Destruction of Gaseous Styrene with a Low-Temperature Plasma Induced by a Tubular Multilayer Dielectric Barrier Discharge

The destruction of gaseous styrene was studied using a low-temperature plasma induced by tubular multilayer dielectric barrier discharge（DBD）.The results indicate that the applied voltage,gas flow rate,inlet styrene concentration and reactor configuration play important roles in styrene removal efficiency （ηstyrene） and energy yield（EY）.Values of ηstyrene and EY reached 96%and 15567 mg/kWh when the applied voltage,gas flow rate,inlet styrene concentration and layers of quartz tubes were set at 10.8 kV,5.0 m/s,229 mg/m^3 and 5 layers,respectively.A qualitative analysis of the byproducts and a detailed discussion of the reaction mechanism are also presented.The results could facilitate industrial applications of the new DBD reactor for waste gas treatment.

Design and characteristics investigation of a miniature low-temperature plasma spark discharge device

Atmospheric pressure low-temperature plasma is a promising tool in biomedicine applications including blood coagulation,bacterial inactivation,sterilization,and cancer treatment,due to its high chemical activity and limited thermal damage.It is of great importance to develop portable plasma sources that are safe to human touch and suitable for outdoor and household operation.In this work,a portable and rechargeable low-temperature plasma spark discharge device(130 mm×80 mm×35 mm,300 g)was designed.The discharge frequency and plume length were optimized by the selection of resistance,capacitance,electrode gap,and ground electrode aperture.Results show that the spark plasma plume is generated with a length of 12 mm and a frequency of 10 Hz at a capacitance of 0.33μF.resistance of 1 MΩ,electrode gap of 2 mm,and ground electrode aperture of 1.5 mm.Biological tests indicate that the plasma produced by this device contains abundant reactive species,which can be applied in plasma biomedicine,including daily sterilization and wound healing.

Study on Polypropylene Film Treated by Low Temperature Glow Discharge

The results of contact angle and X-ray photoelectron spectrometry ( XPS ) reveal the effects of plasma treatment. The treated polypropylene film shows improved wet ability. Comparing the different treating conditions, such as time and atmospheres, the results reveal that there may exist two parallel reactions. And the different atmosphere has the different action in plasma treatment also.

Spatio-temporal evolution characteristics and pattern formation of a gas–liquid interfacial AC current argon discharge plasma with a deionized water electrode

A discharge ignited by an AC power source in contact with deionized water as one of the electrodes is investigated.Immediately after initiation,the discharge exhibits a unique phenomenon:the gas-phase discharge is extended into the liquid.Later,a cone-like structure is observed at the liquid surface.Synchronous monitoring of current–voltage characteristics and liquid properties versus time suggests that the discharge shapes are functions of the liquid properties.The spatio-temporal profiles indicate the potential effects of water,ambient air impurities,and metastable argon on the discharge chemistry.This becomes more obvious near the liquid surface due to increasing production of various transient reactive species such as centerdot OH and NO centerdot.Moreover,it is revealed that thermalization of the rotational population distributions of the rotational states(N′⩽6,J′⩽13/2)in the Q1 branch of the OH(A2Σ+,υ′=0→X2Π3/2,υ′′=0)band ro-vibrational system is influenced by the humid environment near the liquid surface.In addition,the transient behaviors of instantaneous concentrations of long-lived reactive species(LRS)such as H2O2,NO−2,and NO−3 are observed with lengthening the discharge time.The production of multiple transient and LRS proposes AC excited gas–liquid argon discharge as a potential applicant in industrial wastewater cleaning,clinical medicine,and agriculture.

A comparison among optical emission spectroscopic methods of determining electron temperature in low pressure argon plasmas

In this article, four kinds of optical emission spectroscopic methods of determining electron temperature are used to investigate the relationship between electron temperature and pressure in the cylindrical plasmas of dc glow discharges at low pressures in laboratory by measuring the relative intensities of ArI lines at various pressures. These methods are developed respectively on the basis of the Fermi-Dirac model, corona model, and two kinds of electron collision cross section models according to the kinetic analysis. Their theoretical bases and the conditions to which they are applicable are reviewed, and their calculation results and fitting errors are compared with each other. The investigation has indicated that the electron temperatures obtained by the four methods become consistent with each other when the pressure increases in the low pressure argon plasmas.

