低温等离子体与天然丝光沸石协同降解正己醛

本文研究了在低温等离子体和天然丝光沸石(Natural Mordenite,NMOR)的共同作用下对低浓度正己醛的降解性能。研究结果表明,在降解低浓度正己醛的反应中,低温等离子体与天然丝光沸石之间能产生很好的催化协同作用,当放电功率为2.8W时,反应温度为80℃时,干燥空气气氛下,天然丝光沸石对1 200 mL.m-3正己醛的去除率为93.9%;另外天然丝光沸石经酸处理后,这种协同作用可以进一步提高,正己醛的去除率达到96.5%;天然沸石的结构性能稳定,在实验条件下,天然沸石连续使用55 h,催化活性未见下降。     

Study of SO2 Removal Using Non-thermal Plasma Induced by Dielectric Barrier Discharge (DBD)

Dielectric Barrier Discharge (DBD) non-thermal plasma reactors built with three different dielectric materials for SO₂ removal were studied. The discharge characteristics of the three dielectrics, namely glass, Teflon, and glass fiber-based epoxy resin, were analyzed using Lissajous figures. From the Lissajous figures, the transition charge and energy deposition for each dielectric material were determined. When both the discharge characteristics and mechanical processability were considered, glass fiber-based epoxy resin was regarded as the best dielectric barrier among the three for DBD plasma reactors. A multi-cell DBD reactor built with glass fiber-based epoxy resin was used for treating air stream containing SO₂. SO₂ % removal decreased with increasing initial SO₂ concentration in a biphasic fashion. SO₂ removal was greatly improved by adding NH₃ into the air stream. Raising the relative humidity of the air stream also helped SO₂ removal. A SEM (scanning electron microscope) test illustrated some changes in surface morphology of Teflon and glass fiber-based epoxy resin.     

Evaluation of Energy Balance in a Batch and Circulating Non-thermal Plasma Reactors During Organic Pollutant Oxidation in Aqueous Solution

Plasma Chemistry and Plasma Processing - This work presents the treatment of an organic waste solution using gliding arc plasma in moist air, which is an excellent source of oxidizing species....     

Performance of an Ozone Decomposition Catalyst in Hybrid Plasma Reactors for Volatile Organic Compound Removal

In order to enhance the energy efficiency of nonthermal plasma methods for volatile organic compound decomposition in a catalyst-hybrid plasma reactor, we used a Cu–Cr catalyst to dissociate ozone into active atomic oxygen species at low temperatures. We investigated the conditions necessary to obtain the synergetic effect in single-stage and two-stage combinations. The ozone decomposition catalyst was not effective for the reaction under plasma discharge in the single-stage combination. In the two-stage combination, the efficiency increased by increasing the amount of catalyst. Although the propensity of catalysts for active oxygen species formation from ozone decomposition is important for optimizing the reaction efficiency, the surface area is even more important. We conclude that ozone decomposition catalysts are more effective in the two-stage combination compared to the single-stage.     

Non-thermal Plasma Activated Water for Increasing Germination and Plant Growth of Lactuca sativa L

Plasma Chemistry and Plasma Processing - Non-thermal plasma is widely considered as an effective technology for applications in agriculture. Particularly, numerous reports studies have highlighted...     

Removal of Hexanal by Non-thermal Plasma and MnOx/y-Al2O3 Combination

研究了在低温等离子体和催化剂共同作用下低浓度正己醛的降解反应.结果表明,等离子体与γ-Al2O3之间产生了很好的催化协同作用,在低放电功率(2.8W)和低温(80 ℃)下,干燥空气气氛中,γ-Al2O3对0.12％正己醛的去除率为87.1％;当γ-Al2O3负载7.5％MnOx后,正己醛去除率达到96.5％,其效果与Pt/γ-Al2O3相当.7.5％MnOx/γ-Al2O3在实验条件下连续使用50h,其催化活性未见下降.     

