High-intensity Ultrasonication Research Articles

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.

Effects of High-Intensity Ultrasound Pretreatment on Structure, Properties, and Enzymolysis of Walnut Protein Isolate.

The purpose of this paper was to investigate the effect of high-intensity ultrasonication (HIU) pretreatment before enzymolysis on structural conformations of walnut protein isolate (WPI) and antioxidant activity of its hydrolysates. Aqueous WPI suspensions were subjected to ultrasonic processing at different power levels (600–2000 W) and times (5–30 min), and then changes in the particle size, zeta (ζ) potential, and structure of WPI were investigated, and antioxidant activity of its hydrolysates was determined. The particle size of the particles of aqueous WPI suspensions was decreased after ultrasound, indicating that sonication destroyed protein aggregates. The ζ-potential values of a protein solution significantly changed after sonication, demonstrating that the original dense structure of the protein was destroyed. Fourier transform infrared spectroscopy indicated a change in the secondary structure of WPI after sonication, with a decrease in β-turn and an increase in α-helix, β-sheet, and random coil content. Two absorption peaks of WPI were generated, and the fluorescence emission intensity of the proteins decreased after ultrasonic treatment, indicating that the changes in protein tertiary structure occurred. Moreover, the degree of hydrolysis and the antioxidant activity of the WPI hydrolysates increased after sonication. These results suggest that HIU pretreatment is a potential tool for improving the functional properties of walnut proteins.

Characterisation of microfibrils cellulose isolated from oil palm frond using high-intensity ultrasonication

This study highlighted the utilization of agricultural byproducts as an alternative fiber resource to be used as one of the materials for reinforcement biocomposite. Cellulose was extracted from oil palm frond using the alkaline treatment and successfully isolated into microfibril via the combination of carboxymethylation pre-treatment ultrasonication to get highly crystalline and good thermal stable microfibers. 4% NaOH was used during alkaline treatment and followed by oxidative bleaching with 30% H2O2. Once the extracted cellulose is chemically pre-treated with monochloroacetic acid, it was subjected to 30 minutes ultrasonication treatment to reduce its size. The detailed comparative analysis using SEM, FTIR and TGA was conducted in this work revealed some breakages of intramolecular hydrogen bonds and glycosidic bonds that occurred during the alkaline and bleaching treatment of oil palm biomass. The SEM images showed significant morphology of rigid, organized and highly ordered cellulose fibrils changed into aggregated fibril bundles of microfibrils after ultrasonication. The results from the infrared spectrums revealed that the mild alkaline treatments and oxidative bleaching were able to remove a large fraction of lignin and hemicelluloses to leave a clean cellulose sample. The isolated microfibrils cellulose exhibit good thermal stability as almost 50% of its initial mass remains at a temperature of 300 °C. These findings demonstrate that oil palm fronds can be utilized for biocomposite reinforcement applications.

Ultrasonic structural modification of myofibrillar proteins from Coregonus peled improves emulsification properties

This study evaluated the effects of high intensity ultrasonication (HIU, 100, 150, 200, and 250 W) and treatment time (0, 3, 6, 9, and 12 min) on the structure and emulsification properties of myofibrillar proteins (MPs) from Coregonus peled. These investigations were conducted using an ultrasonic generator at a frequency of 20 kHz (ultrasonic probe). Analysis of the carbonyl content and total number of sulfhydryl groups showed that HIU significantly improved the oxidative modification of MPs (P < 0.05). SDS-PAGE profiling showed significant degradation of the myosin heavy chain (P < 0.05). In addition, Fourier transformed infrared spectroscopy (FTIR) revealed that HIU altered these treated MP secondary structures, this was due to molecular unfolding and stretching, exposing interior hydrophobic groups. Particle size analysis showed that HIU treatment reduced particle sizes. Solubility, emulsification capacity, and emulsion stability were improved significantly, and each decreased with an increase in treatment time (up to 12 min), indicating aggregation with prolonged sonication. These results indicate that HIU could improve the emulsification properties of MPs from C. peled, demonstrating a promising method for fish protein processing.

