This paper investigates the degradation of chlorobenzene by dielectric barrier discharge (DBD) coupled with MnOx/γ-Al2O3 catalysts. MnOx/γ-Al2O3 catalysts were prepared using the impregnation method and were characterized in detail by N2 adsorption/desorption, x-ray diffraction and x-ray photoelectron spectroscopy. Compared with the single DBD reactor, the coupled reactor has a better performance on the removal rate of chlorobenzene, the selectivity of COx, and the inhibition of ozone production, especially at low discharge voltages. The degradation rate of chlorobenzene and selectivity of COx can reach 96.3% and 53.0%, respectively, at the specific energy density of 1350 J l–1. Moreover, the ozone concentration produced by the discharge is significantly reduced because the MnOx/Al2O3 catalysts contribute to the decomposition of ozone to form oxygen atoms for the oxidation of chlorobenzene. In addition, based on analysis of the byproducts, the decomposition mechanism of chlorobenzene in the coupled reactor is also discussed.

A new combined reactor with Hg/Ar electrodeless ultraviolet (EDUV) activated by DBD for 3,4-dichlorodiphenyl ether abatement is presented.The effect of specific input energy and feeding gas component on 3,4-dichlorodiphenyl ether removal efficiency has been explored.Compared with a single DBD system,this new combined process performed a significant promotion on 3,4-dichlorodiphenyl ether abatement.Experiment results verified that active oxygen clearly contributed to the synergistic activity of DBD-EDUV system.Results of emission spectra showed that UV radiation of 253.7 nm could be detected in the DBD-EDUV system.Further,the products of DBD-EDUV process were analyzed via gas chromatographymass spectrometer (GC-MS) to reveal involved decomposition mechanism.

An in situ electron-induced deNOx process with CNT activated by DBD was achieved. • Carbon atoms on CNT surface were verified to be excited by plasma in DBD-CNT system. • Reactions between NOx and excited C result in synergistic effect of DBD-CNT system. In this study, a new in situ electron-induced process is presented with carbon nanotubes (CNTs) as a reduction agent activated by dielectric barrier discharge (DBD) for nitrogen oxide (NOx) abatement at low temperature (<407 K). Compared with a single DBD system and a DBD system with activated carbon (DBD-AC), a DBD system with carbon nanotubes (DBD-CNT) showed a significant promotion of NOx removal efficiency and N2 selectivity. Although the O2 content was 10%, the NOx conversion and N2 selectivity in the DBD-CNT system still reached 64.9% and 81.9% at a specific input energy (SIE) of 1424 J/L, and these values decreased to 16.8%, 31.9% and 43.2%, 62.3% in the single DBD system and the DBD-AC system, respectively. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were utilized to investigate surface changes in the CNTs after activation by DBD to explore the NOx reduction abatement mechanism of this new process. Furthermore, the outlet gas components were also observed via Fourier transform infrared spectroscopy (FTIR) to help reveal the NOx reduction mechanism. Experimental results verified that carbon atoms excited by DBD and the structure of CNTs contributed to the synergistic activity of the DBD-CNT system. The new deNOx process was accomplished through in situ heterogenetic reduction reactions between the NOx and carbon atoms activated by the plasma on the CNTs. In addition, further results indicated that the new deNOx process exhibited acceptable SO2 tolerance and water resistance.

The effects of using CH4 as an assistant reduction agent in plasma-assisted NH3–SCR were investigated. The new hybrid reaction system performed better than DBD–NH3–SCR when the O2 concentration varied from 2% to 12%. Compared with DBD–NH3–SCR, DBD–NH3–CH4–SCR (NH3:CH4 = 1:1) showed a more significant promotion effect on the performance and N2 selectivity for NOX abatement. When the O2 concentration was 6% and the SIE was 512 J/L, the NO removal efficiency of the new hybrid system reached 84.5%. The outlet gas components were observed via FTIR to reveal the decomposition process and its mechanism. This work indicated that CH4, as an assistant agent, enhances DBD–NH3–SCR in excess oxygen to achieve a new process with significantly higher activity at a low temperature (≤348 K) for NOX removal.

