超声功率对电化学沉积铜过程速率的影响

测定了H2SO4-CuSO4溶液中，超声频率为24kHz时，超声功率对铜电化学阴极沉积过程速率的影响。实验结果表明，在超声作用下铜电化学阴极沉积过程的电流密度明显提高，即超声作用能提高过程的沉积速率。超声对铜电化学沉积过程速率强化程度随超声功率的增加而增大；在相同温度和超声功率下，超声强化速率的效果从反应控制区域（低操作过电位）向传质控制区（高操作过电位）过渡时而更加显著；在其它条件相同的情况下，超声对铜电化学沉积过程速率的强化程度随温度的升高而减小：超声强化速率的效果与溶液中铜离子的浓度基本无关。     

超声提取防风多糖的抗氧化活性研究

采用不同电功率和频率的超声波辅助提取防风多糖,通过体外抗氧化实验,研究了多糖抗氧化活性与超声电功率及频率的变化规律。实验结果表明:超声频率为135kHz、电功率为290W时,提取的防风多糖得率最高,达到7.12%。超声频率在80kHz和135kHz,电功率范围在150W～220W时提取的防风多糖抗氧化活性较高。超声提取防风多糖能够提高提取效率,选择适当的电功率和频率能达到较好的抗氧化活性效果。     

微波、超声及其联用萃取黄连中总生物碱的对比研究

采用紫外分光光度法,以黄连中总生物碱提取量为评价指标,对比了微波辅助萃取、超声辅助萃取、超声-微波联用辅助萃取、微波-超声联用辅助萃取黄柏中总生物碱,比较了4种不同萃取方式对提取量的影响。结果表明,在萃取黄连中总生物碱时,微波萃取优于超声萃取和超声-微波联用萃取;微波萃取和微波-超声联用萃取相比较,黄连中总生物碱提取量相差不大,说明微波萃取黄连中总生物碱比较完全,微波萃取后没有必要再用超声萃取。     

超声法提取余甘树皮中单宁的研究

本文研究了以水替代有机溶剂作为提取剂，利用超声技术提取余甘树皮中单宁的最佳条件。研究结果表明：当超声频率为40kHz，功率为100W，作用时间为15-20min，固液比为1：24时，可一次性提取得到含量较高的缩合型单宁，同时达到节约有机提取剂和减少污染的双重效果。     

超声场强化超临界CO2萃取除虫菊酯的初步研究

本文以除虫菊花中的除虫菊酯萃取为对象,研究用超临界CO2对其萃取时,施加超声场对萃取物降解及萃取速率的影响.结果表明,在实验范围内施加超声场(200kHz,200W电功率)没有引起超临界CO2流体"空化",从而没有使易分解组分除虫菊酯降解;施加超声场可以提高除虫菊酯的萃取速率,且对萃取速率的影响比用水为共溶剂强,在实验范围内,萃取优化工艺条件为萃取压力(20MPa);施加超声场(200kHz,200W电功率);萃取温度(40℃);添加共溶剂水(0.5ml水/g干花);CO2流量(2.0L·min-1).     

多超声协同的溴化锂溶液空化气泡动力学特性

超声空化有助于强化盐溶液沸腾传热过程.为改善溴化锂水溶液在真空条件下的发生效率,提出了多超声协同强化吸收式制冷系统的溴化锂水溶液发生过程方法.构建了多超声协同的气泡动力学数学模型,探讨了不同因素对溶液空化特性的影响.通过搭建超声波强化发生器内溶液传热过程的试验台,对理论结果进行了可行性验证.研究结果表明:多超声协同相比单振子对真空发生器内溶液空化特性的影响,具有更明显的强化作用;频率为25 kHz,总超声功率为60 W时,双超声振子和单超声振子的系统发生率较无超声时分别提高了10.26％和5.69％,超声强化传热效率随着溶液浓度的增加而减弱.     

