Syngas Production from Propane Using Atmospheric Non-thermal Plasma

Propane steam reforming using a sliding discharge reactor was investigated under atmospheric pressure and low temperature (420 K). Non-thermal plasma steam reforming proceeded efficiently and hydrogen was formed as a main product (H₂ concentration up to 50%). By-products (C₂-hydrocarbons, methane, carbon dioxide) were measured with concentrations lower than 6%. The mean electrical power injected in the discharge is less than 2 kW. The process efficiency is described in terms of propane conversion rate, steam reforming and cracking selectivity, as well as by-products production. Chemical processes modelling based on classical thermodynamic equilibrium reactor is also proposed. Calculated data fit quiet well experimental results and indicate that the improvement of C₃H₈ conversion and then H₂ production can be achieved by increasing the gas fraction through the discharge. By improving the reactor design, the non-thermal plasma has a potential for being an effective way for supplying hydrogen or synthesis gas.     

Atmospheric Pressure Ammonia Synthesis Using Non-thermal Plasma Assisted Catalysis

This paper described a novel and green approach on catalytic ammonia synthesis using non-thermal plasma (NTP). The process studied in this paper involves the synthesis and absorption of ammonia under atmospheric pressure and low temperature. The effects of operational parameters including applied voltage, frequency, gas component and flow rate on ammonia synthesis under NTP conditions are studied in this paper. In addition, different selected catalysts and absorbents were investigated under different conditions of NTP treatment and the ammonia efficiency was reported and analyzed. Ru catalyst with carbon nanotube support, along with Cs promoter and micro porous absorbents including Molecular Sieve 13X and Amberlyst 15 yield the highest ammonia efficiency in this process. Results further indicated that frequency and applied voltage of 10,000 Hz and 6000 V, with N₂:H₂ feed ratio of 3:1 provided the optimized efficiency of ammonia synthesis of 2.3 gNH₃/kWh.     

Graphitization of Carbon Particles in a Non-thermal Plasma Reactor

The production of nanomaterials using non-thermal plasmas remains the focus of ongoing investigations due to advantageous properties of this class of processes, most notably the intense plasma-induced heating arising from energetic recombination events occurring at the surface of nanoparticles, which allows for the tailored synthesis of crystalline nanoparticles. In this work, the authors discuss an in situ, in-flight Fourier Transform Infrared absorption spectroscopy technique to investigate the temperature variation of carbon nanoparticles during their synthesis in an acetylene–argon–hydrogen non-thermal RF plasma. Based on the FTIR measurements, decreasing hydrogenation levels and the progressive onset of an incandescence signal were observed at increasing RF input power. In the high RF power region, the carbon particle temperature, derived by fitting the corresponding FTIR spectra with a modified Planck’s law, shows values above 2000 K. The corresponding ex situ characterization of the synthesized materials by Transmission Electron Microscopy and Raman Spectroscopy displays the production of highly graphitic particles and loss of bonded hydrogen from the material, hence supporting the substantial nanoparticle heating derived from the FTIR measurements.     

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.     

Measurement of Ozone Production in Non-thermal Plasma Actuator Using Surface Dielectric Barrier Discharge

Plasma actuators for flow control are intensively studied, but the production of ozone by the surface dielectric barrier discharge used in the actuators has never been quantified. Since ozone is harmful to human health, it is important to quantify its production for an application of this type of actuator on a land vehicle. This paper describes an experimental study to measure the concentration of ozone produced by an actuator with different parameters: amplitude and frequency of the applied high voltage, and the electrode configuration (shape, spacing and length). The results show that, under our experimental conditions, the production of ozone is directly proportional to the power dissipation. The production rate was measured at 21 g/kWh. Although the rate is much lower than that of an industrial ozonizer, it is still far from being negligible and should be taken into account for the future application of these actuators.     

Effect of Plasma Deposition Using Low-Power/Non-thermal Atmospheric Pressure Plasma on Promoting Adhesion of Composite Resin to Enamel

This study investigated the effect of monomer deposition through a low-power, non-thermal atmospheric pressure plasma (NT-APP) on adhesion of resin composite to enamel and its durability. The adhesion of resin composite to enamel and its durability were compared using micro-shear bond strength (MSBS) tests, with or without monomer deposition and before or after thermocycling (TC). The bond strength data were interpreted using Weibull analysis. Hydrophilicities of treated ceramic surfaces were compared with contact angle measurements. Surface characterization was performed with a Fourier transform infra-red spectrophotometer and X-ray photoelectron spectroscopy. The fracture mode at the interface was evaluated using a stereomicroscope and a scanning electron microscope. The plasma polymer deposition of benzene and 1,3-butadiene using the low-power NT-APP improved the MSBS of resin composite to enamel (p < 0.05). Surface characterization suggested improved wettability and changes in the chemical composition of the plasma-deposited enamel surface. However, the mean values of the MSBS of the plasma polymer-deposited groups decreased after TC (p < 0.05). After TC, the Weibull modulus (m) values increased in all the groups, especially in the plasma polymer-deposited groups. Plasma polymer deposition improved enamel adhesion but failed to improve durability in terms of mean bond strength. However, the plasma polymer deposition increased the Weibull modulus m after TC, which indicated that the scatter of the bond strength was narrowed with respect to durability.     