Electrode structure and electron energy effects on NO abatement were studied in two different structure DBD reactors. Final product analysis of NO abatement in coaxial cylinder dielectric barrier discharge (CC-DBD) and tubular multilayer dielectric barrier discharge (TM-DBD) reactors indicated that the electrode structure of TM-DBD was better under low O2 concentration conditions, but the result was opposite because the new NOx was produced in TM-DBD when O2 concentration was increasing. In addition, results of particle-in-cell with Monte Carlo collisions (PIC-MCC) simulation manifested that the largest and the average electron energy were 12.09 eV and 3.35 eV in TM-DBD reactor, respectively, while they were 5.25 eV and 2.96 eV in CC-DBD reactor, respectively. CC-DBD electrode structures are preferable for better NO abatement and no new NOx under oxygen-containing condition.

The photolytic and photocatalytic degradation rates of Rhodamine B (RhB) in wastewater were investigated and compared through irradiation with UV light of three wavelengths (207 nm, 222 nm, and 254 nm). UV light of all three wavelengths exhibited good RhB degradation capability under both acidic and alkaline conditions. When UV light energy is about 690 J, the RhB degradation rate is the highest (78.93%) under UV 222 nm, followed by that under UV 207 nm (70.44%) and UV 254 nm (25.17%). At each wavelength, the reaction kinetics of RhB was investigated with and without the addition of H2O2. The degradation rate of RhB was found to increase at the presence of H2O2. Photolysis mechanisms under the three UV light wavelengths were proposed based on the electrospray ionization mass spectra results, which indicated that RhB underwent different degradation pathways at different UV wavelengths. This study could help enhance understanding of the capability of the UV light of 207, 222, and 254 nm to degrade water pollutants.

This study aimed to discuss the removal of hydrogen sulfide (H2S) with non-thermal plasma produced by a multilayer tubular dielectric barrier discharge reactor, which is useful in the field of plasma environmental applications. We explored the influence of various factors upon H2S removal efficiency (eta(H2)s) and energy yield (Ey), such as specific energy density (SED), initial concentration, gas flow velocity and the reactor configuration. The study showed that we can achieve eta(H2)s of 91% and the best Ey of 3100 mg kWh(-1) when we set the SED, gas flow velocity, initial H2S concentration and layers of quartz tubes at 33.2 Jl(-1), 8.0 ms(-1), 30mg m(-3) and five layers, correspondingly. The average rate constant for the decomposition of hydrogen sulfide was 0.206 g m(-3) s(-1). In addition, we also presented the optimized working conditions, byproduct analysis and decomposition mechanism.

This paper discusses the conversion of nitric oxide (NO) with a low-temperature plasma induced by a catalytic packed-bed dielectric barrier discharge (DBD) reactor. Alumina oxide (Al2O3), glass (SiO2) and zirconium oxide (ZrO2), three different spherical packed materials of the same size, were each present in the DBD reactor. The NO conversion under varying input voltage and specific energy density, and the effects of catalysts (titanium dioxide (TiO2) and manganese oxide (MnOx) coated on Al2O3) on NO conversion were investigated. The experimental results showed that NO conversion was greatly enhanced in the presence of packed materials in the reactor, and the catalytic packed bed of MnOx/Al2O3 showed better performance than that of TiO2/Al2O3. The surface and crystal structures of the materials and catalysts were characterized through scanning electron microscopy analysis. The final products were clearly observed by a Fourier transform infrared spectrometer and provided a better understanding of NO conversion.

This paper discusses the removal of nitric oxide (NO) with low-temperature selective catalytic reduction driven by a dielectric barrier discharge with ammonia (NH3) as a reductant. We explored the effects of NH3, O2, temperature and water under different applied voltage on NO removal at atmospheric pressure. The results showed that when the gas concentration ration of NH3/NO was 0.23–0.67, the NO removal efficiency and the energy consumption was acceptable. The NO removal efficiency reached 84% under an applied voltage of 7 kV, 400 ppm NO and 90 ppm NH3 at a temperature of 150 °C. Water vapor had a negative effect because NO formation reactions were strengthened and NH3 was oxidized directly rather than reduced NO molecules. The outlet gas components were observed via Fourier transform infrared spectroscopy for revealing the decomposition process and mechanism.

