High-intensity Ultrasonic Irradiation Research Articles

Green sonochemical synthesis and fabrication of cubic MnFe2O4 electrocatalyst decorated carbon nitride nanohybrid for neurotransmitter detection in serum samples

The binary nanomaterials and graphitic carbon based hybrid has been developed as an important porous nanomaterial for fabricating electrode with applications in non-enzymatic (bio) sensors. We report a fast synthesis of bimetal oxide particles of nano-sized manganese ferrite (MnFe2O4) decorated on graphitic carbon nitride (GCN) via a high-intensity ultrasonic irradiation method for C (30 kHz and 70 W/cm2). The nanocomposites were analyzed by powder X-ray diffraction, XPS, EDS, TEM to ascertain the effects of synthesis parameters on structure, and morphology. The MnFe2O4/GCN modified electrode demonstrated superior electrocatalytic activity toward the neurotransmitter (5-hydroxytryptamine) detection with a high peak intensity at +0.21 V. The appealing application of the MnFe2O4/GCN/GCE as neurotransmitter sensors is presented and a possible sensing mechanism is analyzed. The constructed electrochemical sensor for the detection of 5-hydroxytryptamine (STN) showed a wide working range (0.1–522.6 μM), high sensitivity (19.377 μA μM−1 cm−2), and nano-molar detection limit (3.1 nM). Moreover, it is worth noting that the MnFe2O4/GCN not only enhanced activity and also promoted the electron transfer rate towards STN detection. The proposed sensor was analyzed for its real-time applications to the detection of STN in rat brain serum, and human blood serum in good satisfactory results was obtained. The results showed promising reproducibility, repeatability, and high stability for neurotransmitter detection in biological samples.

Formation mechanism of nanoporous silver during dealloying with ultrasonic irradiation.

Nanoporous silver (NPS) with an extreme coarsened 3-dimensional bi-continuous ligament and nanopore structure could be prepared by chemical dealloying with high-intensity ultrasonic irradiation (UI). The formation mechanism of NPS dealloying with UI was different from NPS obtained through free corrosion. It evolved into NPS with a new lump forming-disintegrating mechanism. Ultrasonic irradiation had strong effects on the dealloying process of NPS. The stirring effect produced by ultrasonic vibration could promote the corrosion of Cu and facilitate the diffusion of Ag atoms. Therefore, the coarsening rate of the ligament was increased significantly. Dealloying assisted by UI could generate an extremely coarsened microstructure of which ligament and pore sizes were much larger than those obtained from free corrosion dealloying.

Synergistic effect of low and high intensity ultrasonic irradiation on the direct growth of ZnO nanostructures on the galvanized steel surface: investigation of the corrosion behavior

Considering the current interest in the preparation of modified surfaces with fixed nanostructures, in this research, the hot water treatment was chosen as a simple and efficient procedure for the direct growth of ZnO nanostructures (ZnO NSs) on the metallic surface. To improve the method and reduce the cost of experiments, the commercial galvanized steel (steel containing a thin layer of zinc) was used as the base substrate. The use of the galvanized steel as an inexpensive and available metal surface has advantages compared to the pure Zn foil (used in other researches). In addition, in the present work, the effective pretreatment of the base substrate surface by applying the chemical etching under the low intensity ultrasonic irradiation facilitated the reaction progress (Zn → ZnO) in a shorter time and relatively low temperature in comparison to many reports. To find the effect of acoustic energy on the final ZnO morphology, the hot water treatment was carried out under conventional and sonochemical conditions. Finally, as a practical application, resulting surfaces were coated with electroless Ni-P deposits and the effect of as-grown ZnO NSs (as the sublayer) on improvement in the corrosion protection of binary Ni-P deposits was evaluated by the electrochemical method.

