介质阻挡放电技术处理挥发性有机物的研究进展

介质阻挡放电技术在处理低浓度挥发性有机物（VOCs）过程中具有反应快速、工艺简单及适应范围广等优点而受到广泛关注。本文从介质阻挡放电单独使用和介质阻挡放电协同催化两方面进行了概括总结。首先,简述了介质阻挡放电处理VOCs所用的驱动电源和等离子体发生器的研究现状及气体性质对VOCs降解性能的影响;其次,介绍了介质阻挡放电协同催化的两种方式（内置式和后置式）及各自情况下采用不同催化剂强化VOCs去除性能、提高能量效率、抑制副产物生成的过程机理;最后,分析了介质阻挡放电技术处理低浓度VOCs过程中存在的关键问题,并提出了未来的重要研究方向为：等离子体催化体系中VOCs的界面反应机理;催化剂的抗积碳性能的提高;适用于多组分VOCs的高效催化剂的开发。     

Catalysis assisted plasma decomposition of benzene using dielectric barrier discharge

Atmospheric non‐thermal plasma generated by dielectric barrier discharge was applied to decompose benzene with a sheet type catalyst of platinum supported by alumina. The experimental results indicated that an enhancement of the decomposition by the catalyst was achieved at low concentration of benzene. Ozone produced in the plasma seemed not to contribute to the decomposition. The deactivation of the catalyst was also observed due to decomposition products such as CO and a solid deposit. However a heating treatment could regenerate the catalyst. The results suggested the plasma‐catalyst hybrid reactor was the effective method to solve volatile organic compound (VOCs) problem.     

介质阻挡放电等离子体反应器降解盐酸四环素

采用介质阻挡放电等离子体反应器降解盐酸四环素（TC）,研究了输入功率、放电间距、气体流量、初始浓度等参数对盐酸四环素降解效果的影响,结果表明当输入功率为1.3 W,放电间距为2.5 mm,气体流量为150 ml·min^-1,初始浓度为100 mg·L^-1时降解效果最好,放电处理30 min盐酸四环素的降解率达到92%。动力学研究表明盐酸四环素的降解过程符合拟二级动力学方程。检测了降解过程中生成的中间产物,提出了盐酸四环素的降解路径与机理。     

Degradation of an azo dye Orange II using a gas phase dielectric barrier discharge reactor submerged in water

A dielectric barrier discharge (DBD) system employing wastewater as one of the electrodes was applied to the degradation of an azo dye, Orange II. The main advantage of this system is that reactive species like ozone and ultraviolet (UV) light produced by the DBD can be utilized for the treatment of wastewater. This system was able to remove the chromaticity and destroy the benzene and naphthalene rings in the dye molecule effectively. The results obtained under several conditions revealed that the UV emission from the DBD reactor could enhance the degradation of the dye, particularly in the presence of titanium oxide photocatalyst. The products resulting from the destruction of the rings in the dye molecule were found to be highly recalcitrant against further oxidation to smaller molecules. The change in the initial dye concentration showed that the reaction order was around 0.8 with respect to the dye concentration. The reduction in the concentration of total organic carbon was much more efficient with oxygen than with air.     

Removal of iopromide from an aqueous solution using dielectric barrier discharge

BACKGROUND: Both ionic and nonionic ICM are recalcitrant to ozone and traditional waste water treatment plants. In this study, the efficiency of one kind of ICM‐iopromide (IOPr) removal from an aqueous solution using a dielectric barrier discharge (DBD) method was investigated. RESULTS: An energy density of 1.5E05 J L^?1 resulted in the most significant removal (98.8%) of IOPr. At this energy density, no decrease in total organic carbon (TOC) was observed. Based on the IR spectra, degradation of the IOPr molecule involved hydroxylation, carbonylation and deiodination. BOD₅/COD measurements indicated that the biodegradability of IOPr increased significantly as a result of DBD treatment. The byproducts of IOPr after DBD treatment were more polar and easily adsorbed and biodegraded by the activated sludge. The removal of IOPr from the solution followed first‐order kinetics, with Ks of 0.10 min^?1, 0.11 min^?1, 0.44 min^?1 and 0.15 min^?1 corresponding to energy densities of 1E + 05 J L^?1, 1.3E + 05 J L^?1, 1.5E + 05 J L^?1 and 1.8E + 05 J L^?1, respectively. The kinetics of the deiodination reactions were more complex due to subsequent iodide oxidation. CONCLUSION: DBD is very effective as a pretreatment or advanced treatment method for increasing the recalcitrant chemical's biodegradability and making subsequent biological treatment more efficient. © 2012 Society of Chemical Industry     

