•The decomposition of benzene can be as high as 98% in CO2 and H2 carrier gases.•Selectivity to lower hydrocarbons (C1–C5) increased from 13% to 91% in H2 carrier gas.•No formation of solid residue ...in H2 carrier gas.•Selectivity to methane (82%) increases with temperature.
Cracking of benzene in a non-thermal plasma (NTP) dielectric barrier discharge reactor (DBD) was investigated in CO2 and H2 carrier gases. Benzene was acting as an analogue for gasification tar, and CO2 and H2 are abundant in gasifier product gas. A parametric study in terms of specific input energy (SIE), residence time, concentration and temperature was performed to determine the optimal conditions for tar conversion. It was found that almost complete removal of benzene (36 g/Nm3) was observed in each carrier gas above 30 kJ/L and at 4.23 s. Lower hydrocarbons (<C6) (LHC) and solid residue were common products in both carrier gases. The selectivity to LHC in H2 carrier gas was higher (12%) than CO2 (2%) carrier gas, and CO was the major gaseous product in CO2 carrier gas. However, the problem of solid formation in the reactor was completely eradicated by operating at elevated temperatures in H2 carrier gas. The selectivity to lower hydrocarbons increased with increasing temperature. At 400 °C in H2 carrier gas, the selectivity to LHC reached 91% with no formation of solid residue. The major lower hydrocarbons at these conditions were CH4 (82%) and C2 (C2H6 + C2H4) 6.6%.
Polycyclic aromatic hydrocarbons (PAHs) in soil are not only detrimental to environment but also to human health. Double dielectric barrier discharge (DDBD) plasma reactor used for the remediation of ...pyrene contaminated soil was studied. The performance of DDBD reactor was optimized with influential parameters including applied voltage, type of carrier gas, air feeding rate as well as pyrene initial concentration. The analysis of variance (ANOVA) results showed that input energy had a great effect on pyrene remediation efficiency followed by pyrene initial concentration, while, the effect of air feeding rate was insignificant. More specifically, the remediation efficiency of pyrene under air, nitrogen and argon as carrier gas were approximately 79.7, 40.7 and 38.2% respectively. Pyrene remediation efficiency is favored at high level of applied voltages and low level of pyrene initial concentration (10 mgkg−1) and air feeding rate (0.85 L/min). Moreover, computation of the energy efficiency of the DDBD system disclosed that an optimal applied voltage (35.8 kV) and higher initial pyrene concentration (200 mgkg−1) favored the high energy efficiency. A regression model predicting pyrene remediation under DDBD plasma condition was developed using the data from a face-centered central composite design (FCCD) experiment. Finally, the residual toxicity analysis depicted that the respiratory activity increased more than 21 times (from 0.04 to 0.849 mg O2 g−1) with a pyrene remediation efficiency of 81.1%. The study demonstrated the DDBD plasma technology is a promising method not only for high efficiency of pyrene remediation, but also recovering biological function without changing the physical-chemical properties of soil.
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•Operational parameters of DDBD plasma for pyrene remediation was optimized.•Pyrene degradation process fit for the second order kinetic model.•Prediction model for pyrene remediation in DDBD system was developed.•Bioactivity of pyrene contaminated soil can be recovered after plasma treatment.•Bioactivity is important for comprehensive evaluation along with remediation and energy efficiency.
The degradation of triclosan (TCS) in aqueous solution by dielectric barrier discharge (DBD) plasma with activated carbon fibers (ACFs) was investigated. In this study, ACFs and DBD plasma coexisted ...in a planar DBD plasma reactor, which could synchronously achieve degradation of TCS, modification and in situ regeneration of ACFs, enhancing the effect of recycling of ACFs. The properties of ACFs before and after modification by DBD plasma were characterized by BET and XPS. Various processing parameters affecting the synergetic degradation of TCS were also investigated. The results exhibited excellent synergetic effects in DBD plasma-ACFs system on TCS degradation. The degradation efficiency of 120 mL TCS with initial concentration of 10 mg L−1 could reach 93% with 1 mm thick ACFs in 18 min at input power of 80 W, compared with 85% by single DBD plasma. Meanwhile, the removal rate of total organic carbon increased from 12% at pH 6.26–24% at pH 3.50. ACFs could ameliorate the degradation efficiency for planar DBD plasma when treating TCS solution at high flow rates or at low initial concentrations. A possible degradation pathway of TCS was investigated according to the detected intermediates, which were identified by liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC–QTOF-MS) combined with theoretical calculation of Gaussian 09 program.
•Degradation of aqueous triclosan by using DBD plasma and ACFs was investigated.•The ACFs showed efficient synergistic effect with DBD plasma for various processing parameters.•The ACFs achieved modification and in situ regeneration during triclosan degradation.•Main intermediates and the pathway of triclosan degradation by DBD plasma were proposed.
