Ultrasonic Dispersion Process Research Articles

Preparation and characterization of chitosan/bacterial cellulose composite biodegradable films combined with curcumin and its application on preservation of strawberries

We provided in detail a simple and environmentally-friendly method to prepare a biodegradable composite film using chitosan (CS) and bacterial cellulose (BC) with excellent dispersion. CS was grafted onto BC by Schiff base reaction firstly, and then obtained the nano-sized fibrils by ultrasonic dispersion process (CS-OBC). Different concentrations of curcumin (Cur, 0 %, 0.1 %, 0.3 %, 0.5 %, and 0.7 %, w/v) were incorporated into CS-OBC composite films prepared with optimal film-forming parameters. Mechanical and antioxidant properties, including moisture content, water solubility, and contact angles, were evaluated to determine the effects of Cur addition on the composite films (CS-OBC-Cur). It was found that Cur addition increased the hydrophobicity and oxygen permeability of the film, and that the CS-OBC-0.5%Cur active film exhibited excellent barrier properties, hydrophobicity, and mechanical properties. In addition, polyphenol release was retarded when the active film was in a simulated fat system. The film showed superior preservation of strawberries compared with ordinary PE film and significantly slowed the oxidation of edible oils. These results suggest that CS-OBC-Cur films are a promising food packaging material.

Effect of dispersion method on microstructure and properties of Ni-P–Al2O3 (sol)-PTFE composite coating

In order to alleviate the agglomeration of nanoparticles in the plating solution, the dispersion effect of binary nanoparticles in Ni–P–Al2O3–PTFE composite coating was studied by physical and chemical dispersion methods. The effects of different dispersion methods on the microstructure, hardness and friction coefficient of the composite coating were discussed. Through the performance evaluation of the composite coating, it is found that the effect of using appropriate dispersant and ultrasonic dispersion process is good, which can make the nanoparticles fully dispersed in the solution and evenly distributed in the coating, the composite amount of nanoparticles in the deposition layer is also high. The results show that it has a good effect on improving the wear-resisting and antifriction properties of the composite coatings.

Effect of cavitation bubble on the dispersion of magnetorheological polishing fluid under ultrasonic preparation

In the ultrasonic dispersion process, the ultrasonic cavitation effect can seriously affect the dispersion efficiency of magnetorheological polishing fluid (MRPF), but the mechanism remains unclear now. Through considering the continuity equation and Vand viscosity equation of the suspension, a revised cavitation bubble dynamic model in the MRPF was developed and calculated. The effects of presence or absence of solid particles, the volume fraction of solid particles, and viscosity on the cavitation bubble motion characteristics in the MRPF were discussed. Settlement experiments of the MRPF under ultrasonic and mechanical dispersion were observed. Analysis of particle dispersion is made by trinocular biomicroscope and image processing of the microscopic morphology of the MRPF. The results show that the high volume fraction of carbonyl iron particle (CIP) will significantly weaken the cavitation effect, and the low volume fraction of green silicon carbide (GSC) has a negligible effect on the cavitation effect in the MRPF. When the liquid viscosity is greater than or equal to 0.1 Pa·s, it is inconvenient to produce micro-jets in the MRPF. The sedimentation rate of the MRPF prepared by ultrasonic dispersion is lower than mechanical dispersion when the volume fraction of CIP is between 1% and 25%. The dispersion ratio under ultrasonic dispersion is lower than that under mechanical dispersion. The experimental results fit the simulation well. It offers a theoretical basis for exploring the ultrasonic cavitation effect in the industrial application of the MRPF.

