Non-thermal Plasma Technology Research Articles

Core-Shell Nanoparticles for Pulmonary Drug Delivery.

Nanoscale drug delivery systems have provoked interest for application in various therapies on account of their ability to elevate the intracellular concentration of drugs inside target cells, which leads to an increase in efficacy, a decrease in dose, and dose-associated adverse effects. There are several types of nanoparticles available; however, core-shell nanoparticles outperform bare nanoparticles in terms of their reduced cytotoxicity, high dispersibility and biocompatibility, and improved conjugation with drugs and biomolecules because of better surface characteristics. These nanoparticulate drug delivery systems are used for targeting a number of organs, such as the colon, brain, lung, etc. Pulmonary administration of medicines is a more appealing method as it is a noninvasive route for systemic and locally acting drugs as the pulmonary region has a wide surface area, delicate blood-alveolar barrier, and significant vascularization. A core-shell nano-particulate drug delivery system is more effective in the treatment of various pulmonary disorders. Thus, this review has discussed the potential of several types of core-shell nanoparticles in treating various diseases and synthesis methods of core-shell nanoparticles. The methods for synthesis of core-shell nanoparticles include solid phase reaction, liquid phase reaction, gas phase reaction, mechanical mixing, microwave- assisted synthesis, sono-synthesis, and non-thermal plasma technology. The basic types of core-shell nanoparticles are metallic, magnetic, polymeric, silica, upconversion, and carbon nanomaterial- based core-shell nanoparticles. With this special platform, it is possible to integrate the benefits of both core and shell materials, such as strong serum stability, effective drug loading, adjustable particle size, and immunocompatibility.

Non-thermal plasma enhances rice seed germination, seedling development, and root growth under low-temperature stress

Recently, non-thermal plasma (NTP) technologies have found widespread application across diverse fields, including plant growth, medical science, and biological and environmental research. Rice (Oryza sativa L.) is exceptionally sensitive to temperature changes. Notably, low-temperature stress primarily affects the germination and reproductive stages of rice, often leading to reduced crop yield. This study aimed to identify optimal conditions for enhancing rice seed germination and seedling growth under low temperatures using NTP technology. Our research indicated that NTP treatment at 15.0 kV for 30 s optimally promotes rice seed germination and growth under low-temperature stress. Furthermore, NTP treatment increases the activity and expression of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), under low-temperature conditions. Moreover, it downregulates the expression of β-ketoacyl-[acyl carrier protein] synthase I (KASI) and cis-epoxy carotenoid dioxygenase 3 (NCED3) and upregulates the expression of alternative oxidase (AOX1B), BREVIS RADIX-like homologous gene (BRXL2), WRKY transcription factor 29 (WRKY29), and EREBP transcription factor 2 (EREBP2) in roots after tandem 7 days low-temperature (16 ℃) and 7 days room-temperature (28 ℃) treatments. Transcriptomic analysis revealed the involvement of various key genes in phosphotransferase activity, phosphate-containing compound metabolic processes, and defense responses. These analyses provide comprehensive information on gene expression at the transcriptional level, offering new insights for a deeper understanding of candidate genes required for root growth in rice.

Physico-chemical surface modification of the natural leather using gliding arc discharge: An in-depth analysis of improving surface and mechanical properties

