Improving the property of calcium ferrite using a sonochemical method

Power ultrasonic vibration was applied to the solidification of calcium ferrite (CF) melt in this study. The results indicated that power ultrasound can promote the formation of CF by accelerating the solidification process. Ultrasonic vibration greatly refined the CF grains, resulting the grain size decreased from 1893 to 437 μm. Meanwhile, ultrasonic vibration significantly enhanced the compressive strength, reduced the reduction time and improved the reducibility of CF slags. With ultrasonic treatment, the ultimate compressive strength of samples increased from 37.5 to 67.8 MPa, and the reduction time decreased from 225 to 136 min.     

A sonochemical route for the encapsulation of drug in magnetic microspheres

This study focused on the preparation and characterization of magnetic targeted antibiotic microspheres (MTAMs). MTAMs were prepared by a sonochemical method in the presence of hydrophobic Fe₃O₄ nanoparticles and tetracycline. The properties of MTAMs were characterized by transmission electron microscopy, Fourier-transform infrared spectrum, thermogravimetric analysis, vibration sample magnetometry, and bacteriostatic experiment. The results indicated that the superparamagnetic microspheres have ultrafine size (below 230 nm), high saturation magnetization (80.90 emu/g), high biocompatibility, biodegradability, controlled-release, and antibiotic effect. It has been proved that MTAMs can carry out the function of magnetic targeted drugs delivery system by putting together magnetic materials and antibiotics. The possible formation mechanism of MTAMs was also discussed. In summary, MTAMs had potential in medical imaging, drug targeting, and catalysis.     

A novel method for the preparation of III-V semiconductors: sonochemical synthesis of InP nanocrystals

A novel method for the preparation of III–V semiconductor has been provided in this paper. At room temperature, InP nanocrystals with diameter of ≈9 nm were successfully obtained under high-intensity ultrasonic irradiation for 4 h from the reaction of InCl₃·4H₂O, yellow phosphorus and KBH₄ in the mixed solvents of ethanol and benzene. Changing some parameters can effectively control the size of the products and possible explanations were offered. The products were characterized by X-ray powder diffraction, transmission electron microscope and electron diffraction pattern. The ultrasonic irradiation and the solvents are both important in the formation of the product.     

A sonochemical method for the preparation of cadmium sulfide and cadmium selenide nanoparticles in aqueous solutions

Sonochemistry is a branch of chemistry where sound energy in the form of ultrasound is used to influence the course of reactions. A short-term, local increase in temperature occurs when the solutions and suspensions are irradiated by ultrasound. This happens because the substance absorbs the ultrasound waves. The purpose of this research was the synthesis of CdS and CdSe nanoparticles. We used cadmium sulfate hydrate (CdSO₄·8/3H₂O), elemental S and Se. Aqueous solutions of NaOH, Na₂SO₃ and EDTA were used as the solvents.During the syntheses, we used a direct immersion ultrasound probe by vibracell. The device operates with a constant frequency of 20 kHz, with the possibility to change the amplitude and with it the input of energy to the time unit. The products were characterized by X-ray powder diffraction (XRD), thermal analyses (TGA, SDTA) and TEM analyses.     

Some insights in the sonochemical preparation of cobalt nano-particles

The preparation of cobalt nano-particles from a solution of Co(CO)₃(NO) in n-decane under ultrasonication with a frequency of 20 kHz yielded cobalt particles of a size of ca. 5 nm. The presence of either silica or oleic acid in the solution reduced the particle size to ca. 3 and 2 nm, respectively. The resulting particle size is independent of the ultrasonication time, initial Co(CO)₃(NO) concentration, ultrasound intensity and solution temperature. It is postulated that bubble collapse generates multiple nucleation sites resulting in the formation of cobalt particles with a rather uniform particle size distribution.     

Research on the removal of near-well blockage caused by asphaltene deposition using sonochemical method

Near-well blockage caused by asphaltene deposition often occurs during the process of crude oil exploitation. It can reduce the porosity and permeability of reservoirs and seriously affects the migration and exploitation of oil and gas. In this paper, removing near-well blockage caused by asphaltene deposition using sonochemical method is investigated. Six PTZ transducers with different parameters are used to study the deplugging effect. Results show that the optimal ultrasonic frequency and power for plugging removal are 20 kHz and 1000 W respectively. it is found that lower ultrasonic frequency is good for asphaltene deposition plug removal when ultrasonic power is constant; as the power of the sensor increases, the effect of removing the asphaltene deposition plug gets better, ultrasonic power can well make up for the attenuation of ultrasonic energy caused as frequency increases; the effects of removing asphaltene deposition plug for the three cores with different initial gas logging permeability all get worse no matter what type of transducer is used; the effect of asphaltene deposition plug removal for the three cores samples all become better and then tend to be stable as ultrasonic treatment time increases further; considering of reducing construction cost and oil reservoir protection, ultrasonic processing has a lot of unexampled advantages compared with chemical injection, such as good adaptability, low cost, simple operation, non-pollution and benefit for the sustainable development of oil field; affected by the synergistic effect of ultrasonic and chemical agents, the combined treatment effect of ultrasound and chemical agents is significantly better than using ultrasound or chemical agents alone.     