Synthesis of Nanocrystalline Cobalt Ferrite by the Sonochemical Method in Highly Basic Aqueous Solution

This study reported the preparation of nanocrystalline CoFe2O4 in single step by the sonochemical method in highly basic aqueous solution without requiring of high temperature calcination process. To prepare nanocrystalline CoFe2O4, the mixed solution of the required molar ratio of cobalt nitrate hexahydrate (Co (NO3).6H2O) and ferric nitrate nonahydrate (Fe (NO3).9H2O) was precipitated in high concentration of sodium hydroxide medium solution (NaOH) under high intensity ultrasonic irradiation (20 kHz, 150 W/cm2). The effect of NaOH concentration (5, 10, 15 and 20 M) on phase formation, microstructure and magnetic property of CoFe2O4 was investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) results showed that the as-prepared powders were single phase CoFe2O4 with cubic spinel structure. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study showed that nanocrystalline CoFe2O4 had monosized distorted spherical morphology and an agglomeration of the nanocrystalline CoFe2O4 into nanoparticles was observed when increasing the NaOH concentration. The nanocrystalline CoFe2O4 exhibited superparamagnetic property and the saturation magnetization (Ms) obtained from vibrating sample magnetometry (VSM) was found to correlate with the crystallite size and varied from 39-45 emu/g.

Effects of Ultrasound Irradiation on the Preparation of Ethyl Cellulose Nanocapsules Containing Spirooxazine Dye

This article presents the influence of low frequency, high intensity ultrasonic irradiation on the characteristics (average size, polydispersity index) of ethyl cellulose nanocapsules encapsulating a photochromic dye. Photochromic nanocapsules were prepared by the emulsion-solvent evaporation method. The acoustic densities entering the system were systematically studied with respect to their abilities to modify and reduce the average sizes and polydispersity indexes of the nanocapsules. Scanning electron microscope, confocal laser microscope, and dynamic light scattering were utilised to characterise the structure, shape, size, and polydispersity of ethyl cellulose photochromic nanocapsules. We were able to tailor the size of the photochromic nanocapsules simply by varying the acoustic densities entering the system. At an acoustic density of 1.5 W/mL and 60 s of continuous irradiation, we were able to prepare an almost monodispersed population of the nanocapsules with an average size of 193 nm.

Fabrication and Characterization of Nano-Sized Starch Particles

An efficient method of preparing nanostarch using high-intensity ultrasonic irradiation and acid hydrolysis was discussed. The transmission electron microscope (TEM) showed that the nanosized starch particles were in shape of sphere with the size of 80-120 nm, and their surfaces were rough with many flocci. The Fourier transform infrared spectrometer (FT-IR) revealed that the products maintained the original biological characteristics, and the molecules did not undergo any chemical changes. In addition, the effects of experimental conditions were analyzed and a plausible mechanism was proposed to explain the formation of the nanostarch.

Preparation of nanoporous silver micro-particles through ultrasonic-assisted dealloying of Mg-Ag alloy ribbons

Nanoporous silver (NPS) micro-particles were prepared successfully by combining high-intensity ultrasonic irradiation (UI) and chemical dealloying process of rapidly solidified Mg-Ag precursors. The length scale of the ligaments in NPS is 100±30 nm, which is insensitive to the concentration of the hydrochloric acid (HCl) solution and the intensity of the UI. However, smaller NPS micro-particles with a size of 50±20 μm can be obtained by dealloying the precursor ribbons in a much more concentrated HCl solution under UI. It is supposed that the cavitation phenomena induced by UI treatment may play a key role in disaggregating the precursor ribbons into the present NPS micro-particles during dealloying.

Controlled Cavitation at Nano/Microparticle Surfaces

Here we proposed a model that describes the nucleation of cavitation bubbles on nano/microparticle surfaces, which is of significance for the yet unsolved problem of particle-cavitation interaction. The model was verified through rational experimental design varying parameters including particle size, their shapes and additives. The surface morphology evolution of particles under high intensity ultrasonic irradiation in aqueous solution can be tailored by changing the nucleation energy barrier of cavitation bubbles on particle surfaces. Cavitation-induced breakage of particles under sonication has also been addressed, which predicts the critical effect of the initial size of solid particles in affecting ultrasound-driven intraparticle fracture. These results shed light on the effect of commonly used sonication treatments on nanostructured materials and sonochemical surface modification in particle science and technology.

