Sonochemical degradation of organophosphorus pesticide in dilute aqueous solutions

Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2—12 Process parameters studied include pH, steady state temperature, concentration, and the type of gases. Greater than 96% hydrolysis was observed in 30 minutes through this process and the rate of destruction increased with the help of more soluble and low thermal inert gas. So with Krypton, omethoate was found to undergo rapid destruction as compared with Argon. In the presence of ultrasound, the observed first order rate of hydrolysis of omethoate is found to be independent of pH. The formation of transient supercritical water(SCW) appears to be an important factor in the acceleration of chemical reactions in the presence of ultrasound. A detailed chemical reaction mechanism for omethoate destruction in water was formulated. Experimental results and theoretical kinetic mechanism demonstrated that the most of the omethoate undergo destruction inside the cavitating holes. A very less effect of temperature on the degradation of omethoate within a temperature range of 20—70℃ proves that a small quantity of omethoate undergoes secondary destruction in the bulk liquid.

Sonochemical Synthesis of Core/Shell Structured CdS/TiO_2 Nanocrystals Composites

A simple sonochemical route for the surface coating of titanium dioxide on cadmium sulfide nanocrystal was reported. After 2 h ultrasonic irradiation treatment, the mixture of CdS nanocrystals and tetrabutyl titanate in an aqueous medium yielded CdS/TiO2 nanocrystals composites with core/shell structure. The thickness of TiO2 layer with smooth interface could be easily controlled via changing the concentration of the precursors and the time of irradiation. The core/shell nanocrysrals were characterized by X-ray diffraction, transmission electron microscope and UV-vis spectrometry techniques. The prepared semiconductor composites with particular band structure present appealing properties especially in photochemical activity.

Nanostructured Cadmium Sulfide:Sonochemical Synthesis,Optical Properties and Formation Process

Semiconductor CdS nanoparticles were synthesized by the sonochemical reduction of a mixed aqueous solution of CdCl2, Na2S2O3 and (CH3)CHOH in Ar atmosphere at room temperature. The results of a detailed investigation with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrum and optical absorption spec-troscopy are reported. A clearly red shift of the absorption edge and a broad absorption band related to the surface states of nanoparticles have been observed in the optical absorption spectra with the increasing of CdS particle size. The mechanisms of the CdS nanoparticle formation and size growth during sonochemical irradiation were discussed. This convenient method is found to be an efficient way to produce other chalcogenides as well.

Synthesis of self-assembled nanorod vanadium oxide bundles by sonochemical treatment

Self-assembled nanorod of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity sonochemical technique. The synthesized materials were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM） and temperature-programmed reduction （TPR） in H2. Catalytic behaviour of the materials over anaerobic n-butane oxidation was studied through temperature-programmed reaction （TPRn）. Catalytic evaluation of the sonochemical treated V2O5 products was also studied on microreactor. XRD patterns of all the vanadium samples were perfectly indexed to V2O5. The morphologies of the nanorod vanadium oxides as shown in SEM and TEM depended on the duration of the ultrasound irradiation. Prolonging the ultrasound irradiation duration resulted in materials with uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles. H2-TPR profiles showed that larger amount of oxygen species were removed from the nanorod V2O5 compared to the bulk. Furthermore, the nanorod vanadium oxide bundles, which were produced after 90, 120 and 180 min of sonochemical treatment, showed an additional reduction peak at lower temperature （-850 K）, suggesting the presence of some highly active oxygen species. TPRn in n-butane/He over these materials showed that the nanorod V2O5 with highly active oxygen species showed markedly higher activity than the bulk material, which was further proven by catalytic oxidation of n-butane.