Leather, a widely used material in various industries, presents challenges in terms of dye uptake, hydrophilicity, and environmental concerns associated with chemical wet processing. In this context, non-thermal plasma technology offers a promising alternative for leather surface modification. In this study, the gliding arc, with air and water vapor plasmas, was used for the surface modification of natural leather for the first time. The influence of the treatment time and also the plasma gas chemistry on the surface chemical bonding, surface morphology, wettability, water absorption time and absorption capacity, color, and mechanical properties of the leather were investigated. The results showed that in the water vapor gliding arc discharge, the produced active oxygen and hydroxyl species can effectively react with the functional groups and break the relatively weak hydrocarbon CH bonds in the chemical composition of the natural leather. SEM images showed increased pore depth and diameter on the leather surface after air and water vapor plasma treatment with mean diameters of 76 μm and 92 μm, respectively. The tensile stress-strain curves illustrated that despite small cracks were created on the plasma treated samples, the elongation at break (ultimate strain) increased from 83.7 % to 88.5 % and 91.8 % for the samples treated with the air and the water vapor plasmas for 5 min, respectively. The water contact angle decreased from 96° to 55° and 48° after only 5-second treatment with the air and the water vapor plasmas, respectively. The same trend was also observed for the water absorption time and the absorption capacity of the treated samples. Also, the color analysis showed that the color change in the plasma treated samples was not detected by the unaided eye. It was also found that water vapor plasma has a better influence on the physico-chemical properties of the leather.

Generation of Plasma-Activated Fluids for Successful Disinfection of Pseudomonas aeruginosa in Liquid Environments and Determination of Microbial Damage

The application of the non-thermal atmospheric pressure plasma technology is a promising tool for microbial inactivation. During the activation process, many reactive substances and radicals arise associated with physicochemical changes in the fluid and massive pH drop. In this study, we analyzed and optimized plasma activation settings and conditions of water and liquids to obtain inactivation of the waterborne microorganism Pseudomonas aeruginosa in a liquid environment. The minimal electrical output was 60 Watt with 20 min activation time followed by 30 min contact time with 108 cells/mL. Using higher electrical power (>90 W) with a Lab Unit generating plasma-activated water, a shorter activation time (<10 min) was sufficient for bacterial inactivation. The organic and inorganic composition of the activated liquid with different mineral salt concentrations is of utmost importance for the yield of reactive species during the plasma activation process and consequently for the antimicrobial effect. Plasma-activated fluids with high organic and inorganic contents demonstrated lower inactivation efficiencies than low loaded fluids; yet antimicrobial efficacy could be achieved by increasing the electrical power and activation time. For sufficient inactivation of bacterial suspensions, at least half a volume unit of plasma-activated water had to be added after appropriately optimized activation. Further dilutions reduced the antimicrobial effect. PAW lost activity after being left standing for a prolonged time after activation, so for maximizing the antimicrobial effect a direct use after activation is recommendable. Bacterial inactivation was shown by the absence of colony forming units on culture media and, at the molecular level, damage to the membrane and inactivation of enzymes were observed. Plasma-activated fluids demonstrated a high potential in applications as microbiological disinfectant in liquids.

Cold atmospheric pressure air plasma jet disinfection of table eggs: Inactivation of Salmonella enterica, cuticle integrity and egg quality

Eggshell cuticles are first lines of defense against egg-associated pathogens, such as Salmonella enterica serovar Enteritidis (SE). Infections from eggs contaminated with this strain remain a significant risk. In addition, changes in the cuticle are closely related to changes in egg safety. The emerging non-thermal atmospheric pressure plasma technology enables a high rate of microbial inactivation at near-ambient temperatures, making it ideal for food safety applications. This study examines the effects of a cold atmospheric pressure air plasma jet (CAAP-J) on eggshell cuticle and egg quality whilst inactivating SE. Shell eggs inoculated with SE (7 log10 cfu/egg) were used as the samples to test the decontamination performance of the device. The tests were conducted using an industrial CAAP-J with different power levels (600–800 W), exposure times (60–120 s), at a fixeddistance of 20 mm from the plasma jet and an air flow rate of 3600 L/h. It was found that the best results were obtained after 120 s at maximum plasma power (800 W). Subsequent to the implementation of this plasma procedure, it was determined that no viable cells could be detected. After CAAP-J treatment, the temperature remains below 50.5 °C, thereby minimizing the risk of altering egg quality. All specific measurements (egg white pH, yolk pH, yolk color, HU, and eggshell breaking strength) have shown that CAAP-J treatment has no negative effect on egg quality. No changes in eggshell cuticle quality after CAAP-J treatment was confirmed through scanning electron microscope (SEM).

