Pulsed power generators have widely used in pulsed plasma applications. This article provides a newly developed all-solid-state pulsed power generator (PPG) with a high boost ratio (HBR) for ...dielectric barrier discharge (DBD) applications. By using a common low-voltage power supply, the proposed generator achieves high-voltage pulses via simply connecting modules in series without regard for isolation problems due to inductive voltage adder technology. For HBR, we introduce a step-up transformer to enhance voltage gain further. The topology effort of the step-up transformer focuses on a high primary-secondary side voltage ratio. However, the high booster ratio output is accompanied by the problem of waveform oscillation, especially for capacitive DBD load. Therefore, this article proposes a novel diode-resistor shaping method to solve the aforementioned waveform distortion problems. Working principles of developed PPG as well as additional shaping circuit are described, the impact of the shaping branch is analyzed and detailed parameter calculations are given for the selection of passive components. Finally, a portable 10 kV prototype setup with ∼400 voltage gain ratio (25 V input) was implemented and experimented with different DBD applications, validating the concept of the proposed PPG analysis.
•A MnCe/Ti catalyst with good oxidation performance for NO and SO2 was prepared.•A NTP catalytic oxidation system was constructed to simultaneously remove NO and SO2.•Highest NO and SO2 removal ...efficiencies (86.9% and 100%) were achieved.•Removal efficiency and interactions between NO and SO2 were analyzed.•The novel reactor enhanced the removal efficiency and reduced the energy consumption.
In this paper, non-thermal plasma (NTP) discharge and catalyst were integrated, and the dielectric barrier discharge (DBD) reactor was used to prepare a MnCe/Ti catalyst. We then measured its surface characteristics. A NTP catalytic oxidation experimental system based on the MnCe/Ti catalyst was constructed for simultaneous desulfurization and denitrification, and the efficiency of the system for the simultaneous removal of NO and SO2 in simulated flue gas was verified. The effects of specific energy density (SED), flue gas flow rate, and the initial concentrations of NO and SO2 on the removal efficiencies as well as the interactions between NO and SO2 were analyzed. The NO and SO2 removal efficiencies and the corresponding energy efficiency of the integrated system were compared to the system using only the DBD reactor. The results showed that the MnCe/Ti catalyst exhibited higher dispersion of metal oxide active components on the surface and had a higher content of catalytic oxidation active substances than non-doped Mn/Ti and Ce/Ti catalysts. With a SED in the range of 30–250 J/L, the NO and SO2 removal efficiencies increased as the SED increased. At low initial concentrations (200 mg/m3 NO and 1000 mg/m3 SO2), the highest NO and SO2 removal efficiencies (86.9% and 100%) were achieved. Versus the flue gas treatment system using only the DBD reactor, the system using the MnCe/Ti catalyst-filled DBD reactor simultaneously removed NO and SO2 with enhanced efficiencies and reduced system energy consumption—this is a reference for further optimization of the flue gas treatment system using a DBD-wet electrostatic precipitator (WESP).
•EmimOTf/DBD synergistically enhanced SCFA production during sludge fermentation.•Solubilization, hydrolysis, and acidogenesis were facilitated by EmimOTf/DBD.•EmimOTf/DBD promoted the generation of ...•OH, 1O2, •O2− and ONOO−.•EmimOTf/DBD enriched SCFA-forming bacteria and decreased SCFA-consuming bacteria.•EmimOTf/DBD favored sludge dewatering and heavy metal removal.
This study explored the potential application of plasma coupling ionic liquid on disintegration of waste activated sludge and enhanced production of short-chain fatty acids (SCFAs) in anaerobic fermentation. Under optimal conditions (dosage of ionic liquid EmimOTf = 0.1 g/g VSS (volatile suspended solids) and discharge power of dielectric barrier discharge plasma (DBD) = 75.2 W), the EmimOTf/DBD pretreatment increased SCFA production by 302 % and acetic acid ratio by 53 % compared to the control. Mechanistic investigations revealed that the EmimOTf/DBD combination motivated the generation of various reactive species (such as H2O2, O3, •OH, 1O2, ONOO−, and •O2−) and enhanced the utilization of physical energies (such as heat). The coupling effects of EmimOTf/DBD synergistically improved the disintegration of sludge and biodegradability of dissolved organic matter, promoting the sludge anaerobic fermentation process. Moreover, the EmimOTf/DBD pretreatment enriched hydrolysis and SCFAs-forming bacteria while inhibiting SCFAs-consuming bacteria. The net effect was pronounced expression of genes encoding key enzymes (such as alpha-glucosidase, endoglucanase, beta-glucosidase, l-lactate/D-lactate dehydrogenase, and butyrate kinase) involved in the SCFA-producing pathway, enhancing the production of SCFAs from sludge anaerobic fermentation. In addition, EmimOTf/DBD pretreatment facilitated sludge dewatering and heavy metal removal. Therefore, EmimOTf/DBD pretreatment is a promising approach to advancing sludge reduction, recyclability, and valuable resource recovery.