Efficient cleavage of strong hydrogen bonds in sugarcane bagasse by ternary acidic deep eutectic solvent and ultrasonication to facile fabrication of cellulose nanofibers

From the perspective of green chemistry, it is of great significance to produce cellulose nanofibers (CNFs) with more environmentally friendly and sustainable materials. This study investigated the efficient cleavage of strong hydrogen bonds occurred in sugarcane bagasse (SCB), ultrafast fabrication of CNFs through a 20 min microwave-assisted ternary carboxylic acid deep eutectic solvent (Mw-TCADES) deconstruction and sweep frequency ultrasonic (SFU) separation pretreatment. It also investigated the subsequent high-intensity ultrasonication (HIU) fibrillation process. After pretreating SCB with two different TCADES (choline chloride: oxalic acid: AlCl3·6H2O, and choline chloride: lactic acid: AlCl3·6H2O, molar ratio 1:1:0.2), the cellulose content of the SCB was 56.2 and 62.6%, respectively. The CNFs obtained after the two Mw-TCADES treatments contained 0.74 and 0.84 mmol/g carboxylic acid groups, and the crystallinity was 58.05 and 60.71%, respectively. Meanwhile, the CNFs obtained under the optimum treatment conditions (Mw-TCADES, 100 °C, 20 min and HIU) showed high thermal stability, which exhibited promising potential for further applications. Under the optimum conditions, the CNFs had a length of about 400–600 nm, width of around 15–17 nm, and a height of about 6–7 nm. The results showed that the TCADES can be used effectively as an alternative to the traditional acid–base pretreatment method and provide a green and efficient method for the utilization of lignocellulosic materials and the separation of CNFs.

Isolation and Characterization of Cellulose Nanofibrils from Banana Pseudostem, Oil Palm Trunk, and Kenaf Bast Fibers Using Chemicals and High-intensity Ultrasonication

ABSTRACT The adoption of high-intensity ultrasonication in the isolation process of cellulose nanofibrils (CNF) as an economical, timesaving, and environmental-friendly process has been explored. Three types of raw organic fibers, i.e., banana pseudostem, oil palm trunk, and kenaf bast were analyzed for the production of CNF using the process mentioned earlier. Before the raw organic fibers were subjected to a high-intensity ultrasonication process, it underwent an alkaline treatment to eliminate the non-cellulosic compounds. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) micrographs confirmed the presence of nanofibrils in all three different types of CNF. The frequency, amplitude, and duration of ultrasonication used in this study were sufficient to produce CNF. Fourier-transform infrared spectroscopy (FTIR) results indicated that the chemical treatment employed in this paper was effective in removing the compounds, especially lignin and hemicellulose. The increase in crystallinity, which is one of the advantages of CNF, was observed from the X-ray diffraction (XRD) results. Hence, it can be deduced that high-intensity ultrasonication could simplify the complex process of CNF isolation compared to the conventional method, widening the utilization and source of CNF in the industry.

Chemical-Physical Treatment for Production of Cellulose Nanofiber from Kenaf Bast Fiber

ABSTRACT This paper presents the isolation of kenaf bast fiber to produce cellulose nanofiber (CNF) using chemical-physical treatment (e.g. delignification, bleaching and ultrasonication). Raw bast fiber was bleached and then subjected to high-intensity ultrasonication at four different output powers (100 W, 200 W, 400 W and 700 W). SEM and TEM analysis of treated bast fiber revealed that the morphological structure of CNF with diameter distribution in the range less than 100 nm (100 W) to 10 nm (700 W). Hemicellulose and lignin content were successfully reduced by chemical treatments, as there was increment of the cellulose content in the fiber more than 90% recorded. Higher ultrasonication output power attributes to the decreasing diameter size of CNF. This finding reflected that smaller CNF fibrils provide larger surface area per volume ratio. Larger stretching vibration of – OH group is detected as the higher composition of cellulose in CNF. CNF produced also had higher thermal stability than raw bast fiber after undergoes the chemical-physical treatment. Therefore, chemical-physical treatment did not only to attribute the success of deposition of lignin and hemicellulose, but also to increase the nano-sized fiber distribution in CNF suspension.

