalt are compatible, and sulfurized eucommia ulmoides gum (SEUG) and asphalt are more compatible than EUG. However, SEUG-modified asphalt has better mechanical properties than EUG, and the best preparation conditions are 10 wt% doping and 1 h of 180 °C shearing. Primarily, physical modifications are required for gutta-percha-modified asphalt.

Extraction of Eucommia ulmoides gum and microbial lipid from Eucommia ulmoides Oliver leaves by dilute acid hydrolysis

OBJECTIVES

Eucommia ulmoides gum (EUG) is an important natural biomass rubber material, which is usually extracted from Eucommia ulmoides Oliver (EUO). In the extraction process of EUG, pretreatment is the most important step which can efficiently damage EUG-containing cell wall and improve yield of EUG.

RESULTS

The FT-IR, XRD, DSC and TG results showed that the thermal properties and structure of the EUG from the dilute acids hydrolysis residue are similar with that of the EUG directly extracted from EUO leaves (EUGD). EUO leaves hydrolysis with AA had the highest EUG yield (16.1%), which was higher than the EUGD yield (9.5%). In the case of the EUO leaves hydrolysis with 0.33 ~ 0.67 wt% of acetic acid (AA), the total sugar was stable in the range of 26.82-27.67 g/L. Furthermore, the EUO leaves acid hydrolysate (AA as reagent) was used as carbon sources for lipid-producing fermentation by Rhodosporidium toruloides. After 120 h of fermentation, the biomass, lipid content and lipid yield were 12.13 g/L, 30.16% and 3.64 g/L, respectively. The fermentation results indicated organic acids were no toxic for Rhodosporidium toruloides and the AA also could be used as carbon source for fermentation.

Fermentation performance of oleaginous yeasts on Eucommia ulmoides Oliver hydrolysate: Impacts of the mixed strains fermentation

This present study mainly focused on the investigation and optimization of the fermentation performance of oleaginous yeasts on Eucommia ulmoides Oliver hydrolysate (EUOH), which contains abundant and diverse sugars. More importantly, the impacts of the mixed strains fermentation compared with the single strain fermentation were analyzed and evaluated, through systematic investigations of substrate metabolism, cell growth, polysaccharide and lipid production, COD and ammonia-nitrogen removals. It was found that the mixed strains fermentation could effectively promote a more comprehensive and thorough utilization of the various sugars in EUOH, greatly improve COD removal effect, biomass and yeast polysaccharide production, but could not significantly improve the overall lipid content and ammonia nitrogen removal effect. In this study, when the two strains with the highest lipid content (i.e. L. starkeyi and R. toruloides) were mixed-cultured, the maximum lipid yield of 3.82 g/L was achieved, and the yeast polysaccharide yield, COD and ammonia-nitrogen removal rates of the fermentation (LS+RT) were 1.64 g/L, 67.4% and 74.9% respectively. When the strain with the highest polysaccharide content (i.e. R. toruloides) was mixed-cultured with the strains with strong growth activity (i.e. T. cutaneum and T. dermatis), a large amount of yeast polysaccharides could be obtained, which were 2.33 g/L (RT+TC) and 2.38 g/L (RT+TD) respectively. And the lipid yield, COD and ammonia-nitrogen removal rates of the fermentation (RT+TC), (RT+TD) were 3.09 g/L, 77.7%, 81.4% and 2.54 g/L, 74.9%, 80.4%, respectively.

N-doped carbon fibers in situ prepared by hydrothermal carbonization of Camellia sinensis branches waste for efficient removal of heavy metal ions

N-doped carbon fibers (NCFs) were in situ prepared by Camellia sinensis branches waste through hydrothermal carbonization with urea/ZnCl2 at 160-280 °C under 0.8-8.9 MPa. The structural characteristics of NCFs were investigated by elemental analysis, SEM, TEM, XRD, XPS, Raman spectra, and BET surface area. The highest N content of NCFs obtained at 280 °C was 8.96%, and the main forms of doped N were pyridinic N, pyrrolic N, and graphitic N. Moreover, NCFs were applied to remove metal ions successfully. The results showed that NCF-240 had the maximum adsorption amounts of 106.52, 125.23, and 153.49 mg/g for Cu2+, Pb2+, and Zn2+, respectively, while NCF-280 had the best removal ability on Cr6+ (145.67 mg/g). Finally, it demonstrated that the adsorption behavior of NCFs was well fitted by the pseudo-second-order kinetic and the Langmuir adsorption isotherm models.

