Corona Discharge Plasma Research Articles

Hydrazine-enhanced NO conversion in a pulsed corona discharge plasma (PCDP) reactor: Behaviors and mechanism

The NO conversion efficiency in a pulsed corona discharge plasma (PCDP) reactor in the presence of a new additive, hydrazine hydrate (N2H4·H2O), was studied, and the reaction mechanism was analyzed. The NO conversion efficiency reached 62.5%, and the NO conversion Energy Yield (EY) reached 20.9 gNO/kWh, which is higher than that obtained using water or ammonia additives under the same conditions. The predominant elementary reactions and radicals, as well as the mechanism by which the additive enhanced the NO conversion process, were determined by comparing experimental data with theoretical simulation results and by performing a sensitivity analysis. After the addition of N2H4·H2O, the N2H4 reacts with radicals generated in the PCDP reactor to form a large quantity of strongly reducing species with NH2 as the predominant component, which can directly reduce NO to N2 and effectively prevent the generation of N2O. Compared with the traditional PCDP-based De-NOx process in which nitric acid is generated by oxidation with an additional neutralization step required, this new PCDP-based De-NOx process with N2H4·H2O addition is superior because NO is mostly reduced to N2. The study provides a basis for the application of N2H4·H2O as a synergist to improve NO abatement in a PCDP reactor.

Effect of corona discharge plasma on microbial decontamination of dried squid shreds including physico-chemical and sensory evaluation

Non-thermal techniques for microbial decontamination in foods are becoming more promising. This work aims to evaluate the suitability and effectiveness of corona discharge plasma jet (CDPJ) for the inactivation of microbial contaminants of dried squid shreds. CDPJ was generated using 20 kV pulsed DC voltage and at a 58 kHz frequency. Upon the CDPJ treatment (0–3 min) of dried shreds, contaminants namely aerobic bacteria, marine bacteria and Staphylococcus aureus were inactivated by 2.0, 1.6, and 0.9 log units, respectively. Also, a 0.9 log reduction of yeasts and molds contaminants was observed. The inactivation pattern fitted well to the pseudo-first-order model rather than first-order kinetic model. The CDPJ treatment did not exert statistically significant (P > 0.05) changes in color characteristics and volatile basic nitrogen content of dried squid shreds as compared with untreated controls. In contrast, the moisture and thiobarbituric acid reactive substances levels of shreds were significantly (P < 0.05) altered by the plasma exposure. However, the treatment exerted no significant (P > 0.05) impact on the sensory characteristics of dried squid shreds. The CDPJ was found to be effective for microbial decontamination of real-world samples of dried squid. This technology can readily be applied to commercial dried squid processing.

Processes of carbon disulfide degradation under the action of a pulsed corona discharge

Experiments on decomposition of carbon disulfide CS2 in air under the action of a pulsed nanosecond corona discharge have been carried out. The energetic efficiency of the degradation amounted to 290–340 g (kW h)–1, which is significantly higher than with the use of a corona discharge at a constant voltage. The main degradation products are sulfur dioxide SO2, carbonyl sulfide COS, sulfuric acid, and carbon dioxide. Processes occurring in pulsed corona discharge plasma and leading to carbon disulfide degradation are considered. Different methods of air purification from carbon disulfide are compared.

Effect of corona discharge plasma jet treatment on decontamination and sprouting of rapeseed (Brassica napus L.) seeds