Ultrasonic-assisted synthesis of nickel tungstate nanoparticles on poly (3,4-ethylene dioxythiophene):poly (4-styrene sulfonate) for the effective electrochemical detection of caffeic acid

Herein, the ultrasonic-assisted synthesis of NiWO4 nanoparticles on poly(3,4‐ethylenedioxythiophene)–polystyrenesulfonate (PEDOT:PSS) for the electrochemical determination of caffeic acid (CFA) was investigated systematically. The NiWO4 nanoparticles and NiWO4@PEDOT:PSSx nanocomposite were synthesised through high-intensity ultrasonication in a bath sonicator. The as-prepared materials distinct nature was evaluated using electron microscopic and spectroscopic analysis, and the electrocatalytic properties of the sensor materials were determined through cyclic voltammetry (CV) and linear sweep voltammetry (LSV). CV examination indicated that the enhanced redox behaviour of CFA at a low potential is attributed to the incorporation of PEDOT:PSS into the NiWO4@PEDOT/PSS nanocomposite and their synergistic effects. The NiWO4@PEDOT:PSS sensors exhibited a low detection limit and high sensitivity of 74 nM and 969.49 μA mM−1 cm−2 towards CFA in LSV. Overall, the proposed sensor exhibited excellent analytical performance and uncompromised essential sensor features, such as selectivity, stability, repeatability and reproducibility. The NiWO4@PEDOT:PSS sensors have good practical compatibility in CFA detection in commercial coffee/red wine samples and are thus potential practical sensors.

Rheological study of cellulose nanofiber disintegrated by a controlled high-intensity ultrasonication for a delicate nano-fibrillation

Herein, the rheological properties of 2,2,6,6-tetramethylpiperidin-1-oxyl radical-oxidized cellulose nanofiber (TOCNF) suspensions individualized using high-intensity ultrasonication were investigated. The surface charge density of the nanofibers and sonication time were 0.659–1.24 mmol/g and 30–600 s, respectively. With increased surface charge density, the minimum time required for disintegration decreased due to the repulsive force between oxidized nanofibers. Additionally, increased sonication time enhanced the TOCNF nanofibrillation, thereby forming networks between the nanofibers. Further disintegrating TOCNF increased shear viscosity and yield stress of TOCNF suspensions. Based on the crowding factor theory, the relationship between the average fiber width and sonication time was found at various surface charge densities. Ultrasonication was considered as an energy saving and precisely controllable nanofibrillation method. This research shows the change of fiber shapes during the nanofibrillation process, and suggests an estimation of disintegration degree by the relationship between the rheological properties and TOCNF morphology.

Preparation of lignin containing cellulose nanofibers and its application in PVA nanocomposite films

Lignin containing cellulose nanofibers (LCNFs) were successfully prepared from wheat straw using an acid hydrotrope of p-toluene sulfonic acid (p-TsOH) combined with ultrasonication. p-TsOH pretreatment was applied below 80 °C to selectively remove hemicellulose and lignin and generate purified cellulose fibers containing approximately 15% lignin. Subsequently, high-intensity ultrasonication was used for <6 min to effectively defibrillate the p-TsOH-pretreated cellulose fibers to nanoscale fibers. AFM and TEM analyses showed that the diameter distribution of the resultant nanofibers decreased with the increase in ultrasonic intensity. The FTIR and XRD results indicated that the molecular structures and cellulose crystallinity were not changed during the ultrasonic process. An amount of 5 wt% of the obtained LCNFs was introduced into a polyvinyl alcohol (PVA) matrix. The resulting nanocomposite products exhibited improved thermal performance and surface properties compared with the pure PVA matrix. The mechanical properties, including the tensile stress and Young's modulus, were enhanced significantly, although the elongation at the break was slightly decreased. PVA composites with the addition of LCNFs are expected to be used in a variety of fields, such as biodegradable plastics, pharmaceutical carrier, filtration media and packaging materials.