Ionic liquid assisted sonochemical synthesis of NiS submicron particles

A novel synthesis methodology is reported for the preparation of NiS submicron particles in a green solvent 1-butyl-3methylimidazolium tetrafluoroborate (BMImBF4) ionic liquid (IL), using ultrasonic sonochemical technique. Structural, morphological and optical properties of nickel sulfide powders were obtained by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS). Composition was corroborated by energy dispersive X-ray spectroscopy (EDXS), both in the SEM and in the TEM. Regular shape particles were obtained under high-intensity ultrasonic irradiation for 105min from the reaction between nickel nitrate and thioacetamide in ethanol/BMImBF4 (80:20), respectively. After vacuum annealing treatment at 180°C overnight, spherical crystalline NiS particles were observed. The powders showed a band gap of 0.74eV.

Feasibility of Using High-Intensity Ultrasound Assisted Biodiesel Production from Mixed Crude Palm Oil in Two-Step Process

Biodiesel from a high free fatty acid (FFA) mixed crude palm oil (MCPO) can be produced to high fatty acid methyl ester (FAME) conversion by a two-step process. The first process is an acid-catalyzed esterification to reduce FFA in oil followed by a base-catalyzed transesterification process to produce biodiesel from esterified oil. In this study, the transesterification of esterified oil with methanol in the presence of potassium hydroxide (KOH) was performed in a 1,000 W ultrasonic homogenizer at a low frequency of 18 kHz. The use of high-intensity ultrasound to accelerate the reaction, the high surface power density of 1.62 W.mm-2 and the volumetric acoustic energy of 20 W.mL-1 were fixed. The objective of this study was to determine the various parameters (methanol concentration, KOH concentration, and initial temperature of oil) to produce the FAME conversion. The results showed that over 98 wt.% of FAME could be achieved with 5 g KOH/liter of oil, 15 vol.% of methanol, the total residence time of 20 seconds, and temperature of 30 oC. Moreover, the glycerides were rapidly converted to the FAME within reaction time of 10 seconds when the base-catalyst of 10 g KOH/liter of oil, and 20 vol.% of methanol were used. Consequently, the use of high-intensity ultrasonic irradiation can minimize the chemical cost, electricity cost, and reaction time.

Mechanical and thermal properties of bio‐based CaCO3/soybean‐based hybrid unsaturated polyester nanocomposites

Bio‐based calcium carbonate nanoparticles (CaCO3) were synthesized via size reduction of eggshell powder using mechanical attrition followed by high intensity ultrasonic irradiation. The transmission electron microscopic (TEM) and BET surface area measurements show that these particles are less than 10 nm in size and a surface area of ∼44 m2/g. Bio‐based nanocomposites were fabricated by infusion of different weight fractions of as‐prepared CaCO3 nanoparticles into Polylite® 31325‐00 resin system using a non‐contact Thinky® mixing method. As‐prepared bio‐nanocomposites were characterized for their thermal and mechanical properties. TEM studies showed that the particles were well dispersed over the entire volume of the matrix. Thermal analyses indicated that the bio‐nanocomposites are thermally more stable than the corresponding neat systems. Nanocomposite with 2% by weight loading of bio‐CaCO3 nanoparticles exhibited an 18°C increase in the glass transition temperature over the neat Polylite 31325 system. Mechanical tests have been carried out for both bio‐nanocomposites and neat resin systems. The compression test results of the 2% Bio‐CaCO3/Polylite 31325 nanocomposite showed an improvement of 14% and 27% in compressive strength and modulus respectively compared with the neat system. Details of the fabrication procedure and thermal and mechanical characterizations are presented in this article. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1442–1452, 2013

