Effect of ultrasound on ammonium leaching of zinc from galmei ore

The effect of ultrasound on ammonium leaching of zinc from galmei has been investigated. The use of an ultrasonic field allows the leaching time to be decreased by a factor of ten on account of the decrease in the diffusion layer thickness on the surface of the galmei which has been leached.     

Effect of ultrasound on the dissolution of copper from copper converter slag by acid leaching

This work presents the optimum conditions of dissolution of copper in copper converter slag in sulphuric acid ferric sulphate mixtures in the presence and absence of ultrasound. The Taguchi method was used to determine the optimum conditions. The parameters investigated were the reaction temperature, acid concentration, ferric sulphate concentration and reaction time. The optimum conditions for the maximum dissolution of copper were determined as follows: reaction temperature, 65 °C; acid concentration, 0.2 M; ferric sulphate concentration, 0.15 M; reaction time 180 min. Under these conditions, extraction efficiency of copper, zinc, cobalt, and iron from slag were 89.28%, 51.32%, 69.87%, and 13.73%, respectively, in the presence of ultrasound, while they are 80.41%, 48.28%, 64.52%, and 12.16%, respectively, in the absence of ultrasound. As seen from the above results, it is clear that ultrasound enhances on the dissolution of Cu, Zn, Co and Fe in the slag.     

Effect of ultrasound power on HCl leaching kinetics of impurity removal of aphanitic graphite

This study aimed to investigate the effect of ultrasonic power and temperature on the impurity removal rate during conventional and ultrasonic-assisted leaching of aphanitic graphite. The results showed that the ash removal rate increased gradually (∼50 %) with the increase in ultrasonic power and temperature but deteriorated at high power and temperature. The unreacted shrinkage core model was found to fit the experimental results better than other models. The Arrhenius equation was used to calculate the finger front factor and activation energy under different ultrasonic power conditions. The ultrasonic leaching process was significantly influenced by temperature, and the enhancement of the leaching reaction rate constant by ultrasound was mainly reflected in the increase of the pre-exponential factor A. Ultrasound treatment improved the efficiency of impurity mineral removal by destroying the inert layer formed on the graphite surface, promoting particle fragmentation, and generating oxidation radicals. The poor reactivity of hydrochloric acid with quartz and some silicate minerals is a bottleneck limiting the further improvement of impurity removal efficiency in ultrasound-assisted aphanitic graphite. Finally, the study suggests that introducing fluoride salts may be a promising method for deep impurity removal in the ultrasound-assisted hydrochloric acid leaching process of aphanitic graphite.     

Intensification of leaching process by dual-frequency ultrasound

Ultrasound is gaining importance in metal extraction process. In the previous laboratory scale investigation the authors have established the positive influence of ultrasound on copper recovery from oxide ores of Malanjkhand, Madhya Pradesh, India in an ammonical media. The process parameters in a conventional agitation method were optimized and a maximum recovery of ≈32% in 20 min was obtained without sonication. The recovery was increased to ≈78% by the application of ultrasound over the same period with several advantages like decrease in leaching time and the reagent consumption. In the present study the leaching process is intensified by studying the metal recovery variation at different ultrasonic frequencies (20, 40, 43 and 720 kHz) and intensities (up to 8 W cm⁻²) with sonication time. The results show that sinusoidal ultrasound even at larger intensity has some limitations with single frequency. However, simultaneous application of dual frequency 20 and 40 kHz ultrasound enhanced extraction rates along with increased yield. While conventional single frequency exposure at either one of the two frequencies at the same acoustic power level did not yield similar results, application of two wave sources, as used in the study revealed that it is possible to save energy through lowering of time of operation process.     