Sprout-related outbreaks of foodborne illnesses are increasingly becoming a food safety concern. Different pathogenic microorganisms that originate from sprout seeds are known to play a crucial role in the pathogenesis of such outbreaks. Therefore, in order to decontaminate and also to enhance the germination of seeds, the applications of non-thermal plasma based techniques are increasingly being investigated in the field of agricultural science as an alternative to conventional pre-germination treatments. This work was aimed to evaluate the effectiveness of corona discharge plasma jet (CDPJ) for microbial decontamination of rapeseed seeds, and also studied the plasma treatment effect on the seed germination and physicochemical properties of sprouts (grown from the plasma-treated seeds). Aerobic bacteria, molds and yeast, Bacillus cereus, Escherichia coli, Salmonella spp. were detected as contaminants in the seeds. All the detected microorganisms were reduced in the range of 1.2–2.2 log CFU/g upon the CDPJ treatment for 3 min. The inactivation patterns are better explained using pseudo-first-order kinetics. The plasma treatment of seeds up to 2 min showed positive effects on their germination rate and seedling growth. Physicochemical and sensory characteristics of rape sprouts were unaffected due to the CDPJ treatment of their respective seeds. Therefore, the CDPJ treatment of rapeseed seeds has not only reduced the seed microbial load, but also contributed to the enhancement of their germination rate and seedling growth, without adversely affecting the physicochemical and sensory characteristics of their corresponding sprouts.

Remediation of PAH-contaminated soil by pulsed corona discharge plasma

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic organic pollutants of great environmental and health concern. PAHs are very persisted in soils and sediments which make it very difficult to remove them from soil. Therefore, remediation of PAH-contaminated sites has become an important environmental issue. The objective of this work was to study PAH degradation by pulsed corona discharge plasma system. Phenanthrene (Phe) was used as the model pollutant. The Phe-contaminated soil samples were prepared by adding appropriate amount of Phe dichlormethane solution (200 mg/L) into a given amount of pretreated soil, and Phe distributed uniformly in the soil at about 100 mg/kg. The experimental system mainly consisted of a pulse high-voltage power supply and a reactor vessel. The high-voltage electrode comprised of six stainless-steel needles and the ground electrode was a stainless-steel plate. The concentration of Phe was determined by HPLC system after being extracted out from soil. Effect of run parameters such as pulse voltage, pulse frequency, air flow rate, gas atmosphere, and initial concentration of Phe on Phe degradation was investigated, and the consumption of ozone during discharge process was also studied. The results showed that degradation efficiency of Phe (initial concentration 100 mg/kg) approached approximately 70 % after 40 min of discharge treatment under the conditions of pulse voltage 18 kV, pulse frequency 70 Hz, and air flow rate 0.8 L/min, which increased with the pulse voltage and pulse frequency due to the enhancement of input energy. An optimal air flow rate of 0.8 L/min was observed to obtain a maximum Phe degradation efficiency. Oxygen atmosphere favored Phe degradation due to high concentration of generated O-reagents, and ozone was found to act on Phe degradation. The concentration of Phe had influence on remediation capacity that increased with the amount of Phe in soil. The results confirmed that pulsed corona-discharge plasma was a potential method for remediation of PAH-contaminated soil. This study offered a viable treatment option for remediation of Phe-contaminated soil, which was expected to remove PAHs other than Phe from soil with further development.

Corona discharges with water electrospray for Escherichia coli biofilm eradication on a surface

Low-temperature plasma (cold), a new method for the decontamination of surfaces, can be an advantageous alternative to the traditional chemical methods, autoclave or dry heat. Positive and negative corona discharges in air were tested for the eradication of 48-h Escherichia coli biofilms grown on glass slides.The biofilms were treated by cold corona discharge plasma for various exposure times. Water electrospray from the high voltage electrode was applied in some experiments. Thermostatic cultivation of the biofilm, and confocal laser scanning microscopy (CLSM) of the biofilm stained with fluorescent dyes were used for biocidal efficiency quantification.Up to 5 log10 reduction of bacterial concentration in the biofilm was measured by thermostatic cultivation after exposure to both corona discharges for 15min. This decontamination efficiency was significantly enhanced by simultaneous water electrospray through the plasma. CLSM showed that the live/dead ratio after treatment remained almost constant inside the biofilm; only cells on the top layers of the biofilm were affected. DAPI fluorescence showed that biofilm thickness was reduced by about 1/3 upon exposure to the corona discharges with electrospray for 15min. The biofilm biomass loss by about 2/3 was confirmed by crystal violet assay.