Experimental Research of Inactivation Effect of Low-Temperature Plasma on Bacteria

The killing logarithms index in killing a vegetative form in an explosure of about 90s and a spore in an explosure of about 120s, by using a low-temperature plasma produced by dielectric barrier discharge （DBD）, reached 5. The speed in killing the strains tested, by using a low-temperature plasma, was the highest with E. Coli, then S. Aureus and B. Subtilis var niger spore. The results of the scanning electron microscope showed that the low-temperature plasma destroyed the outer structure of the bacteria and that the vegetative form was more susceptible to the inactivation effect of the low-temperature plasma than was the spore. This indicated that the effects of the high voltage and high velocity particle flow, in plasma, penetrating through the outer structure of the bacteria might play a dominant role during the inactivation of the bacteria.

Remove of Phenolic Compounds in Water by Low-Temperature Plasma: A Review of Current Research

Phenolic compounds have very strong toxicity, so it has been paid sharply attention to find an effective way of controlling the wastewater containing phenolic compounds. The work on this subject done by domestic and overseas scholars is studied in this paper, and the progress of researches on low-temperature plasma treatment is summarized through the electrical discharge types, mechanism, kinetics of phenolic compounds decomposition and combination of several methods with low-temperature plasma treatment. In addition, the crucial problem and the developing tendency on low-temperature plasma treatment for phenol-bearing wastewater are briefly discussed.

The Experimental Investigations of Dielectric Barrier Discharge and Pulse Corona Discharge in Air Cleaning

The dielectric barrier discharge (DBD) and pulse corona discharge(PCD) plasma generator was used to remove NH3, H2S, C7H8 etc. from atmosphere. The principle and characteristic of the two ways was discussed in the article. The test shows the result of PCD is better than that of DBD.

Experimental Study on Inactivation of Bacterial Endotoxin by Using Dielectric Barrier Discharge

The low-temperature plasma （LTP） generated by dielectric barrier discharge （DBD） was used to sterilize the E.coli endotoxin, which is usually difficult to kill by traditional methods. Three different concentrations of bacterial endotoxin （1 EU/mL, 0.5 EU/mL and 0.25 EU/mL） were treated by LTP for different time （20 s, 40 s and 60 s）. Tachypleus amebocyte lysate （TAL） method was employed to detect the concentration variation of bacterial endotoxin before and af- ter the plasma treatment, and endotoxic shock mice model was used to evaluate the inactivation effects of LTP on endotoxin for further study. Experimental results demonstrated that, DBD plasma can inactivate the bacterial endotoxin quickly and effectively, and when the LTP treatment time was increased, the concentrations of bacterial endotoxin decreased gradually （after 60 s plasma treatment, its inactivation effect was beyond the Chinese pharmacopoeia standard）, and the average survival time of mice gradually extended. The possible inactivation mechanisms are proposed to be related to reactive oxygen species （ROSs）.

Wastewater Decontamination from Microorganisms by Electrospraying Corona Discharge

A novel water treatment technique, based on a combination of electrospraying and pulsed corona discharge, has been used for bio-decontamination of wastewater. The electrospraying process has been found to increase the surface area of the treated wastewater, and hence increases the efficiency of the corona treatment process. The phase diagram of the discharge, which characterizes the discharge regimes, has been identified experimentally. The survival ratio of the microorganisms has been investigated experimentally as a function of the applied voltage and the numbers of treatment runs using air and oxygen as working gases. Microorganism surface has been examined using scanning electron microscope (SEM), which enabled in understanding the decontamination mechanisms of the treated microorganism. A complete decontamination has been achieved after only one run for an applied voltage higher than 16 kV when the discharge system was operated in oxygen gas. Optical emission spectrum of the electrosprayed water confirmed the existence of OH-radicals responsible for decontamination process.

双针-板结构脉冲气泡放电等离子体固氮研究

大气压低温等离子体可以利用空气直接进行氧化固氮,具有反应条件温和、参数灵活可控、避免温室气体排放等优点.本文利用双针-板电极在水中形成气泡放电等离子体,以空气为放电气体进行了固氮研究,分析了产物浓度和固氮能耗的影响因素.研究结果表明,等离子体中含有丰富的氮原子、氧原子、氢原子、激发态氮分子等活性物种,可高效合成硝态含氮产物.研究发现,脉冲参数、电极间隙、工作气体组分对气泡放电等离子体的固氮性能有重要影响.装置最高NO~-_x合成速率为19.2μmol/min,最小能耗约为11 MJ/mol.此外还发现,电极间隙为6 mm时,固氮性能最优;空气中增加适量氧气(氧气/氮气比例为0.4)可以增强产物合成,降低能耗.