In-Situ Oxidative Polymerization of Pyrrole Composited with Cellulose Nanocrystal by Reactive Ink-Jet Printing on Fiber Substrates

A simple and novel method for the deposition of polypyrrole (PPy) and cellulose nanocrystal (CNC) composites on different fiber substrates by reactive ink-jet printing was proposed. PPy/CNCs composites were successfully prepared, and the surface resistance of conductive layer deposited on different fiber substrates is the least when the monomer concentration is 0.6 M. PPy/CNCs were deposited on polyethylene terephthalate (PET) to form a conductive layer by adding polyvinyl alcohol (PVA), and the optimum sintering temperature is 100 °C (monomer/PVA ratio 4.0, conductivity 0.769 S cm⁻¹). The PPy/CNCs conductive layer deposited on the paper has the lowest surface resistance and the best adhesion, and the surface resistance of PPy/CNCs conductive layer decreases first and then increases with the increase of sulfonate concentration. Moreover, the volume of anion in sulfonate will affect the arrangement and aggregation of PPy molecular chain in composite materials. Appropriate sulfonate doping can improve the conductivity and stability of conductive paper, and the maximum conductivity is 0.813 S cm⁻¹. Three devices based on PPy/CNCs conductive paper were proposed and fabricated. Therefore, this ink-jet printing provides a new method for the preparation of conductive materials, sensors, energy storage and electromagnetic shielding, etc.

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.

Development of nitrile rubber/eucommia ulmoides gum composites for controllable dynamic damping and sound absorption performance

Aiming at enhancing the damping and sound absorption performances of nitrile rubber (NBR) incorporated Eucommia ulmoides gum (EUG), a series of NBR/EUG composites were successfully fabricated using an open mixing mill. The co-vulcanization behaviors, fracture surface morphology observations, mechanical and thermal properties and damping and sound absorption performances of NBR/EUG composites were investigated systematically. It was shown that the crystalline area and the amorphous area in NBR/EUG composites displayed a sea-island phase distribution and most of the EUG crystals were β-form crystals. Compared to that of neat NBR, the tensile strength and storage modulus of NBR/EUG composites increased dramatically with the increasing EUG content, owing to the gradually increasing number of crystals in the NBR/EUG composites. In addition, the incorporation of EUG into the NBR matrix distinctly improved the sound absorption performance of NBR/EUG composites. This work is expected to provide a new insight into the fabrication of other composite materials with controllable damping and sound absorption properties.

Nitrile rubber (NBR)/Eucommia ulmoides gum (EUG) composites were successfully fabricated with controllable dynamic damping and sound absorption performances, owing to the changeable EUG crystal number in different NBR/EUG composites.

Fluorescent nanocellulose-based hydrogel incorporating titanate nanofibers for sorption and detection of Cr(VI)

Chromium pollution is a major environmental concern; thus, effective and multifunctional adsorbents for removing the Cr(VI) ion are urgently needed. A fluorescent nanocellulose-based hydrogel (FNH) incorporating titanate nanofibers (TNs) was developed for the sorption and detection of Cr(VI) ion. The chemical and physical structures of the hydrogels, as well as their sorption and detection properties, were studied. The predicted maximum adsorption capacity and the lowest detection limit of FNH were 648.4 mg/g and 0.039 μg/L, respectively. Furthermore, the sorption and detection mechanisms of FNH were discussed in detail. These results showed that the excellent sorption and detection might be mainly attributed to the three-dimensional (3D) porous structure constructed by TNs and cellulose nanocrystals modified with carbon dots, which improved the sorption ability and provided the rapid visual response to Cr(VI). Furthermore, cost analysis showed that FNH was cheaper than activated carbon in removing the Cr(VI) ion. This work established a facile technique in developing low-cost and multifunctional adsorbents.

Effects of Eucommia ulmoides gum content and processing conditions on damping properties of E. ulmoides gum/nitrile-butadiene rubber nanocomposites

In order to improve the effective damping of nitrile-butadiene rubber (NBR) in a wider temperature range, Eucommia ulmoides gum (EUG) was incorporated into NBR to prepare nanocomposites. Atomic force microscopy (AFM) showed that EUG was dispersed in NBR matrix in the form of nanocrystals. Compared with pure NBR, the mechanical properties of NBR/EUG (80/20) composites are significantly improved. Dynamic thermo-mechanical analysis (DMA) showed that there are two dynamic mechanical loss peaks in two composites. With the increase of EUG component, the peak value of loss factor (tanδ) decreases gradually at −10 °C, and the temperature corresponding to the peak value tends to move towards high temperature, while the peak area increases gradually at −50 °C. Parking and repeated mixing make both loss peaks move towards high temperature. The differential scanning calorimetry analyzer (DSC) results expressed that the melting temperature and peak area of EUG after vulcanization decreased significantly compared with that before vulcanization. Hence, the damping effect of NBR can be improved and its damping temperature range can be widened by adding EUG and changing processing conditions.