Simulation and Experimental Study for Degradation of Organic Dyes Using Dual pin‐to‐plate Corona Discharge Plasma reactors for Industrial Wastewater Treatment

AbstractThis work researches the possibility of increasing the dye removal efficiency from wastewater using nonthermal plasma. A study for the optimal air gap distance between dual pin and surface of Acid Blue 25 dye solution and thickness of ground plate is carried out using 3D‐EM simulator to find maximum electric field intensity at the tip of both pins. The consequences display that the best gap for corona discharge is approximately 5 mm using 15 kV source. In addition, the optimum plate thickness is 0.1 mm. These distance and thickness were mentioned are constant during the study of other factors. Dual pin‐to‐plate high‐voltage corona discharge plasma system is presented to investigation experimentally the gap distance, thickness of ground plate, initial dye concentration, pH solution and conductivity on the amount of Acid Blue 25 dye color removal efficiency from wastewater. There is a large consensus among the simulation and experimental work in the air gap and thickness of ground plate. Where the decolorization for air gap 5 mm is 95.74 at time 35 min compared with 91% and 17% for 1 mm and 20 mm gap distance respectively. Also, the discharge energy at each air gap are calculated. Measurement results for the impact of thickness of an Aluminum ground plate on color removal competence showed color removal efficiencies of 86.3%, 90.78% and 98.06%, after treatment time 15 min for thicknesses of 2, 0.5 and 0.1 mm respectively. The decolorization behavior utilizing dual pin‐to‐plate corona discharge plasma system display 82% pigment evacuation proficiency inside 11min. The complete decolorization was accomplished within 28min for distinctive examined introductory color focuses 5 ppm up to 100 ppm. Likewise, the impacts of conductivity by utilizing diverse salts as AlCl3, CaCl2, KCl and NaCl and with distinctive focuses have been explored. The rising of the solution conductivity leads to the reduction of decolorization efficiency. The decolorization efficiency and discharge energy are calculated at different concentration molarity for AlCl3, CaCl2, KCl and NaCl. It was observed that the presence of salts at the same concentration level substantially decreased the rate and the extent of decolorization. The results indicate that the optimum pH for the decolorization of Acid Blue 25 dye is in the range between 3 and 6. Furthermore the conductivity and discharge energy were measurement at each value of pH. Energy yield for decolorization and Electrical Energy per Order (EE/O) under different initial pH value were calculated. A kinetic model is used to define the performance of corona discharge system under different value of pH. The model of pseudo ‐zero, pseudo‐first order, and pseudo‐second order reactions kinetic are utilized to investigate the decolorization of Acid Blue 25 dye. The rate of degradation of Acid Blue 25 dye follows the pseudo‐first order kinetics in the dye concentration. Energy consumption requirements for decolorization was considered. The outcomes will be useful for designing the plasma treatment systems suitable for industrial wastewaters. (© 2016 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Reducing fouling of polyethersulfone microfiltration membranes by corona air plasma

In this study, the surface of polyethersulfone (PES) microfiltration membranes was modified by corona discharge plasma in order to improve the antifouling properties and separation performance of the membranes. For this purpose, the PES microfiltration membranes were fabricated by the vapor-induced phase inversion coupled with the nonsolvent-induced phase inversion technique. The effect of the corona power and exposure time on the surface properties and separation performance of the membranes for microfiltration of skim milk was studied. The analysis of the filtration transport resistances was also performed to evaluate the antifouling performance of the corona-modified membranes. The results indicated that the exposure time and applied power of the corona treatment had effects on the membrane surface modification as the surface hydrophilicity, wettability, and morphology of the membranes were significantly changed depending on the corona modification conditions. Moreover, the analysis of the transport resistances revealed that the cake resistance was the main resistance to transport and the fouling, cake and total filtration resistances for the corona-modified PES membranes were low in comparison to the neat PES membranes, which implies that the fouling tendency of the PES membranes modified by the corona air plasma was considerably reduced.

