Ultrasonic-assisted Synthesis Research Articles

Ultrasonic-assisted synthesis and solar photoactivity investigation of Ce, B co-modified TiO2 nanoparticles

► Ce, B co-modified titania nanoparticles synthesized by ultrasonic assisted sol–gel method. ► The preparation processes are all under mild condition (low temperature). ► The samples exhibited high photocatalytic activity under solar light irradiation. In this study, Ce and B co-modified TiO 2 nanoparticles were prepared using an ultrasonic-assisted sol–gel method. The prepared sample was characterized by X-ray diffraction, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy and BET analysis. In order to detect the effect of dopants on the titania, the photocatalytic activity of these as-prepared titania nanoparticles was determined by following the degradation of the reactive dye methylene blue under solar light irradiation. The activity was compared to that of pure titania. It was revealed that the photocatalytic activity of the Ce and B co-modified titania nanoparticles produced a significant enhancement compared to pure titania. The apparent rate constant of the as-prepared co-modified titania was 3 times higher than that of pure titania.

Ultrasonic-Assisted Synthesis of 1,3-Diaryl-2,2-dichloroaziridine Derivatives in the Presence of Phase-Transfer Catalyst under Low-Concentration Alkaline Conditions

Abstract In this research, rapid and efficient preparation of 1,3-diaryl-2,2-dichloroaziridines through the reaction of Schiff base compounds with dichlorocarbene yielded in situ in the presence of cetyltrimethylammonium bromide (CTAB) as phase-transfer catalyst under ultrasonic irradiation is described. The advantages of this reaction are very short reaction times, excellent product yields, simplicity of the method, and high purity of products.

Ultrasonic-assisted synthesis and magnetic studies of iron oxide/MCM-41 nanocomposite

Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 °C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption–desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g −1. An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles.

Ultrasonic-assisted synthesis of magnetite based MRI contrast agent using cysteine as the biocapping coating

Magnetite nanoparticles (mean particle size ranging from 10 to 20 nm) were prepared by a biomolecule-assisted solution-phase approach under ultrasonic irradiation. Cysteine was used as the capping agent in the solution. The results show that cysteine could be an efficient biocapping agent in producing Fe 3O 4 nanoparticles. The crystal structure and magnetic properties of the nanoparticles were characterized by XRD and VSM techniques, respectively. FT-IR was used to investigate the presence of cysteine on the nanoparticles surface. The influence of pH value of the solution on the size distribution and hydrodynamic size of nanoparticles were studied by TEM and DLS methods, respectively. The MTT assay performed by incubation of L929 cells, showed the good biocompability of synthesized ferrofluids. In vitro T1 and T2 relaxivity measurements along with in vivo studies, which were conducted on rats, demonstrate that synthesized nanoparticles are applicable as the contrast agents, especially for imaging of the lymphatic system.

Ultrasonic-assisted synthesis of Pd–Ni alloy catalysts supported on multi-walled carbon nanotubes for formic acid electrooxidation

Pd–Ni alloys with different compositions (i.e. Pd 2Ni, PdNi, PdNi 2) dispersed on multi-walled carbon nanotubes (MWCNTs) are prepared by ultrasonic-assisted chemical reduction. The X-ray diffraction (XRD) patterns indicate that all Pd and Pd–Ni nanoparticles exist as Pd face-centered cubic structure, while Ni alloys with Pd. The transmission electron microscopy (TEM) images show the addition of nickel decreases the particle size and improves the dispersion. The X-ray photoelectron spectroscopy (XPS) spectra demonstrate the electronic modification of Pd by nickel doping. The electrochemical measurements reveal that the PdNi catalysts have better catalytic activity and stability for formic acid electrooxidation, among them PdNi/MWCNTs is the best. The performance enhancement is ascribed to the increase of electroactive surface area (EASA) and nickel doping effect which might modify the electronic structure.