Carboxymethyl chitosan incorporated with gliadin/phlorotannin nanoparticles enables the formation of new active packaging films

Advanced carboxymethyl chitosan (CMCS) based functional films were fabricated by involving some amounts of gliadin/phlorotannin nanoparticles (GPNPs) using a solution casting method. GPNPs were synthesized by an antisolvent precipitation approach, and they presented a spherical morphology with a mean diameter of 145.30 ± 2.06 nm. The effect of GPNPs concentration on the structural, physical, antioxidant and antimicrobial properties of CMCS-GPNPs (C-G) functional films was evaluated. It was found that the added GPNPs were homogeneously distributed over the whole CMCS matrix, allowing to reduce the free volume of the nanocomposite matrix and subsequently improve the physical properties of the final film (evidenced by mechanical and water barrier properties). FT-IR spectra indicated the intermolecular interactions, such as hydrogen bonds and electrostatic interaction, within the matrix of the nanocomposite films were increased. Impressively, the anti-ultraviolet properties, antioxidant activity and antimicrobial behaviors of the as-formed C-G functional films were greatly enhanced compared to the pure CMCS film. All these results suggested that our as-prepared C-G nanocomposite films could be a promising food packaging material.

Fabrication of Millable Polyurethane Elastomer/Eucommia Ulmoides Rubber Composites with Superior Sound Absorption Performance

Sound absorbing materials combining millable polyurethane elastomer (MPU) and eucommia ulmoides rubber (EUG) were successfully fabricated via a physical blending process of EUG and MPU. The microstructure, crystallization performances, damping, mechanical and sound absorption properties of the prepared MPU/EUG composites were investigated systematically. The microstructure surface of various MPU/EUG composites became rough and cracked by the gradual incorporation of EUG, resulting in a deteriorated compatibility between EUG and MPU. With the increase of EUG content, the storage modulus (E') of various MPU/EUG composites increased in a temperature range of -50 °C to 40 °C and their loss factor (tanδ) decreased significantly, including a reduction of the tanδ of MPU/EUG (70/30) composites from 0.79 to 0.64. Specifically, the addition of EUG sharply improved the sound absorption performances of various MPU/EUG composites in a frequency range of 4.5 kHz-8 kHz. Compared with that of pure MPU, the sound absorption coefficient of the MPU/EUG (70/30) composite increased 52.2% at a pressure of 0.1 MPa and 16.8% at a pressure of 4 MPa, indicating its outstanding sound absorption properties.

Efficient removal of acetic acid by a regenerable resin-based spherical activated carbon

Carboxylic acids are the main pollutant of industrial wastewater during the advanced oxidation process (AOPs). In this study, a resin-based spherical activated carbon (RSAC, AF₅) as an adsorbent was examined and acetic acid was used as a model substrate for adsorption investigation. The pH = 3, temperature = 298 K were fixed by batch technique. The pseudo-second-order kinetic model, the intraparticle and external models are fitted well, and it was found that the adsorption of acetic acid onto AF₅ was controlled by liquid film diffusion. A Freundlich model indicated that the adsorption process was heterogeneous multimolecular layer adsorption on the surface. AF₅ shows good regenerative ability; the recovery rate of adsorption capacity was ∼88% after five cycles. Chemical oxygen demand (COD) adsorption removal rate could be maintained at 100% for over 35 h in an actual AOPs effluent, and could be eluted for 100% after 8 h by 0.8wt% NaOH. Characterizations, including XRF, XRD, TG/DSC,FTIR, SEM and N₂ adsorption, showed that the excellent adsorption performance was mainly due to the microporous structure and large specific surface area (1,512.88 m²/g), the adsorption mechanism mainly included pore filling effect and electrostatic attraction. After five adsorption recycles, AF₅'s pore characteristic did not change significantly. This study provides a scientific basis for the wastewater standard discharge process of AOPs coupled adsorption.

