Comparative Study between Single- and Double-Dielectric Barrier Discharge Reactor for Nitric Oxide Removal

Degradation of trichloroethylene by double dielectric barrier discharge (DDBD) plasma technology: Performance, product analysis and acute biotoxicity assessment

Trichloroethylene is carcinogenic and poorly degraded by microorganisms in the environment. Advanced Oxidation Technology is considered to be an effective treatment technology for TCE degradation. In this study, a double dielectric barrier discharge (DDBD) reactor was established to decompose TCE. The influence of different condition parameters on DDBD treatment of TCE was investigated to determine the appropriate working conditions. The chemical composition and biotoxicity of TCE degradation products were also investigated. Results showed that when SIE was 300 J L^-1, the removal efficiency could reach more than 90%. The energy yield could reach 72.99 g kWh^-1 at low SIE and gradually decreased with the increase of SIE. The k of the Non-thermal plasma (NTP) treatment of TCE was about 0.01 L J^-1. DDBD degradation products were mainly polychlorinated organic compounds and produced more than 373 mg m^-3 ozone. Moreover, a plausible TCE degradation mechanism in the DDBD reactors was proposed. Lastly, the ecological safety and biotoxicity were evaluated, indicating that the generation of chlorinated organic products was the main cause of elevated acute biotoxicity.

High energy efficient degradation of toluene using a novel double dielectric barrier discharge reactor

A double dielectric barrier discharge (DDBD) reactor was established to decompose toluene with high energy efficiency. Differences in discharge characteristics including visual images, voltage-current waveforms, Lissajous figures, and temperature variation, were determined between the DDBD and SDBD reactors. Removal efficiency, mineralization rate, CO₂ selectivity, and energy yield were used to evaluate the toluene abatement performance of the two reactors. Compared to the SDBD reactor, the DDBD reactor exhibited more uniform and stable discharges due to a change in discharge mode. In addition, the DDBD reactor's dissipated power and reactor temperature (including the gas, barrier and ground electrode) were significantly lower than those in the SDBD reactor. At 22-24 kV, the DDBD reactor showed a higher toluene removal efficiency and mineralization rate, while at 14-16 kV, the SDBD reactor exhibited higher respective value. The energy efficiency of the DDBD was 2.5-3 times that of the SDBD reactor, and the overall energy constant k_overall of the DDBD reactor (1.47 mL/J) was significantly higher than that of the SDBD reactor (0.367 mL/J) as revealed by the kinetics study. Lastly, a plausible toluene degradation mechanism in the DDBD and SDBD reactors was proposed based on organic intermediates that formed during toluene decomposition.

Abatement of Toluene by Reverse-Flow Nonthermal Plasma Reactor Coupled with Catalyst

In order to make full use of the heat in nonthermal plasma systems and decrease the generation of by-products, a reverse-flow nonthermal plasma reactor coupled with catalyst was used for the abatement of toluene. In this study, the toluene degradation performance of different reactors was compared under the same conditions. The mechanism of toluene abatement by nonthermal plasma coupled with catalyst was explored, combined with the generation of ozone (O3), NO2, and organic by-products during the reaction process. It was found that a long reverse cycle time of the reactor and a short residence time of toluene decreased the internal reactor temperature, which was not beneficial for the degradation of toluene. Compared with the dielectric barrier discharge (DBD) reactor, toluene degradation efficiency in the double dielectric barrier discharge (DDBD) reactor was improved at the same discharge energy level, but the concentrations of NO2 and O3 in the effluent were relatively high; this was improved after the introduction of a catalyst. In the reverse-flow nonthermal plasma reactor coupled with catalyst, the CO2 selectivity was the highest, while the selectivity and amount of NO2 was the lowest and aromatics, acids, and ketones were the main gaseous organic by-products in the effluent. The reverse-flow DBD-catalyst reactor was successful in decreasing organic by-products, while the types of organic by-products in the DDBD reactor were much more than those in the DBD reactor.

Niobium doping enhanced catalytic performance of Mn/MCM-41 for toluene degradation in the NTP-catalysis system

The destruction of toluene in a dielectric barrier discharge (DBD) reactor with Nb-Mn/MCM-41 had been investigated and compared with X (X = Cu, Ce, Co)-Mn/MCM-41 catalysts. The XRD and TEM result confirms that the metal species were highly dispersed on the MCM-41. The results of XPS, O₂-TPD and H₂-TPR clearly demonstrate that Nb doping facilitated formation of lattice oxygen (O_latt) and the acid sites, which are all beneficial to catalytic degradation of toluene. Compared to X (Cu, Ce, Co)-Mn/MCM-41, Nb-Mn/MCM-41 had the most contents of O_latt, the most amounts of acid sites and the strongest acidity. Consequently, the catalytic performance tests identify that Nb-Mn/MCM-41 had the best catalytic performance, the highest removal efficiency and CO₂ selectivity as well as carbon balance especially at low SIE. These results indicate that Nb was an important promoter improving the activity and CO₂ selectivity of Mn/MCM-41 for the decomposition of toluene in NTP-catalysis system.

The byproduct generation analysis of the NOx conversion process in dielectric barrier discharge plasma

Abatement of NO_x through non-thermal plasma (NTP) processes has been developed over the past several years.

Nitric oxide decomposition using atmospheric pressure dielectric barrier discharge reactor with different adsorbents

An NO removal rate of 99% and energy efficiency of 99.4 g NO per kW h were obtained on NaY zeolite using the adsorption–desorption and decomposition process in a self-made coaxial cylinder-type dielectric barrier discharge reactor.