Application Of Ultrasonic Irradiation Research Articles

Turbulence induced shear controllable synthesis of nano FePO4 irregularly-shaped particles in a counter impinging jet flow T-junction reactor assisted by ultrasound irradiation

FePO4 (FP) particles with a mesoporous structure amalgamated by nanoscale primary crystals were controllably prepared using an ultrasound-intensified turbulence T-junction microreactor (UTISR). The use of this type of reaction system can effectively enhance the micro-mixing and remarkably improve the mass transfer and chemical reaction rates. Consequently, the synergistic effects of the impinging streams and ultrasonic irradiation on the formation of mesoporous structure of FP nanoparticles have been systematically investigated through experimental validation and CFD simulation. The results revealed that the FP particles with a mesoporous structure can be well synthesised by precisely controlling the operation parameters by applying ultrasound irradiation with the input power in the range of 0–900 W and the impinging stream volumetric flow rate in the range of 17.15–257.22 mL·min−1. The findings obtained from the experimental observation and CFD modelling has clearly indicated that there exists a strong correlation between the particle size, morphology, and the local turbulence shear. The application of ultrasonic irradiation can effectively intensify the local turbulence shear in the reactor even at low Reynolds number based on the impinging stream diameter (Re < 2000), leading to an effective reduction in the particle size (from 273.48 to 56.1 nm) and an increase in the specific surface area (from 21.97 to 114.97 m2·g−1) of FP samples. The FPirregularly-shaped particles prepared by UTISR exhibited a mesoporous structure with a particle size of 56.10 nm, a specific surface area of 114.97 m2·g−1and a total pore adsorption volume of 0.570 cm3·g−1 when the volumetric flow rate and ultrasound power are 85.74 mL·min−1and 600 W, respectively.

Crystallization of citicoline sodium by anti-solvent assisted with ultrasound

Citicoline sodium tend to agglomerate during the crystallization process which can't be well solved by changing some conventional crystallization conditions. To solve this problem, an ultrasonic-assisted crystallization method was developed in this paper. The effects of ultrasound on the crystal metastable zone widths (MSZWs), induction time, crystal habit, and particle size distribution (PSD) were studied experimentally. The dynamic method was used to determine the solubility of Citicoline sodium in ethanol–water binary mixed solvents. The induction time and the MSZWs were measured under ultrasound and silent conditions. Moreover, the crystallization process was optimized using ultrasonic-assisted anti-solvent crystallization method. The influence of ultrasound on crystal habit during the crystallization process could be observed by optical microscope. Ultrasound optimized products can be characterized by scanning electron microscope (SEM), laser particle size analyzer, X-ray powder diffraction and infrared spectroscopy. The experimental results showed that the MSZWs and the induction time could be reduced by the application of ultrasonic irradiation. The agglomeration and crystal habit of Citicoline sodium could be improved by optimizing the crystallization process with ultrasound. After optimization, the mass yield was increased to 95 %, the median particle size DV (50) was about 10 μm and the PSD was narrower.

Spectroscopic and microscopic studies of Co, Ce, and Pd containing gamma-alumina as catalysts for cyclohexene oxidation

The oxidation of cyclohexene belongs to the most important reactions in organic chemistry and leads to the production of the precursors for surfactants, polymers, agrochemicals, and drugs. So far, however, due to a complex reaction mechanism, it was hard to find the catalyst of satisfactory properties.Attractive catalysts in this reaction could be sonochemically prepared Co, Ce, and Pd containing γ-Al2O3, which is the object of the undertaken research. What is more, this combination of metals in the oxide system has not been studied. The analysis of catalytic performance indicated that all studied catalysts were active in the catalytic oxidation of cyclohexene. For metal-containing alumina (Me=Co, Ce, Pd), the conversion of cyclohexene was 61–84%. The best catalyst was Co5Ce5/γ-Al2O3s, prepared via the sonochemically-assisted procedure.It was also shown that the application of ultrasonic irradiation during the preparation of samples enhanced metal distribution over alumina support, resulted in smaller crystallites of prepared materials, and caused higher surface area with simultaneous smaller both pore size and pore volume in comparison with counterparts prepared via the standard procedure. XRD, Ra, and DR..-UV–vis spectroscopies indicated the coexistence of Co as Co3O4 and CoAl2O4 spinel, however, Ce was found in the form of CeO2. The addition of Pd to Co/γ-Al2O3 did not influence the status of cobalt.

