Low-temperature Plasma Technology Research Articles

Real-Time Calculation of CO2 Conversion in Radio-Frequency Discharges under Martian Pressure by Introducing Deep Neural Network

In recent years, the in situ resource utilization of CO2 in the Martian atmosphere by low-temperature plasma technology has garnered significant attention. However, numerical simulation is extremely time-consuming for modeling the complex CO2 plasma, involving tens of species and hundreds of reactions, especially under Martian pressure. In this study, a deep neural network (DNN) with multiple hidden layers is introduced to investigate the CO2 conversion in radio-frequency (RF) discharges at a given power density under Martian pressure in almost real time. After training on the dataset obtained from the fluid model or experimental measurements, the DNN shows the ability to accurately and efficiently predict the various discharge characteristics and plasma chemistry of RF CO2 discharge even in seconds. Compared with conventional fluid models, the computational efficiency of the DNN is improved by nearly 106 times; thus, a real-time calculation of RF CO2 discharge can almost be achieved. The DNN can provide an enormous amount of data to enhance the simulation results due to the very high computational efficiency. The numerical data also suggest that the CO2 conversion increases with driving frequency at a fixed power density. This study shows the ability of the DNN-based approach to investigate CO2 conversion in RF discharges for various applications, providing a promising tool for the modeling of complex non-thermal plasmas.

Nanosecond pulsed gliding arc plasma for ammonia synthesis: better insight from discharge mode and vibrational temperature

Low-temperature plasma technology is a promising technological route to achieve green and efficient ammonia synthesis at ambient temperature and pressure. In this work, a Laval nozzle type gliding arc plasma reactor was designed for the direct synthesis of ammonia from N2 and H2 discharges ignited by a high voltage nanosecond pulsed power supply to investigate the effect of different electrode gaps, pulse voltages, and V N2:V H2 on ammonia synthesis. The nanosecond pulsed plasma discharges were characterized through oscilloscope and optical emission spectroscopy (OES). The maximum rate of NH3 synthesis was 538.12 μmol·h−1 at 1.5 mm electrode gap, 16 kV peak pulse voltage, 6 kHz pulse repetition frequency, 100 ns pulse width, 100 ns pulse rising edge, 100 ns pulse falling edge, and 200 mL·min−1 total gas flow rate with V N2:V H2 = 1:1. It was demonstrated that the discharge mode of the nanosecond pulsed gliding arc plasma can transit from a unipolar state to a bipolar state determined by the duty cycle accompanied with higher discharge power and vibrational temperature. Bipolar discharge mode is beneficial to improve the efficiency of plasma ammonia synthesis because of it can strengthen the plasma discharge and increase the vibrational temperature. The ammonia synthesis rate and N2 conversion rate increased with the increase of the discharge power and vibrational temperature.

AgIn5S8/g-C3N4 Composite Photocatalyst Coupled with Low-Temperature Plasma-Enhanced Degradation of Hydroxypropyl-Guar-Simulated Oilfield Wastewater.

The effective treatment and recovery of fracturing wastewater has always been one of the difficult problems to be solved in oilfield wastewater treatment. Accordingly, in this paper, photocatalytic-coupled low-temperature plasma technology was used to degrade the simulated wastewater containing hydroxypropyl guar, the main component of fracturing fluid. Results indicated that hydroxypropyl-guar wastewater could be degraded to a certain extent by either photocatalytic technology or plasma technology; the chemical oxygen demand and viscosity of the treated wastewater under two single-technique optimal conditions were 781 mg·L-1, 0.79 mPa·s-1 and 1296 mg·L-1, 1.01 mPa·s-1, respectively. Furthermore, the effective coupling of AgIn5S8/gC3N4 photocatalysis and dielectric-barrier discharge-low-temperature plasma not only enhanced the degradation degree of hydroxypropyl guar but also improved its degradation efficiency. Under the optimal conditions of coupling treatment, the hydroxypropyl-guar wastewater achieved the effect of a single treatment within 6 min, and the chemical oxygen demand and viscosity of the treated wastewater reduced to below 490 mg·L-1 and 0.65 mPa·s-1, respectively. In the process of coupled treatment, the AgIn5S8/gC3N4 could directly absorb the light and strong electric field generated by the system discharge and play an important role in the photocatalytic degradation, thus effectively improving the energy utilization rate of the discharge system and enhancing the degradation efficiency of hydroxypropyl guar.