Ultrasonic-assisted synthesis of polyaniline nanosticks, and heavy metal uptake performance

Polyaniline (PANI) nanosticks with an average diameter of about 40 nm and a length of about 150 nm or longer were successfully synthesized by a facile template-free method in aqueous solution under ultrasonic irradiation. The morphology and structure of the as-prepared PANI nanosticks were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectra and UV–vis absorption spectra. The heavy metal uptake performance of the as-prepared PANI nanosticks was determined by using Cu(II) ions as pollute model. It was found that the as-prepared PANI nanosticks could be considered to have potential applications in water treatment for the removal of Cu(II) ions.

Ultrasonic-Assisted Synthesis of Au Nanobelts and Nanowires

Au one-dimensional (1D) nanostructures, including nanobelts and nanowires, have been synthesized in an ethylene glycol (EG)/polyvinylpyrrolidone (PVP) system by a simple and convenient seed-mediated growth method. The nanobelts and nanowires have aspect ratios up to 600, a length distribution ranging from several to tens of microns, and an average width of 100 nm. In this method, we used an ultrasonic process to promote the formation of Au seeds, which largely determines the morphology of final product. Additionally, we have found that the ultrasonic process significantly increases the fabrication yield of 1D nanostructures. Further experimental results show strong polarization dependence of Surface-Enhanced Raman Scattering (SERS) on a single Au 1D nanostructure. This convenient, versatile and low-cost synthesis method can be applied to 1D nanostructures composed from a range of materials, making it widely applicable to many areas of modern science and technology.

Ultrasonic-assisted synthesis of chrysin derivatives linked with 1,2,3-triazoles by 1,3-dipolar cycloaddition reaction

The 1,3-dipolar cycloaddition reaction between 7-(3-azidopropoxy)-5-hydroxyflavone and phenylacetylene was carried out to investigate the synthesis of 7-(3-(4-phenyl-1,2,3-triazol-1-yl)propoxy)- 5-hydroxyflavone in presence of ultrasound (sono-synthesis) and absence of ultrasound (conventional method) under relatively optimized solvent and catalyst conditions. The reaction rate was notably accelerated with the help of ultrasound irradiation. An experiment was especially carried out for investigating the acceleration mechanism of ultrasound on the cycloaddition. A novel series of chrysin derivatives linked with 1,2,3-triazoles were obtained by the copper(I)-catalyzed 1,3-dipolar Huisgen cycloaddition reaction using t-BuOH/H 2O (1:1 v/v) as reaction solvents and CuSO 4·5H 2O/sodium ascorbate as the catalyst at room temperature in the presence of ultrasound irradiation. Their structures are elucidated by NMR, ESI MS, IR and Elemental analysis.

Ultrasonic-assisted synthesis of hydrophobic magnesium hydroxide nanoparticles

In this paper, with the aid of ultrasonic irradiation, hydrophobic magnesium hydroxide (MH) nanoparticles were synthesized via one-step precipitation reaction, in which the reactant solutions were simultaneously added into an organic phase instead of an aqueous phase. Tween 80 was added as a stabilizer, dispersant and surface modifier. During this synthesis process, ultrasonic irradiation could restrict the crystal growth of MH on each lattice plane and improve hydrophobicity of MH nanoparticles. Addition of Tween 80 was favourable to obtain smaller sized MH nanoparticles with even crystal growth and better dispersibility, and to further enhance the hydrophobic property of MH nanoparticles based on its bridging function between surface of MH nanoparticles and aliphatic compounds in organic phase. In addition, the morphology and the properties of obtained MH nanoparticles were characterized by XRD, FESEM, FT-IR, TGA, respectively. The improved hydrophobicity and dispersibility of surface modified MH nanoparticles were also verified by the sedimentation tests.

An efficient ultrasonic-assisted synthesis of imidazolium and pyridinium salts based on the Zincke reaction

A mild and efficient method has been developed using ultrasound irradiation for the synthesis of imidazolium and pyridinium salts based on the Zincke reaction. Tertiary nitrogen nucleophiles such as pyridines and imidazoles can be alkylated with primary amine by simply using their ammonium form Zincke salts. In almost all cases, a clear yield increase results and a dramatic reduction of the reaction time accompanied by an improved quality of the products occurs.