Ultrasonic irradiation as a green production route for coupling crystallinity and high specific surface area in iron nanomaterials

Coupling high crystallinity with high specific surface area in engineered nanomaterials is imperative whenever both chemical endurance regarding particle dissolution and a large specific surface area are needed for environmental clean-up purposes. Gathering both properties in the same particulate system is not trivial. In this work, A L-9 orthogonal array of experiments was used to assist a liquid-phase reduction method aiming to synthesize zero valent iron nanoparticles (nZVI) that could offer a large specific surface area while presenting a well-developed crystalline structure. The experimental variables included the reductant addition rate, the precursor (Fe+3) concentration, the (reductant/Fe3+) ratio, (R), and also the application of ultrasonic irradiation (UI) to the precipitating medium. The results show that NaBH4/FeCl3 ratio and Fe+3 concentration have opposite effects on the specific surface area of the synthesized particles whereas the effect of reductant addition rate is negligible. Moreover, the introduction of UI in the precipitation process benefits considerably the surface area of the particles while preserving or even enhancing the crystallinity of the precipitated nanomaterials. The effects of UI were interpreted in the frame work of the classical nucleation theory. This work raises the potential of UI as an environmentally friendly method to be applied to other precipitation systems which could end up in finer powder particles with better crystallinity.

Study on synergistic toughening of polypropylene with high-density polyethylene and elastomer-olefin block copolymers under ultrasonic application

In this study, we prepared the blends of polypropylene (PP) and high-density polyethylene (HDPE) with elastomer-olefin block copolymers (OBC) using an ultrasonic twin-screw extruder and investigated the mechanical, thermodynamic, and rheological properties of the blends. We examined the interfacial interactions among PP, OBC, and HDPE and observed that the PP/OBC/HDPE blends formed a core-shell structure with HDPE as the core and OBC as the shell. The crystallization temperature as well as the crystallinity of the blends were improved thanks to the heterogeneous nucleation between PP- and OBC-covered HDPE particles. Moreover, the impact strength of PP/OBC/HDPE blends was increased by three times as compared with PP because of the addition of 10 phr OBC and 15 phr HDPE; however, the viscosity increased slightly. Furthermore, it was evident from the fracture surface morphologies of PP/OBC/HDPE blends that the OBC-covered HDPE particles became smaller under the application of ultrasonic irradiation; hence, the interfacial interactions between the particles and the PP matrix were enhanced and the impact strength of the blends was improved.

Characterisation of well-adhered ZrO2 layers produced on structured reactors using the sonochemical sol–gel method

The aim of this study was to obtain thin zirconium dioxide coatings on structured reactors using the sonochemical sol-gel method. The preparation method of metal oxide layers on metallic structures was based on the synergistic combination of three approaches: the application of ultrasonic irradiation during the synthesis of Zr sol-gel based on a precursor solution containing zirconium(IV) n-propoxide, the addition of stabilszing agents, and the deposition of ZrO2 on the metallic structures using the dip-coating method. As a result, dense, uniform zirconium dioxide films were obtained on the FeCrAlloy supports. The structured reactors were characterised by various physicochemical methods, such as BET, AFM, EDX, XRF, XRD, XPS and in situ Raman spectroscopy. The results of the structural analysis by Raman and XPS spectroscopy confirmed that the metallic surface was covered by a ZrO2 layer without any impurities. SEM/EDX mapping revealed that the deposited ZrO2 covered the metallic support uniformly. The mechanical and high temperature tests showed that the developed ultrasound assisted sol-gel method is an efficient way to obtain thin, well-adhered zirconium dioxide layers on the structured reactors. The prepared metallic supports covered with thin ZrO2 layers may be a good alternative to layered structured reactors in several dynamics flow processes, for example for gas exhaust abatement.