Electrochemical Performance of Starch-Polyaniline Nanocomposites Synthesized By Sonochemical Process Intensification

The present study deals with the intensified synthesis of starch-polyaniline(starch-PANI)nanocomposite using an ultrasound-assisted method.Starch is a key component in this nanocomposite,which acts as a backbone of the nucleation of PANI.The Electrochemical property of the nanocomposite arises due to the addition of PANI.This is one of green approach for the synthesis of bio nanocomposite using ultrasound.The crystallinity of the composite is evaluated using the Scherrer Formula.The starch-PANI nanocomposite was characterized by XRD,FT-IR,Raman,XPS and TEM.The composite nanoparticles show spherical morphology.The elemental composition of starch-PANI showed O 1s peak at 546 eV,N 1s peak at 416 eV,C 1s peak at 286 eV and S 1s peak at 176 eV.The electrochemical studies of the starch-PANI electrodes are evaluated by cyclic voltammetry(CV),galvanostatic charge/discharge(GCD),and electrochemical impedance spectroscopy(EIS).Starch-PANI electrode has shown the maximum specific capacitance of 499.5 F/g at 5 mV/s scan rate.

Anatase Titanium Dioxide Coated Single Wall Carbon Nanotubes Manufactured by Sonochemical-Hydrothermal Technique

A novel, cost effective, sonochemical-hydrothermal technique was used for the deposition of nanosized anatase titanium dioxide (TiO2) onto single wall carbon nanotubes (SWCNTs). This technique is described and the characterization of the synthesized TiO2-SWCNTs is reported. The characterization techniques employed include scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). From the characterization the size and morphology of the synthesized TiO2 nanoparticles (deposited on the SWCNTs) are reported. Furthermore, it is demonstrated that the created TiO2 nanoparticles are chemically attached to the SWCNTs. Also, an important correlation between calculated TiO2 crystal size and the red shifts in the lowest Raman TiO2 (E.g.) predominate peak is reported. The synthesized TiO2-SWCNTs have potential for large scale production and application in a variety of new technologies such as clean energy power generation devices, electrical storage devices, photocatalysts, and sensors.

Structural,morphological and magnetic properties of(Ni_(0.5)Co_(0.5))[Ga_(x)Gd_(x)Fe_(2-2x)]O_(4)nanoparticles prepared via sonochemical approach

The impact of Ga^(3+)and Gd^(3+)co-substitution on different types of behavior of Ni-Co nanospinel ferrites(NSFs),(Ni_(0.5)Co_(0.5))[Ga_(x)Gd_(x)Fe_(2-2x)]O_(4)(0.000≤x≤0.025),was investigated.NSFs were fabricated through ultrasound irradiation.The structure,composition,and spherical morphology of all products were verified by numerous characterization techniques such as X-ray diffraction(XRD),scanning and transmission electron microscopes(SEM and TEM),and selected area electron diffraction(SAED).Mossbauer spectra are composed of two ferromagnetic sextets and one paramagnetic doublet.These spectra were fitted to extract hyperfine parameters of the doped samples.Both sublattices'hyperfine magnetic field decreases with substitution.The isomer shift values show that the Mossbauer spectra are composed of magnetic Fe^(3+)sextets.The magnetization measurements at variable magnetic field(M-H)were investigated via a vibrating sample magnetometer(VSM)at temperatures(T)from 300 to 10 K.All NSFs disclose ferrimagnetic behavior at both 300 and 10 K at which they are soft and hard,respectively.We determined that the remanence magnetization(M_(r)),saturation magnetization(M_(s)),and magneton number(n_(B))decrease with increasing Ga^(3+)and Gd^(3+)ions contents.The reduction in these values is predominantly recognized to be the impact of cation redistribution and surface spins on tetrahedral(T_(d))and octahedral(O_(h))sites.As the Ga^(3+)and Gd^(3+)contents increase,the coercivity(H_(c))is also found to decrease.

Efficient Synthesis of Graphene Nanoribbons Sonochemically Cut from Graphene Sheets

We report a facile approach to synthesize narrow and long graphene nanoribbons (GNRs) by sonochemically cutting chemically derived graphene sheets (GSs). The yield of GNRs can reach ~5 wt% of the starting GSs. The resulting GNRs are several micrometers in length, with ~75% being single-layer, and ~40% being narrower than 20 nm in width. A chemical tailoring mechanism involving oxygen-unzipping of GSs under sonochemical conditions is proposed on the basis of experimental observations and previously reported theoretical calculations;it is suggested that the formation and distribution of line faults on graphite oxide and GSs play crucial roles in the formation of GNRs. These results open up the possibilities of the large-scale synthesis and various technological applications of GNRs.

