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1.
The power density modulates the dynamics of the chemical reactions during the ultrasonic breakdown of organic compounds. We evaluated the ultrasonic degradation of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) at various power densities (30 W/L–262 W/L) with and without sparging Argon. We observed pseudo-first-order degradation kinetics at an initial PFASs concentration of 100 nM over a range of power density. The rate kinetics of degradation shows a non-linear increase with an increase in power density. We proposed a four-parameter logistic regression (4PLR) equation that empirically fits the degradation rate kinetics with the power density. The 4PLR equation predicts that the maximum achievable half-life of PFOA and PFOS sonochemical degradation are 1 and 10 min under a given set of experimental conditions. The high bulk-water temperature (i.e., 30 °C) of the aqueous sample helps increase the degradation rate of PFOA and PFOS. The addition of oxidants such as iodate and chlorate help enhance PFOA degradation in an argon environment at an ultrasonic frequency of 575 kHz. 相似文献
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Flat Langmuir probes, a flush mounted probe and an insulated antenna were used to investigate the correlation between the plasma density and the occurrence of radio frequency‐ and X‐band‐noise as a fingerprint for parametric decay processes in a magnetized linear plasma device. The decay products of the driving microwave may influence the entire scenario of electron and ion heating in the plasma. 相似文献
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《Comptes Rendus Physique》2014,15(5):468-478
Three examples of results achieved from cooperative works with microwave and plasma research groups in Toulouse (France) are presented in this paper. They are focused on the use of few non-thermal plasmas to make a microwave device reconfigurable. The relative permittivity of such a plasma medium can be tuned from unity to negative values. This special feature appears to be very attractive, although the electromagnetic losses are significant. The use of plasmas with planar waveguides and within metamaterials is discussed. In addition, the basic principles of a scanning antenna built with a leaky wave in a plasma layer are presented. 相似文献
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Perfluorooctanoic acid (C7F15COOH, PFOA) is an aqueous anionic surfactant and a persistent organic pollutant. It can be easily adsorbed onto the bubble-water interface and both mineralized and degraded by ultrasonic (US) cavitation at room temperature. The aim of this study is to investigate whether the effect of US on the degradation of PFOA in solution can be enhanced by the addition of surfactant. To achieve this aim, we first investigated the addition of a cationic (hexadecyl trimethyl ammonium bromide, CTAB), a nonionic (octyl phenol ethoxylate, TritonX-100), and an anionic (sodium dodecyl sulfate, SDS) surfactant. We found the addition of CTAB to have increased the degradation rate the most, followed by TritonX-100. SDS inhibited the degradation rate. We then conducted further experiments characterizing the removal efficiency of CTAB at varying surfactant concentrations and solution pHs. The removal efficiency of PFOA increased with CTAB concentration, with the efficiency reaching 79% after 120 min at 25 °C with a 0.12 mM CTAB dose. 相似文献
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I. S. Burkhanov L. L. Chaikov N. A. Bulychev M. A. Kazaryan V. I. Krasovskii 《Bulletin of the Lebedev Physics Institute》2014,41(10):297-304
Size distributions of tungsten oxide particles produced in the plasma discharge in the liquid phase upon exposure to ultrasound were studied by the dynamic light scattering method. Particles produced by this method under ultrasonic cavitation (USC), in the absence of cavitation, and without cavitation followed by ultrasonic processing are compared. The behavior of concentrations of particles of various size groups is comparatively estimated by the data on particle sizes and scattering intensity using the Rayleigh-Gans-Debye approximation. It is shown that ultrasonic processing improves the aggregative stability of suspension; in a suspension of particles produced under USC, large aggregates eventually decay into individual small particles. 相似文献
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Elvira L Sampedro L Montero de Espinosa F Matesanz J Gómez-Ullate Y Resa P Echevarría FJ Iglesias JR 《Ultrasonics》2006,45(1-4):92-99
