Isolated Cellulose Nanofibers Research Articles

Crystallization by Acid Hydrolysis-Sulfonation of Cellulose Nanofibers from <i>Eichhornia crassipes</i>

This study reports the synthesis of cellulose nanocrystals (CNC) sulfonation from the isolated cellulose nanofibers (CNF) of the Eichhornia crassipes stems. The crystallization of fibers was done by varying the time of sulfonation, 30 min (CNC30) and 60 min (CNC60), in 6M sulfuric acid. Scanning electron microscope images (SEM), and energy dispersive X-ray spectroscopy (EDS) revealed that the crystals have a grain flakey-like structure with the detected presence of oxygen, carbon, and sulfur (due to the sulfonation) atoms. Using Fourier transform infrared spectroscopy (FTIR), unique functional groups of CNCs were detected. Further, the X-ray diffraction (XRD) scans revealed that CNCs have a cellulose-Ib monoclinic unit cell structure with Miller indices (200) and (400). Additionally, results showed that CNC30 has 74.45% and CNC60 has 76.13% crystal index percent and a crystal thickness of 0.048 nm for CNC30 and 0.047 nm for CNC60. Lastly, d-spacing of CNC30 and CNC60 exhibited values of 3.26 Å and 3.20 Å, respectively. These results warrant further studies on future applications of the produced CNC from Eichhornia crassipes fibers.

Bacterial Cellulose-Based Biofilm Forming Agent Extracted from Vietnamese Nata-de-Coco Tree by Ultrasonic Vibration Method: Structure and Properties

Bacterial cellulose has recently received more attention in several fields including biology and biomedical applications due to its outstanding physicochemical properties such as thermal stability, biodegradability, good water holding capacity, and high tensile. Cellulose, the most abundant biomolecule on Earth, is available in large amounts in plants. However, cellulose in plants is accompanied by other polymers such as hemicellulose, lignin, and pectin. On the other hand, highly purified bacterial cellulose without impurities is produced by several microorganisms. In which, the most active producer is Acetobacter xylinum. A. This study developed a new process using sonication to isolate bacterial cellulose from nata-de-coco Vietnam. Sonicating time and temperature, two important engineering factors, were considered and discussed (Temperature: 55, 60, 65, 70°C; Time: 15, 30, 60, 90 min). Research results have established that the ultrasonic vibration time of 60 minutes at 65 degrees Celsius gives the best structural properties of BC. The morphology, structural, and thermal properties of the obtained films were investigated by SEM, FTIR, and TGA. Besides, tensile strength was also evaluated. The results show that sonication is not only a favorable technique to isolate cellulose nanofibers but it also enhances their crystallinity.

Isolation and Characterization of Cellulose Nanofiber Obtained From Agriculture Waste

Background: The fibers of date palm [DPFs] were used as a raw material to isolate cellulose nanofibers [CNFs] to assess their potential as reinforcements of composite materials in producing Bioplastic. The isolation of Nano cellulose [NCs] from DPF is still lacking, and the authors are not aware of any previous publication concerning the isolation of NCs from DPF. Objective: The date palm has huge potential in the application as a reinforcement agent to manufacture bio-nano composites and can be considered a renewable source of nanofibers with an etymology to agro-waste. Method: High-purity cellulose nanofibers were isolated from DPFs through an environmentally friendly treatment process that combined chemical [alkali & bleaching] and mechanical [ball milling]. Results: A high yield of CNFs was successfully extracted, with 50% CNFs from overall DPFs. Scanning electron microscopy [SEM] results revealed the effects of isolation treatments on fiber morphology and showed long, loose nanofiber bundles with 8–100 nm in diameter. FTIR results showed that noncellulosic components were effectively removed. X-ray diffraction analysis revealed the improved crystallinity of the processed fibers with a high crystalline index of 69.78%. Conclusion: TGA results showed an enhancement in the thermal properties of the nanofibers. The removal of hemicellulose and lignin increased the crystallinity of the fibers, and the extracted CNFs were used in the synthesis of Bioplastic by using glycerol as a plasticizer and corn starch as a matrix using the casting method. The feasibility study proved that NC production is feasible in Oman and was successfully yielding cellulose nanofibers with potential in advanced applications. The availability of raw materials is sufficient to sustain the plan with a total capital investment of OMR 9,694,127, an operating cost of OMR 10,058,976, and a total annual net profit of OMR 2,235,445.926 which shows an ROI of 23%/year with a payback period of 4.34 years.