Application of ultrasonic irradiation as a benign method for production of glycerol plasticized-starch/ascorbic acid functionalized MWCNTs nanocomposites: Investigation of methylene blue adsorption and electrical properties

A solution mixing and ultrasonic dispersion method as a green, the fast, inexpensive and effective technique was utilized to prepare glycerol plasticized-starch (GPS)/ascorbic acid (AA)-MWCNTs nanocomposites (NCs) via the introduction of various amounts of AA-MWCNTs (3, 6 and 9wt%) as filler into GPS matrix. The GPS was synthesized by addition of glycerol (50%) as a plasticizer to starch which enhances its flexibility. Characterization of the obtained GPS/AA-MWCNTs NCs was accomplished by different techniques. The optimum filler content for the generation of fine electrical conductivity and good mechanical properties was found to be about 3wt%. The distribution of AA-MWCNTs at the low content (3wt%) in the GPS matrix was better due to the strong linkage between nanofiller and GPS in GPS/AA-MWCNTs NC. The results of adsorption studies showed that the fabricated NC can be a good adsorbent for removal of methylene blue (MB) dye from aqueous solutions.

A Novel, Green Synthesis of Deuterium Labeled Compounds

While deuterium (D) is barely different from its most abundant isotope hydrogen (H), the additional neutron makes a significant difference in the properties of deuterated compounds. While metabolic enzymes easily transform drug molecules to metabolites that the body can excrete, the introduction of deuterium to drugs appears to strengthen the resistance of drugs toward metabolism. The higher the stability, the longer the drug can work, which may result in lower dosage, therefore less side effects. In fact, the carbon‐deuterium bond is known to be six‐ten times stronger than its C‐H counterpart. There are several known methods for the introduction of deuterium to organic compounds; most methods, however, do not conform to the recent expectations and standards of sustainable synthesis. In order to develop an environmentally benign deuteration method we have turned our attention to the Al‐H2O system that is commonly applied for hydrogenation reactions. Replacing the H2O with its deuterated version D2O this hydrogen generating system can be turned to an easy and safe source of deuterium. The application of either the commercially available Ni‐Al alloy or Al only in conjunction with common hydrogenation catalysts, such as Pd or Pt, for the H‐D exchange of compounds with reactive C‐H bonds can be easily performed, while yielding no harmful byproducts. The low reactivity of the aluminum metal can be significantly enhanced by the application of ultrasonic irradiation. The H‐D exchange reaction can be carried out under relatively mild conditions; in more difficult cases the application of microwave irradiation yields the final products in a 1 h reaction. The success of the method was demonstrated by applying a broad variety of compounds from essential amino acids to actual drug compounds. By generating stronger bonds, the drugs would be able to remain active for an extended period of time, allowing the use of lower amounts, thus significantly improve the safety of their use.

Improvement of organic solar cells using aluminium microstructures prepared in PEDOT:PSS buffer layer by using ultrasonic ablation technique