Natural Polymer Eucommia Ulmoides Rubber: A Novel Material

As the second natural rubber resource, Eucommia ulmoides rubber (EUR) from Eucommia ulmoides Oliver is mainly composed of trans-1,4-polyisoprene, which is the isomer of natural rubber cis-1,4-polyisoprene from Hevea brasiliensis. In the past few years, the great potential application of EUR has received increasing attention, and there is a growing awareness that the natural polymer EUR could become an emerging research topic in field of the novel materials due to its unique and excellent duality of both rubber and plastic. To gain insight into its further development, in this review, the extraction, structure, physicochemical properties, and modification of EUR are discussed in detail. More emphasis on the potential applications in the fields of the environment, agriculture, engineering, and biomedical engineering is summarized. Finally, some insights into the challenges and perspectives of EUR are also suggested.

Fabrication and Characterization of Chitosan/Cellulose Nanocrystal/Glycerol Bio-Composite Films

Cellulose nanocrystal (CNC)-reinforced bio-composite films containing glycerol were produced using the solution casting technique. The influences of the addition of CNC (2, 4, and 8 wt%) and glycerol (10, 20, and 30 wt%) on the properties of the bio-composite films were studied in the present work. The resulting films were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetry analysis (TGA), and according to their tensile, water absorption, and light transmission behavior. The introduction of 4 wt% CNC into the chitosan film did not affect the thermal stability, but the presence of 20 wt% glycerol reduced the thermal stability. The addition of 4 wt% CNC to the chitosan film increased its tensile strength, tensile modulus, and elongation at break by 206%, 138%, and 277%, respectively. However, adding more than 8 wt% CNC resulted in a drastic reduction in the strength and ductility of the chitosan film. The highest strength and stiffness of the chitosan bio-composite film were attained with 4 wt% CNC and 20 wt% glycerol. The water absorption and light transmission of the chitosan film were reduced dramatically by the presence of both CNC and glycerol.

Use of gamma irradiation technology for modification of bacterial cellulose nanocrystals/chitosan nanocomposite film

The objective of this work was to investigate the influence of different gamma ray dosages (5, 10, and 10 kGy) on the structural, mechanical, surface and barrier properties of chitosan (Ch) based nanocomposite film. The results showed gamma irradiation caused an increase in the surface hydrophobicity, water vapor permeability and sensitivity of films to water and also, yellowness and opacity of films increased, simultaneously. By increasing the irradiation doses up to 10 kGy, the mechanical properties of Ch/BCNC film was significantly enhanced. As observed by FTIR spectra, no change occurred in the chemical functional groups of the films during irradiation. XRD studies confirmed that crystallinity of films was increased after irradiation. The nanocomposite film irradiated by 10 kGy had the highest thermal stability. In conclusion, gamma radiation can be considered as a safe method for sterilization of foods and modification of Ch/BCNC film properties.

Preparation and characterization of carboxymethyl cellulose-based composite films reinforced by cellulose nanocrystals derived from pea hull waste for food packaging applications

Pea hull is a renewable, readily available and abundant agricultural waste whose high-value utilization deserves more attentions. This work aimed at the isolation of cellulose nanocrystals (CNC) from pea hull and evaluation its reinforcement capability for carboxymethyl cellulose (CMC) film. The obtained CNC displayed needle-like shapes with length of 81-286 nm, diameter of 8-21 nm, aspect ratio of 16 and crystallinity index of 0.77. The effects of CNC content on the morphologies, optical, mechanical, water vapor barrier and thermal properties of CMC/CNC films were investigated. SEM images showed that the CNC was evenly distributed in the CMC matrix to form homogenous films when the content of CNC was ≤5 wt%. The CMC/CNC composite films showed improved UV barrier, mechanical strength, water vapor barrier and thermal stability. Compared with pure CMC film, an increase of 50.8% in tensile strength and a decrease of 53.4% in water vapor permeability were observed for 5 wt% CNC-reinforced composite film. Furthermore, 5 wt% CNC-reinforced composite film was used for red chilies packaging, which is very effective at reducing weight loss and maintaining vitamin C compared with uncoated red chilies. These results indicated that the CMC/CNC composite film may have promising application potential as edible food packaging material.