Kinetic modeling of plasma methane conversion in a dielectric barrier discharge

Methane conversion by plasma offers a promising route to produce higher value-added products. As plasma reaction is a relatively complex process, kinetic modeling is necessary to obtain a general pattern of the complex interaction on the basis of chemical reaction and products. In this paper, we present a method to obtain the kinetic rate coefficient (k) from the experimental data. Although plasma reaction was classified as chemically complex interaction, the reactions showed a certain pattern of the mechanism. In pure methane injection, the decomposition of methane by plasma could initiate coupling reactions and produce C₂H₆, C₃H₈, and C₄H₁₀. Dehydrogenation of C₂H₆ into C₂H₄ and then to C₂H₂ could be clearly seen by the higher value of the reaction rate constant of C₂H_n + 2 to C₂H_n − 2. Using the rate constant values (k) obtained by this method, the pathways of the methane conversion by a dielectric barrier discharge can be drawn.     

Hydrophobic coating of silicate phosphor powder using atmospheric pressure dielectric barrier discharge plasma

A stable superhydrophobic coating was successfully deposited on commercial silicate‐based orange phosphor by using atmospheric pressure dielectric barrier discharge plasma with hexamethyldisiloxane (HMDSO) and HMDSO/toluene mixture as precursors. Owning to the good optical properties, the deposited film acts not only as a hydrophobic protective layer but also as an antireflection optical thin film capable of improving the phosphor photoluminescence efficiency. The plasma‐polymerized film based on Si?O?Si backbone containing methyl and phenyl nonpolar functional groups exhibited high‐water‐repellent characteristics. It was found that the water contact angle gradually increased with increasing the aging time and remained unchanged at about 140° after 1‐month aging. Besides, the thermal stability of the coated phosphor under high‐temperature condition was substantially enhanced by the aging. The findings of this work can contribute to improving the durability and reliability of the phosphor, eventually the long‐term stability of phosphor‐based light emitting diodes in practical applications. © 2014 American Institute of Chemical Engineers AIChE J, 60: 829–838, 2014     

Hydrogen from steam methane reforming by catalytic nonthermal plasma using a dielectric barrier discharge reactor

A scaled-up dielectric barrier discharge (DBD) reactor has been developed and demonstrated for the production of hydrogen from steam methane reforming (SMR) by catalytic nonthermal plasma (CNTP) technology. Compared to SMR, CNTP offers conversion at ambient pressure (101.325 kPa), low temperature with better efficiency, making it suitable for distributed hydrogen production with small footprint. There have been several lab-scale DBD reactors reported in the literature. Dimension of the scaled-up DBD reactor is about six times the lab-scale version and can produce 0.9 kg H₂/day. The scale-up is, however, nonlinear; several technical innovations were required including spray nozzle for homogeneous introduction of steam, perforated tube central electrodes for generation of homogeneous plasma. Conversion efficiency of the scaled-up DBD reactor is 70–80% at 550°C and 500 W. A continuous run of 8 hr was demonstrated with typical product gas composition of 69% H₂, 6% CO₂, 15% CO, 10% CH₄.     

Surface treatment of sol-gel bioglass using dielectric barrier discharge plasma to enhance growth of hydroxyapatite

Surface treatment of sol-gel bioglass is required to increase its biomedical applications. In this study, a dielectric barrier discharge (DBD) plasma treatment in atmospheric pressure was performed on the surface of [SiO₂-CaO-P₂O₅-B₂O₃] sol-gel derived glass. The obtained bioglass was treated by plasma using discharge current 12mA with an exposure period for 30 min. The type of discharge can be characterized by measuring the discharge current and applied potential waveform and the power dissipation. Apatite formation on the surface of the DBD-treated and untreated samples after soaking in simulated body fluid (SBF) at 37 °C is characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), inductively coupled plasma (ICP-OES) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). We observed a marked increase in the amount of apatite deposited on the surface of the treated plasma samples than those of the untreated ones, indicating that DBD plasma treatment is an efficient method and capable of modifying the surface of glass beside effectively transforming it into highly bioactive materials.     

