Single Dielectric Barrier Discharge Research Articles

Degradation of thiamphenicol by La-Fe2O3/DBD/HCP synergistic catalytic system

In this study, a highly efficient La-Fe2O3/dielectric barrier discharge (DBD)/honeycomb ceramic plate synergistic catalytic system was successfully constructed by using modified iron oxide (Fe2O3) catalyst coating assisted DBD plasma, and the prepared catalytic coating was fully characterized by various techniques. The results indicate that the lanthanum (La) is efficiently and uniformly doped in Fe2O3, and the modified La-Fe2O3 catalyst exhibited a better photocatalytic performance. The overuse of Thiamphenicol (TAP), as a typical chloramphenicol antibiotic, has led to its accumulation in the aquatic environment. Accordingly, TAP was selected as the target contaminant to evaluate the catalytic activity of the synergistic system. The results confirmed that the catalytic ability of the synergistic catalytic system was significantly improved, and the data showed that the degradation rate of the synergistic system reached 99.1% under the same conditions compared with 68.2% for the single DBD plasma, which effectively improved low energy efficiency limitations of the single DBD technology. Through quantitative measurements of the concentrations of dissolved ozone (O3) and hydrogen peroxide (H2O2) in the system and radical trapping experiments, combined with emission spectroscopy, the mechanism of synergistic system degradation of TAP was analyzed. The intermediates in the degradation process were characterized by high-resolution mass spectrometry, and the degradation pathway of TAP was proposed based on the analysis of the intermediates and their combination with theoretical calculations. This study presents a theoretical basis for the improvement of DBD technology and a technical guide for the removal process of antibiotics from industrial wastewater.

Mechanistic study on 4, 4'-sulfonylbis removal with CO2/Ar gas-liquid DBD plasma

In this study, a single dielectric barrier discharge (DBD) coaxial reactor was used to degrade 4, 4'-sulfonylbis (TBBPS) in water using greenhouse gas (CO2) and argon as the carrier gases. The investigation focused on CO2 conversion, reactive species formation, gas-liquid mass transfer mechanism, and degradation mechanism of TBBPS during the discharge plasma process. With the decrease of CO2/Ar ratio in the process of plasma discharge, the emission spectrum intensity of Ar, CO2 and excited reactive species was enhanced. This increase promoted collision and dissociation of CO2, resulting in a series of chemical reactions that improved the production of reactive species such as ·OH, 1O2, H2O2 and O3. These reactive species initiated a sequence of reactions with TBBPS. Results indicated that at a gas flow rate of 240 mL/min with a CO2/Ar ratio of 1:5, both the highest CO2 conversion rate (17.76%) and TBBPS degradation rate (94.24%) were achieved. The degradation mechanism was elucidated by determining types and contents of reactive species present in treatment liquid along with analysis of intermediate products using liquid chromatography-mass spectrometry techniques. This research provides novel insights into carbon dioxide utilization and water pollution control through dielectric barrier discharge plasma technology.

Characteristics of the O(1S) to O(1D) 557.7 nm green emission observed in an argon plasma jet

An extensive study on the green auroral emission characterization is presented based on a single dielectric barrier discharge geometry argon plasma jet driven by a kHz sine voltage. The plasma was generated by using 99.999% pure argon and the observed 557.7 nm green line resulted from the excited O(1S) state. An optical emission spectroscopy method using line ratios of argon was used to obtain the electron density and electron temperature under different conditions in the downstream region. The characteristics of discharge and green emission with variations in interelectrode distance, applied voltage (power) and flow rate are discussed. The spatially diffuse distribution of O(1S), owing to its long lifetime, is shown by the short exposure imaging. Two discharge regimes are presented, accompanied by two distinct branches of the green emission intensity, with a clear conclusion that the 557.7 nm emission is favored in the low electron temperature environment. In this work, the intense and diffuse green plume only forms when the downstream electron density is approximately lower than 1 × 1014 cm−3 and the electron temperature is lower than 1.1 eV. By charging the two electrodes in two opposite ways, it is shown that the green emission from oxygen is favored in the case where the electric field and the electron drift are not continuous.