The experiment was carried out in a cylindrical dielectric barrier discharge（DBD）reactor assisted with a catalyst to decompose toluene under different humidity.In order to explore the synergistic effect on removing toluene in the catalysis-DBD reactor,this paper investigated the decomposition efficiency and the energy consumption in the catalysis-DBD and the non-catalyst DBD reactors under different humidity.The results showed that the catalysis-DBD reactor had a better performance than the non-catalysis one at the humidity ratio of 0.4%,and the removal efficiency of toluene could reach 88.6% in the catalysis-DBD reactor,while it was only 59.9% in the non-catalytic reactor.However,there was no significant difference in the removal efficiency of toluene between the two reactors when the humidities were 1.2% and 2.4%.Additionally,the degradation products were also analyzed in order to gain a better understanding of the mechanism of decomposing toluene in a catalysis-DBD reactor.

For their distinguished global warming potential (GWP100) and long atmosphere lifespan, CF4, SF6 and SF5CF3 were significant in the field of greenhouse gas research. The details of discharging character and the optimal parameter were discussed by using a Dielectric Barrier Discharge (DBD) reactor to decompose these potent greenhouse gases in this work. The results showed that SF6 could be decomposed by 92% under the conditions of 5 min resident time and 3000 V applied voltage with the partial pressure of 2.0 kPa, 28.2 kPa, and 1.8 kPa for SF6, air and water vapor, respectively. 0.4 kPa CF4 could be decomposed by 98.2% for 4 min resident time with 30 kPa Ar added. The decomposition of SF5CF3 was much more effective than that of SF6 and CF4 and moreover, 1.3 kPa SF5CF3, discharged with 30 kPa O-2, Ar and air, could not be detected when the resident time was 80 s, 40 s, and 120 s, respectively. All the results indicated that DBD was a feasible technique for the abatement of potent greenhouse gases.

Bromate（BrO3） is a disinfection by-product in drinking water, and its removal is very difficult especially at low levels.60 Co gamma rays were used to remove BrO3in aqueous solution in this study. The effects of absorbed doses, BrO3initial concentration, gas saturation, p H value and coexisting anions(Cl, NO 3, SO2 4and HCO 3=CO32 -)on BrO3reduction were evaluated. After 4.0-k Gy irradiation of air-equilibrated solution of 30.7 lg/L BrO3, the residual BrO3was 8.3 lg/L, which is below the maximum contaminant level of drinking water. The BrO3reduction rate increased with the dose, in the order of N2[ air [ O2[ N2O atmosphere under similar conditions. The results also show that high p H favored the BrO3removal. According to the experimental results, it can be concluded that the efficiency of decomposing BrO3by reactive species followed the order of e aq[ H [ HO2 [ O2. Coexisting Cl, HCO 3=CO32 -and SO2 4ions have little effect on BrO3removal, whereas NO3can inhibit its removal as a result of competition with BrO3for e aq.

The destruction of gaseous toluene was carried out in a tubular multilayer dielectric barrier discharge reactor which can yield a steady state of low-temperature plasma with an array structure. The research was investigated under different relative humidities, input voltages, energy densities, energy consumption and the reactor processing capacities. The results showed that the highest removal efficiency and processing capacity () were acquired using an additional dielectric with the width of 2mm between adjacent discharge quartz tubes, and the removal efficiency of toluene reached 86.5% and increased to 6272kg/sm(3) at a voltage of 6kV. The gas-phase by-products (O-3, NOx, COx and intermediate organics) were also presented and the reaction mechanism was described according to the decomposition reaction tunnels.

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(η styrene ) and energy yield（EY）.Values of η styrene 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.

BACKGROUND With the rapid growth of the semiconductor and thin film transistor liquid crystal display manufacturing industries, large quantities of the potent greenhouse gas nitrogen trifluoride ( NF 3 ) is in demand. But perfluorocarbons are very stable compounds because of their molecular structures. Therefore, in the atmosphere, NF 3 is difficult to oxidize by O 3 , NO , NO 2 , and OH radicals, except by excited oxygen atoms O( 1 D ) that can react with it to form NF 2 or other products. In this study the possible degradation process of NF 3 in the ‘controlled release of radicals’ reactor is discussed. RESULTS Under the conditions of 5 mmHg partial pressure of NF 3 and 600 mmHg total pressure with buffer gas of argon, NF 3 was photodegraded in an in situ reactor with a ‘controlled release of radicals’ system. The results indicated that reductive double bonds and allyl radicals, slowly released from polyisoprene irradiated by a UV lamp emitting 185 and 253.7 nm of light, could contribute to the NF 3 degradation in the CRR system. The NF 3 degradation efficiency, significantly affected by O 2 and almost independent of N 2 , reached 96% with a kinetic rate constant k ≈ 1.77 × 10 −4 s −1 after 300 min of ultraviolet irradiation. CONCLUSION According to the experimental results, a potential way of continuous photoreduction of NF 3 was found , since excited double bonds and allyl radicals are consequently released by irradiating the surface of the polymer matrix. The considerable degradation reaction constant of NF 3 and no fluoride byproducts in gas make it possible for industry application. © 2013 Society of Chemical Industry