High-intensity ultrasonication treatment improved physicochemical and functional properties of mussel sarcoplasmic proteins and enhanced the stability of oil-in-water emulsion

This study investigated the effects of high-intensity ultrasonication (HIUS) treatment (0, 5, 10, 20, 30 min) on the physicochemical and functional properties of mussel sarcoplasmic proteins (MSP). MSP dispersion was treated by HIUS (20 kHz) at 600 W for 5, 10, 20 and 30 min. The results showed that HIUS treatment changed the physicochemical properties of MSP, thereby increasing the stability of the emulsion stabilized by ultrasonicated MSP. HIUS treatment improved the functional properties of MSP, including solubility, foaming ability, foaming stability, emulsifying activity index, emulsifying stability index, percentage of adsorbed proteins. More uniform emulsions with smaller droplets and higher stability were observed. There was a decrease in particle size, zeta-potential and turbidity of ultrasonicated MSP. Proteins partially unfolded as a result of HIUS treatment. Associations between conformation structure, physicochemical properties and functional properties were also found. It can be speculated that improvements in functional properties were caused by the changes in conformation structure and physicochemical properties. The results suggested that HIUS treatment has great potential in modifying the foaming and emulsifying properties of shellfish proteins, and ultrasonication treatment at 20 kHz, 600 W for 20 min was the optimum condition for modification.

Microstructural modification of recycled aluminium alloys by high-intensity ultrasonication: Observations from custom Al–2Si–2Mg–1.2Fe–(0.5,1.0)Mn alloys

The effect of ultrasonication on the solidification microstructure of recycled Al-alloys is investigated using custom Al–2Si–2Mg–1.2Fe–xMn alloys (x = 0.5 and 1%, in wt.%) through cooling curve measurement, optical and electron microscopy, X-ray diffraction, differential scanning calorimetry and computational thermodynamic calculations. Applying ultrasonication throughout the primary-Al nucleation stage resulted in refined non-dendritic grain structure. Cooling curves indicate a noticeable reduction in primary-Al nucleation undercooling and reduction of the recalescence peak under ultrasonication. However, terminating ultrasonication prior to the nucleation of primary-Al led to dendritic grains with marginal refinement. Without ultrasonication, coarse Chinese-script α−Al15(Fe,Mn)3Si2 intermetallics developed from initially polygonal particles due to interface growth instability under thermo-solutal undercooling. In contrast, ultrasonication produced refined and polygonal α−Al15(Fe,Mn)3Si2 particles by promoting nucleation and growth stabilisation under strong fluid flow. The enhanced nucleation from ultrasonication is presumably due to the pressure-induced shift of freezing point along with improved wetting of insoluble inclusions under cavitation. The present results show that ultrasonication can effectively modify the Fe-intermetallics and refine the grain structure in recycled Al-alloys.

Structural, optical, magnetic properties and visible light photocatalytic activity of BiFeO3/graphene oxide nanocomposites

In this paper, structural, magnetic, optical, and photocatalytic properties of BiFeO3/graphene oxide (BFO/GO) nanocomposites have been compared with BFO nanoparticles. To obtain the optimum photocatalytic activity, GO nanosheets were mixed at different weight percentages (wt%) with BFO nanoparticles using high-intensity ultra-sonication. The samples were analyzed using x-ray diffraction, field-emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, vibrating sample magnetometer, Fourier-transform infrared spectroscopy, and ultraviolet-visible spectroscopy. The magnetization curves show that mixing 9 wt% GO with BFO (BFO-GO9) with respect to BFO indicates a weak ferromagnetic behavior. The photocatalytic tests indicate that that the amount of pH and catalyst dosage all significantly influenced the catalytic performance of BFO/GO for degradation of methylene blue and methyl orange. Although the photocatalytic activity of BFO/GO nanocomposites has been enhanced with the weight percentage of GO, the BFO-GO9 photocatalyst having smaller particle size presents advantages such as high removal efficiency, low cost, and non-toxicity.