Обезвоживание пищевых продуктов под действием ультразвуковых колебаний с удалением влаги без фазового перехода

Introduction. Dehydration of heat-sensitive and easily oxidized food products require particular temperatures. Exposure to ultrasonic vibrations is an alternative dehydration method that presupposes moderate thermal treatment. The research objective was to identify the optimal range of sound pressure and to design a small-volume dryer.
 Study objects and methods. The study featured two novel ultrasonic potato dryers at t = 60 ± 1°C and a drying agent flow rate of 0.50 ± 0.03 m/s.
 Results and discussion. The analysis of the drying curves revealed a period of constant flow rate at a low ultrasonic exposure and its absence at a high level of exposure of ≥ 160 dB, which indicated the start of the ultrasonic dispersion process of liquid from the potato surface. The dispersion occurred due to cavitation spraying of liquid without phase transition, which significantly reduced energy consumption. As the sound pressure increased in the range from 150 to 165 dB, the drying speed increased up to 26% by 5 dB. The optimal range of the sound pressure was 160–165 dB, which optimally combined energy consumption and drying time. The research resulted in two 6 kg horizontal and vertical drum dryers that provided even ultrasonic exposure during drying.
 Conclusion. The convective ultrasonic potato drum dryers reduced the drying time by 44–47%

Dispersion State and Damage of Carbon Nanotubes and Carbon Nanofibers by Ultrasonic Dispersion: A Review.

Dispersion of carbon nanotubes and carbon nanofibers is a crucial processing step in the production of polymer-based nanocomposites and poses a great challenge due to the tendency of these nanofillers to agglomerate. Besides the well-established three-roll mill, the ultrasonic dispersion process is one of the most often used methods. It is fast, easy to implement, and obtains considerably good results. Nevertheless, damage to the nanofibers due to cavitation may lead to shortening and changes in the surface of the nanofillers. The proper application of the sonicator to limit damage and at the same time enable high dispersion quality needs dedicated knowledge of the damage mechanisms and characterization methods for monitoring nano-particles during and after sonication. This study gives an overview of these methods and indicates parameters to be considered in this respect. Sonication energy rather than sonication time is a key factor to control shortening. It seems likely that lower powers that are induced by a broader tip or plate sonicators at a longer running time would allow for proper dispersions, while minimizing damage.

Novel two-step process for remediation of Cs-contaminated soil assisted by magnetic composites

In this study, a new approach to remediate Cs+-contaminated soil using magnetic composites to improve both the efficiency of separation of clay particles and Cs+ desorption is proposed. An ultrasonic dispersion and magnetic separation process were first performed to selectively remove clay particles from soil. In the soil dispersion solution, polyethylenimine-grafted Fe3O4 nanoparticles were selectively bonded with clay particles through electrostatic attraction, enabling the clay particles to be easily separated from the solution under an external magnetic field. In a Cs+ desorption process, Cs+ removal increased with increasing HNO3 concentration and temperature; the addition of K+ to the acid solution further enhanced Cs+ desorption by replacing Cs+ on the accessible sites of the sand. The addition of a magnetic adsorbent (Fe3O4@SiO2@KTiFC, where KTiFC is potassium titanium(IV) hexacyanoferrate) to the acid treatment substantially improved Cs+ desorption (95.2%) by preventing re-adsorption of Cs+ onto the sand. Based on these results, we evaluated the applicability of the proposed process to the decontamination of radioactive soil. The clay separation process substantially reduced the radioactivity level of the soil from 1630 to 222 Bq/kg by concentrating most of the 137Cs into the magnetic fraction. After treatment of the residual sand using the optimized Cs+ desorption method, the final radioactivity of the treated soil (73.5 wt% of initial soil) was 53 Bq/kg, which is less than the clearance level (100 Bq/kg). Therefore, the proposed method is potentially an effective and practical approach for the decontamination of radioactive soil.

Low angle-dependent structural colours from redispersion of silica photonic crystal film

Structural colour has attracted more and more attentions owing to its advantages of non-fading, environment friendly and non-toxic. According to its behaviour with respect to the viewing angle, there are two groups: iridescent (angle-dependent) and nor iridescent (angle-independent). However, many applications in textile and fashion require stable colour which means the colour shows low angle dependent. In this work, 314nm silica nanoparticle was synthesized by using a solvent varying technic which based on Stöber method. Iridescent structurally coloured film was directly self-assembled by gravity sedimentation of silica nanoparticle. Then, film was triturated and redispersed by ultrasonic dispersion process. Low angle-dependent structurally coloured film was then obtained by the redispersed silica nanoparticles. The effect of redispersion time on the structural colours was studied. The result shows that a twenty-minute redispersion gives a less bright but low angle-dependent structural colour film.