Improvement of leaching process of Geniposide with ultrasound

The effect of ultrasound on the leaching process, in which Geniposide is leached from the Gardenia fruit by deionized water at 20 degrees C, was investigated. The phase equilibrium and the dynamics were measured at static, stirring, and ultrasonically assisted conditions, respectively. The experimental results show that the extraction yield of Geniposide with ultrasound at 0.1533 W cm(-2), is increased by 16.5%, in comparison with that without ultrasound when the ratio of the solvent volume to the fruit weight is 40 ml/g. A model for mass transfer, based on the intraparticle diffusion and the external mass transfer, was developed. And the dynamic curves calculated by the model are in a good agreement with the experimental data. The external mass transfer coefficient k(f)/R and intraparticle diffusion coefficient D(e)/R2 were obtained by fitting of the experiment data. The external mass transfer coefficient with ultrasound at 0.1533 W cm(-2) is 1.63 times higher than that in static process, and the intraparticle diffusion coefficient with ultrasound at 0.1533 W cm(-2) is 3.25 times higher than that in static process.     

Effect of ultrasound on oil removal from soils

The soil-flushing method enhanced by ultrasonic waves is a new technique that potentially can become an effective method for in situ remediation of the ground contaminated by NAPL hydrocarbons. This study investigated the effectiveness of ultrasound enhancement in the soil-flushing method for a range of conditions involving soil type, soil density, flushing rate, and sonication power. The study was conducted in the laboratory using specially designed and fabricated equipment. The test results indicated that the rate of contaminant extraction increased considerably with increasing sonication power up to the level where cavitation occurred. The effectiveness of sonication-enhanced soil-flushing can be expressed as a function of (D(10))(2)*i, in which D(10) is the effective grain size, and i is the hydraulic gradient.     

Effect of temperature on crystalline silicon solar cells processed from chemical and metallurgical route

Effect of temperature on monocrystalline and multicrystalline silicon solar cells processed from chemical (EG-Si) and metallurgical (SoG_M-Si) routes was investigated in the range of 280–350 K. The temperature coefficients of important parameters related with the cell property were discussed. Experimental results indicate that the T-coefficient of conversion efficiency (η) of multicrystalline EG-Si cell processed from chemical is only 68% that of the monocrystalline EG-Si cell. Furthermore, the η of both types of SoG_M-Si cells decrease much less than that of the EG-Si cells with the increase in temperature. Additionally, the recombination fraction, the minority carrier lifetime, the carrier mobility decrease and the band-gap shrinkage were also investigated to reveal the intrinsic temperature dependence mechanism. In order to confirm the results, we used numerical simulation software AMPS-1D (analysis of microelectronic and photonic structure in one dimension program) to simulate the temperature dependence of solar cell performances. The results of numerical simulation were basically consistent with the experimental results.     

Effect of ultrasound on the reaction of trans-β-methylstyrene with lead tetraacetate

The detail of the reaction of trans-β-methylstyrene with lead tetraacetate in acetic acid was studied. The effect of ultrasonic irradiation using a horn-type reactor was examined and discussed from the viewpoint of the switching of the mechanism from mainly ionic to mainly radical.     

The influence of ultrasound on the capacity of lead accumulators

An increase of 12%–40% in the capacity of lead accumulators is obtained by the action of ultrasound. Simultaneously, the number of discharge cycles is increased. These achievements are important when considering the problem of energy. A few causes of the results obtained are explained.     

Effect of ultrasound on the activity of alliinase from fresh garlic

Alliinase is a homodimeric glycoprotein found most often in genus Allium plants. In this study, alliinase was purified from fresh garlic by using ammonium sulfate precipitation and gel filtration on a Sephacryl S-200 column. Homogeneity of the purified protein with a molecular weight of 54,000 Da was confirmed by SDS-PAGE. The effect of ultrasound on the alliinase activity was further studied. The optimal parameters for stimulating the alliinase activity were as follows: ultrasonic intensity, 0.5 W/cm(2) and ultrasonic frequency, 40 kHz. Under the optimal conditions, ultrasonic irradiation did not affect the enzyme's optimal temperature and pH, and improved its thermal stability. The low frequency and mild intensity ultrasound could increase the alliinase activity about 47.1%. Under ultrasound, the alliinase activity was inhibited by exogenous pyridoxal 5'-phosphate (PLP) and K(+), and obviously enhanced by Fe(2+). However, PLP and both of the metal ions showed opposite effects in the absence of ultrasound. Ultrasound could retard or slow down the inhibitory effect of l-cysteine on the alliinase activity. These results indicated that the activity of alliinase from fresh garlic might be enhanced by the low frequency and mild intensity ultrasound.     