Effects of Preparation Method on the Physicochemical Properties of Cationic Nanocellulose and Starch Nanocomposites.

Nanocellulose (NC) has attracted attention in recent years for the advantages offered by its unique characteristics. In this study, the effects of the preparation method on the properties of starch films were investigated by preparing NC from cationic-modified microcrystalline cellulose (MD-MCC) using three methods: Acid hydrolysis (AH), high-pressure homogenization (HH), and high-intensity ultrasonication (US). When MD-MCC was used as the starting material, the yield of NC dramatically increased compared to the NC yield obtained from unmodified MCC and the increased zeta potential improved its suspension stability in water. The NC prepared by the different methods had a range of particle sizes and exhibited needle-like structures with high aspect ratios. Fourier transform infrared (FTIR) spectra indicated that trimethyl quaternary ammonium salt groups were introduced to the cellulose backbone during etherification. AH-NC had a much lower maximum decomposition temperature (Tmax) than HH-NC or US-NC. The starch/HH-NC film exhibited the best water vapor barrier properties because the HH-NC particles were well-dispersed in the starch matrix, as demonstrated by the surface morphology of the film. Our results suggest that cationic NC is a promising reinforcing agent for the development of starch-based biodegradable food-packaging materials.

Effects of High-Intensity Ultrasound Pretreatment on Structure, Properties, and Enzymolysis of Soy Protein Isolate.

The objective of this study was to investigate the effects of different high-intensity ultrasonication (HIU) pretreatment on the structure and properties of soybean protein isolate (SPI) as well as enzymatic hydrolysis of SPI by bromelain and antioxidant activity of hydrolysates. The HIU-treated SPI fractions showed a decrease in the proportion of α-helices and β-turns and an increase in the content of β-sheets and random coils based on Fourier-transform infrared spectroscopy. Near-infrared spectra and fluorescence spectra analyses provided support for the changes in secondary and tertiary structures of SPI after ultrasound treatment. The particle size of SPI decreased from 217.20 nm to 141.23 nm and the absolute zeta potential increased. Scanning electron microscopy showed that HIU treatment changed apparent morphology. Dynamic and static light scattering of ultrasonicated samples showed that SPI structure had changed from hard-sphere to hollow-sphere or polydisperse and monodisperse gaussian coils. HIU pretreatment significantly increased the hydroxyl-radical scavenging and the degree of hydrolysis of the SPI hydrolysates.

Development of a new extraction method based on high-intensity ultra-sonication to study RNA regulation of the filamentous cyanobacteria Planktothrix.

Efficient RNA extraction methods are needed to study transcript regulation. Such methods must lyse the cell without degrading the genetic material. For cyanobacteria this can be particularly challenging because of the presence of the cyanobacteria cell envelope. The great breath of cyanobacterial shape and size (unicellular, colonial, or filamentous multicellular) created a variety of cell lysis methods. However, there is still a lack of reliable techniques for nucleic acid extraction for several types of cyanobacteria.Here we designed and tested 15 extraction methods using physical, thermic or chemical stress on the filamentous cyanobacteria Planktothrix agardhii. Techniques based on the use of beads, sonication, and heat shock appeared to be too soft to break the Planktothrix agardhii cell envelope, whereas techniques based on the use of detergents degraded the cell envelope but also the RNA. Two protocols allowed to successfully obtain good-quality RNA. The first protocol consisted to manually crush the frozen cell pellet with a pestle and the second was based on the use of high-intensity ultra-sonication. When comparing these two, the high-intensity ultra-sonication protocol was less laborious, faster and allowed to extract 3.5 times more RNA compared to the liquid nitrogen pestle protocol. The high-intensity ultra-sonication protocol was then tested on five Planktothrix strains, this protocol allowed to obtain >8.5 μg of RNA for approximatively 3.5 × 108 cells. The extracted RNA were characterized by 260/280 and 260/230 ratio > to 2, indicating that the samples were devoid of contaminant, and RNA Quality Number > to 7, meaning that the integrity of RNA was preserved with this extraction method. In conclusion, the method we developed based on high-intensity ultra-sonication proved its efficacy in the extraction of Planktothrix RNA and could be helpful for other types of samples.