Facile sonochemical method for preparation of Cs2HgI4 nanostructures as a promising visible-light photocatalyst

Attempts are continuing to discover novel and efficient solutions to promote water grade and industrial sewage treatment. For the first time, we present a novel Cs₂HgI₄ photocatalyst functional below visible radiation. Cs₂HgI₄ nano photocatalyst has been prepared via an accelerated sonochemical approach to examine its photocatalytic progression. Several construction circumstances, including variations of power and time of sonication and performance of different surfactant types, were conducted to produce fine particles with uniform morphology. FESEM images attested that the presence of surfactant had an adverse and destructive effect on the morphology of products. The bandgap for Cs₂HgI₄ nanostructures was determined to be approximately 2.3 eV, making these nanostructures desirable for photocatalytic applications. The photocatalytic data confirmed that Cs₂HgI₄ could destroy acidic coloring agents greater than basic ones. The highest photodegradation was observed for methyl orange with 76.8%.     

Simplified sonochemical preparation of titania embedded with selected metals for purification of benzene and toluene

Titania (TiO₂) photocatalysts, each embedded with one of six metals (Ag, Ce, Co, Fe, Mg, and Mn), were prepared using a simplified ultrasonic process. The characteristics of the prepared metal-embedded TiO₂ (metal–TiO₂) were determined using transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, photoluminescence emission spectroscopy, UV–visible spectroscopy, and nitrogen adsorption–desorption. Except for Co–TiO₂, the metal–TiO₂ photocatalysts showed improved performance for the decomposition of gaseous benzene and toluene, which are two of the most problematic indoor air pollutants that can cause a variety of adverse health symptoms, under daylight lamp irradiation. Photocatalytic activity was greatest for the Mg–TiO₂ sample, followed by, in order, the Ag–TiO₂, Ce–TiO₂, Fe–TiO₂, Mn–TiO₂, unmodified TiO₂, and Co–TiO₂ samples. Although Mg–TiO₂ showed the least redshift in its light absorption and the highest electron–hole recombination rate among the metal–TiO₂ photocatalysts, it yielded the highest photocatalytic activity, likely because of its increased adsorption capacity and anatase composition. The degradation of benzene and toluene over Mg–TiO₂ improved as ultrasound treatment amplitude increased from 20 to 37 μm, then decreased gradually as amplitude was further increased to 49 μm. Degradation efficiency also improved as ultrasound operation time increased from 30 to 60 min, then decreased gradually as amplitude was further increased to 90 min. Overall, this process could be utilized to prepare metal–TiO₂ photocatalysts with improved performance for the decomposition of gas phase pollutants under daylight lamp irradiation.     

改进的油浸法测量聚硅氧烷微球的折射率

在传统的油浸法基础上,引入透光率指标来判断粉体与浸液折射率的差异,测量了聚硅氧烷微球粉体的折射率.该方法将传统油浸法的适用范围扩展至超细粉体甚至纳米粉体的折射率测量.     

Effect of the method of preparation on the interaction between Ni and TiO2

Hydrogen chemisorption, magnetic measurements, temperature programmed reduction spectra, and FT-infrared spectra show that samples of nickel supported on TiO₂ prepared by incipient wetness are strikingly different from those prepared by ion-exchange. For the incipient wetness samples, the amount of hydrogen chemisorption decreased as the reduction temperature was increased from 300 to 500°C. In addition, the saturation magnetization of the nickel also decreased, indicating a loss of ferromagnetic nickel due to a reaction between the nickel and the TiO₂. In contrast, for samples prepared by ion-exchange, there was no reaction between the nickel and TiO₂; the hydrogen uptake increased as the reduction temperature was increased to 500°C and no loss of ferromagnetic nickel was detected. We propose that surface hydroxyl groups are important in the initial steps of the reaction between the nickel and TiO₂.     