Effects and Mechanisms of Non-Thermal Plasma-Mediated ROS and Its Applications in Animal Husbandry and Biomedicine.

Non-thermal plasma (NTP) is an ionized gas composed of neutral and charged reactive species, electric fields, and ultraviolet radiation. NTP presents a relatively low discharge temperature because it is characterized by the fact that the temperature values of ions and neutral particles are much lower than that of electrons. Reactive species (atoms, radicals, ions, electrons) are produced in NTP and delivered to biological objects induce a set of biochemical processes in cells or tissues. NTP can mediate reactive oxygen species (ROS) levels in an intensity- and time-dependent manner. ROS homeostasis plays an important role in animal health. Relatively low or physiological levels of ROS mediated by NTP promote cell proliferation and differentiation, while high or excessive levels of ROS mediated by NTP cause oxidative stress damage and even cell death. NTP treatment under appropriate conditions not only produces moderate levels of exogenous ROS directly and stimulates intracellular ROS generation, but also can regulate intracellular ROS levels indirectly, which affect the redox state in different cells and tissues of animals. However, the treatment condition of NTP need to be optimized and the potential mechanism of NTP-mediated ROS in different biological targets is still unclear. Over the past ten decades, interest in the application of NTP technology in biology and medical sciences has been rapidly growing. There is significant optimism that NTP can be developed for a wide range of applications such as wound healing, oral treatment, cancer therapy, and biomedical materials because of its safety, non-toxicity, and high efficiency. Moreover, the combined application of NTP with other methods is currently a hot research topic because of more effective effects on sterilization and anti-cancer abilities. Interestingly, NTP technology has presented great application potential in the animal husbandry field in recent years. However, the wide applications of NTP are related to different and complicated mechanisms, and whether NTP-mediated ROS play a critical role in its application need to be clarified. Therefore, this review mainly summarizes the effects of ROS on animal health, the mechanisms of NTP-mediated ROS levels through antioxidant clearance and ROS generation, and the potential applications of NTP-mediated ROS in animal growth and breeding, animal health, animal-derived food safety, and biomedical fields including would healing, oral treatment, cancer therapy, and biomaterials. This will provide a theoretical basis for promoting the healthy development of animal husbandry and the prevention and treatment of diseases in both animals and human beings.

Plasma-assisted synthesis of nano-sulfur adsorbent for efficient removal of mercury from flue gas

Adsorbents injection technology is one of the most promising strategies to control mercury emission from flue gas. However, existing literature has shown leaching risk of mercury and halogen from commercial halogen impregnated adsorbents. Therefore, we proposed a novel and convenient fabrication method for nano-sulfur adsorbent assisted with nonthermal plasma technology in order to address these issues. The morphology, number concentration and size distribution of as-obtained nano-sulfur particles was determined by High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Mobility Particle Sizer (SMPS). The mercury adsorption experiments showed nano-sulfur adsorbent (removal efficiency: 88.2 %) was more effective than micron-sized elemental sulfur (less than 10 %). Furthermore, the chemical composition of elemental sulfur allotropes (S6, S7 and S8) was determined using High-performance Liquid Chromatography-Mass Spectrometry (HPLC-MS). It was found that nano-sulfur particles contained higher proportions of S6 (1.53 %) and S7 (1.29 %) allotropes, which are the active materials in elemental sulfur. To investigate the effects of adsorption temperature and simulated flue gas on the performance of nano-sulfur adsorbent, the optimal adsorption temperature of 110 °C was determined, indicating its suitability for coal-fired power plants equipped with a low-temperature electrostatic precipitator system. Additionally, it was observed that simulated flue gas had slight inhibitory effects on the adsorbent performance, with a reduction of approximately 5 % in Hg0 removal efficiency. In summary, this research proposed a novel method for synthesizing nano-sulfur adsorbent and revealed the differences in sulfur allotropes' reactions with mercury, thereby deepening our understanding of the mercury-sulfur reaction mechanism.