Synergistic low-temperature plasma (DBD) treatment of n-hexane gas

The experiment is based on a single dielectric barrier discharge (DBD) plasma generator, using micro-discharge to produce non-equilibrium plasma synergizing with two different catalysts (TiO2, 4A molecular sieve) to decompose n-hexane gas. In the n-hexane degradation experiment, the study investigates the influence of factors such as the type of catalyst, discharge voltage, and flow rate on the degradation rate of n-hexane. The experiments revealed that in all synergistic experiments with catalysts, the degradation rate of n-hexane increased with the decrease in flow rate and with the increase in voltage. Among the four catalysts selected, the 4A molecular sieve catalyst showed the best removal effect for n-hexane gas, reaching 73.2%.

Ionic wind and ozone generation in a single magnetic fluid dielectric barrier discharge plasma actuator with different electrode configurations

Plasma actuators are compact wind power generators without mechanical power mechanisms. Plasma actuators have been investigated and developed. In a previous study of the authors, a single dielectric barrier discharge (DBD) plasma actuator using magnetic fluid (MF), termed “MF-DBD plasma actuator,” was proposed for application to fanless air purification devices that can collect low-resistive particulate matter, such as diesel particulate, by electrostatic force without re-entrainment. The fundamental characteristics of the MF-DBD plasma actuator, such as ionic wind, temperature distribution, and ozone and ion concentrations, were investigated in the previous study. The advantage of an MF-DBD plasma actuator is that the position and shape of the MF electrode can be controlled using a magnetic field. In view of this advantage, in this study, ionic wind and ozone generation in a single MF-DBD plasma actuator with different electrode configurations is investigated for the future development of MF-DBD plasma actuators and their application in fanless air purification. In these experiments, the width of the insulated electrode and the distance between the exposed and insulated electrodes are varied. As a result, in the case of a constant applied voltage, the ionic wind velocity and ozone concentration depend only on the overlap between the magnetic fluid and the insulated electrode, and these values increase as the overlap increases. It is clarified that a large overlap between the MF and insulated electrodes can generate an efficient ionic wind in terms of wind velocity and energy consumption.

Synergistic catalysis degradation of amoxicillin by DBD plasma-catalyst system constructed by DBD plasma and Ce0.5Bi0.5VO4/HCP coating

A highly catalytic activity dielectric barrier discharge (DBD) plasma-catalyst synergistic system was constructed by DBD plasma and Ce0.5Bi0.5VO4/honeycomb ceramic plate (Ce0.5Bi0.5VO4/HCP) catalytic coating. Various characterization techniques were employed to analyze the physicochemical properties of the prepared photocatalysts. The catalytic activity of different catalytic systems was evaluated using amoxicillin (AMX) as the target contaminant. The DBD plasma-catalyst synergistic system exhibited significantly enhanced catalytic capacity compared to the single DBD plasma system. H2O2 and O3 concentrations in the solution during the reaction were monitored, and their formation process and roles were analyzed. The TOC results indicated that AMX exhibits a good mineralization rate in the synergistic system, and the 3D EEMs further revealed the changes in organic pollutant types during the mineralization process. The possible degradation pathways of AMX were inferred through mass spectra results and theoretical calculations. Additionally, the LC50 results for fathead minnow and daphnia show a significant downward trend of the main degradation intermediates. A possible synergistic mechanism was discussed based on the characterization results, experimental data, and relevant literature. This study offers a straightforward technical approach and theoretical backing for the synergistic wastewater treatment using DBD plasma combined with photocatalysts.