Solvent-Free Ultrasonic Dispersion of Nanofillers in Epoxy Matrix.

Dispersion of carbon nanotubes and carbon nanofibers is a crucial processing step in the production of polymer-based nanocomposites and poses a great challenge due to the tendency of nanofillers to agglomerate. One of the most effective methods for dispersion is the use of a three-roll mill, which is a well-established method and results in agglomerates below 5 µm. Nevertheless, this process is time-consuming and thus a limiting factor for industrial applications. Our aim was to establish an easy and efficient ultrasonic dispersion process, characterize the dispersion parameters, and compare both methods, ultrasonication and the three-roll mill. We applied rheological tests and analyzed the agglomerate sizes by an image fit of the microscopy images. All these analyses combined deliver a valuable set of information about the dispersion’s quality and, therefore, allows the improvement and further adaptation of the dispersion process.

Effect of sintering insulation time on the properties and microstructure of graphite-copper composite

The copper powder and graphite powder were used as raw materials to fabricate the graphite-copper composite by low temperature cold pressure powder metallurgy sintering method. The powders were mixed by ultrasonic dispersion and mechanical ball grinding process. The effects of sintering insulation time on the properties and microstructure of graphite-copper composite were investigated. The result showed that the distribution of graphite on the copper matrix was uniformly and formed a good interface by using the ultrasonic dispersion and mechanical ball grinding process. When the sintering insulation time was raised from 3 hours to18 hours, the friction coefficient and wear rate were decreased in the initial stage (from 3 hours to 12 hours) meanwhile the Vickers hardness (HV0.5) reached its maximum value 61.9HV when the sintering insulation time was 12 hours. The SEM (scanning electron microscope) images indicated that the increased sintering insulation time was helpful to distribute the graphite phased in composite relatively homogeneous with the sintering insulation time within 12 hours. However, the properties of graphite-copper composite also showed a downward or stable trend with the sintering Insulation time increasing from 12 hours to 18 hours.

Nano-sized fibrils dispersed from bacterial cellulose grafted with chitosan

Bacterial cellulose is an attractive material due to its outstanding biocompatibility, nanometer size and high purity, but the difficulty of dispersing has restricted its wide applications. In this study, chitosan was grafted onto bacterial cellulose by Schiff base reaction, and then obtained the nano-sized fibrils by ultrasonic dispersion process. Different concentrations of NaIO4 with various time and temperature were applied, and the maximum grafting amount of chitosan was 12.38%. The obtained products were characterized by FTIR, XRD, SEM and TEM. From the dispersibility and stability behavior research, the suspension containing chitosan was more uniform and showed better acid and temperature stability. It can also be observed in SEM and TEM images that the bacterial cellulose were dispersed into single ones and the diameter of the isolated fibril was 30–80 nm.

Influences of multi-walled carbon nanotube (MCNT) fraction, moisture, stress/strain level on the electrical properties of MCNT cement-based composites

Multi-walled carbon nanotube (MCNT) cement-based composites (MNTCCs) with seven different volume additions of MCNT (V) were prepared with surfactant ultrasonic dispersion process. A Wheatstone-based data acquisition technique was developed to simultaneously obtain the electrical resistances, the uniaxial stresses (σc), and the longitudinal strains (εl) of the cured MNTCCs under compressive loading. The percolation threshold, humidity impact on initial resistivity (ρin), and self-sensing piezoresistivity under mono- and cyclic-loading of the MNTCCs were correspondingly investigated. Results reveal that, the ρin of MNTCC successively conforms to tunneling transition and percolation effect along with V increment; Fraction change in resistivity (Δρ) of MNTCCs with 1.31 vol.% MCNT (round percolation threshold) after excluding humidity impact can steadily and linearly alter with σc or εl, and effectively reflect the microstructure changes and crack emerging; The corresponding strain sensitivity, reproducibility of the Δρ-εl curve can maintain above 132, less than 5%. These consequences favor the MNTCCs to be intrinsic sensors applied in infrastructure for real-time monitoring of cyclic loadings with high sensitivity, stable and fast responses.

