Pressure Glow Discharge Plasma Research Articles

Degradation of methylene blue through atmospheric pressure glow discharge plasma treatment

The degradation of Methylene Blue (MB) dye through treatment with an atmospheric pressure glow discharge plasma is presented in this work. The set-up used in this work has the advantage of being very simple without any gas supply. Plasma was diagnosed using optical emission spectroscopy, and rotational temperature of the hydroxyl radicals was measured. The effects of plasma current, treatment time, polarity and material of the electrodes on degradation of MB dye were studied. Experimental results showed that the degradation of dye increased with plasma current and treatment time. Polarity of the electrodes also have an effect in that the liquid cathode mode has about 14% higher degradation efficiency than liquid anode mode. Interestingly, it was found that anodic dissolution of copper electrode aids in degradation of MB dye by initiating Fenton like reactions involving copper ions, which was absent in the case of stainless steel electrode. After 40 min of treatment, the maximum degradation efficiency and COD removal rate achieved was 77% and 74% respectively, while the degradation yield obtained was 0.32 g.kW–1.h–1.

Synthesis of magnesium oxide and zinc oxide powders in a glow discharge plasma at atmospheric pressure

Investigation of the processes involved in the synthesis of magnesium oxide and zinc oxide powders using the thermal effects of an atmospheric-pressure glow discharge plasma in an inert gas flow are described. The discharge operates in a repetitively pulsed mode with pulse repetition rate of several tens of kilohertz and pulse duration up to 12 μs, discharge current of 600 mA and voltage up to 300 V. These parameters lead to thermal erosion of magnesium or zinc inserts in a molybdenum crucible. The chemical and phase composition of the erosion products were determined using TEM/EDS and X-ray diffraction analysis, and the composition of the plasma was assessed by optical emission spectrometry. This experimental approach allows fabrication of powders of these metal oxides with characteristic particle size 10–50 nm, and the formation of coatings of these materials in a one-step process.

Determination of arsenic and antimony by atmospheric pressure glow discharge portable emission spectrometer with solid acid hydride generation

In this work, the use of solid acid hydride generation (HG) for the simultaneous determination of As and Sb in environmental water samples by miniaturized atmospheric pressure glow discharge plasma optical emission spectrometer (APGD-OES) was evaluated. It was found that HG with the use of sulfamic acid tablets can achieve comparable sensitivity with conventional HCl-KBH4 for As and Sb determination by APGD-OES, which avoids the safety issue encountered in the use of hydrochloric acid and greatly facilitates field analysis. Under optimal conditions, the obtained detection limits (LODs) are as low as 1.26 μg L−1 for As and 0.72 μg L−1 for Sb, respectively. Moreover, it offers good repeatability, where the relative standard deviations (RSDs) are less than 2.5%. The accuracy of the proposed method was validated by the analysis of simulated natural water reference samples. Furthermore, it has been successfully applied to the determination of tap water, pond water, and hot spring samples. All these results clearly demonstrate the proposed simple, cost-effective and field-deployable method provides a promising approach for the field analysis of As and Sb.

AC-driven atmospheric pressure glow discharge co-improves conversion and energy efficiency of CO2 splitting

Gap distance and discharge power have great influence on the morphology and characteristics of glow plasma. Unfortunately, there is few research on the influence law and mechanism of these factors for CO2 splitting by glow plasma. In this study, an AC-driven atmospheric pressure glow discharge (APGD) plasma reactor was developed for CO2 splitting. Through the rational design on the plasma reactor accompanied by numerical simulation and systematic experimentation, the unique influence laws and mechanisms on CO2 splitting behavior are unveiled. Several key parameters, such as gap distance, discharge power and gas flow rate, are found able to play synergistic roles in tailoring plasma reactor to co-improve the conversion and energy efficiency. At an optimized gap distance, sufficient electron collisions along the main channel results in the largest active plasma volume, leading to the optimal CO2 splitting performance. The conversion and energy efficiency could also be co-improved by synchronously increasing the discharge power and gas flow rate at a given specific energy input (SEI) value, which exhibits an opposite feature of dielectric barrier discharge (DBD) plasma, because larger plasma volume increases the probability of collision dissociation reaction and lower gas temperature decreases the rate of recombination reaction. The AC-driven APGD reactor can achieve maximum conversion of 11.96% and maximum energy efficiency of 41.51% which superior to the results of most atmospheric pressure plasmas. This work gains insights into the behaviors of AC-driven APGD plasma in CO2 splitting and potentially opens an avenue to develop plasma technology for sustainable CO2 utilization.