Detection and treatment of VOCs in the food industry

Volatile organic compounds (VOCs) are common pollutants in the atmosphere, which will do some harm to the environment and the human body. At present, the detection and treatment of VOCs are mainly concentrated in chemical, petroleum, pharmaceutical, household and other industries, but few scholars have studied the management of VOCs emitted by food industry. According to the characteristics of VOCs emitted from food industry, this article summarizes the research progress of relevant detection methods (gas chromatography, gas chromatography-mass spectrometry, gas chromatography-ion mobility spectrometry, electronic nose technology) for VOCs emitted from food industry in recent years, focusing on the research progress, advantages, and disadvantages of destruction technology (combustion method, low temperature plasma technology, biological method), treatment and recovery technology (adsorption method, absorption method, condensation method, membrane separation method) and combination technology for VOCs emitted from food industry. Based on the understanding of various governance technologies and the relevant policy requirements of VOCs governance, the future research trends in this field are prospected.

Application of low-temperature plasma technology in the field of agriculture

The low-temperature plasma crop seed treatment technology has opened up a new way for the application of plasma in crops, creating a new path for high and stable yield of crops, and enriching agricultural yield increasing technology. This article briefly describes the innovative development of low-temperature plasma seed treatment technology, introduces the series of applications of plasma technology in crop seeds, as well as the biological effects and activation mechanisms of plasma. It also looks forward to the development and application prospects of plasma seed treatment technology.

Degradation performance and mechanism of microcystins in aquaculture water using low-temperature plasma technology

The eutrophication of aquaculture water bodies seriously restricts the healthy development of the aquaculture industry. Among them, microcystins are particularly harmful. Therefore, the development of technologies for degrading microcystins is of great significance for maintaining the healthy development of the aquaculture industry. The feasibility and mechanism of removing microcystins-LR by dielectric barrier discharge (DBD) plasma were studied. DBD discharge power of 49.6 W and a treatment time of 40 min were selected as the more suitable DBD parameters, resulting in microcystin-LR removal efficiency of 90.4%. Meanwhile, the effects of initial microcystin-LR concentration, initial pH value, turbidity, anions on the degradation effect of microcystin-LR were investigated. The removal efficiency of microcystin-LR decreased with the increase of initial microcystin-LR concentration and turbidity. The degradation efficiency of microcystin-LR at pH 4.5 and 6.5 is significantly higher than that at pH 8.5 and 3.5. HCO3− can inhibit the removal efficiency of microcystin-LR. Furthermore, five intermediates products (m/z = 1029.5, 835.3, 829.3, 815.4, 642.1) were identified in this study, and the toxicity analysis of these degradation intermediates indicated that DBD treatment can reduce the toxicity of microcystin-LR. e－aq, •OH, H2O2, and O3 have been shown to play a major role in the degradation of microcystin-LR, and the contribution ranking of these active species is e－aq > •OH > H2O2 > O3. The application of DBD plasma technology in microcystin-LR removal and detoxification has certain development potential.

Effect of high voltage discharge on germination characteristics of vetch seeds at high altitude

High-voltage electrostatic fields and low-temperature plasma technology at atmospheric pressure have an important impact on biological growth promotion. Therefore, a multi-needle-column-plate corona plasma generator is proposed in this paper. The negative corona voltammetry characteristics of multi-needle-plate electrodes and multi-needle-column-plate electrodes with different electrode spacing are investigated experimentally, and the electric field distribution of the device is simulated. The device was also applied to vetch seeds at high altitudes to investigate the effect of discharge on germination and root length. The results show that the introduction of column electrodes can effectively improve the electric field distribution of the device so that the device can provide two modes of high voltage electrostatic field and corona plasma field, and ensure the uniform treatment of seeds when the electrode spacing is 3 cm. The treatment of this device accelerates seed germination and promotes root growth, and is more effective under the combined influence of higher electric field strength, ionic wind generated by the discharge, and the active species than a single factor with a lower electric field, as well as shortening the duration of action. The high voltage electrostatic fields at −3 kV, −6 kV, and −9 kV and the corona discharge plasma fields at −12 kV, −15 kV, and −18 kV can effectively accelerate the germination of vetch seeds as well as promote the root growth under the treatment time of 10 min, 20 min, and 30 min. The optimal conditions were −9 kV for 30 min and −15 kV for 10 min, respectively.