An eight-channel ultrasonic detecting device for microbiological quality evaluation of packed liquid foods is presented in this paper. This device makes possible a non-invasive detection of the microbial growth in liquid foods with no need to open the carton-based packages where they are contained. Thermal and humidity stabilization are required inside the measuring chamber. The changes in the liquid media produced by the microorganism growth induce variations in the ultrasonic propagation parameters giving a non-invasive evidence of the developing contamination. For that purpose, the amplitude and time of flight of an ultrasonic 800 kHz tone burst travelling through an UHT milk pack are analysed. Inoculated and sterile packs were tested to evaluate the performance of this new non-invasive ultrasonic microbiological quality sensor. 相似文献
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Ultrasound (US) and Microwaves (MW) are effective methods for processes intensification. Their combined use in the same reactor can lead to remarkable results. Recently there has been a resurgence of interest in this field for new synthetic applications using reactors based upon existing technologies. We describe here a new type of apparatus in which the thermal energy is continuously removed from the system making possible the use of high power and adjustable ultrasonic and microwave densities throughout the process. The installation consists of a glass reactor located in a monomode applicator which is immersed at the same time in an ultrasonic device which can be operated at different frequencies and powers. A liquid, transparent to microwaves, was used to couple ultrasonic energy to the reactor and to remove the heat generated. Comsol software was used to get information about the distribution of ultrasonic and microwave energy between the reactor liquid and the coupling fluid. The performance was assessed using the conversion of p-nitrophenol into 4-nitrocatechol as a chemical dosimeter and a transesterification. 相似文献
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Degradation of reactive brilliant red K-BP in aqueous solution by means of ultrasonic cavitation was investigated for a variety of operating conditions. It is found that the degradation of reactive brilliant red K-BP in aqueous solution follows pseudo-first-order reaction kinetics and the degradation rate is dependent on the initial concentration of reactive brilliant red K-BP, the temperature and acidity of the aqueous medium. The effects of Fe2+, Fenton reagent and NaCl addition on the sonochemical degradation of reactive brilliant red K-BP were also investigated. The results obtained here indicate that the degradation rate of brilliant red K-BP in aqueous solution was substantially accelerated by Fe2+, NaCl or Fenton reagent addition. 相似文献
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Microwave plasma in liquid is a new plasma technology and becomes more and more concerned due to its large spatial distribution and high density of plasma. In this paper, methylene blue is degraded using plasma which is generated by 2450 MHz microwave in liquid. Effects of microwave power, initial concentration and pH on the degradation rate of methylene blue are studied respectively. Results show that the degradation rate of methylene blue increases with increasing of microwave power, and decreases with increasing pH in the range of 6‐8; When the initial concentration is less than 12.5 mg/L, the maximum degradation rate of methylene blue increases with increasing of its initial concentration, which can reach 96.56%. However, when the initial concentration is more than 12.5 mg/L, the maximum degradation rate appears decreased. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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��������ɣ��������������������������ΰ���� ǿ 《核聚变与等离子体物理》2018,38(3):368-372
报道了利用多腔耦合微波表面波等离子体增强化学气相沉积(PECVD)的方法制备类金刚石(DLC)薄膜。通过发射光谱(OES)测量,对Ar等离子体中的各种放电参数以及全部四个腔室内放电的均匀性作出评估。采用表面轮廓仪测量了薄膜的厚度;薄膜的表面形貌、组成结构通过原子力显微镜(AFM)、激光拉曼光谱和X射线衍射光谱(XPS)进行了表征。在12.5μm厚度的有机薄膜聚酯(PET)表面沉积一定厚度DLC后,通过测量水蒸气透过率(WVTR)对DLC薄膜的阻隔性能进行了研究。结果表明,这种多腔耦合微波表面波等离子体装置,不仅能够实现四个腔室同时相对均匀的放电,也能够实现单个腔室的轴向均匀放电。制备的DLC薄膜结构致密、成分均匀,可以使PET薄膜阻隔性能提高约20倍。 相似文献
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Yu. V. Pyl’nov S. S. Koshelyuk P. Pernod Yu. I. Kutlubaeva 《Physics of Wave Phenomena》2012,20(3):231-234
The possibility of using phase conjugation in ultrasonic tomography to reconstruct the distribution of liquid flow velocities is discussed. The results of experiments aimed at reconstructing the distribution of flow velocities in the vortex cross section by the back projection method are shown. A mathematical model of acoustic wave propagation in a medium with a stationary liquid flow and an algorithm for reconstructing the velocity distribution using a 64-element acoustic antenna have been developed. The results of numerical experiment are discussed. 相似文献