Comparative study of sonochemical reactors with different geometry using thermal and chemical probes

Laboratory scale 20 kHz sonochemical reactors with different geometries have been tested using thermal probes, the kinetics of H(2)O(2) formation, and the kinetics of diphenylmethane (DPhM) sonochemical darkening. Results revealed that the overall sonochemical reaction rates in H(2)O and DPhM are driven by the total absorbed acoustic energy and roughly independent the geometry of the studied reactors. However, the sonochemical efficiency, defined as eta=VG/S, where G is a sonochemical yield of H(2)O(2), V is a volume of sonicated liquid, and S is a surface of the sonotrode, was proved to increase with the decrease of S. This phenomenon was explained by growing of the maximum cavitating bubble size with ultrasonic intensity and its independence towards the specific absorbed acoustic power. For the cleaning bath reactor the kinetics of the sonochemical reactions in H(2)O and DPhM depends strongly on the reaction vessel materials: the reaction rates decreased with the increase of the materials elasticity. Kinetic study of H(2)SO(4) sonolysis using a sonoreactor without direct contact with titanium sonotrode showed that sulphate anion is an effective scavenger of OH() radicals formed during water sonolysis.     

A sonochemical method for the selective synthesis of alpha-HgS and beta-HgS nanoparticles

A novel sonochemical method for the selective synthesis of alpha-HgS (cinnabar) and beta-HgS (metacinnabar) nanoparticles in aqueous solutions is reported in this paper. alpha-HgS and beta-HgS nanoparticles have been selectively prepared by choosing sodium thiosulfate and thiourea as the sulfur source respectively. To study the crystalline structure, size, morphology and composition of the products, characterization techniques including X-ray powder diffraction, transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis are employed. The optical properties of the nanoparticles are investigated by UV-visible absorption spectroscopic measurements. The direct band gap of the as-prepared alpha-HgS nanoparticles with an average size of 12 nm is calculated to be 2.8 eV according to the absorption spectrum. In the case of the beta-HgS nanoparticles with an average size of 13 nm, a broad absorption peak is observed in the UV-visible absorption spectrum, which can be ascribed to the special surface state of this sample. Probable mechanisms for the sonochemical formation of alpha-HgS and beta-HgS nanoparticles in aqueous solutions are presented. The optimum pH value of the stock solutions and the effect of sonication time on the particle size are also investigated.     

Degradation of dichlorvos containing wastewaters using sonochemical reactors

The present work deals with application of sonochemical reactors for the degradation of dichlorvos containing wastewaters. The sonochemical reactor used in the work is a simple ultrasonic horn type operating at 20 kHz with a power rating of 270 W. The effect of different operating parameters such as operating pH, temperature and power density on the extent of degradation has been investigated initially followed by intensification studies using additives such as hydrogen peroxide, Fenton's reagent and CCl(4). It has been observed that low frequency sonochemical reactors can be effectively used for treatment of pesticide wastewaters and acidic conditions and optimum values of temperature and power dissipation favors the degradation of dichlorvos. The efficacy of sonochemical reactors can be further enhanced by using different additives at optimized loadings. Complete removal of the pesticide at the given loading has been obtained using an optimized combination of ultrasound and Fenton's chemistry. The controlling mechanism for the sonochemical degradation has been confirmed to be the free radical attack based on the studies involving radical scavengers. The novelty of the present work is clearly established as there have been no earlier studies dealing with degradation of dichlorvos pesticide using sonochemical reactors operating at low frequency which offers distinct advantage in terms of cost and the stability of the reactor.     

Efficient sonochemical degradation of perfluorooctanoic acid using periodate

A rapid and efficient treatment method, using periodate (PI) for sonochemical oxidation of persistent and bioaccumulative perfluorooctanoic acid (PFOA) was developed. With an addition of 45 mM PI, 96.5% of PFOA was decomposed with a defluorination efficiency of 95.7% after 120 min of ultrasound (US). The removals of PFOA were augmented with an increase in PI doses. In all the PI + US experimental runs, decomposition efficiencies were essentially similar to those of defluorination, indicating that PFOA was decomposed and mineralized into fluoride ions. Lower solution pHs resulted in an increase in decomposition and defluorination efficiencies of PFOA due to acid-catalyzation. Dissolved oxygen increased the amount of IO₄ radicals produced, which consumed the more effective IO₃ radicals. Consequently, presence of oxygen inhibited the destruction of PFOA. The PFOA degradation rates with different gases sparging are in the following order: nitrogen > air > oxygen. Effects of anions follow the Hofmeister effects on PFOA degradation (i.e., Br⁻ > none ⩾ Cl⁻ > SO₄²⁻). Br⁻ could react with OH to yield radical anion Br₂⁻ that enhances the PFOA degradation. A reaction pathway was also proposed to describe the PI oxidation of PFOA under US irradiation.     