Efficient reduction of CO2 to C2 hydrocarbons by tandem nonthermal plasma and photocatalysis

CO2 photoreduction to hydrocarbons is a carbon-neutral technology for renewable energy. However, this strategy is challenged by the thermodynamic stability of CO2 and the low efficiency of multi-photoelectron utilization. In this paper, tandem nonthermal plasma and photocatalysis were used to effectively improve the efficiency of CO2 reduction to C2. We first activated CO2 by nonthermal plasma technology (NTP) and then converted the activated CO2 into C2 products by Cd0.8Zn0.2S/In2O3 photocatalyst with a special nanostructure. Without the addition of any sacrificial agent, the C2 yield of the catalyst reached 0.382 μmol h−1, which is one of the highest performances to date. In situ experimental and computational studies show that CO2+ activated by NTP has higher π orbital and HUMO levels of lone pair electrons and promotes the reduction of CO2+ by injecting electrons into the vacant orbital of the active site of Zn. At the same time, the unique structure of Cd0.8Zn0.2S/In2O3 photocatalyst can extend the life of charge through the optical field enhancement effect, and then react with the CO2+ intermediates generated by NTP technology to promote the coupling of C-C bonds, and finally promote the photocatalytic multi-electron reaction to produce C2 hydrocarbons.

Phenol decomposition by gas–liquid phase discharge treatment with different metal electrodes: A comparison study

In recent years, non-thermal plasma technology as an advanced oxidation process has received increasing attention for wastewater treatment. In previous studies, the discussion about the effects caused by different metal electrodes in the plasma treatment system is limited. In this work, phenol degradation efficiency and H2O2 formation with Al, Ti, Fe, Ni, Cu, W, and Mo electrodes were investigated. The use of Fe, Ni, and Al electrodes results in higher phenol removal, than that using W, Cu, Mo, and Ti electrodes. After 70 min of discharge treatment, phenol was continuously decomposed in the solution in the Fe, Cu, and Mo electrodes systems. High peak voltage promoted phenol degradation and H2O2 generation, especially for Fe, Ti and Ni electrodes. The alkaline condition is more conducive to phenol degradation than the neutral and acidic conditions regardless of the electrode type. Fe, Al, Cu, and Ni electrodes are affected more by the adjustment of the conductivity with Cl− than that with SO42−. The dominant influence on H2O2 production and decomposition could be attributed to the catalysis of metal particles and metal ions produced by electrode erosion. According to the radical quenching experiments, the main radicals in the degradation of phenol when using each electrode material were analyzed.

Regulating oxygen vacancies and hydroxyl groups of α-MnO2 nanorods for enhancing post-plasma catalytic removal of toluene

Although nonthermal plasma (NTP) technology has high removal efficiency for volatile organic compounds (VOCs), it has limited carbon dioxide (CO2) selectivity, which hinders its practical application. In this study, α-MnO2 nanorods with tunable oxygen vacancies and hydroxyl groups were synthesized by two-step hydrothermal process to enhance their activity for deep oxidation of toluene. Hydrochloric acid (HCl) was used to assist in synthesis of α-MnO2 nanorods with tunable oxygen vacancies, furtherly, more hydroxyl groups were introduced to HCl-assisted synthesized α-MnO2 by K+ supplement. The results showed that the as-synthesized nanorods exhibited superior activity, improved by nearly 30% removal efficiency of toluene compared to pristine MnO2 at SIE = 339 J/L, and reaching high COx selectivity of 72% at SIE = 483 J/L, successfully promoting the deep oxidation of toluene. It was affirmed that oxygen vacancies played an important role in toluene conversion, improving the conversion of ozone (O3) and resulting in higher mobility of surface lattice oxygen species. Besides, the enhancement of deep oxidation performance was caused by the increase of hydroxyl groups concentration. In-situ DRIFTS experiments revealed that the adsorbed toluene on catalyst surface was oxidized to benzyl alcohol by surface lattice oxygen, and hydroxyl groups were also found participating in toluene adsorption. Overall, this study provides a new approach to designing catalysts for deep oxidation of VOCs.