Dielectric barrier discharge plasma-coupled rare-earth modified Er3+-BiOI catalytic materials for degradation of organic pollutant benzohydroxamic acid in mineral beneficiation waster: Performance, degradation pathway, and its mechanism

A dielectric barrier Discharge (DBD) plasma catalytic system for synergistic degradation of benzohydroxamic acid (BHA) was established. A series of Er3+-BiOI samples doped with rare earth elements (Er3+) were prepared by the hydrothermal synthesis method. The characterization showed that Er3+-BiOI had a microglobular structure assembled by nanosheets, and the specific surface area of Er3+-BiOI was larger than that of pure BiOI. The degradation performance showed that in the DBD/Er3+-BiOI system, the highest BHA degradation efficiency reached 96.3 % with 4 % Er3+. Compared with the DBD-BiOI system and the single DBD system, the degradation efficiency of BHA increased by 9.1 % and 17.5 %, respectively. Meanwhile, the kinetic constants and cofactors were also the highest, at 3.36 and 2.88 times the DBD-BiOI system, respectively. The radical capture experiments showed ∙OH, ∙O2−, and cavities play a key role in the degradation of BHA, while O3, H2O2, e−, and H+ promote the degradation of BHA. The intermediates in the degradation of BHA were determined by LC-MS, and the possible degradation pathways of BHA were predicted. Finally, the degradation mechanism of BHA in the DBD/4 % Er3+-BiOI system was proposed.

A novel strategy of peracetic acid activation by dielectric barrier discharge plasma for bisphenol a degradation: Feasibility, mechanism and active species dominant to degradation pathway

As a typical endocrine disruptor, bisphenol A (BPA) can not only affect the reproduction and development of aquatic organisms, but also pose a significant threat to environmental safety and human health. This work proposed a novel strategy of peracetic acid (PAA) activation by dielectric barrier discharge (DBD) plasma for BPA degradation. It can be confirmed that DBD plasma can effectively activate PAA. 93.4 % BPA was destructed in the DBD/PAA system, which was 39.8 % higher than that in the DBD system alone. The energy yield (G50) of the DBD/PAA system was 211.5 g/kWh, while the single DBD system was only 59.7 g/kWh. The degradation efficiencies of chemical oxygen demand (COD) and total organic carbon (TOC) were also improved. The active substances such as OH, CH3C(O)OO, 1O2, O2−, and e− were important for the degradation of BPA in the DBD/PAA system. The pH dropped, and the total conductivity rose in the degradation processing of BPA. Three-dimensional fluorescence spectroscopy, liquid chromatography mass spectrometry (LC-MS) and density functional theory (DFT) simulation were adopted to investigate the degradation mechanism and process. The toxicity of intermediates in three degradation pathways to aquatic organisms was reduced. The degradation efficiency of BPA was more effective as input power increased and initial concentration decreased. BPA was more easily degraded under acidic solutions than under alkaline and neutral solutions. In addition, the effects of typical inorganic ions and humic acids on BPA degradation in the DBD/PAA system were examined. Finally, the DBD/PAA system is suitable for the application of various pollutants and actual wastewater. This research proposes an innovative idea and reference for PAA activation and plasma application in wastewater treatment.

Effect of gas components on the degradation mechanism of o-dichlorobenzene by non-thermal plasma technology with single dielectric barrier discharge

In this paper, the degradation of o-DCB under different gas-phase parameter conditions was investigated using the SDBD-NTP system. The results showed that the increase in initial and oxygen concentrations had opposite effects on the degradation of o-DCB. Among them, the increase of oxygen concentration promoted the degradation of o-DCB. Relative humidity promoted and then inhibited the degradation of o-DCB. The highest degradation efficiency of o-DCB was achieved at RH = 15%, reaching 91% at 29W. In the study of by-products, it was found that O3 and NOx were the main inorganic by-products, and that different oxygen levels and relative humidity conditions had a large effect on the production of O3 and NOx. In all of them, the concentration of O3 decreased with the increase of input power. NOx increased with increasing oxygen concentration, but the increase in relative humidity inhibited the production of NO and N2O and promoted the conversion of NO2. A study of organic by-products revealed this. In the absence of oxygen, a higher number of benzene products appeared. Whereas, with the addition of oxygen, only in the by-products under conditions where no relative humidity was introduced, benzene ring products were predominantly present in the by-products. However, when RH was added, n-hexane was found to be present in the by-products. This may be because the introduction of OH• favors the destruction of the benzene ring. Finally, the possible reaction pathways and reaction mechanisms of o-DCB under different gas-phase parameters are given. It provides a reference for future related scientific research as well as scientific problems in practical applications.