SYNTHESIS OF HYBRID SiC/SiO2 NANOPARTICLES AND THEIR POLYMER NANOCOMPOSITES

In the present investigation, silicon carbide (β-SiC) nanoparticles (~ 30 nm) were coated on silicon dioxide (SiO2) nanoparticles (~ 200 nm) using sonochemical method. The resultant hybrid nanoparticles were then infused into SC-15 epoxy resin to enhance the thermal and mechanical properties of SC-15 epoxy for structural application. To fabricate an epoxy-based nanocomposite containing SiC/SiO2 hybrid nanoparticles, we have opted a two-step process. In the first step, the silica nanoparticles were coated with SiC nanoparticles using high intensity ultrasonic irradiation. In a second step, 1 wt.% of as-prepared SiC/SiO2 particles were dispersed in epoxy part-A (diglycidylether of bisphenol A) using a high intensity ultrasound for 30 min at 5°C. The part-B (cycloaliphatic amine hardener) of the epoxy was then mixed with part-A- SiC/SiO2 mixture using a high-speed mechanical stirrer for 10 min. The SiC/SiO2 /epoxy resin mixture was cured at room temperature for 24 h. The SiC nanoparticles coating on SiO2 was characterized using X-ray diffraction (XRD) and high resolution transmission electron microscope (TEM). The as-prepared nanocomposite samples were characterized using thermo gravimetric analysis (TGA) and differential scanning calorimeter (DSC). Compression tests have been carried out for both nanocomposite and neat epoxy systems. The results indicated that 1 wt.% (SiC) + (SiO2) loading derived improvements in both thermal and mechanical properties when compared to the neat epoxy system.

Optimization of continuous acid-catalyzed esterification for free fatty acids reduction in mixed crude palm oil using static mixer coupled with high-intensity ultrasonic irradiation

The major problem of biodiesel production from mixed crude palm oils (MCPOs) is the high free fatty acid (FFA) content. To achieve good conversion from MCPO to esters, the FFA should not exceed 1wt.% or 2mgKOHg−1 of acid value when using base-catalyzed transesterification to produce biodiesel. In this study, reduction of the acid value in MCPO with methanol in the presence of sulfuric acid as an acid-catalyst was performed in continuous esterification using static mixer coupled with ultrasonic reactor. A 1000W ultrasonic homogenizer was operated at 18kHz frequency in a 100mL continuous-reactor. Response surface methodology (RSM); a 5-level, 2-factor, central composite design (CCD), was employed to optimize the two important reaction variables (methanol and sulfuric acid concentrations). To minimize chemical costs in order to reduce the acid value from 28mgKOHg−1 to less than 2mgKOHg−1, 18vol.% of methanol, 2.7vol.% of sulfuric acid, and 20Lh−1 of MCPO flow rate are recommended.

Influence of adsorbed gas at liquid/solid interfaces on heterogeneous cavitation

The presence of dissolved gas at the solid/liquid interface can play a crucial role in heterogeneous cavitation. Here we focus our attention on the relationship between gas conditions and cavitation nucleation at planar solid surfaces with alternating hydrophobic/hydrophilic properties. Tapping mode atomic force microscopy and optical microscopy were used to monitor the gas adsorption on the patterns before sonication. Scanning electron microscopy revealed the effects of collapsing cavitation bubbles on the irradiated surfaces. High intensity ultrasonic irradiation (20 kHz) induces the formation of an interfacial gas layer at the solid surface immersed in different liquid media (water saturated with different gases, such as argon, nitrogen or carbon dioxide) by accelerating the adsorption of dissolved gas. Subsequently, the gas rearranges in diverse nano- or microstructures which take further part in the cavitation process. A solvent-exchange method was also applied to induce the formation of artificial gaseous domains accumulated at the solid surface in order to facilitate the cavitation process. By varying the gas adsorption time it is possible to accelerate or to slow down heterogeneous cavitation. The experimental findings on heterogeneous cavitation are discussed in terms of interfacial bubble nucleation and bubble attraction and growth on patterned solid surfaces in liquid media.

ChemInform Abstract: Synthesis and Characterization of HfO2 Nanoparticles by Sonochemical Approach.

AbstractHfO2 nanoparticles are synthesized by high intensity ultrasonic irradiation of an aqueous solution of HfCl4 and NaOH under ambient conditions for 1 h.

Preparation of water soluble CdSe and CdSe/CdS quantum dots and their uses in imaging of cell and blood capillary

A novel method for the synthesis of water-soluble CdSe and CdSe/CdS quantum dots (QDs) under the assistance of high-intensity ultrasonic irradiation is reported. As-prepared CdSe/CdS QDs were characterized by X-ray powder diffraction and high-resolution transmission electronmicroscopy. The absorption and fluorescence emission spectra were measured to investigate the effect of CdS passivation on the electronic structure of the quantum dots. After the growth of CdS shell, the photoluminescence quantum yields of CdSe/CdS core–shell quantum dots increased three times more than that of the original CdSe QDs. The QDs were successfully used for the fluorescence imaging of cells and blood capillary.