Multifunctional performance of gC3N4-BiFeO3-Cu2O hybrid nanocomposites for magnetic separable photocatalytic and antibacterial activity

Highly active gC3N4-BiFeO3-Cu2O nanocomposites were successfully prepared via a facile, cost effective and eco-friendly method of hydrothermally wet precipitation combined with ultrasonic dispersion process. The prepared samples were characterized by XRD, FTIR, HRSEM, EDS, TEM, UV–Vis DRS, PL, VSM, BET and electrochemical properties. By means of these analysis for examine the crystal phase, nanostructure, band gap and light-harvesting properties were carried out. UV-DRS spectra indicate that the bandgap of g-C3N4 (2.7 eV) reduced to 2.59 and 2.21 eV by mixed with corresponds to BiFeO3 and BiFeO3/Cu2O nanomaterials. The ideal photocatalytic activity of the gC3N4-BiFeO3-Cu2O nanocomposites, where RhB dye under visible light irradiation which was up to 4.36 and 2.52 times as the higher photodegradation ability to compare pristine g-C3N4 and gC3N4-BiFeO3 catalyst. The magnetization was confirmed by VSM studies, and hence, after the photocatalytic reaction, the magnetically separable catalyst can be quickly separated from the water by an external magnetic field. The superior photocatalytic performance is due to the synergistic effect on the interface of BiFeO3/Cu2O in the gC3N4-BiFeO3-Cu2O nanocomposites has reduced the bandgap which enables high separation efficiency of the charge carrier, suppressed recombination rate and their high surface area. Moreover, the chief gC3N4-BiFeO3-Cu2O catalyst can exhibited the lesser charge transfer resistance (impedance), enhances of photocurrent responses, whereas exposed to the development of photocatalytic appearance and more charge carrier ability. Also, the antibacterial activity of the gC3N4-BiFeO3-Cu2O nanocomposite has showing a well deactivation in both G+ (S. aureus) and G− (E. coli) bacteria’s whereas compare to other prepared samples.

Methods of dispersion and stabilization of several nanomaterials in water

ABSTRACTCarbon nanomaterials are highly hydrophobic that affect their dispersion stability in aqueous solutions and make them limited in practical applications. In order to improve the stability of nanofluid and find the configuration parameters under the conditions of ultrasonic treatment and dispersant, the dispersion stabilization methods and dispersion mechanism were studied in this paper. Multi-walled carbon nanotubes (MWCNTs, 95% MWCNTs), graphene(GNP) and single-walled carbon nanotubes (SWNTs) were selected which with the highest thermal conductivity. Ultrasonic parameters were selected as 285 W and 10 min. The best dispersant for MWCNTs, 95% MWCNTs, GNP and SWNTs was SDBS and optimal ratios (SDBS/ MWCNTs, 95% MWCNTs, GNP, SWNTs) were (0.5-4):1, (1-4):1, (0.25-2):1, (1-4):1 respectively. The dispersion stability of the four nanofluids from good to bad were 95% MWCNTs, MWCNTs, SWNTs and GNP in turn. During the ultrasonic dispersion process, the long carbon tubes were interrupted into shorter carbon tubes, multi-layer GNP was divided into single layers. SDBS added functional groups into the carbon structure of nanomaterials, increasing the number of hydrophilic functional groups and enhancing the dispersion stability.