超声对蛋白质盐析作用的研究

在蛋白质（牛血清白蛋白）-水胶体溶液中加入无机盐，利用蛋白质盐析的原理粗分离蛋白质是常用的生物分离技术。本文试图利用超声强化蛋白质盐析分离过程。讨论了声场参数，即频率、声强、超声辐射时间对该过程的影响。实验表明超声处理牛血清白蛋白时，20kHz超声辐照比无超声处理可缩短了近4．5小时的静置时间，20kHz超声处理可得到约90％的最高蛋白质收率；不同超声频率下有不同的最佳声压值，频率较低时的盐析效果较好；超声辐照并非时间越长越好，超声辐照2min时，牛血清白蛋白的收率最大。由此证明超声技术可加速盐析后的蛋白质沉降速度。     

3种不同提取方法测定百癣夏塔热片中的总黄酮

采用索氏提取、超声提取、微波萃取对百癣夏塔热片中总黄酮进行提取.3种方法均采用20倍(mL/g)甲醇;其中索氏提取时间为6h;超声提取时间为1h;微波萃取辐射时间:10min;温度:100C.以芦丁为标准品,用分光光度法测定,波长为510nm,芦丁浓度与吸光度呈良好的线性关系(r=0.9999).微波萃取、索氏提取和超...     

超声提取-反相高效液相色谱法测定牛膝中蜕皮甾酮

比较了超声提取与回流提取法在提取牛膝中活性成分蜕皮甾酮的提取效率，在频率为1100kHz时超声提取40min可获得稳定的提取效率。采用Shim-Pack CLC-ODS色谱柱，甲醇：水＝40：60（V／V，％）为流动相，在波长248nm下，测定牛膝中蜕皮甾酮，线性范围为2－200μg/mL（r=0．9998），检出限为0．052μg/mL（S/n=3），加标加收率为98．3％－103％。     

双频温控式声化学反应器的研制

介绍一种双频温控式声化学反应器。采用水循环降温方法，使变幅杆式反应头能在大功率状态下长时间稳定辐射，并能有效地将声化学反应器内因超声热效应引起的温升控制在5℃左右。利用自动控制及转换电路，使声源既能在20kHz或35kHz中任一单频辐射工作，又能双频自动交替辐射工作，且工作性能稳定，输出电功率在0-800W可调。     

Comparison between the use of polyether ether ketone and stainless steel columns for ultrasonic-assisted extraction under various ultrasonic conditions

The ultrasound-assisted extraction (UAE) was conducted using the stainless steel (SS) and polyether ether ketone (PEEK) columns and analyzed with high-performance liquid chromatography (HPLC) to understand the mechanism of ultrasound-assisted chromatography (UAC). Empty SS and PEEK columns were used to extract dyes from a fabric under identical conditions with several parameters including the initial ultrasonic bath temperatures (30 °C and 40 °C), ultrasound power intensities (0, 20, 40, 60, 80, and 100 %), ultrasound operation modes (normal and sweep), and ultrasound frequencies (25 kHz, 40 kHz, and 132 kHz) to compare their extraction capabilities. After 30 min of extraction, the amount of extract was determined by HPLC. The PEEK material was significantly affected by ultrasonic radiation compared to the SS material, especially at a higher temperature (40 °C), power intensity (100 %), and frequency (132 kHz) with sweep mode. At a maximum power density of 45 W/L, the extraction effectiveness ratio of PEEK to SS was in the range of 1.8 - 3.9 depending on the specific frequency, initial temperature, and with or without temperature control. The most optimal ultrasound frequencies, in terms of enhancing extraction effectiveness, are in the order of 132 kHz, 40 kHz, and 25 kHz. Unlike the SS material, the PEEK material was more affected by temperature and acoustic effects under identical conditions, especially at 132 kHz ultrasound frequency. In contrast, at lower frequencies of 40 kHz and 25 kHz, no significant differences in the acoustic effects were observed between the PEEK and SS materials. The findings of this study contribute to elucidating the roles of column materials in UAE and UAC.     

Fast and efficient removal of Reactive Black 5 from aqueous solution by a combined method of ultrasound and sorption process

Removal of Reactive Black 5 (RB5) from aqueous solutions was carried by the sorption process in the presence and in the absence of ultrasound. Sorption of the dye on the solid phase was investigated in a series of batch sorption experiments to determine the influence of different parameters such as contact time, amount of sorbent and concentration of pollutant on the removal efficiency of RB5 with and without ultrasound. The experimental data were fitted properly to the Freundlich model and the isotherm constants were 28.2 and 7.4 for k(f) and 0.13 and 0.38 for 1/n in the presence and in the absence of ultrasound (20 kHz) respectively. The data were analyzed with different sorption kinetic models and were better fitted with a pseudo-second-order kinetic model. Two ultrasonic generators at 20 and 500 kHz were used for sonication of the system. This investigation also reveals that RB5 can be removed by higher frequency apparatus (500 kHz) without sorbent in about 60 min sonication. The rate of removal was higher at the higher frequency than at the lower one.     