Effect of ultrasound on desorption kinetics of phenol from polymeric resin

This work mainly involves the study of desorption kinetics of phenol from polymeric resins under the influence of an ultrasound field. A new phase equilibrium-kinetics model (PEKM), for estimation of diffusion coefficient was proposed, kinetic experiments of phenol desorption on NKA-II resin in the presence and the absence of ultrasound were separately conducted, and diffusion coefficients of phenol within an adsorbent particle were estimated by means of proposed PEKM. Results showed that the use of ultrasound could enhance the diffusion of phenol within the resin. The diffusion coefficient of phenol in the resin in an ultrasonic field increased by an order of magnitude in comparison with the diffusion coefficient in the absence of ultrasound. The more intense the ultrasonic field the larger was the diffusion coefficient.     

Removal of pesticide residues from fresh vegetables by the coupled free chlorine/ultrasound process

Pesticide residue in vegetables has been considered as a serious food safety problem across the whole world. This study investigates a novel advanced oxidation process (AOP), namely the coupled free chlorine/ultrasound (FC/US) process for the removal of three typical pesticides from lettuce. The removal efficiencies of dimethoate (DMT), trichlorfon (TCF) and carbofuran (CBF) from lettuce reached 86.7%, 79.8% and 71.3%, respectively by the FC/US process. There existed a synergistic effect in the coupled FC/US process for pesticide removal and the synergistic factors reached 22.3%, 19.0% and 36.4% for DMT, TCF and CBF, respectively. Based on the analysis of mass balance of pesticides, the synergistic effect was probably attributed to the efficient oxidation of pesticides both in vegetables and in water by the generated free radicals and FC. The surface area and surface structure of vegetables strongly affected the removal of pesticides by FC/US. The removal efficiency of DMT increased from 80.9% to 88.1% as solution pH increased from 5.0 to 8.0, and then decreased to 84.1% when solution pH further increased to 9.0. When the ultrasonic frequency changed from 20 to 40 kHz, a remarkable improvement in pesticide removal by FC/US was observed. As the FC concentration increased from 0 to 15 mg L^–l, the removal efficiencies of pesticides increased firstly, and then became stagnant when the FC concentration further increased to 25 mg L^–l. The pesticide degradation pathways based on the identified intermediates were proposed. The total chlorophyll content was reduced by less than 5% after the FC/US process, indicating a negligible damage to the quality of vegetables. It suggests that the FC/US process is a promising AOP for pesticides removal from vegetables.     

Effect of ultrasound on the synthesis of low-modulus zeolites from a metakaolin

It was studied the effect of ultrasonic processing (22 kHz) of the aqueous suspension of metakaolin, sodium hydroxide and alumina with a molar ratio 2Al₂Si₂O₇:12NaOH:2Al₂O₃ on the low-modulus zeolite synthesis processes. To investigate the XRD, SEM, IR, EDS had been used. It was shown that after ultrasonic processing, sodium aluminates are formed, what leads to a change in process of further synthesis. It was found that without ultrasonic processing on the stage of thermal treatment at 650 °C, SOD zeolite (|Na₆|[Al₆Si₆O₂₄]) and sodium aluminosilicate (Na₆Al₄Si₄O₁₇) are synthesized. In the sample after ultrasound during thermal treatment, only sodium aluminosilicates of cubic syngony (Na₆Al₄Si₄O₁₇ and Na₈Al₄Si₄O₁₈) are formed. It was demonstrated that sodium aluminosilicates are precursors for the formation of LTA zeolite (|Na₁₂|[Al₁₂Si₁₂O₄₈]). As a result zeolitization of sodium aluminosilicates after the hydrothermal crystallization in alkaline solution, the sonicated sample contained 97 wt% LTA. Without ultrasonic processing, the product of synthesis contained 50 wt% SOD and 40 wt% LTA.     