SYNTHESIS AND CHARACTERIZATION OF MAGNETIC-HYDROXY APATITE COMPOSITE USINGONE SPOT COPRECIPITATION METHOD

SYNTHESIS AND CHARACTERIZATION OF MAGNETIC-HYDROXY APATITE COMPOSITE USINGONE SPOT COPRECIPITATION METHOD . Nanocomposite of magnetic-hydroxyapatite (MHAP) has the potential to be developed as a biocompatible-biodegradable material for bone cancer diagnosis and therapy. In this study, such composite materials have been successfully synthesized by one-spot coprecipitation method and ultrasonic dispersion. The mass ratio between magnetic and hydroxyapatite fraction were varied to 30:70 (K30), 40:60 (K40) and 50:50 (K50). X-Ray Diffractometer, Transmission Electron Microscope, Fourier Transform-Infrared Spectrometer and Vibrating Sample Magnetometer were used for characterizing the properties of MHAP composite. X-Ray Diffraction pattern reveals the presence of magnetic and HAP phases, confirm the establishment of MHAP composite system. TEM image and FT-IR spectra shows the spherical morphology of magnetic nanoparticles with a size of ~ 10 nm entrapped within HAP nanorod structure without any chemical bonding between the two phase.With such physical composite mechanismand higher energy induce by ultrasonic dispersion process, magnetic fraction of even 50% mass fraction could still be loaded into HAP matrix and provide maximum magnetisation value of 34.6 emu/g. This magnetization value is higher than the result of another study of MHAP synthesis, giving better prospect for bone cancer diagnosis and therapy.

Construction of amorphous Ta2O5/g-C3N4 nanosheet hybrids with superior visible-light photoactivities for organic dye degradation and mechanism insight

Abstract In this paper, amorphous Ta 2 O 5 /g-C 3 N 4 nanosheet (ATCN) hybrid was firstly constructed by a facile ultrasonic dispersion process. In this way, amorphous Ta 2 O 5 nanoparticles anchored evenly onto the surface of g-C 3 N 4 nanosheets, forming the intimate interfacial contacts. The as-prepared ATCN composites exhibited significantly enhanced photocatalytic activities for the degradation of RhB compared to pure g-C 3 N 4 and amorphous Ta 2 O 5 nanoparticles under visible light illumination (λ > 420 nm). The optimal ATCN-3 photocatalyst possessed the highest visible-light photocatalytic activity (99.14%) and the degradation rate constant was 2.0055 h −1 , which was almost 6.2 and 14.9 times as high as those of individual g-C 3 N 4 and amorphous Ta 2 O 5 , respectively. Particularly, ATCN sample had good reusability and stability even after four cycles. Interestingly, amorphous Ta 2 O 5 /g-C 3 N 4 nanosheet hybrid showed higher photocatalytic activity than crystalline Ta 2 O 5 /g-C 3 N 4 . The enhanced photocatalytic performance was assigned to the synergistic effects including high surface area, enhanced visible light harvesting, efficiently interfacial charge transfer and reduced charge recombination. The plausible mechanism for improved photocatalytic properties was elucidated.

Investigation of Surfactant Type, Dosage and Ultrasonication Temperature Control on Dispersity of Metal-Coated Multi-Walled Carbon Nanotubes

We studied the dispersity of multi-walled carbon nanotubes (MWNTs) combined with different metal- lic particles (Ni and Fe). An ultrasonic-assisted water-bath dispersion process was used to dis- perse the metal-coated MWNTs in different solutions and the dispersity was measured using an ultraviolet-visible spectrophotometer. The dispersity and morphology of the MWNTs were characterized using field-emission scanning electron microscopy (FE-SEM) together with digital image processing technology. Effects of dispersant type (sodium dodecyl benzene sulfonate (SDBS), oleic acid, and polymer (TNEDIS)) and surfactant dosage on the dispersity of the metal-coated MWNTs were investigated under controlled and uncontrolled temperatures and results were compared with those from the untreated MWNTs. The results showed that the negative effects of temperature on the ultrasonic dispersion process could be eliminated through a temperature-controlled system. Moreover, the TNEDIS, SDBS, and oleic acid were arranged in the descending order of the dispersion effect degree. The untreated MWNTs, Ni-coated MWNTs, and Fe-coated MWNTs were arranged in the descending degree of dispersity order. Since the metal coating makes the MWNTs harder and more fragile, the metal-coated MWNTs are more likely to fracture during the ultrasonic dispersion process.