N2O5 in air discharge plasma: energy-efficient production, maintenance factors and sterilization effects

N2O5, a reactive species produced by air discharge plasma, has recently attracted much attention. Due to its high reactivity and solubility, N2O5 is a key molecule in nitrogen fixation processes and exhibits promising prospects in plasma biomedicine. However, thus far, it is not well known how to produce N2O5 efficiently and then maintain its concentration under the action of fast removal reactions. In view of this, N2O5 production by dielectric barrier discharge (DBD) alone and by the combination of DBD and gliding arc discharge is compared in this paper. It is found that the combination method can yield over three times the concentration of N2O5 compared to the single DBD method with the optimum discharge power. Moreover, the concentration of N2O5 in the effluent gas can be maintained once O3 also exists because O3 can continually produce N2O5 to compensate for its reduction. Finally, the sterilization effects of both the plasma effluent gas and plasma-activated water have trends similar to the trend of the gaseous N2O5 concentration, implying that N2O5 plays an important role in sterilization. This paper enhances the understanding of N2O5 chemistry in air discharge plasma and provides an effective way to produce and maintain N2O5 for subsequent applications.

Numerical Technique for Implementation of SDBD Plasma Actuators for Flow Control Applications in Wing Surfaces

In the subsequent study a Computational Fluid Dynamics (CFD) analysis technique to simulatea plasma actuator over an airfoil Re= O(205) is presented. The technique uses a two-dimensional Reynolds-Averaged Navier-Stokes Method coupled to the Kloker plasma-fluid model to study the effects of a Single Dielectric-Barrier Discharge (SDBD) as a Plasma Actuator. The CFD technique have been implemented in OpenFOAM platform for two setups, when: i) the actuator was located at x/c=0.03 and ii) x/c=0.1 of the chord length of the airfoil. The magnitude of the body force is equivalent to the results obtained by Hofkens and the actuator operates for both cases in the continuous and in the burst mode. To perform the numerical technique for a stable solution in OpenFOAM,various numerical procedures were tested, including a mixed solver between PISO and SIMPLE algorithm better known as pimpleFoam with nCorrector. The cases were solved in parallel on distributed processors using OpenMPI implementation and the accuracy of the resultsare strongly depends on the choice of grid size, y-plus,wall function and discretization scheme. The results indicate a high potential, suitability and great capabilities of this numerical technique implemented in OpenFOAM platform for free instability flow simulation.

Decomposition of VOCs by a novel catalytic DBD plasma reactor: A pilot study

AbstractA pilot‐scale multi‐tube dielectric barrier discharge (DBD) reactor coupled with a series of Mn−Ag based catalysts for VOCs abatement was set up and investigated. The DBD with 2 %Ag‐MnOx/Al2O3 catalyst exhibited the best performance of removal efficiency (85.4 %) and energy yield (5.2 g/kWh) of toluene at the specific energy density of 39.7 J/L, much higher than the single DBD reactor (34.9 %, 2.1 g/kWh). Moreover, the degradation efficiencies of styrene, dimethyl, ethyl acetate and xylene in the plasma catalysis system were also studied. The catalyst presented high stability during the 50 hours of toluene plasma‐catalysis oxidation. Finally, the physicochemical properties of this catalyst were characterized and discussed using an energy dispersive spectrometer, X‐ray diffraction patterns, and X‐ray photoelectron spectroscopy.

Self‐enhanced plasma brush for therapeutic use in dermatology and its safety assessment

AbstractIn this study, a self‐enhanced plasma brush based on a single dielectric barrier discharge was developed by optimizing the load position for treatment in dermatology. The electrical, optical, and temperature characteristics of the fabricated reactor were investigated. Results show that the length and the width of the plasma brush could reach 20 and 15 mm, respectively. The electric field and the resulting discharge between the reactor and the human impedance model were enhanced and the discharging resistance decreased when introducing a human load. The plume temperature is around 24°C and the current flowing through the human model is lower than the threshold of perception current, which is friendly for human contact. The sterilization effects are verified by killing Escherichia coli.