In the present work we introduce an improvement of organic solar cell efficiency by using aluminium microstructures (Al MSs) dispersed in poly(3,4-ethylene dioxythiophene)-blend-poly(styrene sulfonate) (PEDOT:PSS) buffer layer. Al microstars (in the range of 5–16μm) in addition to Al nanoparticles (Al NPs) have been prepared by new ultrasonic ablation technique through the application of ultrasonic irradiation upon Al thin film immersed in PEDOT:PSS solution. In the beginning, we found that the PEDOT:PSS solution completely dissolves Al thin film before the applying of ultrasonic irradiation as a result of acidic nature of the PEDOT:PSS solution. The action of PEDOT:PSS on the Al film tends to produce Al microcircles, which are dissociated into Al microstars after the applying of ultrasonic irradiation. The short circuit current density, fill factor, and, consequently, power conversion efficiency of the investigated solar cells have been improved by the incorporation of Al microstars, which can facilitate the transport of charge carriers, specifically holes, to be transferred along the axis of the Al microstars in the buffer layer of the solar cell. We found that the increase in ultrasonication time applied upon the solution of PEDOT:PSS-Al microstars diminishes the length of Al microstars and reduces the number of Al microstars' arms. Therefore, further increase in the ultrasonication time tends to decrease the device performance parameters due to the deficit of charge carriers to be transferred in the buffer layer matrix. The Al microstars prepared by ultrasonic ablation technique are pure and free of surfactants and passivation layers that are inevitably present on the surface of the chemically synthesized metal MSs and NPs. The new ultrasonic ablation method is safe (different than laser ablation technique) to prepare metal NPs and MSs in the sensitive organic solvents and solutions which are directly used to prepare organic solar cells. In addition, the new technique enables us to prepare desirable size of Al microstars, which can be suitable for improving organic solar cells and in other different applications.

Effect of ultrasonic irradiation on the preparation of Ag 3 PO 4 particles

Herein is investigated the effect of ultrasonic irradiation on the preparation of Ag3PO4 particles based on the ion-exchange method. X-ray diffraction, scanning electron microscope, diffuse reflectance spectrum and photoluminescence were used to characterise the products. It is found that the application of ultrasonic irradiation at a frequency of 40 kHz leads to the production of uniform spherical particles with an average size of ∼300 nm. However, at a higher ultrasonic frequency of 60 kHz, the prepared sample presents polyhedron-shaped particles in the size range of 6–8 μm, which are constructed from small grains with a size of several hundred nanometres. Without the aid of ultrasonic irradiation, the samples prepared at room temperature or under 50 °C water-bath condition are composed of spherical particles and large-sized agglomerative particles. The photocatalytic activity of Ag3PO4 samples was evaluated by degrading rhodamine B (RhB) under simulated sunlight irradiation. Among these samples, the one prepared at 40 kHz exhibits the highest photocatalytic activity, where the degradation percentage of RhB reaches 96% after irradiation for 60 min.

Kinetics of 2-chlorobiphenyl Reductive Dechlorination by Pd-fe0Nanoparticles

Kinetics of 2-chlorobiphenyl (2-Cl BP) catalytic reductive dechlorination by Pd-Fe 0 nanoparticles were investigated. Experimental results showed that ultrafine bimetallic Pd-Fe 0 e nanoparticles were synthesized in the presence of 40 kHz ultrasound in order to enhance disparity and avoid agglomeration. The application of ultrasonic irradiation during the synthesis of Pd-Fe 0 nanoparticles further accelerated the dechlorinated removal ratio of 2-Cl BP. Up to 95.0% of 2-Cl BP was removed after 300 min reaction with the following experimental conditions: initial 2-Cl BP concentration 10 mg L -1 , Pd content 0.8 wt. %, bimetallic Pd-Fe 0 nanoparticles prepared in the presence of ultrasound available dosage 7g L -1 , initial pH value in aqueous solution 3.0, and reaction temperature 25°C. The catalytic reductive dechlorination of 2-Cl BP followed pseudo-first-order kinetics and the apparent pseudo-first-order kinetics constant was 0.0143 min -1 .