Deposition of polymethyl methacrylate on polypropylene substrates using an atmospheric pressure dielectric barrier discharge

In this work, an atmospheric pressure glow-like dielectric barrier discharge in helium with small admixtures of methyl methacrylate (MMA) is used for the deposition of thin polymethyl methacrylate (PMMA) films. The effect of discharge power and feed composition (monomer concentration) on film properties has been investigated by means of Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results are described by defining a W/FM value, where W is the discharge power, F the monomer flow rate and M is the molecular weight of the monomer. It is shown in this paper, that the deposition rate and the chemical composition of the deposited film change with varying W/FM values. At low W/FM values, high deposition rates of up to 2 nm/s are observed and the plasma-polymerized MMA chemically resembles the conventionally synthesized PMMA. In contrast, using high W/FM values (≥102 MJ/kg) leads to lower deposition rates (as low as 0.9 nm/s), while the plasma-polymerized MMA films contain less ester groups and a larger amount of ether and/or alcohol groups. One should therefore carefully choose the deposition parameters in order to obtain a high deposition rate and a high retention of ester groups in the plasma-polymerized MMA films.     

Deposition of HMDSO-based coatings on PET substrates using an atmospheric pressure dielectric barrier discharge

This paper presents results on the formation of coatings in an atmospheric pressure dielectric barrier discharge using hexamethyldisiloxane (HMDSO) as gaseous precursor. Plasma-polymerized films are deposited onto polyethylene terephthalate (PET) films using argon and argon/air mixtures as carrier gases. The chemical and physical properties of the obtained coatings are discussed in detail using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). FTIR and XPS results show that the composition of the gas phase and the chemical structure of the obtained coatings are clearly correlated. When pure argon is used as working gas, the film is polymeric with a structure close to [(CH₃)₂–Si–O]_n, which means that the deposited films resemble PDMS. However, if plasma-polymerization occurs in argon/air mixtures, the deposited film is silica-like containing only few carbon atoms. These dense SiO_x coatings generally exhibit high barrier properties, while pure HMDSO-derived films might be of importance for selective permeation. From this point of view, the capability of controlling the film composition by varying the operation conditions opens interesting perspectives.     

新型两级介质阻挡放电降解甲基橙的机理研究

采用新型两级介质阻挡放电(DBD)等离子体反应器对甲基橙废水进行降解处理,考察了甲基橙的p H值、电导率、降解率、化学需氧量(COD)随停留时间的变化。采用紫外光谱、红外光谱、液质联用对处理前后的甲基橙废水进行检测,并推测甲基橙降解机理。结果表明:甲基橙废水的p H值随着停留时间的增长而减小,电导率和降解率均随停留时间的增长而增大,甲基橙的COD值随停留时间的增长呈现先减小再升高最后降低趋于平稳的规律;经过表征分析,处理160 min后的甲基橙降废水中含有NO_3~-,HOOCCH_2CH_2CH_2CH_2CH_2SO_3~-,(CH_3)_2NCH_2CH_2CH_2CH_2CH_2COOH等。     

Atmospheric pressure plasma treatment of polyethylene via a pulse dielectric barrier discharge: Comparison using various gas compositions versus corona discharge in air

Modification of polyolefin surfaces is often necessary to achieve improved printability, lamination, etc. Although corona discharge and flame treatments can produce the higher surface energy needed for these applications, the properties of the resulting surfaces are not always optimal. Atmospheric pressure plasma is a surface modification technique that is similar to corona discharge treatment, but with more control, greater uniformity, and higher efficiency. Using an atmospheric pressure plasma unit with a dielectric barrier discharge generated using an asymmetric pulse voltage, the effects of different gases, powers, and linespeeds on polyethylene surface treatment were studied. Our results show that atmospheric pressure plasma can be used to achieve higher long‐term wettability, higher surface oxygen and nitrogen, and a greater range of surface chemistries with better robustness versus standard corona treatment. Atomic force microscopy results suggest significant differences in the mechanism of surface functionalization versus etching and ablation depending on the gases used. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 319–331, 1999     

Immobilization of biologically active species on PA‐6 foils treated by a dielectric barrier discharge