Preparation of Ag-cellulose nanocomposite for the selective detection and quantification of mercury at nanomolar level and the evaluation of its photocatalytic performance

Mercury is a toxic heavy metal that reaches to the water bodies mainly by coal burning, mining and petrol refining. The study was focused to investigate the application of Ag-cellulose nanocomposite to detect and quantify mercury colorimetrically. The Ag-cellulose nanocomposite was characterized by X-ray diffraction, Transmission electron microscopy, Fourier transform infrared spectroscopy, UV-visible spectroscopy, particle size analyzer and zetasizer. The study identified that the presence of other metal ions did not interfere with the detection of Hg²⁺ ion by the probe. The prepared Ag-cellulose nanocomposite-phenylalanine conjugate incorporated paper strip showed an excellent result in Hg²⁺ detection. The Ag-cellulose nanocomposite was used to quantify the unknown concentration of mercury on real sample (environmental sample) and it was found to be highly accurate by confirming with atomic absorption spectrophotometric analysis. The Ag-cellulose nanocomposite showed effective detection at 45 °C, pH 9 and 0.1% of salinity. The Ag-cellulose nanocomposite showed efficient photocatalytic performance under visible light irradiation. The half-life period of MB by Ag-cellulose nanocomposite under visible light was determined to be 90 min. The study suggests the application of prepared probe in photocatalysis and the detection of Hg²⁺ from various environmental samples.

Bio-based active food packaging materials: Sustainable alternative to conventional petrochemical-based packaging materials

In food industry, a growing concern is the use of suitable packaging material (i.e., biodegradable coatings and films) with enhanced thermal, mechanical and barrier characteristics to prevent from contamination and loss of foodstuff. Biobased polymer resources can be used for the development of biodegradable bioplastics. To achieve this goal, biopolymers should be economic, renewable and abundantly available. Bioplastic packaging materials based on renewable biomass could be used as sustainable alternative to petrochemically-originated plastic materials. This review summarizes the recent advancements in biopolymer-based coatings and films for active food packaging applications. Microbial polymers (PHA and PLA), wood-based polymers (cellulose, hemicellulose, starch & lignin), and protein-based polymers (gelatin, keratin, wheat gluten, soy protein and whey protein isolates) were among the materials most widely exploited for the development of smart packaging films. These biopolymers are able to synthesize coatings and films with good barrier properties against food borne pathogens and the transport of gases. Biobased reinforcements e.g., plant essential oils and natural additives to bioplastic films improve oxygen barrier, antibacterial and antifungal properties. To induce the desired functionality the simultaneous utilization of different synthetic and biobased polymers in the form of composites/blends is also an emerging area of research. Nanoscale reinforcements into bioplastic packaging have also been reported to improve packaging characteristics ultimately increasing food shelf life. The development of bioplastic/biocomposite and nanobiocomposites exhibits high potential to replace nonbiodegradable materials with characteristics comparable to fossil-based plastics, additionally, giving biodegradable and compostable characteristics. The idea of utilization of renewable biomass and the implications of biotechnology can firstly reduce the burden from fossil-resources, while secondly promoting biobased economy.

Structural analysis and heavy metal adsorption of N-doped biochar from hydrothermal carbonization of Camellia sinensis waste

N-doped biochar as adsorption material for heavy metal removal has attracted increasing concern in environmental application due to its unique features. Here, N-doped biochar was prepared by hydrothermal carbonization of Camellia sinensis branch waste using KOH/NH₄Cl at 120-280 °C for 2 h under 0.4-6.5 MPa, followed by structural analysis. The results showed that the highest N content determined by elemental analysis could reach up to 6.18% in biochar, and the major N species were involved in graphitic N, pyrrolic N, and pyridinic N. Interestingly, these N-doped biochar exhibited the effective adsorption ability of Cu²⁺, Pb²⁺, Zn²⁺, and Cr⁶⁺. The batch adsorption behavior had a better adjustment to the pseudo-second-order kinetic and the Langmuir adsorption isotherm models. In brief, the present results are attributed to develop low-cost adsorbent for removing heavy metal ions.

Development and characterization of a novel edible film based on Althaea rosea flower gum: Investigating the reinforcing effects of bacterial nanocrystalline cellulose

Althaea rosea flowers were used to procure the gum (ARG) needed for film preparation. Pretest studies suggested 1.5% ARG + 50% glycerol as optimum for film preparation. The reinforcement impact of 3, 5, and 8 wt% bacterial nanocrystalline cellulose (BNC) incorporation (based on the dry weight of ARG) was investigated on the structural, mechanical, physical, thermal, optical, morphological, and barrier properties of films. The Results suggested that increasing the BNC concentration until a certain level (5 wt% BNC) could improve the latter properties. However, at higher concentration (8 wt% BNC), cellulose nanoparticles tended to agglomerate, which led to the impairment of some of those properties, especially barrier properties. According to AFM and SEM results, BNC addition increased surface roughness and coarseness. All BNC-loaded films showed better functions compared to control sample (0 wt% BNC) and the film containing 5 wt% BNC was suggested as the optimum film.