This study investigates experimentally the effects of non-thermal plasma (NTP) induced by a dielectric barrier discharge (DBD) reactor on the characteristics of swirl-stabilized turbulent ...lean-premixed methane/air flames in a laboratory scale combustor by systematically varying the applied AC voltage, VAC, and frequency, fAC. Especially, it is elucidated how the NTP influences the lean blowout (LBO) limits and the characteristics of CO/NOx emissions depending on flame configuration. Without applying the NTP as the mixture equivalence ratio, ϕ, decreases from the stoichiometry to an LBO limit, the flame configuration changes from an M-flame (Regime I) to a conical flame (Regime II) and to a columnar flame (Regime III) for the whole range of the mixture nozzle exit velocity, U0, (4–10 m/s). With the NTP, however, it exhibits only Regimes I and II at relatively-low U0 range (4–6 m/s), while all three regimes at relatively-high U0 range (7–10 m/s). For both velocity ranges, the LBO limits are significantly extended by the NTP enhancing the flame stability. Under the relatively-low U0 range, streamers induced by the DBD reactor play a critical role in stabilizing the flames such that the degree of extension of the LBO limit depends linearly on VAC and fAC. Under the relatively-high U0 range, however, ozone generated by the DBD reactor in Regime III is found to be a major reason in extending the LBO limit, which is substantiated by another flame regime diagram with ozone addition only, and hence, the extension of LBO limit minimally depends on fAC. Simultaneously, the NTP considerably reduces CO emission, while slightly increases NOx emission near the LBO limits due to the enhanced combustion by ozone.
•Ni0.5Co0.5-CPO-27 nanorod array (NRA) in-situ growth on carbon cloth (CC).•Microplasma-synthesized Ni0.5Co0.5-CPO-27 NRA/CC with oxygen vacancies.•Ni0.5Co0.5-CPO-27 NRA/CC acts an efficient ...electrocatalyst for glucose oxidation.•Ni0.5Co0.5-CPO-27 NRA/CC shows high sensing performance for glucose detection.•Ni0.5Co0.5-CPO-27 NRA/CC operates efficiently in beverage and human serum samples.
The rational design of high-efficiency catalysts for non-enzymatic glucose sensing is extremely important for the timely and effective monitoring of glucose content in beverages and human blood. A 3D bimetallic organic framework (Coordination Polymer of Oslo, CPO) nanorod array with oxygen vacancies was green fabricated on carbon cloth (Ni0.5Co0.5-CPO-27 NRA/CC) using dielectric barrier discharge (DBD) microplasma for the first time. Density functional theory (DFT) calculations demonstrated that the oxygen vacancy of Ni0.5Co0.5-CPO-27 can be effectively induced under DBD microplasma conditions. Based on the 3D nanorod arrays with rich oxygen vacancies and bimetallic synergistic effects, as a non-enzyme glucose sensor, the Ni0.5Co0.5-CPO-27 electrode exhibited a sensitivity of 8499.5 μA L/mmol cm−2 and 3239.2 μA L/mmol cm−2 and a limit of detection (LOD) of 0.16 μmol/L (S/N = 3). It has been successfully applied to the determination of glucose levels in real samples such as cola, green tea and human serum.
The feasibility of pollutant removal in aqueous solution by dielectric barrier discharge plasma in combination with Bi2WO6-rMoS2 composite photocatalyst was investigated by choosing sulfamethoxazole ...(SMZ) as the model pollutant. In this study, Bi2WO6-rMoS2 catalysts were synthesized by a modified hydrothermal method and characterized by TEM, XRD, XPS. The results showed that the Bi2WO6 was well loaded on the surface of MoS2. The influences of the main operating parameters including discharge voltage, initial concentration, initial pH, mass ratios and dosages of Bi2WO6-rMoS2 on the removal efficiency of SMZ were studied. The results revealed that the initial concentration of 20 mg L−1 SMZ solution (100 mL) could be degraded by 97.6% with the addition of 0.08 g L−1 Bi2WO6-rMoS2 (1 wt%) at 9 kV after 21 min, compared with 72.5% by single dielectric barrier discharge plasma. Even after four cycling runs, Bi2WO6-rMoS2 (1 wt%) still remained high removal efficiency of SMZ. Moreover, the yields of hydrogen peroxide (H2O2) and Ozone (O3) in plasma discharge process were also investigated, and the results exhibited that adding Bi2WO6-rMoS2 could notably influence the amount of O3 and H2O2. Finally, ten intermediates of SMZ degradation were identified, and the proposed SMZ degradation pathways were deduced based on the detected intermediates.