Ultrasound-assisted bioethanol production from waste newspaper

The present work deals with intensification of bioethanol production from waste newspaper using Saccharomyces cerevisiae using ultrasonic irradiations. The effect of different process parameters such as application of ultrasonic irradiation at different growth phases, irradiation time, ultrasonic power and duty cycle on the bioethanol production has been investigated. The favorable conditions for the maximum yield were established as application of ultrasonic irradiation (duration of 10min) to fermentation broth at 12h of growth phase with 25kHz frequency, 160W power and 20% duty cycle. The bioethanol productivity was increased by 1.8 times from 7.8 to 14.1g/L compared with the non-sonicated control fermentation. Decrease in glucose concentration from 0.63% to 0.2% w/v in ultrasound-assisted fermentation confirmed the improved substrate uptake of the microbial cell due to the application of ultrasound. ESEM analysis also confirmed the changes in the cell morphology leading to improved cell permeability. Results were fitted to an unstructured kinetic model comprising of the kinetic and physiological parameters. Overall, the work has demonstrated an intensified approach for the bioethanol production based on the use of ultrasound.

Transesterification of hazelnut oil by ultrasonic irradiation

ABSTRACTUltrasonic irradiation is considered an effective way to increase mass transfer between immiscible liquid–liquid phases in a heterogeneous system leading to faster transesterification and higher yield and saving excess methanol and catalyst. In this study, the transesterification of hazelnut oil with methanol and ethanol was performed in the presence of potassium hydroxide or sodium methoxide as a catalyst using two types of ultrasonic irradiation with a probe (20 kHz, 200 W) and a bath (35 kHz, 400 W); a conventional production method was also used. The reaction time, alcohol:oil molar ratio, catalyst type (KOH or NaOCH3), and catalyst amount (wt.% of oil) were studied as experimental parameters. The highest methyl ester conversion was obtained as 98.12% by using ultrasonic probe at a 5:1 methanol:oil molar ratio with KOH 1 wt.% of oil as catalyst in 20-min reaction time at autogenous temperature. The application of ultrasonic irradiation by using a probe decreased the level of energy consumption, showing that this method may be a promising alternative compared with the conventional production method.

Combination of ultrasonic irradiation with ionic liquid pretreatment for enzymatic hydrolysis of rice straw

The application of ultrasonic irradiation and ionic liquids (ILs) in the degradation of rice straw under different processes of pretreatment and enzymatic hydrolysis was investigated. Various substrates for enzymatic hydrolysis by cellulase with and without ultrasound were as follows: untreated rice-straw powder (RS); RS treated by ILs of 1-ethyl-3-methylimidazolium ethylsulfate and trihexyl (tetradecyl) phosphonium decanoate with ultrasound at 300 W/(40 kHz, 28 kHz); RS treated by IL of choline hydroxide ([Ch][OH]) with ultrasound at 300 W/40 kHz (CHRS). In ultrasound-mediated enzymatic hydrolysis, the yield of total reducing sugar (TRS) converted from CHRS was up to 96.22% at 240 min and was greater than that from the other substrates; the TRS yield for CHRS with ultrasound was 19.5% greater than that without irradiation. Lignocellulosic biomass pretreated with [Ch][OH] showed the highest efficiency among the tested ILs, and ultrasound can be applied effectively in rice-straw pretreatment and enzymatic hydrolysis.

Characterization of nanoporous carbon fibrous materials obtained by chemical activation of plane tree seed under ultrasonic irradiation

An ultrasonic irradiation was applied for the impregnation by chemical agents in the chemical activation process of new type of active carbon precursor. Plane tree seed, due to the unique fibrous structure and low cost is a promising eco-friendly raw material for the preparation of activated carbon materials. Ultrasonic irradiation was used for the impregnation step allowing the chemical activation by different agents: potassium or sodium hydroxide, hydrogen peroxide and pyrogallol. The porous structures were examined by nitrogen adsorption/desorption isotherms at 77K and electrochemically by cyclic voltammetry. The textures of these materials were observed by scanning electron microscopy. The application of ultrasonic irradiation in the impregnation step increased surface area of the final material more than two times in comparison to the material which impregnation in the activation process was by conventional stirring. Ultrasonic irradiation enhances the chemical activation process and the activated carbon fibrous materials with nanoporous structure were obtained by impregnation of seeds with alkaline hydroxides. Total surface areas of these samples were 976m2g−1 and 1130m2g−1. These fibers have total specific capacitance as high as 125Fg−1 and 53Fg−1 which major fraction in both cases originate from internal micropores structure.