Comparing Non-Thermal Plasma and Cold Stratification: Which Pre-Sowing Treatment Benefits Wild Plant Emergence?

Meadow restoration and creation projects have faced a lack of local seed diversity due to the limited availability of seed sources. Non-thermal plasma technologies are being developed for agriculture and do not cause damage to heat-sensitive biological systems. This technology has shown the potential to improve agronomic seed quality by enhancing germination and promoting plant growth. However, there is almost no information about the effect of non-thermal plasma pretreatment on the seedlings' emergence of wild plant species. Therefore, this study aimed to evaluate the effect of non-thermal plasma on the emergence of 17 plant seeds originating from local meadows in Lithuania and compare it with the cold stratification pretreatment. The results obtained indicate that there were differences in emergence parameters among the species. However, NTP did not show statistically significant differences from the control. Non-thermal plasma improved the kinetic parameters of emergence for a few specific species' seeds, such as Anthyllis vulneraria and Prunella grandiflora, while the cold stratification pretreatment enhanced emergence for a broader range of plants. Significant differences were observed between non-thermal plasma and stratification pretreatment, as well as between the control and stratification groups. Both methods also had a negative impact.

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.

Modeling of the inactivation kinetics of aerobic mesophiles and yeasts and molds natural microbiota in nonthermal plasma-treated pineapple (Ananas comosus) juice.

The nonthermal plasma (NTP) technology is a promising nonthermal technology that can be employed for pasteurization of fruit juice. The effect of NTP on the natural microbiota, namely, aerobic mesophiles (AM), and yeasts and molds (YM) in pineapple juice were examined in the experimental range of 25-45kV up to 10min treatment time. At an applied voltage of 45kV, the AM and YM count reductions of 4.7 and 4.1logcfu/mL were obtained at the end of the 14-min treatment. The inactivation kinetics of microbes were attempted to be explained using nonlinear models, including Weibull+tail, Geeraerd, log-logistic, Coroller, and Cerf. The residual population (Nres ) model parameter in the Geeraerd model explained the tailing behavior of microbes. Furthermore, the estimated values for the scale parameter and destruction rate constants were used to describe the sensitive and resistant percentages of the microbial population. According to statistical parameters (R2 : 0.978-0.999, RMSE: 0.034-0.277) and validation indicators (accuracy factor: 1.013-1.152, bias factor: 0.985-1.12), all models performed well. Akaike's theory was used to select the best-fit model, and the Coroller model was shown to be the most accurate one for AM and YM, exhibiting the lowest Akaike increment (Δi =0). PRACTICAL APPLICATION: Nonthermal plasma may be used as an alternate nonthermal process for this product in order to meet customer appeal for safe and nutritious juice with minimal processing. The goal of this work was to produce a nutritious and safe pineapple juice by using nonthermal processing.

The influence of dielectric materials on CO2 conversion performance of pulsed micro-gap cylindrical dielectric barrier discharge reactor

Abstract Dielectric barrier discharge (DBD) is a non-thermal plasma technology that shows promise for CO2 conversion. However, its efficiency depends on plasma processing parameters, reactor design, and reactor material. This study focused on the effect of dielectric barrier material on the CO2 conversion performance of a pulsed micro-gap DBD reactor. The results of this study show that the DBD reactor with alumina dielectric produced better CO2 conversion performance than the quartz reactor, with a maximum CO2 conversion of 50.17% compared to 21.91% with the quartz reactor. The DBD reactor with alumina dielectric produced a greater current peak and a higher number of micro-discharges than the quartz reactor, which suggests that the number of micro-discharges plays a dominant role in the CO2 conversion performance of the DBD reactor. The use of high dielectric constant material with high surface roughness could enhance the CO2 conversion performance of pulsed micro-gap DBD reactors.