Preparation of zeolite nanorods by corona discharge plasma for degradation of phenazopyridine by heterogeneous sono-Fenton-like process

The plasma-modified clinoptilolite (PMC) nanorods were prepared from natural clinoptilolite (NC) utilizing environmentally-friendly corona discharge plasma. The PMC and NC were characterized by XRD, FT-IR, SEM, EDX, XPS and BET, which confirmed the nanocatalyst formation. The catalytic performance of the PMC in the heterogeneous sono-Fenton-like process was greater than the NC for treatment of phenazopyridine (PhP). The desired amounts were obtained for experimental parameters including initial pH (5), PMC dosage (2g/L), K2S2O8 concentration (2mmol/L), ultrasonic power (300W) and PhP concentration (10mg/L). Reactive oxygen species scavengers decreased the removal efficiency of the PhP. The treatment process followed pseudo-first order kinetic and seven degradation intermediates were identified by the GC–MS technique.

Effect of corona discharge plasma jet on surface-borne microorganisms and sprouting of broccoli seeds.

Different pathogenic microorganisms have been reported to cause sprouts-associated outbreaks. In order to sterilise and enhance the germination of seeds, non-thermal plasma has been increasingly investigated in the field of agricultural science as an alternative to the traditional pre-sowing seed treatments. This work aimed to evaluate the effect of corona discharge plasma jet (CDPJ) on disinfection of the natural bio-contaminants of broccoli seed and also studied the plasma effect on sprout seed germination rate and physico-chemical properties of sprouts. Aerobic bacteria, moulds and yeasts, B. cereus, E. coli, Salmonella spp. were detected on the broccoli seed surface. After 0-3 min treatment using CDPJ, the detected microorganisms were reduced in the range of 1.2-2.3 log units. Inactivation patterns were better explained using pseudo-first-order kinetics. The plasma treatment of seeds up to 2 min exhibited a positive effect on germination rate, seedling growth. The physico-chemical and sensory characteristics of sprouts were unaffected due to the CDPJ treatment of their respective seeds. Corona discharge plasma jet can potentially be used for microbial decontamination of broccoli seeds. In addition, the plasma treatment of broccoli sprout seeds has enabled a significant enhancement in their germination rate and seedling growth without compromising physico-chemical and sensory characteristics of their corresponding sprouts. © 2016 Society of Chemical Industry.

Microbial Decontamination of Dried Alaska Pollock Shreds Using Corona Discharge Plasma Jet: Effects on Physicochemical and Sensory Characteristics.

Nonthermal techniques for microbial decontamination are becoming more common for ensuring food safety. In this study, a corona discharge plasma jet (CDPJ) was used for inactivation of microbial contaminants of dried Alaska pollock shreds. Corona plasma jet was generated at a current strength of 1.5 A, and a span length of 25 mm was maintained between the electrode tip and the sample. Upon the CDPJ treatment (0 to 3 min) of dried shreds, microbial contaminants namely aerobic and marine bacteria, and Staphylococcus aureus were inactivated by 2.5, 1.5, and >1.0 log units, respectively. Also, a one-log reduction of molds and yeasts contaminants was observed. The inactivation patterns are fitted well to the pseudo-first-order kinetics or Singh-Heldman model. The CDPJ treatment did not exert statistically significant (P > 0.05) changes in physicochemical properties, namely color characteristics, volatile basic nitrogen, and peroxide value of dried fish shreds, with some exceptions, as compared to untreated controls. Furthermore, CDPJ treatment had no significant impact on the sensory characteristics of dried fish shreds.

Long-Time Stability of Catalytic Coatings on the Basis of Nanoporous TiO2 under the Influence of Corona Discharge Plasma in Air

ABSTRACTThe present paper contains results of the experimental researches of structure properties of the catalytic coating based on the nanoporous TiO2 film affected by corona-discharge plasma in air atmosphere under atmospheric pressure in the test system of needle-plane electrodes. Coating of the plate electrode was found to influence insignificantly on the discharge current-voltage characteristic, however if there is a coating on the plane electrode surface, an offset is observed towards lower currents under constant voltage at the gap. Obtained data on the surface morphology change shows that under negative corona erosion of the nanoporous TiO2 coating surface is practically absent and under positive corona, decrease of the coating thickness is observed.