Atmospheric pressure glow discharge plasma sintering of solvent-free silver lines made by laser ablation dry aerosol printing

Atmospheric pressure glow discharge plasma sintering of solvent-free silver lines made by laser ablation dry aerosol printing

Development of breathable and liquid/wet bacterial penetration barrier composite laminated fabrics for surgical gown applications

Disposable surgical gowns are used to protect health care workers from microorganisms and body fluids to meet the needs of surgical applications. In addition to protection, it has a significant impact on the surgical team members’ comfort and thus, the success of the operations. In this study, a dual layer surgical gown-an outer layer of film and an inner layer of nonwoven fabric-was developed. Produced composite laminated fabrics are SMS (spunbond/meltblown/spunbond) nonwoven fabric laminated microporous polyethylene film and SMS (spunbond/meltblown/spunbond) nonwoven fabric laminated thermoplastic polyurethane films. These fabrics were compared with nonporous polyethylene film-coated SS (spunbond/spunbond) nonwoven fabric available in the local market. The study aims to investigate the effect of some structural factors of composite nonwoven laminated fabrics, including lamination process, manufacturing process, and film type; microporous or monolithic, nonwoven fabric manufacturing process, and helium atmospheric-pressure glow discharge plasma treatment, on their functional performance properties, including air permeability, water vapour permeability, hydrostatic pressure resistance, and wet bacterial penetration resistance. The results showed that the produced composite fabrics offer outstanding breathability and, thus, the surgical team members' comfort. Produced composite fabrics had no wet bacterial penetration of Staphylococcus aureus and thus contributed to the prevention of the transfer of bacterial pathogens to prevent surgical site infection or post-operative infection. Produced composite fabrics offer superior liquid barriers according to the barrier protection classification of the Association for the Advancement of Medical Instrumentation (ANSI/AAMI PB 70:12) and thus contribute to the prevention of the transfer of body fluids during surgical operations.

Characterization and evaluation of cold atmospheric plasma as seedborne fungal disinfectant and promoting mediator for physico-chemical characteristics of Moringa oleifera seedlings

Non-thermal atmospheric pressure plasmas are a powerful tool to impact seed germination and microbial decontamination. Air large volume atmospheric pressure glow discharge plasma was developed and investigated to improve the biological activities of Moringa oleifera seeds. Ninty ns magnetic pulse compression high voltage system was used to generate the plasma. The plasma discharges current increases with increasing applied voltage and it decreases with increasing discharge gap. There was a steady reduction in the count of seedborne fungi on the application of air cold plasma with complete elimination of fungi at ≥ 10.94 mJ per pulse. The low doses of plasma (2.46 and 4.35 mJ) induced an increase in the seed germination, a significant increase in chlorophyll content (chl a and chl b) and antioxidant activities of the seedlings emerged from soaked or wet seeds rather than dry seeds. At lower plasma doses (2.46 and 4.35 mJ) there was a significant increase in leaf area and chlorophyll content (chl a and chl b) of the seedlings that emerged from H2O2 soaked seeds rather than that of free from H2O2. The plasma was harmful when applied at higher doses (≥ 10.94 mJ) and more harmful to the wet seeds compared to the dry ones.

Increasing DESI-MS Ion Signal by Plasma Treatment.