Efficient treatment of bio-contaminated wastewater using plasma technology for its reuse in sustainable agriculture

Water-related crisis represents one of the significant challenges of the rapidly growing world population. This study demonstrates an example of the novel technology of Non-Thermal Plasma (NTP) wastewater treatment for its sustainable recovery and reuse in agriculture. NTP treatment of wastewater not only causes microbial decontamination but produces Reactive Oxygen and Nitrogen Species (RONS), which can consequently improve seed germination and plant growth. We investigated the effects of the new Fountain Dielectric Barrier Discharge air plasma reactor for the treatment of bulk quantity water contaminated by Staphylococcus epidermidis or Escherichia coli bacteria. Then, employing the treated water for barley seed germination showed >20% enhancement compared to using tap water. The inactivation of bacteria in water was determined in dependence on pH, Oxidation-Reduction Potential, and correlated with chemical RONS produced in the water (hydrogen peroxide, nitrites, and especially nitrates). By utilizing the Responses Surface Methodology, we identified the optimal plasma treatment time per litre required for efficient RONS production and bactericidal effect in the wastewater treatment, which was linearly scalable with water volume. After the optimum plasma treatment time, a sharp drop in pH, and the concentrations of nitrites and hydrogen peroxide were observed, which is related to the peroxynitrite formation leading to the significant bacterial reduction up to 7-log.

The Removal of CH4 and NOx from Marine LNG Engine Exhaust by NTP Combined with Catalyst: A Review.

Compared to diesel, liquefied natural gas (LNG), often used as an alternative fuel for marine engines, comes with significant advantages in reducing emissions of particulate matter (PM), SOx, CO2, and other pollutants. Promoting the use of LNG is of great significance for achieving carbon peaking and neutrality worldwide, as well as improving the energy structure. However, compared to diesel engines, medium- and high-speed marine LNG engines may produce higher methane (CH4) emissions and also have nitrogen oxide (NOx) emission issues. For the removal of CH4 and NOx from the exhaust of marine LNG engines, the traditional technical route of combining a methane oxidation catalyst (MOC) and an HN3 selective catalytic reduction system (NH3-SCR) will face problems, such as low conversion efficiency and high operation cost. In view of this, the technology of non-thermal plasma (NTP) combined with CH4-SCR is proposed. However, the synergistic mechanism between NTP and catalysts is still unclear, which limits the optimization of an NTP-CH4-SCR system. This article summarizes the synergistic mechanism of NTP and catalysts in the integrated treatment process of CH4 and NOx, including experimental analysis and numerical simulation. And the relevant impact parameters (such as electrode diameter, electrode shape, electrode material, and barrier material, etc.) of NTP reactor energy optimization are discussed. The work of this paper is of great significance for guiding the high-efficiency removal of CH4 and NOx for an NTP-CH4-SCR system.