In the field of biomaterials and biomedical devices, surface activation has been focused on creating functional groups capable of preferential adsorption of biologically active species (proteins, enzymes, cells, drugs, etc.). In this way an interface can be created between the synthetic material and the biological medium, with the aim of increasing the compatibility of the implant with the human organism. In our experiments a dielectric barrier discharge (DBD), in helium at atmospheric pressure, was used as the source of energy capable of creating active centers that render the functionalized surface favorable to immobilization of biological molecules. Retention of immunoglobulin (IgG) and heparin biomolecules on polyamide‐6 (PA‐6) surfaces after treatment by the DBD was analyzed by atomic force microscopy, adhesion evaluation, and measurement of the contact angle titration in order to assess this incorporation on the treated surfaces. The marked adsorption of the biomolecules on the active sites created by DBD on the exposed surfaces also was related to a complex set of processes, such as enhanced roughness, increased surface wettability, and modified distribution of cationic and anionic groups on the treated surfaces. All these factors could promote interfacial interactions between the specific groups of the biomolecules existing in the biological medium and the type of cationic and/or anionic groups present on the surface. The efficiency of the DBD treatment showed that the DBD technique is useful for preactivation of the polymer surface for immobilization of other biologically active species (such as drugs and enzymes). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1985–1990, 2003     

Improvement of performance of polyamide reverse osmosis membranes using dielectric barrier discharge plasma treatment as a novel surface modification method

In this research, surface modification of aromatic polyamide thin film composite (TFC) reverse osmosis (RO) membranes was carried out using dielectric barrier discharge (DBD) plasma treatment to improve the performance and fouling resistance of prepared RO membranes. First, polyamide TFC RO membranes were synthesized via interfacial polymerization of m‐phenylenediamine and trimesoyl chloride monomers over microporous polysulfone support membrane. Next, the DBD plasma treatment with 15 s, 30 s, 60 s, and 90 s duration was used for surface modification. The surface properties of RO membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), SEM, AFM, and contact angle measurements. The ATR‐FTIR results indicated that DBD plasma treatment caused hydrogen bonding on the surface of RO membranes. Also, the contact angle measurement showed that the hydrophilicity of the membranes was increased due to DBD plasma treatment. The changes in the membranes surface morphology indicated that the surface roughness of the membranes was increased after surface modification. In addition, it was found that the DBD plasma treatment increased the water permeation flux significantly and enhanced sodium chloride (NaCl) salt rejection slightly. Moreover, the filtration of bovine serum albumin revealed that the antifouling properties of the modified membranes had been improved. POLYM. ENG. SCI., 59:E468–E475, 2019. © 2018 Society of Plastics Engineers     

Influence of operating parameters on plasma polymerization of acrylic acid in a mesh-to-plate dielectric barrier discharge

Plasma polymerization of acrylic acid is an interesting research subject, since the obtained coatings can have significant biomedical applications due to their high surface density of carboxylic acid groups. In this work, plasma-polymerized acrylic acid (PPAA) films are synthesized using a mesh-to-plate dielectric barrier discharge operated at medium pressure (10.0 kPa). Results clearly show that this reactor setup is able to deposit uniform PPAA films in contrast to the commonly used parallel plate reactor. Moreover, carefully planned experiments are conducted to study the influence of discharge power and monomer concentration on the chemical composition and thickness of the PPAA films. Results clearly show that input power strongly influences the properties of the deposited films: with increasing discharge power, monomer fragmentation in the discharge increases leading to a decrease in carboxylic acid functional groups and a lower polymer deposition rate. The effect of monomer concentration is less pronounced: only at very low monomer concentration (0.1 g/h), a decrease in carboxylic acid functional groups can be observed. The chemical composition and thickness of the PPAA films can thus be tailored by adjusting the operational parameters of the discharge.     

Removal of particulate matter from an air stream by a packed dielectric barrier discharge

This study elucidates the feasibility of using a packed dielectric barrier discharge approach to remove particulate matter from an air stream. The experimental results reveal that the particle removal efficiency of the packed dielectric barrier discharge system rose to 92.2% for 0.3 μm particles as the discharge voltage was increased to 20 kV at an operating frequency of 60 Hz. Only when the discharge voltage was sufficiently high to remove particulate matter did the particle removal efficiency increase with the operating frequency. The power required to adjust the discharge voltage was less than that required to adjust the operating frequency at the particular removal efficiency. Accordingly, energy can be saved in a packed dielectric barrier discharge system by adjusting the discharge voltage rather than the operating frequency to remove particulate matter from the air stream.