Papers by Keyword: Ultrasonic Irradiation

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Authors: Wei Xiong, Peng Cui, Mei Juan Yin, Ya Zhong Chen
Abstract: The actual acoustic intensity (I) that reaches membrane is measured by ultrasonic power measuring meter. I is altered by changing the height of membrane (H), the nominal ultrasonic power, or ultrasonic frequency in ultrasonic cleaner. The evolution of the property of polymeric membrane exposed to ultrasonic irradiation is followed by the calculation of membrane damage factor (R). Effect of acoustic intensity on the extent of membrane damage is investigated. The results show that the polytetrafluoroethylene (PTFE) membrane is comparatively resistant under ultrasonic irradiation, the polypropylene (PP) membrane is less resistant, but the nylon 6 (N6) membrane can be damaged seriously by ultrasound. When ultrasonic frequency is 45 kHz, I decreases from 1.04 W•cm-2 to 0.10 W•cm-2 as H rises from 3 cm to 9 cm; I increases from 1.04 W•cm-2 to 1.33 W•cm-2 as the nominal ultrasonic power rises from 200 W to 400 W, and R increases as I rises. When the nominal ultrasonic power is 200 W, I rises from 1.04 W•cm-2 to 1.45 W•cm-2 as ultrasonic frequency increases from 45 kHz to 100 kHz, but R generally remains stable when ultrasonic frequencies are 80 kHz and 100 kHz. Membranes are resistant under ultrasonic irradiation when ultrasonic frequencies are 80 kHz and 100 kHz.
1161
Authors: Mei Juan Yin, Peng Cui, Zhi Hu, Ya Zhong Chen, Wei Xiong
Abstract: Effect of ultrasonic intensity on the degradation of phenol solution is investigated by changing the nominal ultrasonic power, ultrasonic frequency and the position of reactor. The actual ultrasonic intensity (I) that reaches reactor is measured by ultrasonic power measuring meter. It can be found that the ultrasonic intensity varies with ultrasonic parameters. With the nominal power input improving from 60 W to 150 W, the ultrasonic intensity rises from 0.21 W•cm-2 to 1.06 W•cm-2 and the degradation rate of phenol solution (η) increases from 21.7% to 43.7%. However, when I reaches the highest value of 1.71 W•cm-2 at the frequency of 100 kHz, η decreases to the lowest value of 21.5%. The ultrasonic intensity distribution is uneven in the ultrasonic bath and η increases with an increase of I in the vertical direction. The ultrasonic degradation of phenol solution is affected by ultrasonic intensity, but η doesn’t definitely increase with an increase of ultrasonic intensity.
1173
Authors: Li Yun Cao, Chuan Bo Zhang, Jian Feng Huang
Abstract: Nano-particle hydroxyapatite (HAp) was directly prepared by a wet chemical precipitation method with the aid of ultrasonic irradiation in solution using Ca(NO3)2, NH4H2PO4 and NH2CONH2 as source materials. The nano-HAp formation rate at different preparation temperatures and under different ultrasonic irradiation powers was measured and the influence of ultrasonic irradiation power on the synthesis kinetics of the nano-hydroxyapatite was investigated. It was found that the nano-HAp content increased with the increase of ultrasonic irradiation power, preparation temperature and reaction time. Under different ultrasonic irradiation power, an Arrhenius relationship was found between the nano-HAp formation rate and preparation temperature. It showed that with the increase of ultrasonic irradiation power from 100W to 200W and 300W, the synthesis activation energy of nano-HAp crystallites decrease from 63.2 KJ/mol to 59.9 KJ/mol and 48.1 kJ/mol respectively by calculation.
2092
Authors: Yan Hua Zhang, E Yu Ji, Song Tao Chen, Da Min Tian
Abstract: The Heck reaction proceeded in isopropanol under ultrasonic irradiation at ambient temperature (30°C) has been reported in this report. The Heck reaction showed excellent regio- selectivity, enhanced reaction rates, high yields, and the conditions were mild and environmentally friendly. It was found that as a heterogeneous catalyst for the reaction palladium forms nano- particles in-situ, and can be recycled for many times. Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analysis characteried the formation of stable, crystalline Pd(0) nanoparticles as catalyst for the reaction.