Extraction and Isolation of Cellulose Nanofibers from Carpet Wastes Using Supercritical Carbon Dioxide Approach.

Cellulose nanofibers (CNFs) are the most advanced bio-nanomaterial utilized in various applications due to their unique physical and structural properties, renewability, biodegradability, and biocompatibility. It has been isolated from diverse sources including plants as well as textile wastes using different isolation techniques, such as acid hydrolysis, high-intensity ultrasonication, and steam explosion process. Here, we planned to extract and isolate CNFs from carpet wastes using a supercritical carbon dioxide (Sc.CO2) treatment approach. The mechanism of defibrillation and defragmentation caused by Sc.CO2 treatment was also explained. The morphological analysis of bleached fibers showed that Sc.CO2 treatment induced several longitudinal fractions along with each fiber due to the supercritical condition of temperature and pressure. Such conditions removed th fiber’s impurities and produced more fragile fibers compared to untreated samples. The particle size analysis and Transmission Electron Microscopes (TEM) confirm the effect of Sc.CO2 treatment. The average fiber length and diameter of Sc.CO2 treated CNFs were 53.72 and 7.14 nm, respectively. In comparison, untreated samples had longer fiber length and diameter (302.87 and 97.93 nm). The Sc.CO2-treated CNFs also had significantly higher thermal stability by more than 27% and zeta potential value of −38.9± 5.1 mV, compared to untreated CNFs (−33.1 ± 3.0 mV). The vibrational band frequency and chemical composition analysis data confirm the presence of cellulose function groups without any contamination with lignin and hemicellulose. The Sc.CO2 treatment method is a green approach for enhancing the isolation yield of CNFs from carpet wastes and produce better quality nanocellulose for advanced applications.

Facile isolation of cellulose nanofibers from soybean residue

The residue of soybean after extraction of oils, proteins, and soluble polysaccharides is rich in cellulose but not well utilized. Here, we exploited the soybean residue as a raw material to isolate cellulose nanofibers via a robust chemical-mechanical process. The soybean cellulose nanofibers (SCNFs) possessed ∼50 nm diameter and micrometer-scale length. They possessed a high degree of crystallinity (75.9%), negative surface charge (-22.5 mV), and high thermal stability. The hydrogel of SCNFs represented a typical shear-thinning behavior. The viscosity of the hydrogel was influenced by pH, ionic strength, ethanol, and temperature. SCNFs could also be made into flexible and transparent films with high tensile strength, which could be a raw material for food packages. Overall, soybean residue is a cost-effective source to produce cellulose nanofibers.

Isolation and characterization of cellulose nanomaterials from jute bast fibers

This work describes a simple yet effective pathway for extracting cellulose nanomaterials from jute bast fibers by chemical pretreatment to isolate microfibrillated cellulose followed by either mechanical or acid hydrolysis to ultimately isolate cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), respectively. Analyses carried out through Fourier transform infrared spectroscopy (FTIR), X-ray photon spectroscopy (XPS) and solid state 13C nuclear magnetic resonance (NMR) demonstrated that the pretreatments gradually removed lignins and hemicelluloses from the fibers. The yield of microfibrillated cellulose was 56.5% with respect to the initial dry mass of untreated fibers. Scanning electron microscopy (SEM) evaluated the morphological variation in the fiber dimension during the initial chemical pretreatment stages leading to extraction of microfibril 12–15 µm in average width. Transmission electron microscopy (TEM) images confirmed the nano-scale dimension of these nanocelluloses. The thermal stability of jute fibers at different stages of treatment was studied by thermogravimetric analysis. The high yield and high crystallinity of the nanocelluloses demonstrated effective isolation protocol confirming that jute bast fibers can be a valuable source for generation of nanomaterials.

A Facile Chemical Approach to Isolate Cellulose Nanofibers from Jute Fibers

In this work, Jute fibers (JF) were directly treated with HNO3-NaNO2 (JF/HNO3-NaNO2) mixture and simultaneously with NaOH and HNO3-NaNO2 (JF/NaOH/HNO3-NaNO2) mixture successively to extract cellulose nanofibers (CNFs) in a facile and cost-effective manner. Chemical composition, Morphological, structural, spectroscopic, and thermal analysis was carried out. TEM analysis of CNFs synthesized via JF/NaOH/HNO3-NaNO2 and JF/HNO3-NaNO2 showed an average diameter of 7–9 nm and 9–11 nm, respectively. CNFs obtained from alkali treated fibers possessed remarkable crystallinity of 63.9% as compared to 55.5% from raw fibers. Coexistence of both cellulose I and cellulose II type structures in CNFs via. JF/NaOH/HNO3-NaNO2 marks its inexhaustive applicability in industrial sectors.