Ultrasound treatment (low frequency) effects on probiotic bacteria growth in fermented milk

Ultrasound treatment (low frequency) effects on probiotic bacteria growth in fermented milk

High-Yield Preparation of Micro/Nanofibers from Rice Straw Using Superextended Soda–Oxygen Cooking and High-Intensity Ultrasonication

Chemical purification through ultrasonic treatment as a method to prepare energy-saving and environmentally friendly nanofiber from natural lignocellulose has attracted wide attention in academic research. However, purifying cellulose through chemical pretreatment is complicated and inefficient, making it one of the bottlenecks that plague its industrial application. In this paper, the superextended soda–oxygen pulping process successfully purified rice straw cellulose fibers (total lignin 1.57%). Results showed that 82% of the hemicellulose can be removed with a high yield of 43.05% (w/w dry rice straw). In addition, micro/nanofibers can be isolated from the purified cellulose after the conventional ultrasonic process (2000 W, 2 h). The transmission electron microscope shows that the obtained micro/nanofibers were interconnected with fiber bundles, which formed entangled, weblike networks in the suspension. The thermogravimetric analysis results indicated that the degradation temperature of the micro/nanofibers can be increased to approximately 335 °C compared with that of 300 °C of the conventional pulp. After a simple vacuum filtration, a highly transparent film with a smooth surface was produced from micro/nanofibers. The production process has low cost, stable product quality, and high yield, and it is also easy to use in industrial production.

Whey protein stabilized nanoemulsion: A potential delivery system for ginsenoside Rg3 whey protein stabilized nanoemulsion: Potential Rg3 delivery system

In the current research, we systematically investigated the physicochemical stability of the nanoemulsions that were formulated with 90% (v/v) whey protein isolate (WPI) aqueous phase and 10% (v/v) medium chain triglyceride oil phase at neutral pH using high intensity ultrasonication. We measured the physicochemical properties of nanoemulsions stabilized by WPI at different concentrations, including particle size, zeta potential, turbidity, centrifugal stability, and rheological behavior. Besides, we also evaluated the influence of processing conditions (ionic strength, freeze-thaw cycle and thermal treatment) on the nanoemulsion stability. The particle size of WPI nanoemulsions increased by approximately 5% at 25 °C and 8% at 37 °C after 7 weeks’ storage, while the particle size and zeta potential of the nanoemulsions at 4 °C were changed. The 1% WPI stabilized nanoemulsion was very sensitive to Na+ (0.1–0.5 mol/l) and freeze-thaw treatment (3 cycles) with significant increase in particle size and decrease in the absolute value of zeta potential. The turbidity of nanoemulsions decreased by over 50% after freeze-thaw cycles, especially the 1% WPI stabilized nanoemulsion. All samples were still stable under thermal conditions. Among them, the 5% WPI stabilized nanoemulsion showed the best ionic, freeze-thaw, and thermal stability. All tested nanoemulsions showed typical shear-thinning behavior, and the infinite shear viscosity of 5% WPI stabilized nanoemulsions was highest. In conclusion, the 5% WPI stabilized nanoemulsion has the best physicochemical stability under different processing conditions during storage, which has high potential in use as a delivery system for bioactive substances like ginsenoside Rg3 in food technology.

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.