Novel biomorphic Ni/SiC catalysts that enhance cellulose conversion to hydrogen

High-intensity ultrasonic irradiation was used to improve the synthesis of cellulose-fiber-templated β-SiC by poly(carbomethylsilane) infiltration, and this improved method was also applied to the synthesis of biomorphic SiC materials from jute fiber, bark from a paperbark tree, bamboo fibers, and butterfly wing. The method could also be applied to produce a composite material, containing Ca, Si, C, and O, from poly(carbomethylsilane) and the bone of a cuttlefish. The parent structures were replicated with high fidelity in the final ceramics. Cellulose-fiber- and paperbark-templated β-SiC samples were impregnated with Ni particles, and the resulting material was used as a catalyst for cellulose pyrolysis. The Ni/paperbark-templated β-SiC catalyst was more effective for H2 generation, likely because paperbark-templated β-SiC had a higher surface area and average pore size than the cellulose-templated β-SiC.

Effect of different parameters on sonochemical synthesized nanocrystalline TiO2 particles

An ultrasonic-assisted method to directly prepare nanocrystalline TiO2 has been used. TiO2 was synthesized by the hydrolysis of Tetraisopropyl titanate (TIPT) in the presence of de-ionized water and ethanol under high-intensity ultrasonic irradiation (24 KHz, 300 W/cm2) at different conditions. The effect of water content, water-to-TIPT ratio, water-to-ethanol ratio and sonication time on the particle size of TiO2 has been investigated by using design of experiment (DOE). The water content, water-to-TIPT ratio, water-to-ethanol ratio and sonication time were varied in the range 100-150 ml, 50-75 v/v, 20-30 v/v and 3-4 hr, respectively. Particle size of TiO2 was characterized using particle size analyzer. The results of DOE show that water content has the greatest effect on the particle size of TiO2.

COMPARATIVE STUDY OF MICROWAVE AND THERMAL CURING OF HIGH TEMPERATURE EPOXY/CARBON NANOTUBES POLYMER NANOCOMPOSITES AND THEIR PROPERTIES

The high temperature epoxy resin system was cured using microwave and regular oven heating in the presence and absence of multiwalled carbon nanotubes (CNTs) and their properties are studied. For this study, a high temperature EPON-862 resin is used as matrix and CNTs as reinforcement. The EPON-862-part-A resin is used was reinforced with 0.1 wt.%, 0.2 wt.% and 0.3 wt.% of CNTs using a high-intensity ultrasonic irradiation. The curing agent epicure W (part-B) was mixed with EPON-862 resin using a noncontact mixing method (Thinky, Japan). The reaction mixture was cured using a 2.45 GHz (Sharp BP210) microwave oven for only 10 min instead of 8 h for conventional oven heating (curing schedule is 4 h at 120°C, post curing at 170°C for 4 h). The compression tests were performed for all the sample including thermally cured and microwave-cured neat EPON-862, EPON-862/0.1 wt.% CNTs, EPON-862/0.2 wt.% CNTs and EPON-862/0.3 wt.% CNTs. Microwave-cured samples of EPON-862/0.2 wt.% CNTs showed 28.57% and 5.57% increase in compression modulus and compression strength, respectively, as compared to the neat EPON-826 regular oven heating.

A comparative study of ternary Al–Sn–Cu immiscible alloys prepared by conventional casting and casting under high-intensity ultrasonic irradiation

A comparative study on the microstructure of four ternary Al–Sn–Cu immiscible alloys, guided by the recent thermodynamic assessment of the system, was carried out with specific focus on the soft Sn particulate distribution in hard Al-rich matrix in the presence and absence of ultrasonic irradiation during solidification. The results clearly demonstrate high effectiveness of ultrasonication in promoting significantly refined and homogeneously dispersed microstructure, probably aided by enhanced nucleation and droplet fragmentation under cavitation. While conventional solidification produced highly segregated Sn phase at the centre and bottom of Sn-rich alloy ingots, ultrasonic treatment produced effective dispersion irrespective of the alloy constitution in the region around the radiator. At distance >20 mm from the radiator, presumably outside the region of active cavitation, any bulk fluid flow from acoustic streaming appears to be less efficient in preventing segregation of liquids even though still more effective than quiescent solidification conditions.