Optimization of sonochemical method of functionalizing Amino-Silane on superparamagnetic iron oxide nanoparticles using Central Composite Design

Optimization of sonochemical method of functionalizing a Silane coupling agent, Amino-Silane on Superparamagnetic Iron Oxide Nanoparticles (SPION) using Central Composite Design is reported. The Amino-Silane is grafted on the SPION in an iced bath environment using a Vibra-Cell 20 kHz ultrasonic irradiator with 13 mm diameter horn. Throughout the experiment amplitude of the ultrasonic device is maintained at 47%. The percentage atomic compositions of various APTES elements which bind to the SPION due to the ultrasonic irradiation were determined using X-ray photoelectron spectrometer (XPS). The influence of ultrasonic irradiation time and amount of APTES required for facile, rapid and effective functionalization of Organo-metallic compound on SPION are optimized. The optimized sonication time and amount of APTES are 8.49 min and 3.40 ml, respectively. The predicted results were validated with experimental data. Using the optimized values APTES were functionalized on the SPION experimentally and the results were compared. The experimental results validate the predicted data. Results show that very minimum sonication time is required for effective grafting of APTES on SPION.     

The effects of acoustic flow and mechanical flow on the sonochemical efficiency in a rectangular sonochemical reactor

Visualization of cavitation behavior in a rectangular sonochemical reactor at 490 kHz was carried out by a laser sheet technique and the distribution of liquid flow was measured by a laser Doppler velocimeter. The pattern of liquid flow and distribution of acoustic pressure of the rectangular sonochemical reactor were investigated as a function of the input power from 10 to 50 W. The liquid moved upward above the transducer at every power. As increasing the input power, the random flow out side the cylindrical part above the transducer changed into the convective one and the region of the visualized standing wave which was formed in the cylindrical part changed with the input power. The position showing the sonochemical luminescence exists inside or near the region where the standing wave was visualized. Introduction of a stirrer resulted in disturbance of liquid flow and expanded the position showing the sonochemical luminescence, but the luminescence intensity was weakened. The sonochemical efficiency was enhanced by about twice by introduction of the stirrer. From these results, we discussed the effects of liquid flow on sonochemical efficiency with and without a stirrer.     

The sonochemical synthesis and characterization of mesoporous chiral titania using a chiral inorganic precursor

The paper presents a successful sonochemical attempt to synthesize mesoporous chiral titania using a chiral inorganic precursor and dodecylamine, as the surfactant template. The resulting porous structure was characterized by nitrogen sorption experiments, transmission electron microscopy, and small-angle XRD. The enantioselectivity of this mesoporous titania after the extraction of the amine was examined by selective adsorption of enantiomers and racemic aqueous solution of camphor. The selective adsorption was measured by circular dichroism (CD) spectroscopy.     

Surfactant-assisted sonochemical synthesis of hollow calcium silicate hydrate (CSH) microspheres for drug delivery

Hollow calcium silicate hydrate (CSH) microspheres with diameters around 1 μm were synthesized by a surfactant-assisted sonochemical route, and the products were characterized by XRD, SEM, FETEM and BET techniques. The results suggested that the ultrasound radiation, surfactant and Ca source were important factors which affected the formation of hollow microspheres. Based on the observation of products in different reaction systems, the possible mechanism for the formation of hollow CSH spheres was discussed. Furthermore, gentamicin, a typical anti-inflammatory drug, was used to investigate the drug loading and release behavior of the hollow spheres. The results indicated that CSH hollow spheres had high drug loading capacity and favorable drug release behavior, and might be used for preparation of bone grafts with drug delivery properties.     

Acoustic-structural interaction analysis using the component mode synthesis method

The main objective is to analyse the effects of the imposition of common velocity on the acoustic-structural interface via the Component Mode Synthesis Method (CMS). The original contribution of this analytical study is to show the importance of including kinematic compatibility on the structural-acoustic problem. Some background information about the method is provided as a basis for assisting the understanding of the process. Following this, the formulation of the structural-acoustic problem in terms of ‘components’ is described. The results obtained using CMS are compared to those obtained using both a one dimensional wave approach and standard modal analysis. Finally, conclusions are drawn based on the analysis of the results and the extension to three-dimensional acoustic systems discussed.     

Benchmark calculations using the individually selecting configuration interaction method

Further progress is reported on the implementation of the configuration-selecting multi-reference configuration interaction method for massively parallel architectures with distributed memory which allows calculations with Hilbert spaces in excess of 10¹¹ configurations, 2 × 10⁷ of which can now be included in the variational subspace. This code makes it possible to elucidate the importance of the correlated treatment of triple and quadruple excitations into the (3s3p) shell of the oxygen molecule, to account quantitatively for its electron affinity. Also included are extensive calculations to elucidate the reaction pathways of members of the enediyne family.