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.     

Mass transfer enhancement in supercritical fluids extraction by means of power ultrasound

The use of high-intensity ultrasound represents an efficient manner of producing small scale agitation, enhancing mass transfer on supercritical fluids (SF) extraction processes. In this way, a supercritical CO(2) extraction of oil from particulate almonds using power ultrasound was studied. To examine the effect of the acoustic waves all experiments were performed with and without ultrasound. A power ultrasonic transducer for a working frequency of about 20 kHz was constructed and installed inside a high-pressure 5 l SF extractor. The experimental tests were carried out with CO(2) at 280 bar and 55 degrees C. Grounded almonds with an oil content of about 55%, in an amount of 1500 g were deposited inside the SF reactor where the solvent was introduced at a flow rate of 20 kg/h. The results show that the kinetics and the extraction yield of the oil were enhanced by 30% and 20% respectively, when a power of about 50 W was applied to the transducer. The average time of each extraction process was of about 8 h and 30 min. In addition, the transducer was also used as a sensitive probe capable to detect the phase behavior of supercritical fluids when it was driven with low power signals.     

Dosimetry in sonochemistry: the use of aqueous terephthalate ion as a fluorescence monitor

The generation of HO radicals by acoustic cavitation in water was monitored by their reaction with terephthalic acid (TA) anion to produce fluorescent hydroxyterephthalate ions using a cleaning bath (38kHz) and a probe system (20, 40 and 60 kHz) as different sources of ultrasound. When using the ultrasonic bath as a source of energy for sonochemical studies, the shape of the reaction vessel is important. In the case of HO production from water (50 cm³), reaction in a conical flask (100 cm³) produces 2.75 times more radicals than a round-bottomed flask of the same capacity. The fluorescence yield (fluorescence intensity/ultrasound dosage) obtained using the conical flask and ultrasonic bath was similar to that for a probe operating at 40 kHz on the same volume of solution. For a probe system operating at 20, 40 and 60 kHz the greatest sonochemical efficiency was attained at the highest of these frequencies (60 kHz). For the probe system the fluorescence yield is directly proportional to power input and the concentration of TA. The fluorescence yield decreases as the temperature is increased.     

The effect of ultrasonic waves on the oxidation current of chlorpromazine in the 38 and 96 kHz-ultrasonic vibrating electrode voltammetry

In the case of 38 and 96 kHz ultrasonic vibrating electrode (USVE) voltammetry of chlorpromazine, the oxidation current increased considerably with ultrasonic power (amplitude). Movement of the first oxidation product, crimson coloured cation radical, and the streaming of liquid in the neighbourhood of the USVE, were visually observed in order to understand the mechanism of the promotive effects of ultrasound on the oxidation reaction. The reaction profile of the oxidation of chlorpromazine in 38 kHz seems to be somewhat different from that in 96 kHz. However, the mechanical agitation of solution in the area nearest the electrode surface, which is essentially the same fundamental mechanism, takes place in both the cases of 38 and 96 kHz. Both micro- and macro-streamings due to the vibration of a small bubble on the electrode surface with a frequency lower than that of the ultrasonic wave were formed in 38 kHz. These streamings seemed to contribute to the agitation and the exchange of the solution near the electrode surface. However, at the same ultrasonic amplitude, the oxidation current at 96 kHz was much greater than that at 38 kHz. Such a promoting effect of ultrasound on the electrode reaction was considered to be due to the increase of the moving speed or to the acceleration of the particle in the solution.     