Flow control using single dielectric barrier discharge plasma actuator for flow over airfoil

The single dielectric barrier discharge (SDBD) plasma actuator has been developed in the present work for high-accuracy, high-performance computing of flow control applications. The present physics-based SDBD model is a significant improvement over the one developed by Bagade et al., [“Frequency-dependent capacitance–based plasma model for direct simulation of Navier–Stokes equation,” AIAA J. 55, 180–194 (2017)], which was used for planar geometry using sequential computation. Based on the physics of SDBD operation, phase-averaged fully developed body force over an ac cycle is computed and stored, which is reused. Thus, the intensive body force computations are bypassed in the new model, and the body force due to the SDBD plasma actuator is incorporated in the compressible Navier–Stokes equation that is solved in a body-fitted curvilinear coordinates. Here, the modified SDBD model enables performing large-scale simulations for the aerodynamic flow control at low speed and transonic flow past airfoils used in unmanned aerial vehicles and executive jets. The flow control by SDBD plasma actuation is finally compared with other forms of flow control strategies.

Genetic algorithm optimization of a horizontal axis wind turbine blade section performance equipped with a single dielectric barrier discharge plasma actuator utilizing a direct regression model

The usage of a single dielectric barrier discharge plasma actuator (SDBD-PA) device for improving a aerodynamic performance of a locally developed horizontal axis wind turbine blade section is studied with one of the most recent electrostatic models. To characterize this blade section behavior over a wide range of operating conditions of SDBD-PA and to advance its performance with a fully automated optimization algorithm, a computationally cost efficient direct regression model is proposed. In this paper, 512 comprehensive numerical simulations are carried out to derive the direct regression model for aerodynamic performance calculation when the PA is in use. However, to obtain highly accurate results, two different models for angle of attacks higher and less than [Formula: see text] are suggested. The proposed mathematical model within the specified boundary limits allows for a rapid linkage between aerodynamic performance and genetic algorithm which canbe made to acquire optimum results for each case without requiring burdensome numerical simulations. It is identified that superimpose input parameters effects onto each other is not explanatory of the final effect on aerodynamic performance and interaction effects should be seriously taken into consideration at the proposed regression model.

Research on Discharge Characteristics of Three-Electrode Load Under the Pulsed Power Supply

Low-temperature plasma water treatment technology has attracted more and more attention due to its nonselectivity and no secondary pollution. However, high energy consumption limits its further development. In this experiment, a three-electrode structure combining a needle-plate structure and a dielectric barrier discharge (DBD) structure is proposed. The discharge characteristics of the three-electrode structure are studied under the matched all-solid-state pulsed power supply. The results show that three discharges are generated at this three-electrode load within one pulse period. It greatly increases the number of discharges per pulse. Under the same pulse voltage condition, the injected power of the three-electrode load is much higher than the power of the single DBD load. When the voltage is 13 kV, the input power of three-electrode load is increased by 70% compared to single DBD load. When the needle-plate gap is constant, with the increase of DBD air gap, the injected power of the three-electrode load has a maximum value. When the DBD air gap remains unchanged, the injected power of the three-electrode load decreases with the increase of the needle-plate gap.

Efficiency assessment of a single surface dielectric barrier discharge plasma actuator with an optimized Suzen–Huang model

Spatial and time-resolved characteristics of a single surface dielectric barrier discharge (sDBD) actuator are experimentally and numerically investigated. The paper also focuses on the efficiency of sDBD actuators used as flow-control devices. The motivation is the need for developing a cost-effective way to optimize the balance between control performance and actuator power consumption. The study considers the steady state as often employed in experiments as well as the transient regime. Experimental methods to obtain the active power are revisited, and for the first time, the commonly used simplified phenomenological Suzen–Huang model (SHM) is used for the computation of electrical characteristics. The SHM represents fair qualitative features of the starting vortex. However, it fails when time-resolved velocity profiles are compared. Results show that even with an optimized parametrical analysis of the “tuned” plasma variables, the model is not able to fully reproduce the induced wall-jet neither spatially nor temporally. Furthermore, it underestimates the power consumption by more than 80%. The intrinsic challenge of accurately measuring the alternating current of the DBD and the instantaneous mechanical power, together with the failure of representing time-resolved velocity profiles and the underestimated electric power by the model, highlights that a better phenomenological model including gas dynamics and electric characteristics or using a fully coupled physical plasma model is required.