Many studies are focused on using plasma in mass spectrometry as an ionization source or postionization method. In this study, the effect of plasma treatment in the sample preparation step of desorption electrospray ionization (DESI) has been investigated. The plasma treatment of polar samples, including morphine, codeine, captopril, theophylline, fructose, and amphiphilic compounds such as phosphatidylethanolamine (PE) in E. coli bacteria, as well as nonpolar compounds, including thebaine, papaverine, and noscapine, has been followed for ionization efficiency in DESI technique. An atmospheric-pressure glow discharge plasma (GDP) along with the electrospray ionization technique is examined. Plasma treatment before ambient ionization has a dramatic effect on polar and nonpolar sample signals in DESI-TOF mass spectrometry. The intensity of the mass spectrum shows an increase of 1.9-3.4 times for polar compounds, 2.1-2.5 times for nonpolar compounds, and 3.0 times for PE in E. coli bacteria (N = 4). Plasma is a source of reactive atoms, molecules, ions, radicals, and ultraviolet radiation. Plasma surface treatment before DESI analysis by energetic species through momentum/energy transfer yields higher energy surface molecules, leading to more/easier desorption. Under optimal treatment conditions, an improved ion signal intensity is observed without any fragmentation, decomposition, or chemical changes. Ion signals are increased possibly by both increased ionization through protonation of molecules and enhanced subsequent desorption during DESI analysis.

Dry reforming of methane in an atmospheric pressure glow discharge: Confining the plasma to expand the performance

We present a confined atmospheric pressure glow discharge plasma reactor, with very good performance towards dry reforming of methane, i.e., CO2 and CH4 conversion of 64 % and 94 %, respectively, at an energy cost of 3.5–4 eV/molecule (or 14–16 kJ/L). This excellent performance is among the best reported up to now for all types of plasma reactors in literature, and is due to the confinement of the plasma, which maximizes the fraction of gas passing through the active plasma region. The main product formed is syngas, with H2O and C2H2 as by-products. We developed a quasi-1D chemical kinetics model, showing good agreement with the experimental results, which provides a thorough insight in the reaction pathways underlying the conversion of CO2 and CH4 and the formation of the different products.

Evaluation of solution-cathode glow discharge atomic emission spectrometry for the analysis of nanoparticle containing solutions

The Solution Cathode Glow Discharge (SCGD) is a novel atmospheric-pressure glow discharge plasma sustained in the ambient atmosphere that is an appealing alternative to the inductively-coupled plasma as a source for atomic emission spectrometry. Simple, low power, and inexpensive, the SCGD is an attractive source for continuous environmental monitoring applications such as the quantitation of metallic nanoparticle solutions by atomic emission spectrometry. Metallic nanoparticles (NP) with diameters from 5 nm-150 nm were directly analyzed by SCGD-AES and found to exhibit lower, and size-dependent, elemental sensitivity when compared to dissolved free-ion standard solutions. Acid digestion with matrix-matching was shown to be an effective approach to achieve accurate quantitation. The origin of these morphological matrix effects was studied by investigating experimental parameters such as discharge power, solution flow rate, and influence of added surfactants. Examination of the spatial distribution of atomic emission between cathode and anode showed a shift in peak atomic emission towards the anode of the SCGD for some NPs as compared to free-ion solutions. A novel nested capillary design was used to introduce NP into the SCGD without dissolution within the acidic solvent and showed difference in sensitivity from free-ion solutions to be a NP morphological effect. Correlation of NP boiling point with difference in sensitivity between free-ion and NP solutions supports the conclusion that delayed vaporization of nanoparticles is the source of the morphological matrix effect, due primarily to lower rate of vaporization within the SCGD by lower gas temperatures and short residence time. Analysis of NP of different chemical form, and alloyed nanoparticles composed of more than one element, showed correlation with boiling point. Implications of these results on the possible mechanisms by which material is transferred from the liquid cathode into the plasma are considered.