1675
Authors: Sang Geun Lee, J.K. Kim, J.Y. Kwon, Chang Ho Lee, Hoon Cheol Park, Se Mo Son, Seong Soo Park
281
Authors: Zhi Zhang, Chao Liu, Gong Duan Fan, Jing Luo, Yan Dong Wang
Abstract: The control parameters of the removal of Chlorella pyrenoidosa, which was irradiated by low frequency ultrasonic, is optimized by using single factor experiments and response surface methodology (RSM). First of all, the approximate ranges of the ultrasonic frequency, the ultrasonic power and the irradiation time were estimated with single factor experiments for the further experiments. And then the optimized values of the three control parameters were determined, which were analyzed by using central composite design (CCD) and RSM. The results showed that the removal rate of chlorophyll-a could reach to 64.1% after the irradiation for 6.34min by using ultrasonic of 77.7 kHz and 250W. Ultrasonic technology can remove Chlorella pyrenoidosa cells in water quickly and effectively, so as to achieve the purpose of water purification.
1860
Authors: Myoung Seok Sung, Yoon Bok Lee, Yong Jin Kim, Yang Do Kim
Abstract: Cadmium selenide(CdSe) nanoparticles were prepared in the aqueous solution containing isopropyl alcohol by the ultrasonic irradiation at room temperature. The cadmium chloride (CdCl2) and sodium selenosulfate (Na2SeSO3) were used as the cadmium and selenium source, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-Vis absorption spectra and PL spectra were used to characterize the CdSe nanoparticles. XRD analysis revealed the formation of cubic structure CdSe. TEM images showed aggregated CdSe nanoparticles with the size of nanometer scale. Average size of CdSe nanoparticles were about 3.9, 5.0 and 5.1nm with sonication time of 6, 30 and 40 minutes, respectively. The surface emission became less intensive and shifted to red with increasing irradiation time. This paper presents the effects of ultrasonic on the formation of CdSe nanoparticles and its characteristics.
1229
Authors: Mahayatun Dayana Johan Ooi, Abdul Aziz Azlan, Mat Johar Abdullah
Abstract: In this work, a chemically grown ZnO rod – like structure is produced via precipitation and post – sonication treatment based on the hydrolysis of zinc iodide (ZnI2) and diethanolamine (DEA). ZnO rod – like structures with aspect ratio of 3 to 4(diameter of 235 nm and 800 nm in length) was observed from the TEM micrograph.The as-synthesized ZnO wurtzite structure was compared to sample without ultrasonic irradiation treatment to study the effect of bubble implosion on the formation of the particle. In contrast to particles treated with ultrasonic irradiation, micron sized and agglomerated particles were observed in sample without the treatment. The mechanism related to acoustic cavitations and the formation of rod – like structure is explained. The XRD results show polycrystalline structure on both samples. The optical property of ZnO was evaluated using room temperature UV - Visible absorption spectroscopy. The result showed an absorption peak at 381 nm in wavelength.
3
Authors: Shu Guang Zhu, Wen Zhi He
Abstract: In the present work, spent LiCoO2 was processed to remove impurities by ultrasound with the aim to renovate its electrochemical characteristics. The composition and amount of organic materials remained in the LiCoO2 particle surface were characterized by GC-MS, FT-IR and TGA, respectively. The morphology and particle sizes of PVDF (Polyvinylidene fluoride) was analyzed by SEM. Experimental results show that ultrasonic cavitation could be effectively used to remove organic substance stuck on LiCoO2 surface. At room temperature, the spent LiCoO2 was successfully remove impurities, including EC (Ethylene carbonate) and PVDF, with ultrasound applied for 12 h. It can be considered that most of the PVDF (82.0 wt.%) has decomposed under ultrasonic irradiation. Furthermore, the EC has completely decomposed under such ultrasonic irradiation.
1937
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