Inactivation of Bacteria in Oil Field Injection Water by Non-thermal Plasma Treatment

Microbial pollution commonly causes serious pipe corrosion in oil field injection water system. This paper reports on the application of non-thermal plasma to inactivate bacteria in oil filed injection water. As an efficient inactivation technology, pulsed streamer discharge plasma method injects energy into solution through a plasma channel formed by discharge between electrodes and produces various active species in solution with physical effects (electric field, UV etc.) occurring. Saprophytic bacteria, iron bacteria and sulfate reducing bacteria are used as target. The effects of various gases bubbling (oxygen, nitrogen and air) as well as aeration intensity are investigated. Experimental results show that the inactivation efficiency is greatly enhanced by gas bubbling. After 150 s discharge with oxygen bubbling (667 m³ (m³ h)^?1), the inactivation efficiencies of saprophytic bacteria, iron bacteria and sulfate reducing bacteria achieve 1.85, 4.51 and 5.70 log reduction, respectively. The possible mechanism of bacteria inactivation is also discussed.     

Recent Development of Technology in Scale-up of Plasma Reactors for Environmental and Energy Applications

To date, numerous studies have investigated the aftertreatment of exhaust gases from fossil-fueled combustors and combustion engines by plasmas as an environmental plasma application. Owing to the high power requirements of environmental plasma, it is difficult to use the plasma alone for aftertreatment; hence, a hybrid process that combines plasma processing with other techniques is required to reduce the overall power consumption. In developing countries, low-cost plasma hybrid processing has attracted considerable attention as an alternative to the selective catalytic reduction NO_x decomposition (De-NO_x) method and wet lime–gypsum SO_x decomposition method. Moreover, reduced catalytic activity can be enhanced by the plasma because of the decreased exhaust gas temperature, owing to the increased combustion efficiency. This paper reviews studies on successful air pollutant decomposition processes using the plasma chemical process with scale-up reactors. First, experimental techniques and block diagrams of various environmental plasma systems are presented. Subsequently, real-world systems of scale-up plasma reactors are described in detail. Several experimental results suggest that the hybrid treatment of particulate matter and dry De-NO_x is very promising from the viewpoint of energy consumption and material recycling. CO₂ treatment is a very important direction for future work in environmental plasma.

     

Plasma Treated Sepiolite: A New Adsorbent for Removal of Malachite Green from Contaminated Water

Surface modification of clay materials has become an important issue to improve the efficiency of the adsorbent. The adsorption capacity of the clay material can be increased by thermal or chemical modifications. In this study, plasma technology was applied for the surface modification of sepiolite to improve the removal of malachite green from contaminated water. This study is novel in preparing and examining the effectiveness of sepiolite in adsorption of malachite green from contaminated water. To achieve the aim, plasma application time, CO₂, N₂, or Ar plasma gases effect and pH were investigated with respect to the adsorption capacity of MG. The surface properties of raw and plasma treated sepiolite were investigated with SEM, FTIR, BET surface area and XRD measurements. The monolayer adsorption capacity was found to be 143 mg/g.     

Comparative Study of Methane Activation Process by Different Plasma Sources

In this paper, we compare the characteristics of methane activation by diverse plasma sources. The test conditions of reactant flow rate and composition are fixed for each plasma source to eliminate any possible misleading effects from varying test conditions. Among the diverse characteristics of each plasma source, we focus on the electron energy and degree of thermal activation in evaluating the cost-effectiveness of methane decomposition. The reaction is evaluated based on the selectivity of specific products, including H₂, C₂H₆, and C₂H₂. Among the tested plasma sources, those that provide a somewhat thermal environment have a rather high degree of warmness, resulting in higher methane conversion and lower operational costs. As the non-thermal characteristics of the plasma sources become stronger, the selectivity of C₂H₆ increases. This reflects C₂H₆ formation from the direct collision of CH₄ with high-energy electrons. On the other hand, as the degree of warmness increases, the selectivity of H₂ and C₂H₂ increase. The results give an insight into possible tools for process control or selectivity control by varying the degree of warmness in the plasma source. The process optimization and cost reduction of methane activation should be based on this concept of selectivity control.     