Ultrasound-assisted oxidative desulfurization of bunker-C oil using tert-butyl hydroperoxide

This work investigated the ultrasonic assisted oxidative desulfurization of bunker-C oil with TBHP/MoO3 system. The operational parameters for the desulfurization procedure such as ultrasonic irradiation time, ultrasonic wave amplitude, catalyst initial concentration and oxidation agent initial concentration were studied. The experimental results show that the present oxidation system was very efficient for the desulfurization of bunker-C oil and ∼35% sulfur was removed which was dependent on operational parameters. The application of ultrasonic irradiation allowed sulfur removal in a shorter time. The stronger the solvent polarity is, the higher the sulfur removal rate, but the recovery rate of oil is lower. The sulfur compounds in bunker-C oil reacted with TBHP to produce corresponding sulfoxide, and further oxidation produced the corresponding sulfone.

Characterization of blue CoAl2O4 nano-pigment synthesized by ultrasonic hydrothermal method

Nano-sized CoAl2O4 pigments, which have received significant attention as a coloring agent in glaze and bulk tile compositions, were successfully synthesized by substituting mechanical stirring during hydrothermal process with ultrasonic irradiation. Difference in physicochemical and optical properties of the CoAl2O4 pigments prepared by an ultrasonic-assisted-hydrothermal method was characterized using simultaneous thermo-gravimetric and differential thermal analysis (TG–DTA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance spectroscopy, CIELAB colorimetric analysis, and testing in ceramic glazes and bodies. The ultrasonic-assisted CoAl2O4 pigments present a narrow particle size distribution with vivid blue color, and better thermal stability, allowing their use for ceramic inks processed at high temperature. Application of ultrasonic irradiation during the hydrothermal process produces nano-sized powders with better physicochemical and optical properties.

An efficient and facile ultrasonic‐accelerated one‐pot synthesis of N‐acetyl‐2‐aryl‐1, 2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones

AbstractAn application of ultrasonic irradiation in the one‐pot synthesis of N‐acetyl‐2‐aryl‐1,2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones from the condensation reaction between aromatic aldehydes and anthranilic acid in the presence of excess amount of acetic anhydride has been explored. The reactions proceed smoothly under mild and solvent‐free conditions at room temperature in the absence of any catalyst to afford the products in good to excellent yields. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:106–113, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20663

ZnO nanowire/TiO 2 nanoparticle photoanodes prepared by the ultrasonic irradiation assisted dip-coating method

Hybrid ZnO/TiO 2 photoanodes for dye-sensitized solar cells were prepared by combining ZnO nanowire (NW) arrays and TiO 2 nanoparticles (NPs) with the assistance of the ultrasonic irradiation assisted dip-coating method. Results show that the ultrasonic irradiation was an efficient way to promote the gap filling of TiO 2 NPs in the interstices of ZnO NWs. Hybrid ZnO NW/TiO 2 NP electrodes prepared with ultrasonic treatment exhibited better gap filling efficiency and higher visible absorptance. The overall conversion efficiency of the hybrid electrode was 0.79%, representing 35% improvement compared with that of the traditional one (0.58%). The enlarged surface area and improved attachments of TiO 2 NPs onto the walls of ZnO NWs induced by the application of ultrasonic irradiation may be the underlying reason. Electrochemical impedance spectroscopy measurements indicated that hybrid electrodes combined the advantages of improved electron transport along the ZnO NWs and increased surface area provided by infiltrated TiO 2 NPs, both of which are responsible for the improved cell efficiency.

Application of Ultrasonic Irradiation in Synthesis of Novel Bis-heterocyclic aroylthioureas

Application of Ultrasonic Irradiation in Synthesis of Novel Bis-heterocyclic aroylthioureas