Properties of corona discharge plasma near metal surface

Properties of corona discharge near metallic surface were researched. Electrical oscillations in discharge plasma of 1 kHz - 100 MHz rate were registered. Spectrum of electrical oscillations in this range was obtained. Possible plasma waves for observed electronic oscillations explanation are discussed.

Upgrading of anisole using in situ generated hydrogen in pin to plate pulsed corona discharge

In this paper, corona discharge plasma was used for upgrading of anisole as a model compound of lignin derived bio-oil. The required H2was generatedin situ viamethyl decomposition to H2.

Discharge processes and an electrical model of atmospheric pressure plasma jets in argon

In this paper, an atmospheric pressure plasma discharge in argon was generated using a needle-to-ring electrode configuration driven by a sinusoidal excitation voltage. The electric discharge processes and discharge characteristics were investigated by inspecting the voltage-current waveforms, Lissajous curves and lighting emission images. The change in discharge mode with applied voltage amplitude was studied and characterised, and three modes of corona discharge, dielectric barrier discharge (DBD) and jet discharge were identified, which appeared in turn with increasing applied voltage and can be distinguished clearly from the measured voltage-current waveforms, light-emission images and the changing gradient of discharge power with applied voltage. Based on the experimental results and discharge mechanism analysis, an equivalent electrical model and the corresponding equivalent circuit for characterising the whole discharge processes accurately was proposed, and the three discharge stages were characterised separately. A voltage-controlled current source (VCCS) associated with a resistance and a capacitance were used to represent the DBD stage, and the plasma plume and corona discharge were modelled by a variable capacitor in series with a variable resistor. Other factors that can influence the discharge, such as lead and stray capacitance values of the circuit, were also considered in the proposed model.

Destructive effect of atmospheric pressure pulsed corona discharge plasma in air on biofilms of opportunistic bacteria

Импульсный коронный разряд (ИКР) средней частоты в воздухе способен оказывать бактерицидное и бактериостатическое действие на культуру Escherichia сoli М17 как на клеточном, так и на популяционном уровне. Действие ИКР препятствует формированию микробного сообщества и приводит к деструкции уже образованных биопленок. В работе представлены данные электронно-микроскопических исследований ультраструктуры клеток и биопленок после их обработки ИКР в течение 90 секунд. Изменения морфологических свойств клеток E. сoli M17, вызванные обработкой ИКР, подобны изменениям после сублетального и летального теплового воздействия. Библиогр. 32 назв. Ил. 6.

Evaluation and Optimization of Electrode Configuration of Multi-Channel Corona Discharge Plasma for Dye-Containing Wastewater Treatment**supported by China's Postdoctoral Science Foundation (No. 2014M562460), the Initiative Funding Programs for Doctoral Research of Northwest A&F University (No. 2013BSJJ121), and National Natural Science Foundation of China (No. 21107085)

A discharge plasma reactor with a point-to-plane structure was widely studied experimentally in wastewater treatment. In order to improve the utilization efficiency of active species and the energy efficiency of this kind of discharge plasma reactor during wastewater treatment, the electrode configuration of the point-to-plane corona discharge reactor was studied by evaluating the effects of discharge spacing and adjacent point distance on discharge power and discharge energy density, and then dye-containing wastewater decoloration experiments were conducted on the basis of the optimum electrode configuration. The experimental results of the discharge characteristics showed that high discharge power and discharge energy density were achieved when the ratio of discharge spacing to adjacent point distance (d/s) was 0.5. Reactive Brilliant Blue (RBB) wastewater treatment experiments presented that the highest RBB decoloration efficiency was observed at d/s of 0.5, which was consistent with the result obtained in the discharge characteristics experiments. In addition, the biodegradability of RBB wastewater was enhanced greatly after discharge plasma treatment under the optimum electrode configuration. RBB degradation processes were analyzed by GC-MS and IC, and the possible mechanism for RBB decoloration was also discussed.