Electron collision cross section data in plasma etching modeling

Semiconductor chips are the cornerstone of the information age, which play a vital role in the rapid development of emerging technologies such as big data, machine learning, and artificial intelligence. Driven by the growing demand for computing power, the chip manufacturing industry has been committed to pursuing higher level of integration and smaller device volumes. As a critical step in the chip manufacturing processes, the etching process therefore faces great challenges. Dry etching (or plasma etching) process based on the low-temperature plasma science and technology is the preferred solution for etching the high-precision circuit pattern. In the low-temperature plasma, electrons obtain energy from the external electromagnetic field and transfer the energy to other particles through collision process. After a series of complex physical and chemical reactions, a large number of active particles such as electrons, ions, atoms and molecules in excited states, and radicals are finally generated, providing the material conditions for etching the substrate. Dry etching chamber is a nonlinear system with multiple space-time dimensions, multiple reaction levels and high complexity. Facing such a complex system, only by fully understanding the basic physical and chemical reaction of the etching process can we optimize the process parameters and improve the etching conditions, so as to achieve precision machining of the semiconductor and meet the growing demand of the chip industry for etching rate and yield. In the early days, the process conditions of dry etching were determined through the trial-and-error method, which is characterized by high cost and low yield. However, with the help of plasma simulation, nowadays people have been able to narrow the scope of experiment to a large extent, and find out efficiently the optimal process conditions in a large number of parameters. In this review, we first introduce the basic theory of the mostly used models for plasma simulation including kinetic, fluid dynamic, hybrid and global models, in which the electron collision cross sections are the key input parameters. Since the formation of the low-temperature plasma is driven by the electron-heavy particle collision processes, and the active species for plasma etching are generated in the reactions induced by electron impact, the accuracy and completeness of the cross-section data greatly affect the reliability of the simulation results. Then, the theoretical and experimental methods of obtaining the cross-section data of etching gases are summarized. Finally, the research status of the electron collision cross sections of etching atoms and molecules is summarized, and the future research prospect is discussed.

Advances in volatile organic pollutant capture and adsorption degradation treatment technologies

With the continuous development of industry, the emission of volatile organic compounds (VOCs) continues to increase, and the pollution problem becomes increasingly serious. For example, in industrial production processes such as papermaking and traditional Chinese medicine extraction, low-content and complex volatile organic compounds will be produced, which will affect the factory environment. This article introduces the development and research status of VOCs sampling and treatment technology in recent years, explains the advantages and disadvantages of adsorption method, absorption method, membrane separation method, catalytic combustion method, biodegradation method, and low-temperature plasma technology application, and looks forward to the future development trends in this field.

Development of Antibacterial Cotton Textiles by Deposition of Fe2O3 Nanoparticles Using Low-Temperature Plasma Sputtering.

Antibacterial textiles can help prevent infections from antimicrobial-resistant pathogens without using antibiotics. This work aimed to enhance the cotton fabric's antimicrobial properties by depositing Fe2O3 nanoparticles on both sides of its surface. The nanoparticles were deposited using low-temperature plasma technology in a pure oxygen atmosphere, which is environmentally friendly. The Fe2O3 nanoparticles formed clusters on the fabric surface, rather than thin films that could reduce the airflow of the textile. The optimal conditions for the nanoparticle deposition were 200 W of plasma power, 120 min of immersion time, and 5 cm of Fe cathode-textile sample distance. The received antimicrobial textile was tested and the high efficiency of developed materials were successfully demonstrated against 16 microbial strains (Gram-positive and Gram-negative bacteria and fungi).