Higher resolution helium measuring system for deuterium plasma on EAST tokamak via normal Penning gauge

Although the deuterium and helium have almost the same mass,a Penning Optical Gas Analyzer（POGA） system on the basis of the spectroscopic method and Penning discharging has been designed on EAST,since 2014.The POGA system was developed successfully in 2015,it was the first time that EAST could detect helium partial pressure in deuterium plasma（wall conditioning and plasma operation scenario）.With dedicated calibration and proper adjustment of the parameters,the minimum concentration of helium in deuterium gas can be measured as about 0.5% instead of 1% on the other tokamak devices.Moreover,the He and D2 partial pressures are measured simultaneously.At present,the measurable range of deuterium partial pressure is 1×10^-7 mbar to 1×10^-5mbar,meanwhile the range of helium is 1×10^-8 mbar to 1×10^-5 mbar.The measurable range can be modified by means of the adjustment of POGA system＇s parameters.It is possible to detect the interesting part of the gas with a time resolution of less than 5 ms（the 200 ms because of conductance of transfer pipe at present）.The POGA system was routinely employed to wall conditioning and helium enrichment investigation in2015.Last but not the least,the low temperature plasma of POGA is generated by normal penning gauge Pfeiffer IKR gauge instead of Alcatel CF2 P,which has been suspended for a few years and was used for almost all the POGA systems in the world.

Theoretical model of glow discharge plasma

The physical model for glow discharge plasma has been modified. The modified model is also analytic and self-consistent. Electron density distribution under the conditions of longer gap separations and different working gas pressures has been analyzed, and comparison between theory and experiment has been made. The modified model has wider applications, and the theoretical results are in better agreement with the experimental.

Isotope effects of plasma chemical carbon oxidation in a magnetic field

The influence of different factors on the plasma chemical reactions is widely studied today. However, insufficient consideration is given to the research of paramagnetic phenomena which takes place in plasma systems. The results of modeling the process of redistribution carbon isotopes between different phases while oxidizing it in high-frequency low-temperature plasma in an external magnetic field are shown in the article. The equilibrium concentrations of components involved in the oxidation process in a plasma system are defined. A principle possibility of isotope-selective plasma chemical reactions in a magnetic field was experimentally determined. The increase of concentration of 13C in the gas phase up to 1.3 times relative to natural abundance was obtained. It was found that the content of the carbon heavy isotope in the gas phase depends on the magnetic field action area. The best results were achieved with the combination of magnetic field impact area and the priority area of the appearance of plasma chemical reactions products.

千赫兹级介质阻挡放电对亚甲基蓝溶液的降解

针对染料废水的色度大、成分复杂、盐度高、浓度高、降解难等特点,采用千赫兹级大气压介质阻挡放电对亚甲基蓝溶液模拟的染料废水进行处理,研究不同放电条件对亚甲基蓝降解率的影响。使用电流、电压波形图和等离子体发射光谱对介质阻挡放电进行诊断;通过吸光度计算降解率,分析不同放电间隙、针尖形状、放电气氛环境下的亚甲基蓝降解情况。结果表明,0.44 cm放电间隙、斜口针尖、更细的针管可以提高亚甲基蓝降解率,无须另外通入气体、直接以空气为放电气氛的选择更为高效和经济。千赫兹级介质阻挡放电可有效应用于亚甲基蓝溶液的降解,在处理染料废水方面有着广阔的应用前景。

低温放电等离子体对葡萄干中赭曲霉毒素A的降解效果及降解机理

采用低温放电等离子体对葡萄干中赭曲霉毒素A(ochratoxin A,OTA)进行降解,研究不同时间下初始质量浓度、放电电压对葡萄干中OTA降解率的影响。结果表明,葡萄干中初始质量浓度为50?μg/mL的OTA经等离子体在放电电压75 kV时处理10 min被完全降解。利用高效液相色谱-四极杆-静电场轨道阱高分辨质谱检测并鉴定经低温放电等离子体处理的OTA降解产物,结合一级和二级质谱,推测出相对分子质量分别为m/z 426.0715(B)和m/z 158.1540(C)的2种主要降解产物结构及OTA可能的降解路径。等离子体处理前后葡萄干的理化品质没有发生显著变化,挥发性物质除酸类物质中3-甲基丁酸、乙酸、辛酸含量有明显的下降,甲酸、戊酸、2-乙基己酸含量有明显上升外,大部分的酸、醛、醇和酮类物质的相对含量未出现明显变化。研究结果表明低温放电等离子体可以有效地降解OTA,并对葡萄干品质没有显著影响,可为OTA污染的食品降解研究提供参考。