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ABSTRACT A novel synergic effect of ultrasonic nebulization (USN) and ultraviolet (UV) radiation (photolysis) when used in combination has been exploited for efficient generation of conventional hydride elements (As, Bi, Sb, Se, Sn), Hg vapor, and volatile molecular Cd species. Several UV-based systems were studied, the most advantageous design being an ultrasonic nebulizer fitted with a 6 W mercury pen lamp supplying a microliter sample to a quartz oscillator, converting liquid into aerosol at the entrance of the UV spray chamber. Optimal conditions utilized a 40% v/v solution of acetic acid as the generation medium. The volatile species are detected by microwave-induced plasma optical emission spectrometry (MIP-OES). The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times the standard deviation of the blank (LOD, 3σblank criterion, peak height), were 11, 22, 16, 19, 20, 11, and 15 µg L?1 for As, Bi, Sb, Se, Sn, Cd, and Hg, respectively. The method offers relatively good precision (RSD ranged from 3% to 5%) for liquid analysis and microsampling capability. The methodology was validated through determination of elements in two Certified Reference Materials (NRCC DOLT-2, NIST 1643e) and by the aqueous standard calibration technique. 相似文献
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Rapid nonthermal plasma-stimulated inflammation of liquid hydrocarbon (alcohol) films is realized under the conditions of
a surface microwave discharge initiated in quiescent atmospheric-pressure air. The induction period is found, and the velocity
of the intense combustion front is determined. Combustion is initiated by the low-temperature plasma of the surface microwave
discharge that exists at high values of the reduced electric field. It is shown that the induction period varies between 10
and 100 μs depending on the input power, the plasma-stimulated inflammation occurs on the antenna at the site where the surface
microwave discharge burns, and the velocity of the intense combustion front near the antenna reaches 300–350 m/s. 相似文献
18.
V. M. Shibkov L. V. Shibkova P. V. Kopyl O. A. Surkont 《Moscow University Physics Bulletin》2012,67(3):308-311
The process of ignition and combustion of liquid hydrocarbon films under the conditions of a self-maintained surface microwave discharge in still air that is generated on a dielectric antenna in the paired pulse mode is investigated. The effect of the medium pre-excitation, which occurs during the first pulse on the period of induction and intensity of hydrocarbon combustion during the second microwave pulse, is demonstrated. 相似文献
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Solids such as soils and sediments contaminated with per- and polyfluorinated alkyl substances (PFAS) from exposure to impacted media, e.g., landfill leachate or biosolids, direct contaminated discharge, and contaminant transport from atmospheric deposition, have caused significant environmental pollution. Such solids can act as secondary sources of PFAS for groundwater and surface water contamination. There are currently no proven technologies that can degrade PFAS in soil and sediments in a cost-effective, environmentally-friendly, and energy-efficient manner. This study examines the use of coupled high and low-frequency ultrasound in desorbing and degrading PFAS in soil, thereby achieving concurrent treatment and destruction of PFAS in soil. Two common PFAS, namely perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), were used to evaluate treatment performance in soils with both low and high organic matter contents. The test results showed that the ultrasound treatment could significantly reduce PFAS concentrations in artificially contaminated soil; however, no significant degradation was achieved. Ultrasound treatment did improve desorption of PFAS from solid particles, particularly from the highly absorbent organic soil; 68.8 ± 1.8% of PFOA and 45.4 ± 4.1% of PFOS were leached from the soil after ultrasound treatment compared to only 28 ± 0.2% of PFOA and 1 ± 3.1% of PFOS after desorption in water. This work shows that sonication treatment is an effective technology for the removal of PFAS from solids, however, the presence of solids in the solid–liquid slurry can negatively impact ultrasonic cavitation, inhibiting the sonolytic degradation of desorbed PFAS. 相似文献