Biocomposites from Rice Straw Nanofibers: Morphology, Thermal and Mechanical Properties

Agricultural residues are major potential resources for biomass and for material production. In this work, rice straw residues were used to isolate cellulose nanofibers of different degree of oxidation. Firstly, bleached rice fibers were produced from the rice straw residues following chemical extraction and bleaching processes. Oxidation of rice fibers mediated by radical 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) at pH 10 was then applied to extract rice cellulose nanofibers, with diameters of 3–11 nm from morphological analysis. The strengthening capacity of rice nanofibers was tested by casting nanocomposite films with poly(vinyl alcohol) polymer. The same formulations with eucalyptus nanofibers were produced as comparison. Their thermal and mechanical performance was evaluated using thermogravimetry, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. The glass transition of nanocomposites was shifted to higher temperatures with respect to the pure polymer by the addition of rice cellulose nanofibers. Rice nanofibers also acted as a nucleating agent for the polymer matrix. More flexible eucalyptus nanofibers did not show these two phenomena on the matrix. Instead, both types of nanofibers gave similar stiffening (as Young’s modulus) to the matrix reinforced up to 5 wt.%. The ultimate tensile strength of nanocomposite films revealed significant enhancing capacity for rice nanofibers, although this effect was somehow higher for eucalyptus nanofibers.

Efficient fractionation of cellulose nanofibers using spiral microchannel

Plant fiber isolated cellulose nanofibers (CNFs) are the materials with excellent mechanical properties. However, application of CNFs in polymer reinforcement is normally unsatisfactory due to its intertwined size distribution. Efforts to produce uniform sized CNFs have yet to be studied. In present work, spiral microchannel was used to fractionate CNFs based on the balance between inertial lift force (FL) and Dean drag force (FD) exerted on CNFs. The results showed that the smaller length of CNFs equilibrated near the inner microchannel while the larger length of CNFs occupied the equilibrium position away from the inner wall. With the increase of flowrates from 50 to 220 μL/min, fractionation efficiency between inner and middle outlet (EIM) of spiral microchannel A with larger radius curvature (R) from 5 to 15 mm increased from 0 to 75.4%. However, stronger Dean flow attributing to decrease of R (3 mm to 10 mm) of single spiral microchannel B enabled satisfactory fractionation efficiency of 70.9% at flowrate of 90 μL/min. Moreover, the fractionation efficiency of double spiral microchannel with twice as length as microchannel A and three times as length as microchannel B was lower than that of single spiral microchannel at flowrate lower than 90 μL/min. Furthermore, this study exhibited a versatile and simple method for CNFs fractionation with high fractionation efficiency.

Isolated cellulose nanofibers for Cu (II) and Zn (II) removal: performance and mechanisms

TEMPO-oxidized cellulose nanofibers (TOCNFs) were prepared and investigated as low-cost adsorbents for the removal of Cu (II) and Zn (II) from synthetic and natural waters. The adsorption equilibrium was reached within 2 min and adsorption capacity was as high as 102.9 mg g−1 for Cu (II) and 73.9 mg g−1 for Zn (II). Ionic strength showed adverse effect on adsorption capacity, however, TOCNFs with higher carboxymethyl content were less influenced due to their resistance to aggregation. Copper adsorption exhibited strong selectivity over the tested common cations. The adsorptions of Cu (II) and Zn (II) onto TOCNF were endothermic but spontaneous processes, and the binding was driven by entropy increase. A combined interaction mechanism, including ion exchange, coordination and accumulation, was proposed based on the study. All the findings confirmed the great potential of TOCNF application in water purification and reclamation approaches.

A combined homogenization-high intensity ultrasonication process for individualizaion of cellulose micro-nano fibers from rice straw

In this study high quality cellulose fibrils, derived from rice straw by the chemical pretreatment, were fibrillated into cellulose micro/nanofibers through a subsequent homogenization and high-intensity ultrasonication processes. Properly comparing of the fibrillation yield and the morphological structure of the ensuing nanofibers, by means of scanning electron microscopy and transmission electron microscopy, revealed that the long and uniform cellulose nanofibers with desired diameters in the possible range of 6–20 nm and a high aspect ratio of about 177 are obtained when the output power and irradiation time of the conducted ultrasonication exceeded 500 W and 40 min, respectively. The accurate characterization of the chemical structure of the isolated cellulose nanofibers using X-ray diffraction and Fourier transform infrared spectroscopy revealed that lignin and hemicellulose were completely removed from the fibrils and crystallinity of the cellulose fibers increased approximately to 65%. As evidenced by thermogravimetric analysis, isolated cellulose nanofibers indicated good thermal stability. Due to the appropriated properties of ultralong isolated cellulose nanofibers, it is typically expected that they could potentially be utilized in various field such as green nanocomposites, filtration media, tissue engineering, and so on.