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In this study, dielectric barrier discharge (DBD) plasma combined with titanium dioxide/reduced graphene oxide/copper oxide (TiO2/rGO/Cu2O) composites for simultaneous removal of hexavalent chromium ...(Cr(Ⅵ)) and tetracycline (TC) from wastewater were explored systematically. The TiO2/rGO/Cu2O composites were successfully prepared to improve the specific surface area and charge carrier separation rate. When Cr(Ⅵ) and TC coexist, the two pollutants have better removal efficiency without changing the initial pH. Moreover, the removal efficiency of Cr(Ⅵ) and TC could be further improved in the DBD-TiO2/rGO/Cu2O system, indicating that the TiO2/rGO/Cu2O composites also exhibited good synergistic effects with the DBD plasma. The mechanism exploration showed that the TiO2/rGO/Cu2O composite catalyst could be activated in DBD system to produce various active species by photocatalytic reaction, among which photo-generated electrons and •O2- could significantly enhance Cr(Ⅵ) reduction, while photo-generated holes and •OH could improve TC degradation. More importantly, the intermediate products obtained from TC degradation can be oxidized to •CO2- by photo-generated holes, which can also facilitate the reduction of Cr(Ⅵ). This study shows that DBD combined with TiO2/rGO/Cu2O composites are capable of simultaneous Cr(Ⅵ) reduction and TC degradation, which would provide novel ideas for practical wastewater remediation.
In this work, an integrated system combining non-thermal plasma (NTP) and FeMn catalysts was developed for ethylene oxide (EO) oxidation. The effect of Fe/Mn molar ratio on the oxidation rate of EO ...and energy yield of the plasma-catalytic process has been investigated as a function of specific energy density (SED). Compared with the case of using plasma alone, the combination of plasma and FeMn catalysts greatly enhanced the reaction performance by the factor of 25.2% to 97.6%. The maximum oxidation rate of 98.8% was achieved when Fe1Mn1 catalyst was placed in the dielectric barrier discharge (DBD) reactor at the SED of 656.1 J·L−1. The highest energy yield of 2.82 g·kWh−1 was obtained at the SED of 323.2 J·L−1 over the Fe1Mn1 catalyst. The interactions between Fe and Mn species resulted in larger specific surface area of the catalyst. Moreover, the reducibility of the catalysts was improved, while more surface adsorbed oxygen (Oads) was detected on the catalyst surfaces. Moreover, the redox cycles between Fe and Mn species facilitated consumption and supplementation of reactive oxygen species, which contributed to the plasma-catalytic oxidation reactions. The major reaction products of plasma-induced EO oxidation over the FeMn catalysts, including CH3COOH, CH3CHO, CH4, C2H6 and C2H4, were observed using the FT-IR analyzer and GC–MS instrument. The reaction mechanisms of EO oxidation were discussed in terms of both gas-phase reaction and catalyst surface reaction. The redox cycles between Fe and Mn species facilitated the plasma reaction and accelerated the deep oxidation of by-products.
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•Ethylene oxide oxidation was conducted in plasma-catalytic system.•Significant enhancement in plasma oxidation was obtained over FeMn catalysts.•Fe1Mn1 catalyst showed the highest oxidation rate and energy yield.•The interactions between Fe and Mn contributed to ethylene oxide oxidation.•Reaction pathways of plasma-catalytic oxidation of ethylene oxide were analyzed.
The remediation of diesel-contaminated soil is a critical environmental concern, driving the need for effective solutions. Recently, the methodology of Non-thermal Atmospheric Plasma (NTAP) ...technology, which is equipped with a Dielectric Barrier Discharge (DBD) electrode and has become a feasible approach, was proven to be viable. The reactive species from the plasma were exposed to the contaminated soil in this investigation using the NTAP technique. The reacted soil was then extracted using dichloromethane, and the amount of Total Petroleum Hydrocarbon (TPH) removed was assessed. Investigation into varying power levels, treatment durations, and hydrogen peroxide integration revealed significant findings. With an initial concentration of 3086 mg of diesel/kg of soil and a pH of 5.0, 83% of the diesel was removed from the soil at 150 W in under 20 min. Extended exposure to NTAP further improved removal rates, highlighting the importance of treatment duration optimization. Additionally, combining hydrogen peroxide (H2O2) with NTAP enhanced removal efficiency by facilitating diesel breakdown. This synergy offers a promising avenue for comprehensive soil decontamination. Further analysis considered the impact of soil characteristics on removal efficacy. Mechanistically, NTAP generates reactive species that degrade diesel into less harmful compounds, aiding subsequent removal. Overall, NTAP advances environmental restoration efforts by offering a quick, economical, and environmentally benign method of remediating diesel-contaminated soil especially when used in tandem with hydrogen peroxide.