聚丙烯片基不同气氛下等离子体改性及DNA原位合成研究

分别采用氮气／氢气、氨气和氧气三种不同气氛的等离子体处理了聚丙烯片基,先使其表面接枝功能性基团,然后分别进行寡核苷酸原位合成．光电子能谱(XPS)证实了在其表面分别接枝了大量氨基和其它含氮基团．荧光扫描分析并比较了在三种方法处理的聚丙烯片基上合成的寡核苷酸与靶序列杂交后的荧光强度．结果表明：三种方法处理的聚丙烯片基都可用于DNA原位合成,但从处理工艺和荧光分析结果来看,以氮气／氢气等离子体处理的聚丙烯片基最佳。     

Development and Comparative Study of Different Immunoenzyme Techniques for Pesticides Detection

Abstract

Different ELISA techniques have been developed for the detemination of four widely used pesticides: 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), simazine and atrazine. Dependences between the assay scheme and the limiting detectable concentration of the pesticide were studied. The cases of preferential applying of the scheme with immobilized antibodies or one with immobilized pesticide-protein conjugate have been revealed. The following approaches resulting in lowering of ELISA sensitivity were proposed: preliminary incubation of the tested sample with antibodies, immobilization of antibodies via staphylococcal protein A, usage of monovalent fragments of antibodies instead of native ones and chemical modification of the pesticide molecules in the sample. Optimal combinations of these approaches permitted to lower the detection limit of the assays in about 5–30 times. The achieved sensitivities were 3 ng/mL for 2,4-D, 5 ng/mL for 2,4,5-T, 0.05 ng/mL for simazine, and 0.1 ng/mL for atrazine, being acceptable for purposes of ecological monitoring.     

Peculiarities of Energy Efficiency Comparison of Plasma Chemical Reactors for Water Purification from Organic Substances

Plasma Chemistry and Plasma Processing - This paper deals with the problem of parameters choice for energy efficiency comparison of plasma chemical reactors which are applied for water purification...     

Water Oxidation Catalysis by Synthetic Manganese Oxides with Different Structural Motifs: A Comparative Study

Manganese oxides are considered to be very promising materials for water oxidation catalysis (WOC), but the structural parameters influencing their catalytic activity have so far not been clearly identified. For this study, a dozen manganese oxides (MnO_x) with various solid‐state structures were synthesised and carefully characterised by various physical and chemical methods. WOC by the different MnO_x was then investigated with Ce⁴⁺ as chemical oxidant. Oxides with layered structures (birnessites) and those containing large tunnels (todorokites) clearly gave the best results with reaction rates exceeding 1250 ${{\rm{mmol}}_{{\rm{O}}_{\rm{2}} } }$ ${{\rm{mol}}_{{\rm{Mn}}}^{ - 1} }$ h^?1 or about 50 μmol_O2 m^?2 h^?1. In comparison, catalytic rates per mole of Mn of oxides characterised by well‐defined 3D networks were rather low (e.g., ca. 90 ${{\rm{mmol}}_{{\rm{O}}_{\rm{2}} } }$ ${{\rm{mol}}_{{\rm{Mn}}}^{ - 1} }$ h^?1 for bixbyite, Mn₂O₃), but impressive if normalised per unit surface area (>100 ${{\rm{{\rm \mu} mol}}_{{\rm{O}}_{\rm{2}} } }$ m^?2 h^?1 for marokite, CaMn₂O₄). Thus, two groups of MnO_x emerge from this screening as hot candidates for manganese‐based WOC materials: 1) amorphous oxides with tunnelled structures and the well‐established layered oxides; 2) crystalline Mn^III oxides. However, synthetic methods to increase surface areas must be developed for the latter to obtain good catalysis rates per mole of Mn or per unit catalyst mass.     

The Roles of Various Plasma Active Species in Toluene Degradation by Non-thermal Plasma and Plasma Catalysis

Plasma Chemistry and Plasma Processing - Investigating the roles of plasma active species in plasma chemical reaction process can improve understanding of the mechanism of volatile organic...     