•Bi2WO6-rMoS2 nanocomposite was first applied with dielectric barrier discharge (DBD) plasma.•The Bi2WO6-rMoS2 showed efficient synergistic effect with DBD plasma for various processing parameters.•The property changes of Bi2WO6-rMoS2 nanocomposite after plasma treatment were characterized.•The mechanism and possible pathways of SMZ degradation in plasma/Bi2WO6-rMoS2 system were proposed.
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•A DBD reactor with coupled positive and negative surface streamers is reported.•Lower power but higher chemical efficiency compared to single polarity surface-DBD.•Multiple electrode ...structure of same polarity improved ozone synthesis efficiency.•Chemical efficiency improved with gas flow through multiple chambers in series.
A coupled surface dielectric barrier discharge is reported and compared with a surface dielectric barrier discharge with respect to the spatial distribution of the plasma streamers, the energy dissipation in the discharge plasma, the scalability of the discharges, and their efficiency for ozone synthesis and nitric oxide conversion from air. Negative streamers were found to be more effective for the chemical reactions than positive streamers. Scaling of the discharges was achieved by: (i) employing multiple inter-connected electrodes in the same space and (ii) operating stacked discharge chambers in parallel in a compact configuration. The increase in efficiency caused by the two scaling methods allowed us to obtain ozone concentrations of 1–9g/Nm3 with an energy yield of 100–70g/kWh and nitric oxide conversions of 10–95% with an energy cost of 20–80eV/molecule from an initial concentration of ∼330ppm in air. The results are explained on the basis of the streamer development in the two barrier discharge configurations and the results are compared with those reported in the literature.
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•A novel pulse-modulated HF DBD plasma was employed for toluene degradation.•The effects of various factors on toluene degradation were investigated.•Energy consumption and heating ...effect were significantly reduced in pulse-modulated mode.•The key process parameters have been optimized by RSM-CCD model.•The possible toluene degradation pathways by pulse-modulated DBD was proposed.
In the present work, a pulse-modulated high-frequency (HF) dielectric barrier discharge (DBD) plasma has been employed and utilized to evaluate the feasibility of toluene degradation in a multistage rod-type reactor at room temperature. Experimental result indicates that the energy consumption is significantly reduced and heating effect can be effectively suppressed when the DBD plasma is ignited in pulse-modulated mode instead of continuous mode.
The response surface methodology (RSM) based on central composite design (CCD) model has been proposed to evaluate the contribution of key operating parameters including duty cycle and modulation frequency. The proposed model offers a good fit for actal data. The contribution of the modulation frequency is observed to be more dominant compared to the duty cycle for both the degradation efficiency and the energy yield. According to the results provided by the proposed model, the toluene degradation efficiency of 62.9 % and the energy yield of 0.90 g/kWh are obtained under the optimal conditions of 400 Hz modulation frequency and 56 % duty cycle. The effect of initial toluene concentration and gas flow rate have also been investigated. Increasing toluene initial concentration and gas flow rate are found to be unfavorable for the degradation of toluene, however, which are of benefit to the energy yield. A long-time experiment to assess the stability of pulse-modulated DBD has been successful performed. The possible pathways in plasma degradation of toluene is proposed based on the intermediates identification using GC–MS and FTIR.
Ambient mass spectrometry enables fast and direct analysis, requiring minimal or no sample preparation; these attributes have established it as the preferred technique for applications in numerous ...fields (e.g., biomedical, forensic, and environmental). Here we coupled an active capillary plasma ionization source based on a dielectric barrier discharge directly to solid-phase microextraction, achieving a quick (<10 min per sample), green (virtually no samples preparation and thus no solvents involved), sensitive (LODs up to 3 pg mL−1), robust (RSD of <20%), and quantitative (LDR ≥ 2 orders of magnitude) screening method. This study, moreover, shows that intrinsically poorer ionization efficiencies for low-polarity compounds (such as polycyclic aromatic hydrocarbons, PAHs), which precluded their ultra-trace detection, can be partially overcome by adding dopants and lowering the LODs into the pg mL−1 range. Results also show that the presence of these dopants greatly affects the ionization mechanism, resulting in the preferential formation of radical cations versus protonated PAHs. As a proof of concept, this method was applied to the detection of organic microcontaminants in different water matrices (such as tap, ground, and treated wastewater). Common contaminants (e.g., DEET, benzotriazole, β-estradiol) were tentatively detected and, if above the LOQ, quantified (i.e., DEET at 30 pg mL−1). These promising results evidence that this approach is interesting for quick (field) screening methods, and the newly increased efficiency for a larger polarity range additionally expands the range of possible applications.
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•Dopant-assisted dielectric barrier discharge ionization increases the ionization efficiency of compounds of low polarity.•Sensitive (pg mL−1 levels) and quantitative analysis of compounds of a wide polarity range in environmental water samples.•Direct coupling to SPME achieves a simple and high-throughput analysis.•Better limits of detection are achieved for PAHs compared to similar techniques.
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