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。     

Investigation of Non-thermal Plasma Assisted Combustion of Solid Biomass Fuels: Effects on Flue Gas Composition and Efficiency

Plasma Chemistry and Plasma Processing - Interest in biomass is increasing due to the environmental benefits compared to fossil fuels. This study investigates a non-thermal plasma (NTP) device that...     

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.     

电晕放电式低温等离子体电极结构优化

以恶臭气体氨气和硫化氢的降解率为考察指标,系统优化了电晕放电式低温等离子体设备电极间距、电极齿距、电极齿高三个参数。研究表明:氨气和硫化氢的降解首先随着电极间距和齿距的增加而增大,而后随着电极间距的进一步增大而逐渐降低,电极间距13 mm、电极齿距5 mm时具有最大的氨气和硫化氢降解率。当电极齿高7 mm时,氨气和硫化氢的降解率随电极齿高的增加而快速增大,当电极齿高7 mm时,其降解率随着电极齿高的进一步增大而缓慢增大,考虑到电极制作成本,故确定最佳电极齿高为7 mm。此外研究还表明,不同外施功率下,锯齿型(多齿型)的氨气降解率显著高于单一针尖型(单齿型)。     

Non-thermal Plasma as a Priming Tool to Improve the Yield of Pea in Outdoor Conditions

Seed priming is a pre-treatment of seeds leading to the improvement of their germination, the plant growth, and the product yield. In this study we investigated the possibility of the use of non-thermal plasma operating in atmospheric pressure air for seed priming with the objective to improve the yield of pea seeds. Two priming ways were used: an indirect way by using plasma activated water (PAW) generated by the transient spark discharge with water electrospray or the glow discharge batch treatment and a direct exposure of seeds to the pulsed corona discharge. After treatment, the seeds were planted in the outdoor field for about 14 weeks until harvest. The direct plasma treatment resulted in two key results: the strong effectiveness of the pulsed corona plasma improving the yield, and the long-term effect of the plasma seed treatment. The results of the indirect treatment showed that the pea plants from the seeds primed using PAW gained some improved growth parameters, especially the number of seeds per pod and the total number of seeds per plant. The scanning electron microscopy analysis showed that PAW and direct treatment induced some morphology changes at the surface of the pea seeds. This study documents a long-term effect of non-thermal plasma seed priming and contributes to the plasma agriculture applications by suggesting the implementation of non-thermal plasma direct or indirect treatments into the field.

     

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...     

N2/H2 Non-thermal Transferred arc Plasma Nitriding Treatment of Stainless Steel at Atmospheric Pressure

Plasma Chemistry and Plasma Processing - In the paper, a novel metal surface nitriding method is presented by using an atmospheric pressure non-thermal transferred arc plasma technique. In the...     

Stimulation of the Germination and Early Growth of Tomato Seeds by Non-thermal Plasma

The influence of non-thermal plasma on tomato seeds has been investigated using a fluidized bed dielectric barrier discharge generated in air. It was found that plasma-treated seeds germinate faster than untreated ones. Plasma slightly enhanced germination rate and considerably influenced growth parameters. Seedling length and weight are significantly higher than those of untreated seeds. The influence of plasma exposure is more visible on the plant roots, which are substantially longer and more branched. An increase in weight of 20–40% was observed for the plants grown from treated seeds as compared to the control ones. The best results are obtained for relatively short plasma exposure, while too long treatment appears to be detrimental to the seeds.     

Influence of Atmospheric Pressure Non-thermal Plasma on Inactivation of Biofilm Cells

The objective of this study is to investigate the bactericidal efficiency of atmospheric pressure non-thermal (cold) dielectric barrier discharge plasma on biofilms of Staphylococcus aureus and Escherichia coli. In general, cold plasma is a mixture of electrons, ions, neutral atoms and molecules. The different particles in cold plasmas exhibit different energies, i.e. electrons are much more energetic than other particles. This feature of cold plasmas allows to produce chemically reactive species at near room temperature that can be used in biological applications. Bacteria inactivation was performed using the air direct plasma (with reactive species, UV light, excited species and electric fields). Discharge power density during the experiment was equal to 70 mW/cm² and plasma dose was regulated by the treatment time. Bacterial biofilms were treated with the non-thermal plasma for 10–300 s. The most effective reduction in the number of S. aureus cells was found after 300 s of treatment and was 2.77 log₁₀ that is 99.83%. When the biofilm of E. coli was used in the experiment, killing of bacteria was independent of the exposure time and the mortality of cells did not exceed 0.48 that is 66.7% kill. The lethal effect on E. coli and S. aureus cells were observed after 300 and 120 s of plasma treatment, respectively but it was necessary to remove the layers of dead cells. The proposed process of removing dead cell layers was carried out due to the probable shielding effect, i.e. dead cells prevent further penetration of active plasma species into the deeper layers of the biofilm. It was shown that the effectiveness of cell destruction by the non-thermal plasma depends on the thickness of biofilm.     