Plasma-assisted CO2 and N2 conversion to plant nutrient

Colossal research on CO2 and N2 conversion using non-thermal plasma (NTP) technology has been ongoing since many years. The primary focus is on CO and NH3 production through CO2 and N2 conversion, respectively, with high conversion efficiency and low energy consumption with or without catalysts. Although in the present study, we propose that the NTP can assist in converting CO2 and N2 to plant nutrients in the form of plasma-treated/activated water. We used a homemade streamer plasma device and produced plasma-activated water (PAW) using CO2 and N2 feed gas, CO2-activated water (CAW) and N2-activated water (NAW). Later, we used CAW and NAW to treat the radish seeds and evaluate the germination rate, germination percentage, and seeding growth. To understand the chemical changes in PAW after the NTP treatment, we performed a chemical analysis to detect NO2¯, NO3¯, NH4+, and H2O2 along with the PAW pH and temperature shift. Additionally, to understand the other species produced in the gas phase, we simulated chemical reactions using COMSOL Multiphysics® software. Our results show that NOx and NHx species are less produced in CAW than in NAW, but CO2-generated PAW offers a significantly more substantial effect on enhancing the germination rate and seeding growth than NAW. Therefore, we suggested that CO and H2O2 formed during CAW production trigger early germination and growth enhancement. Furthermore, the total plasma reactor energy consumption, NO3¯ and NH4+ selective production percentage, and N2 conversion percentage were calculated. To our best knowledge, this is the first study that uses plasma-assisted CO2 conversion as a nutrient for plant growth.

Scalable non-thermal plasma trielectrode reactor: A theoretical and experimental study on carbon monoxide removal in a nitrogen atmosphere

Non-thermal plasma technology has a great interest for very diverse environmental applications. In this work a trielectrode non-thermal plasma reactor was studied for carbon monoxide (CO) removal, in a nitrogen (N2) atmosphere, both experimentally and theoretically. The reactor combines a dielectric barrier discharge (DBD) with a remote third electrode, DC-biased, to extend the DBD generated plasma region with long streamers permeating its cross section. Also, a theoretical model to predict reactor efficiency, considering possible chemical reactions involved in CO degradation was applied. A good correspondence between experimental and theoretical efficiency values was found. It was concluded that the most relevant reaction was the isocyanate (NCO) radical production. The byproducts of NCO degradation, nitrogen monoxide (NO) and nitrogen dioxide (NO2), were experimentally detected.

Treatment of brilliant blue by plasma and combination plasma with photocatalysis process intensification

ABSTRACT Various treatment methods are widely used to reduce water pollution. Among these techniques, heterogeneous photocatalysis and non-thermal plasma technologies, notably dielectric barrier discharges, are currently the most suitable for water treatment. However, the use of each of these processes alone presents certain limitations. In this study, the brilliant blue (BB) photo-degradation was investigated via the dielectric barrier discharge (DBD) method. The impact of certain process factors, including the model pollutant’s initial concentration (from 5 to 10 mg/L), the airflow rate (240 L/h) as well as the frequency (from 230 to 400 Hz), upon the DBD’s performance in terms of bright blue decomposition and mineralisation was assessed. The latter reached 49.5% for 120 minutes, assuming optimised operating parameters (BB initial concentration of 10 mg/L, airflow rated at 240 L/h, 21 kV as an applied voltage at 400 Hz). It could be said that DBD processing has a high ecological potential for the aqueous degradation of BB. Scavenger analysis indicated that the radicals O2 −°, HO2°, as well as °OH, represent the underlying oxygen reactive species in the process of brilliant blue decomposition. The study showed that both reactive nitrogen species and ROS contribute to the process of BB removal. For approximating real-life requirements, DBD tests were performed in both tap and synthetic water matrices. The degradation and mineralisation of BBs were significantly inhibited in tap water (% Degradation = 71.3, % Mineralisation = 31.6) and synthetic water (% Degradation = 65.41, % Mineralisation = 12), compared to BB degradation and mineralisation in ultrapure water (% Degradation ≥ 98, % Mineralisation = 49.5), after 120 min of irradiation. This proved that inorganic and organic molecules in tap and synthetic water reduce BB degradation efficiency. Thus, our pollutant was treated by the combination plasma-photocatalysis system using cellulose paper-supported titanium dioxide as a photocatalyst, which showed a significant improvement in BB decomposition efficiency versus considering either separate process.

Review of Non-Thermal Plasma Technology for Hydrogenation of Vegetable Oils and Biodiesel

Review of Non-Thermal Plasma Technology for Hydrogenation of Vegetable Oils and Biodiesel