Combination of pulsed corona discharge plasma and gamma-Al 2 O 3 -supported catalysts for polycyclic aromatic hydrocarbon removal in soil

Abstract Removal of polycyclic aromatic hydrocarbon (PAH) in soil by pulsed corona discharge plasma with γ-Al2O3-supported catalysts was studied at normal temperature and atmospheric pressure. Phenanthrene (Phe) was used as the model pollutant. Spontaneous CuO/γ-Al2O3, MnO2/γ-Al2O3, Fe2O3/γ-Al2O3 or TiO2/γ-Al2O3 was added into plasma system. Phe removal, energy efficiency and catalytic property were investigated. The results showed that prepared γ-Al2O3-supported catalysts all exhibited catalytic effects on Phe removal from soil. Removal efficiencies of Phe were improved by 14.1%, 21.4%, 16.5% and 9.1% in 40 min at 5 wt% amount of CuO/γ-Al2O3, MnO2/γ-Al2O3, Fe2O3/γ-Al2O3 and TiO2/γ-Al2O3, respectively. The energy efficiency increased when pulsed corona discharge plasma was combined with catalysts. As each catalyst dosage was increased from 5 wt% to 23 wt%, the energy efficiency of the reactor with discharge alone was further increased by approximately 20%–40%. Furthermore, the catalysts kept stable activity in Phe removal after five times reuse cycle. Effect of pulsed corona discharge plasma on physicochemical properties of catalysts were evaluated through XRD and BET characterization. This study implied a promising combined-application of γ-Al2O3-supported catalysts and pulsed corona discharge plasma for the removal of PAH in soil.

Corona discharge plasma jet for inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on inoculated pork and its impact on meat quality attributes

Corona discharge plasma jet (CDPJ) was used for inactivation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated experimentally onto the surfaces of fresh and frozen pork. CDPJ was generated with an output voltage of 20 kV direct current and a frequency of 58 kHz. Optimal inactivation was found with plasma created at a current of 1.5 A, and at a span length of 25 mm between the plasma electrode tip and the sample. Following CDPJ treatment (0–120 s) of pork samples, reductions in E. coli O157:H7 and L. monocytogenes were 1.5 log and >1.0 log units, respectively. The inactivation pattern fitted well to the Singh-Heldman model or pseudo-first-order kinetics. Compared to untreated pork, with the exception of color and appearance, no statistically significant (P > 0.05) changes were observed in volatile basic nitrogen, peroxide value, or 2-thiobarbituric acid reactive substances of CDPJ-treated pork. Furthermore, CDPJ treatment had no significant impact on the sensory characteristics of frozen pork although there was some effect on unfrozen pork.

Hand-held portable desorption atmospheric pressure chemical ionization ion source for in situ analysis of nitroaromatic explosives.

A novel, lightweight (0.6 kg), solvent- and gas-cylinder-free, hand-held ion source based on desorption atmospheric pressure chemical ionization has been developed and deployed for the analysis of nitroaromatic explosives on surfaces in open air, offering portability for in-field analysis. A small, inexpensive, rechargeable lithium polymer battery was used to power the custom-designed circuitry within the device, which generates up to ±5 kV dc voltage to ignite a corona discharge plasma in air for up to 12 h of continuous operation, and allowing positive- and negative-ion mass spectrometry. The generated plasma is pneumatically transported to the surface to be interrogated by ambient air at a rate of 1-3.5 L/min, compressed using a small on-board diaphragm pump. The plasma source allows liquid or solid samples to be examined almost instantaneously without any sample preparation in the open environment. The advantages of low carrier gas and low power consumption (<6 W), as well as zero solvent usage, have aided in developing the field-ready, hand-held device for trigger-based, "near-real-time" sampling/ionization. Individual nitroaromatic explosives (such as 2,4,6-trinitrotoluene) can be easily detected in amounts as low as 5.8 pg with a linear dynamic range of at least 10 (10-100 pg), a relative standard deviation of ca. 7%, and an R(2) value of 0.9986. Direct detection of several nitroaromatic compounds in a complex mixture without prior sample preparation is demonstrated, and their identities are confirmed by tandem mass spectrometry fragmentation patterns.