Determination of bismuth by optical emission spectrometry with liquid anode/cathode atmospheric pressure glow discharge

Novel atmospheric pressure glow discharge (APGD) plasma systems, sustained between a miniaturized flowing liquid anode (FLA) or cathode (FLC) and a He nozzle jet, were investigated for the determination of Bi by optical emission spectrometry (OES).

The double coupled microwave resonance probes and application for diagnosing atmospheric pressure plasma jet

The double-coupled microwave resonance probe (DMRP) based on the hairpin probe is proposed for diagnosing atmospheric plasma jet (). In this work, the resonance characteristics of DMRP are investigated by numerical simulation. It shows that two resonance peaks on the reflectance spectrum can be observed, and influenced significantly by some parameters, such as the probe separation, the distance to the handheld radio frequency atmospheric pressure glow discharge plasma jet (RF-APGDPJ) and the plasma electron density less than 1017 m−3. Based on two resonance modes of DMRP, the electron densities in the afterglow of RF-APGDPJ at the different rf powers and helium flow rates are diagnosed experimentally by matching the change of FWHM ( and ) measured by vector network analyzer with the simulated relation between the FWHM changes and the plasma density.

The effect of atmospheric pressure glow discharge plasma treatment on the dyeing properties of silk fabric

In this study, the effects of plasma treatment parameters on surface morphology, chemical constituent, dyeability and color fastness of silk fabric were investigated. Atmospheric pressure glow discharge plasma generated with different applied voltages (0 kV to 45 kV) was used to treat the surface of silk fabrics. C I Natural Yellow 3 was used to dye untreated and plasma-treated silk fabrics. The physical analysis based on scanning electron microscopy showed that the surface of silk fabrics was affected by plasma treatment. The chemical analysis was investigated with x-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. The results showed that the content of C 1s decreased with the increasing applied voltage, the content of N 1s and O 1s increased with the increasing applied voltage. The increasing K/S values represented that the dyeability of silk fabrics was improved after plasma treatment. The color fastness to dry and wet rubbing was decreased after plasma treatment.

Development of atmospheric pressure glow discharge plasma assisted CVD system for the deposition of SiOx coatings

A novel, unique and self-designed radio frequency-based atmospheric pressure glow discharge plasma assisted chemical vapor deposition system (APGD-PACVD) has been developed indigenously for the deposition of SiOx coatings. The developed system has been evaluated for continuous, stable and low temperature plasma source for the deposition of adherent and uniform SiOx thin films on silicon substrates using a plasma of argon, helium and hexamethyldisiloxane (HMDSO) gases. The SiOx films deposited on silicon substrates were characterized by Fourier transform infrared spectroscopy (FTIR), field emmision scanning electron microscopy (FESEM) and energy dispersive x-ray analysis (EDXA) for confirmation of chemical structure of the coating. The results demonstrate the deposition of uniform and adherent SiOx films on silicon.

A Convenient Method to Realize Large-Area APGD for Wool Surface Modification

In this paper, a method of realizing large-area atmospheric pressure glow discharge (APGD) plasma in ambient air was investigated. The dielectric barrier discharge (DBD) type was adopted, and the electrode arrangement of a tubular array was designed to achieve large-area APGD (about $1000 \times 60$ mm $^{2}$ ). Optical emission spectroscopy (OES) was used to identify active particles and calculate gas temperature. The results show that the seed electrons can react with N2, O2, and H2O in the air to produce N2 (C-B), N2+, OH, and O3. The gas temperature was calculated to be 410 K–514 K, which is suitable for low-added-value materials treatment. The homogeneity of the plasma temperature was also verified by an infrared camera. Furthermore, a prototype for the wool surface modification was also investigated. The scanning electron microscope (SEM) micrographs and wettability test were adopted, which shows that the plasma can damage the squamae of the natural wool to improve the wettability greatly without burning the wool fiber.