Optimization of cellulose nanofiber production from oil palm empty fruit bunch using Trichoderma sp. with the solid state fermentation method

Cellulose nanofibers were isolated from oil palm empty fruit bunch by delignification using Marasmius sp. and subsequently treated by solid state fermentation using Trichoderma sp. This method used pH values of 4.8, 5.5, and 7 and temperatures of 28 °C, 32 °C, and 37 °C for 7 d. Scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and particle size analysis were performed to determine the properties of the isolated cellulose nanofibers. Results showed that chemical analysis by FTIR, lignin was completely removed from the EFB. It was found that the combination of pH 5.5 and incubation temperature 37 °C were favorable for the SSF process to isolate cellulose nanofibers from oil palm EFB fiber. SSF processing resulted in smooth morphological structures, with a fiber diameter range of 32.6 nm to 36.4 nm.

Synthesis of New Porous Natural Membranes with Nanoparticles Used in Pollute Gas Removal From Petroleum Industries

The aim of the present work is to follow the capacity of adsorption of CO2 by natural cellulose nanofibers, extracted from banana peel and mixed with nano-silver. Following initial characterization, the raw material and the isolated sample were investigated by Energy Dispersive Analysis (EDS), X-ray diffraction (XRD); Fourier- Transformed infrared spectroscopy (FT-IR) and thermal analysis (Hi Res TG). Nitrogen gas adsorption-desorption isotherms of isolated cellulose nanofibers reveal a type I- isotherm, specific to the nano-porous materials.The results of adsorption isotherms of CO2 at 304 K showed that the extracted sample exhibit an adsorption capacity of 12 mmol/g of CO2.

Preparation and characterization of nanocomposite films containing starch and cellulose nanofibers

Starch nanocomposites films were successfully prepared using the isolated cellulose nanofibers (CNFs) at loading from 5 to 20% by solution casting. The morphology, crystallinity, surface hydrophobicity, water vapor permeability, opacity, and mechanical test of nanocomposites films were studied. The CNFs were uniformly distributed within these films up to 15% of CNFs. The incorporation of 20% CNFs in the composite film produced selective aggregation and, thus, inhomogeneity of the CNFs. The contact angle values increased from 49.46° (starch-only films) to 88.57° (CNFs loading at 20%). The incorporation of CNFs hinders the diffusion or permeability of water vapor through the composite. Addition of CNFs to starch films resulted in significant improvement in glass transition temperature (Tg), tensile strength and modulus of elasticity of nanocomposites films.

Rapid ILs-polishing Processes Toward Flexible Nanostructured Paper with Dually High Transparency and Haze

Biodegradable highly nanostructured paper has received great interest in past years due to its excellent optical properties which facilitate its wide applications in green flexible electronics and devices. However, energy and/or time-consuming procedure during the process of fabricating most nanostructured transparent paper are presently the main obstacle to their scalable production. In this work, we demonstrated a novel nanostructured paper with dually high transparency (∼91%) and high haze (∼89%) that was directly fabricated from original paper with rapid ILs-polishing processes. The whole fabricating time only requires 10 min. Compared to the previously reported nanopaper made of the isolated cellulose nanofibers by pure mechanical and/or chemical approaches, this work presented herein is devoted to use green ILs to polish directly the micrometer-sized fibrous paper into the nanostructured paper. This new method brings a rapid fabrication of transparent nanostructured paper while also retaining dual intriguing properties both in optical transmittance and haze. This work is capable of fabricating next-generation flexible and highly transparent and haze paper by a high-speed roll-to-roll manufacturing process with a much lower cost.