Sonochemical Synthesis of Three-dimensional Aggregates of Pd Nanoparticles with High Electrocatalytic Activity Towards Ethanol Oxidation

Flower-like aggregates composed of （4.0±0.8） nm palladium（Pd） nanoparticles were prepared via ultrasonics in the palladium（Ⅱ） chloride（PdCl2） H2O/EtOH（5/1,volume ratio） solution with the addition of a quantity of poly（vinyl pyrrolidone）（PVP） and sodium dodecyl sulfonate（SDS）.The morphologies,crystal structures and the optical properties of the flower-like Pd nanostructures were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,selected area electron diffraction（SAED） and UV-visible absorption spectroscopy,respectively.The mechanism of sonochemical reduction of Pd（Ⅱ） ions was also investigated.The results show that the molar ratio of PVP to SDS affected the formation of the flower-like aggregates of Pd nanoparticles.Moreover,the electrocatalytic properties of Pd aggregates modified glassy carbon electrode for ethanol oxidation were also investigated by cyclic voltammetry（CV）.This material exhibits remarkable electrocatalytic activity for ethanol oxidation in 1 mol/L KOH and appears as a promising candidate to be applied in direct ethanol fuel cells.

Sonochemical Synthesis of Two Dimensional C3N4 Nanosheets Supported Palladium Composites and Their Electrocatalytic Activity for Oxygen Reduction and Methanol Oxidation Reaction

The preparation of highly active electrocatalysts with good durability and low cost for fuel cells is highly desir- able but still remains a significant challenge. Here we synthesized two dimensional （2D） C3N4 nanosheets supported palladium composites （C3N4/Pd） via a simple and convenient sonochemical approach. We have systematically stud- ied the electrocatalytic performance of as-prepared catalysts. We found that the prepared C3N4/Pd composites pos- sessed excellent catalytic activity and stability for oxygen reduction reaction （ORR） in alkaline media. Encourag- ingly, the C3N4/Pd catalysts exhibit the excellent electrocatalytic activity for methanol oxidation reaction （MOR） in alkaline media, even better than that of the commercial Pt/C catalyst, The excellent electrocatalytic performance of the 2D C3N4 nanosheets supported palladium composites catalysts results from their synergy effect between the ul- trathin substrate material with large surface area and excellent dispersion of palladium nanoparticles. This study demonstrates that sonochemical method opens up a new avenue for the preparation of electrocatalysts for fuel cells. We expect these materials are likely to find uses in a broad range of applications, for example, fuel cells, solar cells, batteries and other electrochemical analysis.

Photocatalytic activity of La-doped ZnO nanostructure materials synthesized by sonochemical method

ZnO nanostructure materials doped with different La contents were synthesized by sonochemical method. The products were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,transmission electron microscopy（TEM）, Raman spectroscopy, and Fourier transform infrared spectroscopy（FTIR）. In this research, XRD patterns of pure ZnO and La-doped ZnO are specified as hexagonal wurtzite ZnO structure with no detection of La2O3 phase. SEM and TEM characterization revealed the flower shape of pure ZnO built-up from petals of hexagonal prisms with hexagonal pyramid tips. Upon doping with La, the flower-shaped ZnO is broken into individual 1D prism-like nanorods. Photocatalytic activities of the as-synthesized products were determined by measuring the degradation of methylene blue（MB） under ultraviolet–visible（UV） light irradiation.Among them, the 2.0 mol% La-doped ZnO shows better photocatalytic properties than any other products.