The effect of APGD plasma treatment on silk fabric

ABSTRACTIn this study, silk fabrics were treated with Atmospheric Pressure Glow Discharge (APGD) plasma in the air at a discharge voltage of 35 kV and frequency of 20 kHz. C.I. (Color Index) Natural Yellow 3 was used as a natural dye. The effect of APGD plasma treatment time on the dyeability and colour fastness of silk fabrics has been investigated. The influence of plasma treatment on the surface morphology of silk fabric was characterised using Scanning electron microscopy. X-ray photoelectron spectroscopy measurement showed that the content of nitrogen and oxygen increased with the increasing APGD plasma treatment time. Attenuated Total Reflection Fourier Transform Infrared spectroscopy was used to characterise the functional groups such as –OH, –NH and –COOH on the surface of silk fabrics. The dyeability of silk fabrics was increased obviously after APGD plasma treatment, and the colour fastness of the dyed samples was satisfactory.

Study on formation mechanism of atmospheric pressure glow discharge air plasma jet

Based on the results of needle electrode discharge experiments and electric field simulations, this study proposes a tip extensional ionization theory for explaining the formation mechanism of atmospheric pressure glow discharge (APGD) plasma jets. Under the condition of DC power supply, atmospheric pressure glow discharge (APGD) air plasma jets are realized without airflow. It is found that the necessary initial electrons for discharge are derived from free electrons in space, residual electrons, or runaway electrons, and the difference of the electric field intensity between the needle electrode tip and the lateral side of the needle electrode is an essential condition for the formation of the plasma jet. It is further discovered that a space electric field with transitive change is generated in the formation process of the plasma jet, and therefore a phenomenon occurs: the plasma jet generated from the high voltage electrode exceeds the lateral ground potential electrode. This study provides a theoretical basis for the analysis of the formation mechanism of plasma jet under various discharge conditions and promotes further research such as on the formation process of the lightning leader and lightning protection.

Numerical and Experimental Studies on the Interactions Between the Radio-Frequency Glow Discharge Plasma Jet and the Shielding Gas at Atmosphere

It is a useful method to lengthen the cold atmospheric plasma jet with the aid of gas shielding. In this paper, the interactions between the shielding gas and the radio-frequency atmospheric-pressure glow discharge plasma jet are studied numerically and experimentally. The modeling results show that both the chemical compositions and flowrates of the shielding gas strongly influence the characteristics of the plasma jets. A long helium-shielding plasma jet with a length of 34-35 mm is obtained. The predicted lengths of the plasma shielding jets under specified operating conditions are qualitatively consistent with the experimental measurements.

Investigations on the transformation of vertically aligned CNTs to intramolecular junctions by atmospheric pressure PECVD

Atmospheric pressure glow discharge plasma assisted chemical vapor deposition process is used for the growth of carbon nanotubes (CNTs) on Inconel without using any external catalyst. Four different sets of samples are prepared by varying the growth time. The grown nanostructures are then characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. Field emission measurements are also done on the grown structures. Our investigations revealed that vertically aligned CNTs transformed into intramolecular junctions of CNTs with an increase in deposition time from 4 to 10 min. This time dependence for the transformation is investigated and correlated with other characterization results. It is seen that field emission behavior is the best for the vertically aligned CNTs but it also improves when the junctions of CNTs are present in the matrix after increasing growth time to 15 min. The investigations reveal that branching brings favorable defects in the grown CNTs that can give rise to impressive field emission current density. A schematic model has been prepared based on the experimental findings to find out the reason behind the growth of these junctions and how did they help in improving field emission.

Study of surface atmospheric pressure glow discharge plasma based on ultrathin laminated electrodes in air

A method to generate large-area surface plasma in air by micro-discharge is proposed. Two ultrathin laminated electrode structures of non-insulating and insulating types were formed by using the nanoscale ITO conductive layer. The surface glow discharge in atmospheric air is realized in low discharge voltage by constructing the special electric field of two-dimensional unidirectional attenuation. In particular, the insulating electrode structure can avoid the loss of ITO electrodes so that the discharge stability can be increased, and the treated objects can be prevented from metal ion pollution caused by the electrode in the discharge. It has broad application prospects in the fields of aerodynamics and material surface treatment.