柴油车尾气中烃类物质净化研究进展

随着全球机动车柴油化的发展,柴油车尾气有效可控排放提上日程。柴油车尾气中的碳氢化合物是柴油车在贫燃烧条件下工作时产生的未完全燃烧的碳氢物质。这些烃类物质对健康和环境有害,导致大气污染、臭氧形成和粉尘生成。本文介绍了通过油质改进、机内装置性能优化技术来减少尾气的排放,但这种技术成本昂贵、改善能力有限,所以必须与机外净化后处理技术相结合。现阶段柴油车尾气主流后处理装置有柴油车颗粒过滤器和氧化性催化转换器,它们虽一定程度上减缓了尾气的排放,但过滤筒易堵塞,柴油车排气温度更低,催化剂在温度低的环境下能力不足,因此引进了低温等离子体协同催化净化技术来处理柴油车尾气中的HC。

低温放电等离子体处理对赭曲霉毒素A降解效果及对无核白葡萄干品质的影响

为研究低温放电等离子体对赭曲霉毒素A(ochratoxins A,OTA)的降解效果及对无核白葡萄干品质的影响,以赭曲霉毒素A为目标毒素,分析低温放电等离子体在不同处理时间、不同电压和不同初始浓度下对目标毒素的降解效果,并评估低温放电等离子体处理对无核白葡萄干中的理化指标及色差和香气成分的影响。结果表明:低温放电等离子体不同处理条件对OTA的降解效果明显,不同处理条件均使得赭曲霉毒素A降解率达90.00%以上,以75 kV低温放电等离子体处理5 min后,50μg/mL OTA的降解率高达99.21%。低温放电等离子体处理对无核白葡萄干的理化性质、蛋白浓度、色差均未出现显著影响(P>0.05),无核白葡萄干的香气成分也得到了良好的保持。因此,低温放电等离子体对赭曲霉毒素A具有较明显的降解效果,并且不会对无核白葡萄干的品质产生影响。

不同方波脉冲模式下介质阻挡放电产生臭氧的研究

为提高介质阻挡放电产生臭氧的浓度和产量,文中研究了不同方波脉冲模式下介质阻挡放电产生臭氧的特性。文中对系统放电特性进行分析,计算系统放电功率,研究其在不同极性、不同频率和不同脉宽下产生臭氧的浓度和产量,并对其产生的结果进行了分析和讨论。研究结果表明,在施加正负极性方波脉冲时,臭氧浓度最高,为8.8 g·Nm^(-3);在施加正极性方波脉冲时,臭氧产量最高,为55 g·kWh^(-1)。随着频率的增加,臭氧浓度和产量均呈现先增加后下降趋势。在放电频率为1 kHz时,臭氧浓度最大;在放电频率为1.5 kHz时,臭氧产量最高。在其它参数一定的情况下,随着脉宽的增加,臭氧浓度缓慢增加,臭氧的产量基本无变化。

空气中纳秒脉冲均匀介质阻挡放电研究

大气压空气中均匀介质阻挡放电具有广泛的应用前景,实现均匀放电是介质阻挡放电应用关键之一,因而利用上升沿40ns,脉宽70ns的重复频率纳秒脉冲电源激励在大气压空气中产生介质阻挡放电,介绍了纳秒脉冲均匀介质阻挡放电的电特性和放电图像及放电发射光谱,获得了2ns曝光时间的高速摄影放电图像。发现空气中1mm气隙距离下可以实现均匀放电,气隙距离增加至4mm时放电转变为明显的丝状放电,通过观察发射光谱显示等离子体谱线主要是来自400nm以下的氮分子第二正系。结果证实了大气压空气中利用ns脉冲激励可以产生稳定介质阻挡放电,且能实现均匀放电,是典型非平衡态低温等离子体。