Synthesis of iron oxide nanoparticles via sonochemical method and their characterization

Preparation of iron oxide （α-Fe2O3） nanoparticles was carried out via a sonochemical process. The process parameters sucb as temperature, sonication time and power of ultrasonication play important roles in the size and morphology of the final products. The iron oxide nanoparticles were characterized by trans- mission electron microscopy, X-ray powder diffraction, and thermogravimetric and differential thermal analyses. From transmission electron microscopy observations, the size of the iron oxide nanoparticles is estimated to be significantly smaller than 19 nm. X-ray diffraction data of the powder after annealing provide direct evidence that the iron oxide was formed during the sonochemical process.

Progress in sonochemical fabrication of nanostructured photocatalysts

In recent years,nanostructured photocatalysts have become the research focus due to their immense potential application in environmental purification and energy conversion.The photocatalytic performance of photocatalysts is closely related to their synthesis methods.High-intensity ultrasound irradiation could provide a unique tool for fabrication of photocatalysts with novel nanostructures.Ultrasound induces acoustic cavitation which generates unique physicochemical conditions,e.g.,hot spot（5000℃）,high pressure of 100 MPa,fast rate of heat conduction（〉〉1×10^10℃·s^-1）.These unique physicochemical conditions allow for the synthesis of various nanostructured photocatalysts.This review summarized the recent development in fabrication of photocatalysts with special nanostructures and their applications.The typical sonochemical reactors and parameters in sonochemical synthesis are introduced and discussed.Sonochemically prepared structures including nano-/microspheres,one-dimensional（1D） nanorods,two-dimensional（2D） nanosheets（nanoflakes,nanosquares）,noble metal nanoparticle（NP）-deposited and element-doped photocatalysts are described and summarized.It is believed that sonication is a green methodology,and it holds greatpotential in the near future for nanostructured photocatalyst fabrication.

Helical nanostructure of tubular metal-organic complex synthesized by sonochemical process

Tubular metal-organic complex (C2H9N2)2(C2H10N2)0.5[MoO2(OC6H4O)2] has been synthesized. The title complex crystallizes in the tetragonal system, space group P4(2)/n with a = 25.214(8), c = 7.484(4) ?, and Z = 8. The X-ray structural analysis of the complex reveals tube-like framework which is stabilized by hydrogen bond. Chiral anions [Mo(V)O2(OC6H4O)2]3? of the complex have two types of isomers(λ /δ configuration). Helical nanostructure of this metal-organic complex was formed using a sonochemical method. Sonocation may lead to the transformation from the bulk tubular complex to the helical nanostructure. The as-synthesized nanohelices were all double-stranded and left- and right-handed nanohelices were both formed. The helical nanostructure is a new morphology of inorganic-organic hybrid materials on the nanoscale level and the exact formation mechanism of these helices still needs further investigation.

Sonochemical Synthesis of Graphene Oxide-Wrapped Gold Nanoparticles Hybrid Materials:Visible Light Photocatalytic Activity

Graphene oxide(GO)-wrapped gold nanoparticles(Au NPs)hybrid materials are constructed via one-pot sono-chemical synthesis and self-assembly,using ethylene glycol as the reducing agent.The synthesis process above took only 1 h,and the obtained hybrid materials exist as spheres wrapped with gauze-like GO sheets via ionic in-teraction-based self-assembly.The GO sheets are helpful for the well dispersion of the Au NPs.Furthermore,these materials possess enhanced photocatalytic activity under visible light irradiation,owing to the synergistic effect of the two components in the hybrid materials.Our work may provide a convenient approach to control the size and morphology of the Au NPs for the synthesis of GO-wrapped hybrid materials,which opens up a feasible way to synthesize metal NPs/GO composites.Moreover,this method might lead to developing of a broad class of new functionalized materials wrapped with GO sheets.