Comparative Study of Flow Characteristics Inside Plasma Torch with Different Nozzle Configurations

A numerical analysis of the influence of different nozzle configurations on the plasma flow characteristics inside D.C plasma torches is presented to provide an advanced nozzle design basis for plasma spraying torches. The assumption of steady-state, axis-symmetric, local thermodynamic equilibrium, and optically thin plasma is adopted in a two-dimensional modeling of plasma flow inside the plasma torch. The PHOENICS software is used for solving the governing equations, i.e. the conservation equations of mass, momentum, and energy along with the equations describing the K-epsilon model of turbulence. The calculated arc voltages are consistent with the experimental results when arc current, gas inflow rate, and working gas are the same as the experimental parameters. Temperature, axial velocity contours inside plasma torches, profiles along the torch axis and profiles at the outlet section are presented to show the plasma flow characteristics. Comparisons are made among those torches. The results show that torches with different anode nozzle configurations produce different characteristics of plasma flows, which suggest some important ideas for the advanced nozzle design for plasma spraying. In order to validate the model and to show its level of predictivity, a comparison of the model with experimental results encountered in the literature is presented in the last part.     

Byproducts Generation Characteristics of Non-thermal Plasma for NO Conversion: Effect of Reaction Conditions

Plasma Chemistry and Plasma Processing - Over the years, the combined Non-thermal Plasma (NTP) denitrification process which is used for decomposition of NOx has have become an application...     

Lysozyme Adsorption onto Different Supports: A Comparative Study

The interaction between proteins and solid surfaces has been investigated. The aim of this work is to compare three different materials (hydroxyapatite, polystyrene with core-shell structure (PE-CS) and a functionalized styrene divinylbenzene copolymer) to be used as adsorbents for lysozyme, known as a “hard” protein. Tests were performed according to an experimental design in order to compare the effects of pH, lysozyme and phosphate buffer concentration onto the adsorbed amount of protein. A 2³ factorial design and a cross design, which was performed in triplicate, were used to distinguish the most important variables and to infer about the interaction between them. Hydroxyapatite showed the best performance—higher adsorbed amount of lysozyme and smaller dispersion (72.2 ± 0.9 mg/g). However, PE-CS can be regarded as a promising support as high amounts of lysozyme are adsorbed onto this material with relatively small dispersion.     

Sawdust for the Removal of Heavy Metals from Water: A Review

The threat of the accumulation of heavy metals in wastewater is increasing, due to their abilities to inflict damage to human health, especially in the past decade. The world’s environmental agencies are trying to issue several regulations that allow the management and control of random disposals of heavy metals. Scientific studies have heavily focused on finding suitable materials and techniques for the purification of wastewaters, but most solutions have been rejected due to cost-related issues. Several potential materials for this objective have been found and have been compared to determine the most suitable material for the purification process. Sawdust, among all the materials investigated, shows high potential and very promising results. Sawdust has been shown to have a good structure suitable for water purification processes. Parameters affecting the adsorption mechanism of heavy metals into sawdust have been studied and it has been shown that pH, contact time and several other parameters could play a major role in improving the adsorption process. The adsorption was found to follow the Langmuir or Freundlich isotherm and a pseudo second-order kinetic model, meaning that the type of adsorption was a chemisorption. Sawdust has major advantages to be considered and is one of the most promising materials to solve the wastewater problem.     

Operando DRIFT Spectroscopy Characterization of Intermediate Species on Catalysts Surface in VOC Removal from Air by Non-thermal Plasma Assisted Catalysis

An innovative plasma discharge reactor was developed to fit an infrared cell and to allow the in situ characterization of isopropanol (IPA) and toluene decomposition at the surface of three metal oxides (γ-Al₂O₃, TiO₂ and CeO₂). The impact of the plasma discharge on the conversion of these pollutants, with the material placed in the discharge area, was studied under real time conditions at atmospheric pressure via infrared analysis. The plasma treatment of IPA molecules led to the formation of acetone, propene, acetic acid and/or formic acid. By contrast, the toluene oxidation led to the rapid opening of the aromatic ring, followed by the total oxidation through carboxylic formation of the species arising from the toluene molecules fragmentation.