Study on atomization of grounding electrodes under the influence of magnetic field for dedusting and desulfurization of negative corona discharge

Corona discharge low-temperature plasma technology has good performance in treating dust and removing gaseous pollutants. In this paper, the dust and SO2 in the flue gas are removed by using the ground electrode atomization negative corona discharge device under the action of a magnetic field, and the discharge characteristics of the device, the removal efficiency of dust and sulfur dioxide, and its influencing factors are studied. The results show that the discharge characteristics and dust removal and desulfurization efficiency of the ground electrode atomization negative corona discharge under the action of a magnetic field are superior to the traditional l corona discharge and are almost affected by the extension of the operating time. Finally, the ground electrode atomization negative corona discharge under the action of a magnetic field is analyzed. The dust removal and desulfurization mechanism of corona discharge provide a reference for the development of dust removal and integrated desulfurization equipment.

Mesoporous γ-Al2 O3 Supported Mn–Ce–Co Ternary Oxides for the Efficient Plasma-Catalytic Oxidation of Formaldehyde

Coupling low-temperature plasma technology with catalysts can significantly enhance air purification efficiency and mitigate the generation of secondary pollutants. In this study, mesoporous [Formula: see text]-Al2O3 supported Mn–Ce–Co ternary oxides were introduced into a widely employed tubular dielectric barrier discharges (DBD) reactor for indoor air purification. The plasma-catalytic degradation of HCHO exhibited the following degradation efficiency order: Mn–Ce–Co/[Formula: see text]-Al2O3 [Formula: see text] Mn/[Formula: see text]-Al2O3 [Formula: see text] Mn–Ce/[Formula: see text]-Al2O3 [Formula: see text] Co/[Formula: see text]-Al2O3 [Formula: see text] [Formula: see text]-Al2O3 [Formula: see text] Ce/[Formula: see text]-Al2O3 [Formula: see text] Plasma. When compared to plasma treatment alone, the catalyst resulted in a remarkable 1.8-fold enhancement under conditions of 3.0[Formula: see text]kV, [Formula: see text]C, 60% RH. Additionally, the concentrations of the by-products O3 and NO[Formula: see text] were significantly reduced by 88.2% and 93.3%, respectively. The synergistic interaction between Mn, Ce and Co oxides facilitated the formation and transportation of surface-reactive oxygen species, thereby contributing to the thorough oxidation of HCHO and organic intermediates during the plasma-catalytic process. Moreover, the high specific surface area offered by mesoporous materials enhanced the adsorption and catalytic activity towards HCHO.

Rational regulation of 3D N-doped carbon macro-architectures toward low-temperature plasma catalysis: The roles of nitrogen content and hierarchical porous structure

The application of low-temperature plasma technology with optimized catalysts in water treatment has shown a good application prospect. However, the relationships between catalytic performance and composition (N atom-doping) and structure (hierarchical porous) of catalysts is still unclear. Here, 3D N-doped carbon macro-architectures is designed by thermolysis of energetic Zn-MOF, where triazole ligand with ultra-high nitrogen content provided the possibility for effective nitrogen doping and creation of hierarchical porous structure. In the DBD system, a series of energetic MOF-derived carbon (EMC-x) catalysts with different pyrolysis temperatures (from 700 to 1000 °C) were prepared, and the composition/structure-effective relationship was investigated in detail. Degradation mechanisms and pathways were analyzed by bursting experiments, quantitative detection of H2O2 and O3, three-dimensional excitation-emission matrix spectroscopy (3D-EEM), LC-MS. The results confirmed that EMC-10 with high nitrogen content and hierarchical porous structure has a wide range of applications in synergistic plasma removal of TTCH from water bodies.