Effect of ultrasound on protein functionality

The review focus on the effect of ultrasound on protein functionality. The presence of transient ultrasonic mechanical waves induce various sonochemical and sonomechanical effects on a protein. Sonochemical effects include the breakage of chains and/or the modification of side groups of aminoacids. Sonomechanical modifications by enhanced molecular agitation, might lead to the transient or permanent modification of the 3D structure of the folded protein. Since the biological function of proteins depends on the maintenance of its 3D folded structure, both sonochemical and sonomechanical effects might affect its properties. A protein might maintain its 3D structure and functionality after minor sonochemical effects, however, the enhanced mass transfer by sonomechanical effects might expose internal hydrophobic residues of the protein, making protein unfolding to an irreversible denatured state. Ultrasound enhanced mass transport effects are unique pathways to change the 3D folded structure of proteins which lead to a new functionality of proteins as support shield materials during the formation microspheres. Enzymes are proteins and their reactions should be conducted in a reactor set-up where enzymes are protected from sonic waves to maximize their catalytic efficiency. In this review, focused examples on protein dispersions/emulsions and enzyme catalysis are given.     

Effect of ultrasound on heterogeneous systems

Examples of sonochemical reactions occuring under heterogeneous conditions are discussed with respect to their mechanism. The activation of a metal surface involves complex phenomena, in which parameters of importance seem to be the hardness and the adhesion of the passivating layer. Some considerations are given on the probable link between sonochemistry and tribochemistry.     

Effect of ultrasound on the extraction of total anthocyanins from Purple Majesty potato

This study examined anthocyanin extraction using the application of ultrasound to raw freeze dried, microwaved and raw sliced Purple Majesty potato, a new pigmented potato variety rich in anthocyanins. A 20 kHz probe was used for the sonication at 3 different amplitudes (30%, 50% and 70%) and ethanol in water at different ratios (50:50 and 70:30 v/v) was used for the extraction. Anthocyanin extraction from raw freeze dried purple potato was optimal at an ethanol:water ratio (70:30; v/v) after 5 min of ultrasonication, while the least amount of anthocyanins was extracted from raw sliced potatoes. The application of microwaves (as a pre-treatment) before the UAE resulted in an increase in the amount of anthocyanins extracted and a decrease in the amount of solvent used. Analysis of variance showed that potato form, ultrasonication time, ultrasonication amplitude and solvent ratio as well as two and three way interactions between some of these factors had a very significant effect (p < 0.000) on the amount of anthocyanins extracted.     

Effect of viscosity on ultrasound wave reflection from a solid/liquid interface

A study of the simulated reflection of a wideband ultrasound shear wave from the solid/viscous fluid interface is presented. Various parameters affecting reflection factors including the material properties of the solid, fluid properties like density and viscosity, and the operating frequency are discussed. Simulated ultrasonic response waveforms are compared with the experimentally obtained data for NIST traceable calibration standards of viscosity. A good agreement was observed between the simulated and experimental waveforms at various viscosities and for different solid substrates.     

Effect of ultrasound sonication on electroplating of iridium

Effect of ultrasound sonication was examined on the electroplating of iridium in aqueous hexabromoiridate(III) solution. The electrodeposits were evaluated by observing the defects of the iridium deposits by means of voltammetry, in which the current-potential curves of the iridium deposits on copper were measured. Applying ultrasound sonication to the electroplating of iridium decreased the defects including the cracks in the deposit whenever the glycerol as the additives was contained or not in the electrolyte.     

Effect of ultrasound on deformation of crystalline materials

The results are presented on computer simulation of plastic deformation of a single crystal under action of constant and alternating loads applied simultaneously. A model of nucleation and motion of dislocation lines on the area of simulating with defects arranged randomly is briefly described. Regions of varying the plasticity curve under action of an ultrasound load are found; the influence of the amplitude, frequency, and time of applying the ultrasonic load is determined. It is shown that there is a frequency at which the deformation of the material is maximal.     

超声波对固定化酶活性的影响

本文介绍了超声波对固定化酶的影响，同时对作用过程中的影响因素进行了阐述，并探讨了超声波影响固定化酶的可能机理。