Experimental Study on Purification of Diesel Particulate Matter by Non-thermal Plasma Technology

In order to investigate the effects of non-thermal plasma (NTP) on diesel particulate matter (PM), an engine test bench was built up. An engine exhaust particle sizer (EEPS) was introduced to analyze the emission concentration and size distribution of PM and a thermo-gravimetric analyzer was used to analyze the effects of NTP on the composition of the particulate matter in the exhaust gas. The results show that the size distribution interval of the particle mass concentration falls behind that of the quantity concentration under various loads. When the diesel engine operating speed is 2400 rpm and the load is 25%, after NTP, the proportions of the nucleation mode particles and the accumulative mode particles exhibit a small fluctuation while the proportion of ultrafine particles decreases by 10% due to their large quantity concentration. Under the dual effect of DPF and NTP, the particle quantity concentration decreases by 98%. In order to investigate the effect of NTP on the composition of the PM, a thermo-gravimetric analysis of the particles obtained before and after NTP was carried out. The results show that the proportion of volatile matter falls by 16.05% and solid carbon accounts for an increase of 7.29%. NTP has the ability to improve reduction activity of particles and make particles easier to be oxidized at a lower temperature.     

The Treatment of Water-Based Toxic Waste Using Induction Plasma Technology

A study of the treatment of liquid wastes in a radio frequency (rf) induction plasma reactor is reported. Ethylene glycol was used as a surrogate for the waste because of safety considerations. Thermodynamic analyses demonstrated complete and safe decomposition at the conditions studied. The solution was injected axially into the center of an argon–oxygen plasma operated at a plate power of 50 kW to study blast atomization and operating conditions. A factorial analysis revealed, at a confidence level of 0.99, that both reduction of pressure and liquid flow rate increase the destruction and removal efficiency (DRE) and that a higher plate power increased DRE. The study also revealed that poor atomization was responsible for the reduction of the DRE by 10–15% (to 80–85%) and that 94% of the exothermic energy of the reaction was available for further use. The specific energy requirement (SER) of the process was estimated at 8.33 kWh/kg of solute. This value can be expected to drop significantly with scale-up of the process.     

低温等离子体处理对NiO/A12O3吸附NOx的促进作用

采用共沉淀法制备了不同NiO负载量的NiO/A12O3催化剂,并用于NOx储存还原技术去除NOx反应中.结果表明,当Ni/Al摩尔比为0.3时,NiO/A12O3样品的NOx吸附量最大;随着Ni含量的增加,NiAl2O4晶相减少.沉淀物在高温煅烧前利用低温等离子体处理后,所得催化剂吸附NOx的能力明显增强,当Ni/Al...     

Mechanisms of Xylene Isomer Oxidation by Non-thermal Plasma via Paired Experiments and Simulations

Xylene is a widely used solvent and industrial chemical, but it is also considered to be a volatile organic compound (VOC) pollutant. Meanwhile, non-thermal plasma (NTP) is a potential method for remediating VOC contaminants, especially aromatic hydrocarbons. During NTP degradation of xylene, the different oxidation mechanisms of three isomers, p-xylene, o-xylene and m-xylene, have attracted lots of attention but not been studied at the molecular level. In this study, the individual degradation rates of xylene isomers in a NTP system are measured. The results show the oxidation degradation rates have the following order: o-xylene?>?p-xylene?≈?m-xylene. Molecular dynamics simulations with an applied external electric field were adopted to examine the oxidation process of xylene isomers, as well. The oxidation rates from the simulations were calculated, the order of which is in a good agreement with the experimental results. The oxidation pathways of xylene isomers were analyzed more thoroughly to explain the rate differences. The external electrical field is found to have two effects: one is to speed up the oxidation rate of xylene isomers overall, and the other is to alter the oxidation pathways to increase the probability of the faster ring cleavage pathways of o-xylene.

     

Fluorimetric Analysis of Aluminum in Diluted Hemodialysis Solutions by Using a Novel Schiff Base

A spectrofluorimetric method has been developed for trace amount of aluminum(III) by using a novel Schiff base, N,N′-bis(salicylidene)-1,4-diaminobuthane (BUTAS), and 4-methyl-2-aminophenol (OAP). Since the aluminum complexes are generally fluorescent, aluminum(III) increases the fluorescence intensity of BUTAS-OAP by formation of Al-BUTAS-OAP complex. The fluorescence of the complex is measured at an excitation wavelength of 410 nm with an emission at 526 nm. Aluminum(III) can be detected within a concentration limit of 0.11–1.62 ppb and the lowest detection limit being 0.07 ppb. The proposed method was applied to diluted hemodialysis solution and spectrofluorimetric data was compared with data of standard pharmacopoeia method.