Enhanced surface-insulating performance of EP composites by doping plasma-fluorinated ZnO nanofiller

The surface flashover of epoxy resin (EP) composites is a pivotal problem in the field of high-voltage insulation. The regulation of the interface between the filler and matrix is an effective means to suppress flashover. In this work, nano ZnO was fluorinated and grafted using low-temperature plasma technology, and the fluorinated filler was doped into EP to study the DC surface flashover performance of the composite. The results show that plasma fluorination can effectively inhibit the agglomeration by grafting –CF x groups onto the surface of nano-ZnO particles. The fluorine-containing groups at the interface provide higher charge binding traps and enhance the insulation strength at the interface. At the same time, the interface bond cooperation caused by plasma treatment also promoted the accelerating effect of nano ZnO on charge dissipation. The two effects synergistically improve the surface flashover performance of epoxy composites. When the concentration of fluorinated ZnO filler is 20%, the flashover voltage has the highest increase, which is 31.52% higher than that of pure EP. In addition, fluorinated ZnO can effectively reduce the dielectric constant and dielectric loss of epoxy composites. The interface interaction mechanism was further analyzed using molecular dynamics simulation and density functional theory simulation.

Surface treatment of large-area epoxy resin by water-perforated metal plate electrodes dielectric barrier discharge: Hydrophobic modification and uniformity improvement

Wind power plays a vital role in the field of renewable energy. However, a significant challenge arises when operating wind turbines with epoxy resin blades in temperatures below 0℃, as they tend to ice up, causing unexpected shutdowns. Low-temperature plasma technology emerges as a promising solution that can produce hydrophobic thin films with excellent mechanical properties in an eco-friendly way, but its application is currently limited to small objects. This paper presents a novel design for a large-scale DBD (Dielectric Barrier Discharge) water-perforated metal electrode plasma treatment device that was optimized through simulations to achieve uniform gas discharge at low flow rates. The device successfully deposited a hydrophobic thin film uniformly on the surface of an epoxy resin plate with an average water contact angle of 139.5 ± 2.5°, which is an 87% improvement compared to the untreated surface. In addition, the device reduced the required working gas flow rate by 40–60% compared to existing large-area processing devices, and improved the effectiveness by 16%. Physical and chemical property tests demonstrated that the device’s design increased surface roughness and generated a dense film containing hydrophobic silicon groups (such as Si-O-Si and Si-(CH3)x), contributing to the improvement in hydrophobicity. Overall, the presented device offers an efficient, eco-friendly, and effective method for depositing hydrophobic thin films on large-scale materials, which can enhance wind turbine performance by preventing ice formation on epoxy resin blades.

Tailored design of 2D MOF derived carbon boosting the low temperature plasma catalysis for water treatment: The role of graphitization and hierarchical porous structure

The application of efficient and non-polluting low-temperature plasma technology to address the growing problem of environmental pollution has received increasing attention in recent years. In this study, two-dimensional (2D) Co-ZIF (Co-ZIF-L) derived hollow carbon nanosheets (Co-HCNSs) with high graphitization rate and high porosity were designed. The advantages of structure and composition endow Co-HCNSs-9 with excellent catalytic properties. To verify the effects of graphitization and hollow structure, Co-ZIF-L derived solid carbon nanosheets (SCNSs-9) and Zn-ZIF-L derived hollow carbon nanosheets (Zn-HCNSs-9) were prepared in parallel. In low-temperature plasma applications, the degradation rate of tetracycline (TTCH) was as high as 97% within 30 min, Co-HCNSs-9/dielectric barrier discharge (DBD) system improved the degradation rate of TTCH and the energy efficiency The degradation mechanism of Co-HCNSs-9/DBD was investigated by quenching experiments as a synergistic effect of hydroxyl radicals (OH), singlet oxygen (1O2) and reactive nitrogen species (RNS). In addition, the effects of common anions and natural macromolecular organic compounds in the water column were investigated. Based on 3D fluorescence analysis, liquid chromatography-mass spectrometry and density functional theory calculations, possible degradation pathways of TTCH were proposed. Finally, the safety and environmental friendliness of the system was verified by biological toxicity tests.