Extraction of phenolics and anthocyanins from purple eggplant peels by multi-frequency ultrasound: Effects of different extraction factors and optimization using uniform design

In this work, multi-frequency ultrasound (working modes for the single-, dual- and tri-frequency in simultaneous ways) was applied to extract bioactive compounds from purple eggplant peels. The single-factor experiments were performed by varying six independent variables. A six-level-five-factor uniform design (UD) was further employed to evaluate the interaction effects between different factors. It was found that extraction temperature and extraction time significantly affected the total phenolic content (TPC), whereas the total monomeric anthocyanins (TMA) was mainly influenced by ethanol concentration, extraction temperature and solid-liquid ratio. Based on partial least-squares (PLS) regression analysis, the optimal conditions for TPC extraction were: 53.6 % ethanol concentration, 0.336 mm particle size, 44.5 °C extraction temperature, 35.2 min extraction time, 1:43 g/mL solid-liquid ratio, and similar optimal conditions were also obtained for TMA. Furthermore, the TPC and TMA extraction were investigated by ultrasound in different frequencies and power levels. Compared with single-frequency (40 kHz) and dual-frequency ultrasound (25 + 40 kHz), the extraction yield of TPC and TMA with tri-frequency ultrasound (25 + 40 + 70 kHz) increased by 23.65 % and 18.76 % respectively, which suggested the use of multi-frequency ultrasound, especially tri-frequency ultrasound, is an efficient strategy to improve the TPC and TMA extracts in purple eggplant peels.     

Ultrasonic effects on titanium tanning of leather

The effects of ultrasound on titanium tanning of leather were investigated. Either 20 or 40 kHz ultrasound was applied to the titanium tanning of pigskins. Five different treatment conditions were carried out and the effects were examined, such as leather shrinkage temperature (T(s)), titanium content and titanium distribution in the leather. Overall heat loading was carefully controlled. Results showed that 20 kHz ultrasound effectively improves titanium agent penetration into the hide and increases the leather's shrinkage temperature. Doubling the frequency to 40 kHz produced negligible enhancements. An impressive 105.6 degrees C T(s) was achieved using 20 kHz ultrasound pretreatment of the tanning liquor followed by 20 kHz ultrasound in the tanning mixture (liquor plus pigskins) in a special salt-free medium. Finally, using a unique ultrasonic tanning drum with 26.5 kHz ultrasound, the T(s) reached a record level of 106.5 degrees C, a value not achieved in conventional (no ultrasound) titanium tanning. The ultrasonic effects on titanium tanning of leather are judged to make a superior mineral tanned leather.     

Scaling up continuous ultrasound-assisted extractor for plant extracts by using spinach leaves as a test material

The ultrasound-assisted extraction (UAE) process of chlorophylls (a, b) and carotenoids in aqueous ethanol solutions from spinach leaves was upscaled from a batch laboratory reactor to a continuous modular flow-cell of pilot scale. The extraction in the laboratory scale was organized in a loop reactor, where pulp was circulated between a stirred vessel and the ultrasound reactor. The pilot scale extraction was made in a novel continuous tubular flow-cell reactor. The analysis of the experimental data proved that the ultrasound application provided a better extraction yield. In the laboratory scale, the application of ultrasound (24 kHz and 2500 W/L) showed the 2.6-fold higher maximum extraction yield compared to non-sonicated conventional solvent extraction. In the pilot scale, the effect was less significant (1.9-fold), due to smaller ultrasound power density (25 kHz and 1500 W/L). The scale-up of the UAE was based on equal extraction yield at both scales. The scale-up revealed that 2.5-fold higher volume-specific ultrasound power is required in the pilot scale to reach the yield obtained in the laboratory scale reactor.     

Elimination of standing wave effects in ultrasound radiation force excitation in air using random carrier frequency packets

The ultrasound radiation force has been used for noncontact excitation of devices ranging from microcantilevers to acoustic guitars. For ultrasound radiation force excitation, one challenge is formation of standing waves between the ultrasound transducer and the device under test. Standing waves result in constructive/destructive interference causing significant variations in the intensity of the ultrasound field. The standing-wave induced intensity variations in the radiation force can result from minor changes in the transducer position, carrier frequency, or changes in the speed of sound due to changes in ambient temperature. The current study demonstrates that by randomly varying the ultrasound carrier frequency in packets, it is possible to eliminate the negative consequences resulting from the formation of standing waves. A converging ultrasound transducer with a central frequency of 550 kHz was focused onto a brass cantilever. The 267 Hz resonance was excited with the ultrasound radiation force with a carrier frequency that randomly varied between 525 kHz to 575 kHz in packets of 10 cycles. Because each packet had a different carrier frequency, the amplitude of standing wave artifacts was reduced by a factor of 20 compared to a constant frequency excitation of 550 kHz.