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•This study identifies Non-thermal Atmospheric Plasma (NTAP) technology with a DBD electrode as a solution for TPH remediation.•At optimum experimental condition studied, NTAP was able to remove 83% of diesel from soil at a pH level of 5.0.•NTAP with hydrogen peroxide offers a rapid, cost-effective, and eco-friendly method for cleaning diesel-contaminated soil.
Abstract Based on the Shyy plasma simulation model, this paper studied the control mechanism of positive and reverse DBD-PA (dielectric barrier discharge plasma actuator) on near wall flow, and ...discussed the influence of incoming boundary layer thickness and parallel double DBD-PA on control effect. The results showed that: the positive DBD-PA had an obvious acceleration effect on the near wall flow field, and the acceleration effect first increased and then decreased; the reverse DBD-PA had an obvious deceleration effect on the near wall flow field, and the deceleration effect decreased gradually; increasing the thickness of the incoming boundary layer can improve the control effect, but the improvement effect is gradually reduced; when parallel double DBD-PA, the control effect of positive and reverse DBD-PA is improved by 88.7 % and 62.5 % respectively.
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•A novel technology of coupling DBD and UV was investigated to degrade ENRO.•Approximately 93.9% of the ENRO was removed in the DBD/UV system.•OH played an important part in the ENRO ...degradation.•The DBD/UV system decreased H2O2 concentration, and increased ·OH concentration.•Twelve degradation products were determined by HPLC-MS.
Enrofloxacin (ENRO) as a highly toxic antibiotic poses great threats to human health and environmental safety. In this study, a novel technology of coupling dielectric barrier discharge (DBD) and ultraviolet (UV) was investigated to efficiently degrade ENRO in aqueous, and had a higher degradation rate. The ENRO degradation rate achieved approximately 93.9% at 30 min, and approximately 1.20 g kWh−1 of energy yield (G50) was observed for the combined system. The addition of H2O2 and K2S2O4 improved the ENRO degradation due to the generation of ·OH and ·SO42-. In the presence of NO3–, the ENRO degradation played a tendency to promote first and then decrease, and the presence of SO42- resulted in the positive effect, while the negative effect was shown in the presence of Cl- and CO32–. The trapping experiment indicated that ·OH played an important part in the ENRO degradation. The addition of UV into the DBD system decreased H2O2 concentration in deionized water, and increased ·OH concentration. The DFT analysis showed the degradation mechanisms of ENRO at a molecular level. The degradation of ENRO mainly involved the oxidation of the piperazine group, the removal of ethyl acetate and the substitution of the F atom. The toxicity of ENRO and its degradation intermediates was evaluated.
Atmospheric-pressure diffuse dielectric barrier discharges (DBDs) were obtained in Ar/O2 gas mixture using dual-frequency (DF) excitation at 200 kHz low frequency (LF) and 13.56 MHz radio frequency ...(RF). The excitation dynamics and the plasma generation mechanism were studied by means of electrical characterization and phase resolved optical emission spectroscopy (PROES). The DF excitation results in a time-varying electric field which is determined by the total LF and RF gas voltage and the spatial ion distribution which only responds to the LF component. By tuning the amplitude ratio of the superimposed LF and RF signals, the effect of each frequency component on the DF discharge mechanism was analysed. The LF excitation results in a transient plasma with the formation of an electrode sheath and therefore a pronounced excitation near the substrate. The RF oscillation allows the electron trapping in the gas gap and helps to improve the plasma uniformity by contributing to the pre-ionization and by controlling the discharge development. The possibility of temporally modifying the electric field and thus the plasma generation mechanism in the DF discharge exhibits potential applications in plasma-assisted surface processing and plasma-assisted gas phase chemical conversion.
Toxic organic and heavy metal contaminants commonly exist in industrial waste stream(s) and treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma ...technology was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals were the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration, because part of hydroxyl radicals could be consumed by the low-concentration CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could react with such reductive species as eaq− and •H, which could compete with Cr(VI) and inhibit the reduction. In addition, the presence of Cr(VI) enhanced the degradation and mineralization of CAP; the study of obtained intermediates indicated that the presence of Cr(VI) changed the degradation path of CAP as Cr(VI) would react with reductive species, enhance the generation of hydroxyl radicals, and cause more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology can be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environments.
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•Dielectric barrier discharge plasma works well in treating contaminants.•Synergistic effect exists in treatment of chloramphenicol and Cr(VI).•Presence of Cr(VI) changes degradation path of chloramphenicol.
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