Experimental study on the treatment of dye wastewater by plasma coupled biotechnology

In this experiment, a gas-liquid two-phase discharge water treatment inverse device was designed independently to treat the actual workshop intermediate dye wastewater from a chemical plant. Firstly, the effects of initial concentration of wastewater, initial pH, circulation flow rate of solution, content of Fe2+, content of H2O2, and addition of tert-butanol on the organic removal rate and decolorization rate of dye wastewater treatment were investigated. The results showed that Fe2+ and tert-butanol would react with the active particles (H2O2, ·OH) and inhibit the degradation of the dye wastewater, resulting in the decrease of both organic matter degradation rate and decolorization rate. The experimentally degraded dye wastewater mainly contained benzoic acid and its derivatives in addition to dye molecules, thus the degradation mechanism of benzoic acid was mainly analyzed. Then, the actual dye wastewater treated by low-temperature plasma was combined with the traditional biological treatment technology. The biochemical properties of the wastewater treated by low-temperature plasma technology were greatly improved, and the B/C was increased from the initial 0.17 to 0.33. The effluent after the combined biological method could meet the effluent discharge standard, and the final CODcr reached 198mg/L, BOD5 reached 65mg/L, and pH and chromaticity reached 6.39 and 50, respectively.

Opportunities of Electronic and Optical Sensors in Autonomous Medical Plasma Technologies

Low temperature plasma technology is proving to be at the frontier of emerging medical technologies with real potential to overcome escalating healthcare challenges including antimicrobial and anticancer resistance. However, significant improvements in efficacy, safety, and reproducibility of plasma treatments need to be addressed to realize the full clinical potential of the technology. To improve plasma treatments recent research has focused on integrating automated feedback control systems into medical plasma technologies to maintain optimal performance and safety. However, more advanced diagnostic systems are still needed to provide data into feedback control systems with sufficient levels of sensitivity, accuracy, and reproducibility. These diagnostic systems need to be compatible with the biological target and to also not perturb the plasma treatment. This paper reviews the state-of-the-art electronic and optical sensors that might be suitable to address this unmet technological need, and the steps needed to integrate these sensors into autonomous plasma systems. Realizing this technological gap could facilitate the development of next-generation medical plasma technologies with strong potential to yield superior healthcare outcomes.

Low temperature plasma-assisted synthesis and modification of water splitting electrocatalysts

With the emerging climate and environmental problems, it is necessary to develop renewable energy technologies to alleviate the energy crisis. As one of the most promising technologies for hydrogen production, electrocatalytic water splitting has received extensive research attention in recent years, with efficient electrocatalysts as the key to realizing large-scale hydrogen production. After decades of development, non-noble metal-based materials have been widely studied in the fabrication of water splitting catalysts, while these materials still need to be improved compared to commercial noble metal catalysts. Among the many existing electrocatalyst modification strategies, low temperature plasma technology stands out due to the low energy consumption, high efficiency, and low chemical waste generation. Recent advances in the development and application of low temperature plasma technology in the synthesis and modification of electrocatalytic materials for water electrolysis is highlighted. It is expected to provide reference for the design and research of electrode materials in electrocatalytic water splitting with plasma-assisted technologies.

Harmless process of organic matter in organosilicon waste residue by fluidization-like DDBD reactor: Temperature action and mechanism

Herein, the non-hazardous application of low-temperature plasma technology in solid waste from the silicone industry was investigated by using a fluidization-like double dielectric barrier discharge plasma (DDBD) reactor. The results show ∼92.9% TOC in the organosilicon waste residue could be removed at the conditions (Discharge power: 7.0 W, S/G: 12.5 gminL−1, SIE: 158.0 JL-1), i.e. TOC content decreases from 166.0 g/kg to 11.8 g/kg. At the same time, the energy efficiency of the TOC removal rate reach ∼732.1 gkWh−1, and the temperature of the discharge zone is below 280 °C. According to the TG-MS analysis and infrared thermal imager, it is considered that the heat energy generated in the plasma treatment process can affect the decomposition of organic matter. On the other hand, the samples were characterized before and after treatment by BET, SEM, XRD, FTIR, and GC-MS. It was proposed the organic matter was firstly gasified under the action of plasma and thermal. Then, the active group will generate and react with the C–H, C–C, or C–Si by the bombardment of sufficient energy of charged particles, leading the organic matter further to decompose into small molecules, such as CH4, H2, CO, and CO2.