Highly conductive graphene oxide/polyaniline hybrid polymer nanocomposites with simultaneously improved mechanical properties

Graphene oxide (GO) was added to a polymer composites system consisting of surfactant-wrapped/doped polyaniline (PANI) and divinylbenzene (DVB). The nanocomposites were fabricated by a simple blending, ultrasonic dispersion and curing process. The new composites show higher conductivity (0.02–9.8S/cm) than the other reported polymer system filled with PANI (10−9–10−1S/cm). With only 0.45wt% loading of GO, at least 29% enhancement in electric conductivity and 29.8% increase in bending modulus of the composites were gained. Besides, thermal stability of the composites was also improved. UV–Vis spectroscopy, X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) revealed that addition of GO improves the dispersion of PANI in the polymer composite, which is the key to realize high conductivity.

Real-time monitoring of carbon nanotube dispersion using dynamic light scattering and UV-vis spectroscopy

A process for continuously monitoring the ultrasonic dispersion process of carbon nanotubes (CNTs) was discovered by integrating dynamic light scattering (DLS) and UV-vis spectroscopy. Through a continuous flow approach adapted to the dispersion system, the CNT suspension could be quantitatively characterized in real time. By continuously monitoring and identifying the evolution of mean particle size distribution and transparency of CNT suspension, the effective dispersion parameters and dispersion quality was quantified. Two types of MWNTs of different diameters and lengths were studied. For longer MWNTs with smaller diameters, the dispersion process achieved at a steady 100 nm of agglomerate size with 40 min of sonication. For shorter and large diameter and less entangled MWNTs, after 60 min of sonication, an agglomerate size of 100 nm was achieved, yet the stability decrease. The results show the potential ability of the system to optimize nanoparticle dispersion process for in-line dispersion quality control.

Preparation of PDMS/SiO2 nanocomposites via ultrasonical modification and miniemulsion polymerization

In this paper, the ultrasonic dispersion process was utilized to modify the silica sol nanoparticles by a certain amount of hydroxyl silicone oil (HSO), then in the presence of the modified silica sol, miniemulsion polymerization of octamethylcyclotetrasiloxane (D4) was conducted with dodecylbenzene sulfonic acid (DBSA) as the emulsifier and catalyst, and finally polydimethylsiloxane (PDMS)/silica (SiO2) nanocomposite latex was obtained. The modified silica sol particles, diameter and morphology of the composite latex particles, mechanical properties and thermal stabilities of the composite films were characterized and discussed, respectively. The results showed that the ultrasonic dispersion was an effective method to modify the silica sol particles, the grafted degree of HSO onto silica surface was about 5 %. The morphology of composite latex particles was shown core-shell structure with grafted SiO2 particles encapsulated by PDMS, the introduction of SiO2 improved the mechanical properties and thermal stabilities of polysiloxane composite films.

비타민 B1 유도체 Thiamine Dilauryl Sulfate의 나노 입자 제조를 통한 수용액의 용해도에 따른 항진균 활성 평가

Conventional Thiamine Dilauryl Sulfate (TDS) powder has a low stability. In order to solve this problem, this study was performed to improve the solubility of TDS. The process for enhance solubility of TDS was nano grinding mill and ultrasonic dispersion process. TDS paticle was manufactured to nano size through nano grinding mill process. The size of TDS nanoparticle was measured as average 220 ㎚ by DLS. And The TDS nanoparticle in water solution manufactured through ultrasonic dispersion process. The TDS nanoparticle in water solution was showed the highest solubility with 40% ethanol. These results was increased the concentration of TDS from 200 ppm to 240 ppm in water solution. The TDS nanoparticle in water solution showed diameter of Colletotrichum gloeosporioides growth with smaller than about 1.56 ㎝ compared to the TDS paticle in water solution at same concentration. Also, TDS nanoparticle in water solution showed growth inhibition activity as 59.2% with higher than about 10% compared to the TDS paticle water solution in same concentration. Finally, TDS nanoparticle in water solution was increased solubility through nano grinding mill and ultrasonic dispersion process. Also, the increase of concentration in TDS nanopaticle in water solution according to solubility enhancement lead to an result enhancement of antifungal activity. Consequently, we suggested that the TDS nanoparticle in water solution was more effective than TDS particle in water solution owing to the sub-cellular particle size, ability to persistence and targeting to cell membrane of Colletotrichum gloeosporioides. Furthermore we expected the applicating possibility with bio pesticide.