Ultrasonic-assisted synthesis of two new nano-structured 3D lead(II) coordination polymers: Precursors for preparation of PbO nano-structures

Nano-structures of two new Pb(II) three-dimensional coordination polymers, [Pb 2 (4-pyc) 2 I 2 (H 2 O)] n ( 1 ), {4-Hpyc = 4-pyridinecarboxilic acid} and [Pb(3-pyc)I] n ( 2 ), {3-Hpyc = 3-pyridinecarboxilic acid} were synthesized by a sonochemical method. Nano-structures of two new Pb(II) three-dimensional coordination polymers, [Pb 2 (4-pyc) 2 I 2 (H 2 O)] n ( 1 ), {4-Hpyc = 4-pyridinecarboxilic acid} and [Pb(3-pyc)I] n ( 2 ), {3-Hpyc = 3-pyridinecarboxilic acid} were synthesized by sonochemical method. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compounds 1 and 2 were structurally characterized by single crystal X-ray diffraction and are three-dimensional coordination polymers. The thermal stability of compounds 1 and 2 both their bulk and nano-size were studied by thermal gravimetric and differential thermal analyses and compared. PbO block-structures were obtained by calcination of the nano-structures of compounds 1 and 2 at 400 °C.

Ultrasonic-assisted condensation of chitosan with salicylaldehyde

In order to synthesize an improved adsorbent for heavy metal ions, we studied the condensation reaction of chitosan with salicylaldehyde in ethanol to form a Schiff base. The effect irradiating the reaction using an ultrasonic liquid processor was contrasted with conventional methods. The IR spectra of condensed chitosan prepared by the two methods showed that their molecular structures were identical. The reaction conditions, including solvents, ultrasonic power density and irradiation time, pH, and reactant ratio, were optimized by orthogonal design. A shorter reaction time and a higher product yield were obtained using ultrasonic-assisted synthesis compared with the traditional method. A condensation degree of 89.63% was achieved using the optimized conditions: i.e. ultrasonic irradiation at 180 W for 60 min; 95% ethanol as the solvent, pH 4.0, and salicylaldehyde:chitosan ratio of 6:1.

Nanosized BiVO 4 with high visible-light-induced photocatalytic activity: Ultrasonic-assisted synthesis and protective effect of surfactant

Nanosized BiVO 4 with high visible-light-induced photocatalytic activity was successfully synthesized via ultrasonic-assisted method with polyethylene glycol (PEG). The BiVO 4 sample prepared under ultrasonic irradiation with 1 g PEG for 30 min was consisted of small nanoparticles with the size of ca. 60 nm. The effects of ultrasonic irradiation and surfactant were investigated. The nanosized BiVO 4 exhibited excellent visible-light-driven photocatalytic efficiency for degrading organic dye, which was increased to nearly 12 times than that of the products prepared by traditional solid-state reaction. Besides decoloring, the reduction of chemical oxygen demand (COD) concentration was also observed in the degradation of organic dye, further demonstrating the photocatalytic performance of BiVO 4. After five recycles, the catalyst did not exhibit any significant loss of photocatalytic activity, confirming the photocatalyst is essentially stable. Close investigation revealed that the crystal size, BET surface area, and appropriate band gap of the as-prepared BiVO 4 could improve the photocatalytic activities.

Ultrasonic-assisted synthesis of highly active catalyst Au/MnO –CeO2 used for the preferential oxidation of CO in H2-rich stream

Abstract A series of nano-gold catalysts supported on binary oxides MOx–CeO2 (atomic ratio M/Ce = 1:1, M = Mn, Fe, Co, Ni) are prepared by deposition–precipitation (DP). An innovative and rather convenient ultrasonic pretreatment of the support is employed for Au/MnOx–CeO2 preparation. It is found that for preferential CO oxidation Au/MnOx–CeO2 is more active than Au/CeO2. Ultrasonic pretreatment of MnOx–CeO2 further promotes the performance of Au/MnOx–CeO2, with CO conversion increased by 24 % at 120 °C. Meanwhile, the selectivity of oxygen to CO2 is promoted in the whole temperature range, especially in 80–120 °C, the selectivity is increased by 15–21%. HR-TEM and XRD results indicate that ultrasonic pretreatment is favorable to the formation of much smaller gold nanoparticles (