Sonochemical synthesis and characterization of magnetic separable Fe_(3)O_(4)-TiO_(2)nanocomposites and their catalytic properties

A novel sonochemical method is described for the preparation of Fe_(3)O_(4)–TiO_(2)photocatalysts in which nanocrystalline titanium dioxide particles are directly coated onto a magnetic core.The Fe_(3)O_(4)nanoparticles were partially embedded in TiO_(2)agglomerates.TiO_(2)nanocrystallites were obtained by hydrolysis and condensation of titanium tetraisopropyl in the presence of ethanol and water under high-intensity ultrasound irradiation.This method is attractive since it eliminated the high-temperature heat treatment required in the conventional sol–gel method,which is important in transforming amorphous titanium dioxide into a photoactive crystalline phase.In comparison to other methods,the developed method is simple,mild,green and efficient.The magnetization hysteresis loop for Fe_(3)O_(4)–TiO_(2)nanocomposites indicates that the hybrid catalyst shows superparamagnetic characteristics at room temperature.Photocatalytic activity studies confirmed that the as-prepared nanocomposites have high photocatalytic ability toward the photodegradation of RhB solution.Furthermore,the photodecomposition rate decreases only slightly after six cycles of the photocatalysis experiment.Thus,these Fe_(3)O_(4)–TiO_(2)nanocomposites can be served as an effective and conveniently recyclable photocatalyst.

Effect of Y(OH)_3 microparticles on the electrochemical performance of alkaline zinc electrodes

This work focused on the zinc powder coated with Y(OH)3 microparticles by means of ultrasonic immersion for performance improvement of zinc electrodes in alkaline battery systems.Scanning electron microscopy and other characterization techniques were applied to examine the influence of the ultrasonic power on the sonochemical growth of Y(OH)3 microparticles in direct contact with zinc powder.Electrochemical properties of zinc electrodes containing Y(OH)3 microparticles were discussed through the measurement...

Controlled Microstructure and Photochromism of Inorganic-organic Thin Films by Ultrasound

A series of inorganic-organic thin films based on uniformly dispersed nanoparticles of polyoxometalates （POM）entrapped in polyacrylamide （PAM） matrix were prepared by ultrasonic method with different irradiation time.The microstructure, photochromic behavior and mechanism of the films were studied by transmission electron microscopy （TEM）, ultraviolet-visible spectra （UV-VIS） and Fourier transform-infrared spectroscopy （FT-IR）.The microstructure and photochromic properties of the hybrid thin films could be controlled by ultrasound.TEM image revealed that the average size of phosphotungstic acid （PWA） nanoparticles decreased from 20 to 10 nm with the ultrasound irradiation time from 30 to 60 min. After irradiated with ultraviolet light,the transparent films changed from colorless to blue and showed reversible photochromism. The hybrid film, with ultrasound irradiation for 60 min had higher photochromic efficiency and faster bleaching reaction than the one with ultrasound irradiation for 30 min. FT-IR spectra showed that the Keggin geometry of heteropolyoxometalate was still preserved inside the composites, and the interactions between polyanions and polymer matrix increased as the ultrasound time prolonged. It is suggested that the mechanism of the different photochromic properties for the inorganic-organic thin films is the variation of the microstructure and interfacial interactions induced by ultrasound.

Humidity sensor based on BiOBr synthesized under ambient condition

Flexible humidity sensors are effective portable devices for human respiratory monitoring.However,the current pre-paration of sensitive materials need harsh terms and the small production output limits their practicability.Here,we report a syn-thesis method of single-crystal BiOBr nanosheets under room temperature and atmospheric pressure based on a sonochemic-al strategy.A flexible humidity sensor enabled by BiOBr nanosheets deliver efficient sensing performance,a high humidity sensit-ivity(Ig/I0=550%)with relative humidity from 40%to 100%,an excellent selectivity,and a detection response/recovery time of 11 and 6 s,respectively.The flexible humidity sensor shows a potential application value as a wearable monitoring device for res-piratory disease prevention and health monitoring.

Ultrasonic Activation of Suzuki and Hiyama Cross-Coupling Reactions Catalyzed by Palladium

The coupling reaction of aryl bromide and aryl boronic acid in water/DMF as solvent was studied using a palladium-complex as a catalyst in the presence of ultrasound at room temperature. The effect on the reaction of a base and a solvent was also studied with and without ultrasound and was found to increase the speed of the reaction. In this regard, we propose reaction mechanisms that could explain the results obtained.