Novel nanofibrillated cellulose/polyvinylpyrrolidone/silver nanoparticles films with electrical conductivity properties

Nanofibrillated cellulose (NFC) isolated from rice straw pulp was used with polyvinylpyrrolidone (PVP) and silver nanoparticles (AgNPs) to prepare nanocomposites in the form of flexible films. The later films have promising mechanical and electrical conductivity properties. The isolated cellulose nanofibers were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Silver nanoparticles prepared via in-situ reduction in PVP were characterized using TEM and UV–vis spectroscopy. Tensile properties, microscopic structure, and electrical properties of nanocomposites films were studied. TEM and UV–vis spectroscopy proved the in-situ formation of AgNPs in PVP matrix. Films with good flexibility and tensile strength properties could be obtained from NFC/PVP/AgNPs as revealed from the (SEM) images and tensile properties testing. The electrical conductivity of NFC/PVP/AgNPs supports this system to be an excellent choice for sensitive electronic components packing as it can be used as antistatic and electrostatic dissipative materials.

Morphological and property investigations of carboxylated cellulose nanofibers extracted from different biological species

Carboxylated cellulose nanofibers were extracted from different biological species, including cotton, spruce wood, bamboo and bacterial cellulose, through a combined (2,2,6,6-tetramethyl- piperidine-1-yl)oxyl (TEMPO)-mediated oxidation and mechanical defibrillation treatment. The cross-section dimensions of isolated cellulose nanofibers in suspension were characterized by small-angle X-ray scattering, where the results were in agreement with the transmission electron microscopy measurement. For the spruce wood samples, the effects of three experimental variables in the combined TEMPO-oxidation and mechanical treatment on the dimensions and degree of oxidation of the resulting cellulose nanofibers were quantitatively investigated.

Isolation of Nanocellulose from Pomelo Fruit Fibers by Chemical Treatments

This study aims to isolate cellulose nanofibers from locally abundant pomelo fruit. The peels were subjected to alkali treatment (NaOH) with different concentrations and soaking times. Acid hydrolysis was also carried out to obtain an aqueous suspension of nanocellulose. The treated cellulose fibers were characterized by various methods. Alkali treatment was able to remove noncellulosic constituents. Microscopy techniques yielded morphology of elementary fibers with a compact structure with both micro- and nano-scaled fibers. An improved onset of degradation was likely caused by an increase in crystallinity evidenced by X-ray diffractometry (XRD). Acid hydrolysis could successfully individualize cellulose nanofibers as observed by transmission electron microscopy (TEM).

Structural and mechanical properties of cellulose composites made of isolated cellulose nanofibers and poly(vinyl alcohol)

A composite of cellulose-nanofibers (Cel-F)/polyvinyl alcohol (PVA) was made through a developed water-jet nano-isolation process called the Star Burst processing (SB). The structural and the mechanical properties of the pure Cel-F and the Cel-F/PVA composites were analyzed for comparison. The microstructural analyses revealed the step-by-step nano-isolation procedures of the SB processing, eventually constructing nanofibers with the minimum diameter of ∼23nm. It was also found that the crystallinity of Cel-F was rapidly increased by 14% at the early stage of the SB process, subsequently becoming almost constant, irrespective of the number of the SB treatments. Additionally, Cel-F were homogenously dispersed in PVA matrix after 40 SB treatments. Young’s modulus of the resulting composite was increased by 48%. The results were in good agreement with the outcome of the short-fiber composite theory, indicating a highly potential use of the SB-processed cellulose nanofibers as new reinforcement materials.

Exploration of a Chemo-Mechanical Technique for the Isolation of Nanofibrillated Cellulosic Fiber from Oil Palm Empty Fruit Bunch as a Reinforcing Agent in Composites Materials

The aim of the present study was to determine the influence of sulphuric acid hydrolysis and high-pressure homogenization as an effective chemo-mechanical process for the isolation of quality nanofibrillated cellulose (NFC). The cellulosic fiber was isolated from oil palm empty fruit bunch (OPEFB) using acid hydrolysis methods and, subsequently, homogenized using a high-pressure homogenizer to produce NFC. The structural analysis and the crystallinity of the raw fiber and extracted cellulose were carried out by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The morphology and thermal stability were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric (TGA) analyses, respectively. The FTIR results showed that lignin and hemicellulose were removed effectively from the extracted cellulose nanofibrils. XRD analysis revealed that the percentage of crystallinity was increased from raw EFB to microfibrillated cellulose (MFC), but the decrease for NFC might due to a break down the hydrogen bond. The size of the NFC was determined within the 5 to 10 nm. The TGA analysis showed that the isolated NFC had high thermal stability. The finding of present study reveals that combination of sulphuric acid hydrolysis and high-pressure homogenization could be an effective chemo-mechanical process to isolate cellulose nanofibers from cellulosic plant fiber for reinforced composite materials.