Preparation of graphene-based catalysts and combined DBD reactor for VOC degradation.

The objective of this study was to compare the transformation of by-products between single dielectric barrier discharge (SDBD) and double dielectric barrier discharge (DDBD), to optimize the preparation of graphene-based catalysts and apply them in combination with DBD for volatile organic compound degradation. We compared the degradation performance of SDBD and DDBD, prepared, and characterized graphene-based catalysts. SEM, BET, XRD, and FTIR analyses showed that the morphologies and internal structures of the three catalysts were the best when 0.25mL of [BMIM]PF6 was added. When MnOx/rGO, FeOx/rGO, and TiOx/rGO were used in combination with DDBD, the degradation rates of benzene were found to be 83.5%, 77.2%, and 63.8%, respectively, whereas the O3 transformation rates were 60%, 79%, and 40%, respectively. Moreover, the NO2 transformation rates were 70%, 55%, and 42.5%, respectively, whereas the NO transformation rates were 69%, 39%, and 33.5%, respectively. The CO2 selectivity was 62%, 51%, and 49%, respectively. MnOx/rGO exhibited superior performance in the degradation of benzene series, NO transformation, NO2 transformation, CO2 selectivity, and energy efficiency. On the other hand, FeOx/rGO exhibited superior performance for O3 transformation. Based upon the XPS analysis, it was found that Mn3O4 and Fe3O4 played a leading role in promoting the degradation of benzene series and the transformation of by-products.

Removal of NO by carbon-based catalytic reduction bed loaded with Mn induced by dielectric barrier discharge at low temperature

The current paper reports on a newly developed DBD-Mn/FCRB hybrid system to explore the removal of NOx by reduction without adding reducing gas at low temperature (below 80℃). This technology was established with a fixed carbon-based reduction catalytic reduction bed loaded with manganese (Mn/FCRB) induced by dielectric barrier discharge (DBD). The NO conversion and N2 selectivity in the new hybrid system reached 90.9 and 79.9%, respectively under 8% oxygen content, 1,200 J/L specific input energy (SIE), which were all higher than in the single DBD and DBD-FCRB systems, respectively. The Mn/FCRB was further characterized before and after activation by SEM, XRD and XPS. The possible reaction pathways of denitration were proposed through three processes based on the experimental results: direct denitration of active carbon atoms excited by plasma, reduction by adsorptive C(N) and C(O) complexes on the FCRB surface, and the reaction of nitrogen oxides with by-product CO. In addition, the results also showed that the new in-situ reduction denitration system had strong oxygen shock resistance and water resistance.

SDBD Flexible Plasma Actuator with Ag-Ink Electrodes: Experimental Assessment

In the present work, a single dielectric barrier discharge (SDBD)-based actuator is developed and experimentally tested by means of various diagnostic techniques. Flexible dielectric barriers and conductive paint electrodes are used, making the design concept applicable to surfaces of different aerodynamic profiles. A technical drawing of the actuator is given in detail. The plasma is sustained by audio frequency sinusoidal high voltage, while it is probed electrically and optically. The consumed electric power is measured, and the optical emission spectrum is recorded in the ultraviolet–near infrared (UV–NIR) range. High-resolution spectroscopy provides molecular rotational distributions, which are treated appropriately to evaluate the gas temperature. The plasma-induced flow field is spatiotemporally surveyed with pitot-like tube and schlieren imaging. Briefly, the actuator consumes a mean power less than 10 W and shows a fair stability over one day, the average temperature of the gas above its surface is close to 400 K, and the fluid speed rises to 4.5 m s−1. A long, thin layer (less than 1.5 mm) of laminar flow is unveiled on the actuator surface. This thin layer is interfaced with an outspread turbulent flow field, which occupies a centimeter-scale area. Molecular nitrogen-positive ions appear to be part of the charged heavy species in the generated filamentary discharge, which can transfer energy and momentum to the surrounding air molecules.