This study presents interior microwave discharge electrodeless iodine lamps (IMDEL-I2) that assist the photodegradation of CS2 at room temperature and atmospheric pressure. The investigation examined the photolysis efficiency of CS2, the absolute removal amount (ARA), and the energy yield (EY) under different gas residence times and input powers and also included an analysis of the photodegradation products of CS2. The experimental results indicated that the IMDEL-I2 was capable of emitting ultraviolet (UV) radiation in bands of 206.2, 250-350, and 385-400nm, and vacuum ultraviolet (VUV) light at 178.3, 180.1, 183, 184.4, and 187.6nm. The photodegradation rate of CS2 in the IMDEL-I2 system was 93.4%, with ARA of 18.1mg/s and EY of 82.5mg/kWh at the gas retention time of 1.98s, an input power of 796W, and an initial concentration of 85.6mg/m3. The final photolysis products of CS2 were identified to be SO2, CO2, CO, and COS in the gaseous phase, and (CS)n, SO42-, and sulfur in the solid phase.

Photo-induced transformation in the presence of N(III) is an important pathway for pollutants conversion in atmospheric condensed phase. In this study, the photochemical reaction between 2-chlorobiphenyl and N(III) was investigated in acidic environment by using co-linear laser flash photolysis technique. The photo-induced conversion of 2-PCB is initiated from its rapid oxidation by center dot OH, a primary product from the photolysis of N(III). The second-order rate constant for the reaction between 2-PCB and center dot OH was determined to be (8.9 +/- 1.2) x 10(9) M-1 s(-1). HONO and NO2- were found to be more important than H2ONO+ with respect to the photochemical transformation of pollutants in atmospheric hydrometeors. The complicated photochemical conversion pathways and their significance in the atmosphere were discussed as well in this paper. (C) 2013 Elsevier B.V. All rights reserved.

A novel β-PbO2 anode was prepared by high-pressure tablet forming method.The results showed that this electrode had excellent corrosion resistance.To study the electro-catalytic activity of obtained β-PbO2 anode,the influence of various factors,such as reaction time,load voltage,initial alizarin red concentration,initial pH and inter-electrode distance on the electrolysis efficiency of alizarin red was studied.Compared to graphite anode,the β-PbO2 anode had obvious superiority in both color removal and COD removal rate.A reaction mechanism was proposed based on the molecular structure of alizarin red and GC-MS analysis results.

In this paper, a novel combined non-thermal plasma photolysis reactor was employed to decompose H2S in gas stream at atmospheric pressure. The filling gas pressure, applied voltage, and inlet H2S concentration were altered with the aim to improve the energy efficiency. High H2S removal efficiency could be achieved with sufficient but reasonable energy density deposited on gas stream. The energy consumption per molecule of destructed H2S, 26±1.5eV/molecule, was relatively low as compared with those values reported for plasma reactor operated at non-vacuum pressures and diluted condition. Furthermore, the H2S decomposition mechanism was proposed as direct electron attachment, radicals and excited species attack and photo-dissociation based on byproducts analysis by GC and IC. The results revealed the potential for energy efficient destruction of H2S by combined plasma photolysis process.

This study reports, the photolysis of dimethyl phthalate using 206.2 nm UV light emitted from a locally made novel microwave discharge electrodeless iodine lamp (MDEIL). Optimal preparation parameters of MDEIL were determined as follows: iodine amount, 0.5 mg; krypton pressure, 2 torr and input power, 65 W. Removal efficiency of dimethyl phthalate reached 97.5 % at 20 min irradiation time and 20 mg L-1 initial dimethyl phthalate concentration. A possible mechanism of the dimethyl phthalate photolysis may involve electron transition reactions and reactions with hydroxyl radicals. The intermediates were identified as phthalic acid and 2-hydroxyl acid methyl esters. Results from this study may help promote further studies on the feasibility of MDEIL to decompose more aqueous organic contaminants, including other refractory contaminants.