Preparation and characterization of monodispersed nanocrystalline ZnS in water-rich [EMIM]EtSO 4 ionic liquid using ultrasonic irradiation

A facile, room temperature and environmentally benign green route for the production of monodispersed nanocrystalline ZnS in 7 min by ultrasonic irradiation in aqueous solution of room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium ethyl sulfate, ([EMIM][EtSO 4]), is proposed. The X-ray diffraction (XRD) studies display that the products are well crystallized in the form of hexagonal structure. Energy dispersive X-ray spectroscopy (EDX) investigations reveal that the products are extremely pure. The morphology of as-prepared nanoparticles was characterized by scanning electron microscopy (SEM). The absorption spectra of the product reveal band gap energy of about 4.13 eV, which shows a blue shift of 0.59 eV and can be attributed to the quantum-confinement effect of the ZnS nanoparticles. Based on the experimental results, a possible formation mechanism of the monodispersed nanocrystalline ZnS in the ultrasonic-assisted synthesis in aqueous solution of the RTIL is presented.

Direct ultrasonic-assisted synthesis of sphere-like nanocrystals of spinel Co 3O 4 and Mn 3O 4

A simple sonochemical method was developed to synthesize uniform sphere-like or cubic Co 3O 4 and Mn 3O 4 nanocrystals by using acetate salts and sodium hydroxide or tetramethylammonium hydroxide (TMAH) as precursors. Influence of some parameters such as time of reaction, alkali salts, and power of the ultrasound and the molar ratio of the starting materials on the size, morphology and degree of crystallinity of the products was studied. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FTIR spectroscopy, Thermal gravimetry analysis and differential thermal analysis (TGA/DTA) were used to characterize the nanocrystals.

Ultrasonic-assisted synthesis of visible-light-induced Bi 2MO 6 (M = W, Mo) photocatalysts

Visible-light-induced photocatalysts Bi 2MO 6 (M = W, Mo) nanocrystals have been successfully synthesized via a new ultrasonic-assisted method. Laminar structured Bi 2WO 6 nanoplates with size of ca. 100 nm and Bi 2MoO 6 nanoparticles with size of ca. 150 nm were prepared via ultrasonic pretreatment followed by calcination at 500 °C. The photocatalytic activities of as-prepared Bi 2MO 6 were about 4–6 times higher than that of the products prepared by traditional solid-state reaction (SSR), which were evaluated by the degradation of RhB dye in water under visible light irradiation ( λ > 400 nm). It was found that ultrasonic irradiation played an important role in the formation of the nanomaterials with a smaller crystal size and larger surface area, which was beneficial to their photocatalytic activities. The present study suggested a promising method, as an effective improvement of traditional SSR-process, for the synthesis of other photocatalysts.

Ultrasonic-Assisted Synthesis of Poly(3-hexylthiophene)/TiO2 Nanocomposite and Its Photovoltaic Characteristics

The nanocomposites of poly(3-hexylthiophene) (PAT6) encapsulating titanium oxide (TiO2) with different TiO2 weight fractions were synthesized by in situ ultrasonic-assisted polymerization, and investigated in terms of their optical properties, microstructures and photoconductivity. The interaction between PAT6 and TiO2 and the nature of chain growth were investigated and explained according to the results of Fourier transform infrared spectroscopy (FTIR). The increase in conjugation length of the polymer and the improvement of crystallinity with an increase in TiO2 weight fraction were investigated and explained according to the results of UV–vis absorption spectroscopy, photoluminescence spectroscopy and X-ray diffractometry (XRD). Particle dimensions were measured and the nature of association between the components was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The photoconductivity of the PAT6/TiO2 composite increased markedly and was discussed by taking the photoinduced charge transfer between PAT6 and TiO2 into consideration.