Non-thermal Plasma Technology Research Articles

Synergistic effect on simultaneous treatment of Cr(VI) and chloramphenicol using a non-thermal plasma technology

Toxic organic and heavy metal contaminants commonly exist in industrial waste stream(s) and treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma technology was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals were the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration, because part of hydroxyl radicals could be consumed by the low-concentration CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could react with such reductive species as eaq− and •H, which could compete with Cr(VI) and inhibit the reduction. In addition, the presence of Cr(VI) enhanced the degradation and mineralization of CAP; the study of obtained intermediates indicated that the presence of Cr(VI) changed the degradation path of CAP as Cr(VI) would react with reductive species, enhance the generation of hydroxyl radicals, and cause more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology can be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environments.

Improved hydrolysis of sewage sludge by air-assisted non-thermal plasma for enhanced biomethane recovery.

Conventional pretreatment technologies have been assessed to resolve the slow hydrolysis of sewage sludge, but high operating costs have prevented their wide use. This study investigated non-thermal plasma (NTP) technologies as an alternative to promote anaerobic digestion (AD). Various contact time (CT) and temperature (T) conditions were used to assess how NTP pretreatment improves the methane conversion of organics in sewage sludge. A multi-response surface model (RSM) using a central composite design (CCD) identified the optimal CT (4.6h) and T (45°C). This statistical optimization of NTP pretreatment led to an enhanced biochemical methane potential of 297 ± 46mL CH4 g-1 COD by reducing operating cost as power consumption as low as 0.08 USD L-1. The result was comparable to those of other advanced oxidation processes (0.14 - 0.60 USD L-1) demonstrating that accelerated hydrolysis of sewage sludge using NTP pretreatment show potential for improving renewable energy recovery from sewage sludge.

Non-Thermal Plasma Technology for Further Purification of Flue Gas in the Resource Utilization Process of Waste Mercury Catalyst: A Case Study in Xinjiang, China

This study aims to advance the recycling of mercury-containing waste and promote sustainable development within the polyvinyl chloride (PVC) industry. Our innovative system integrates pre-treatment technology (spraying potassium permanganate and demisting and dust removal) with efficient non-thermal plasma oxidation, resulting in excellent treatment efficiency, low cost, and simple operation. With a processing capacity of 3000 m3/h, the concentration of mercury emissions in flue gas can achieve the target of <0.01 mg/m3, boasting a removal efficiency exceeding 98%, which satisfies the standard “Emission standard of air pollutants for industrial kiln and furnace” (GB 9078-1996). Our results can provide technical support for the comprehensive purification of mercury-containing flue gas during the resource recovery process from mercury-containing waste. The application of our system can contribute to reducing mercury emissions in the PVC industry, lowering occupational exposure risks for workers, and promoting China’s better compliance with “the Minamata Convention on Mercury”.

The effects of corona discharge from a cold plasma source on the physicochemical properties and shelf-life of milk

Milk is a nutrient-rich food and a risk source of foodborne pathogens, yet traditional thermal processing/pasteurization can affect its nutritional value. However, recently, consumer demand for healthy, fresh, and safe “green process” foods has increased, so emerging non-thermal food cold plasma (CP) technology has largely addressed consumer demands for safe and healthy foods by effectively eliminating pathogens from milk. In this study, we examined CP treatment duration (0, 1, 5, and 10 min) and membrane filtration (MF) effects on whole and skim milk with respect to milk characteristics, microbial growth, and xanthine oxidase activity over a 0– 15-day storage period. This study revealed that the shelf life of whole milk and MF skimmed milk with CP10 min amounted to 15 days and that the TPC was <6 log colony forming units (CFU/mL), while titratable acidity was <0.18% in compliance with regulatory standards, with insignificant color changes. Additionally, pH and lipid oxidation values in CP and MF groups were positively correlated with storage time (p < 0.05). Thus, CP treatment released free lipids into milk, with minor oxidative reactions. Critically, no significant effects were observed in terms of nutritional value and xanthine oxidase activity. Hence, we provide valuable processing insights for dairy manufacturers and show that CP10 min treatment positively impacted total plate count (TPC) and thermo-resistant bacteria. Our goal is to reduce the heat load on milk without compromising nutritional quality while maintaining food safety.

Argon non-thermal plasma treatment promotes the development of rice (Oryza sativa L.) in saline alkali environments.

Soil salinization leads to a reduction in arable land area, which seriously endangers food security. Developing saline-alkali land has become a key measure to address the contradiction between population growth and limited arable land. Rice is the most important global food crop, feeding half of the world's population and making it a suitable choice for planting on saline-alkali lands. The traditional salt-alkali improvement method has several drawbacks. Currently, non-thermal plasma (NTP) technology is being increasingly applied in agriculture. However, there are few reports on the cultivation of salt/alkali-tolerant rice. Under alkaline stress, argon NTP treatment significantly increased the germination rate of Longdao 5 (LD5) rice seeds. In addition, at 15kV and 120s, NTP treatment significantly increased the activity of antioxidant enzymes such as catalase and SOD. NTP treatment induced changes in genes related to salt-alkali stress in rice seedlings, such as chitinase and xylanase inhibitor proteins, which increased the tolerance of the seeds to salt-alkali stress. This experiment has expanded the application scope of NTP in agriculture, providing a more cost-effective, less harmful, and faster method for developing salt-alkali-tolerant rice and laying a theoretical foundation for cultivating NTP-enhanced salt-alkali-tolerant rice.

Efficient degradation and enhanced α-glucosidase inhibitory activity of apricot polysaccharides through non-thermal plasma assisted non-metallic Fenton reaction

Dielectric barrier discharge (DBD) was a commonly used non-thermal plasma (CP) technology. This paper aimed to enhance the biological activity of apricot polysaccharides (AP) by using dielectric barrier discharge (DBD-CP) assisted H2O2-VC Fenton reaction for degradation. The degradation conditions were optimized through response surface methodology. The molecular weight (Mw) of degraded apricot polysaccharides (DAP) was 19.71 kDa, which was 7.25 % of AP. The inhibition rate of DAP (2 mg/mL) was 82.8 ± 3.27 %, which was 106.87 % higher than that of AP. DBD-CP/H2O2-VC degradation changed the monosaccharide composition of AP and improved the linearity of polysaccharide chains. In addition, a novel apricot polysaccharide DAP-2 with a Mw of only 6.60 kDa was isolated from DAP. The repeating units of the main chain of DAP-2 were →4)-α-D-GalpA-(1 →, the branch chain was mainly composed of α-D-GalpA-(1 → 2)-α-L-Rhap-(1→ connected to O-3 position →3,4)-α-D-GalpA-(1→. The complex structure formed by the combination of DAP-2 and α-glucosidase was stable. DAP-2 had a higher α-glucosidase binding ability than the acarbose. These results suggested that DAP-2 had the potential to be developed as a potential hypoglycemic functional food and drug.

Experimental activities in view of hydrogen- deuterium equilibrium reaction in dielectric barrier discharge reactor: Effects of plasma treatment parameters and reactor design

Cryogenic distillation (CD) is a crucial process for separating and concentrating tritium in the tritium fuel cycle of fusion reactors. The equilibrator plays a vital role in decomposing HD, DT, and HT to improve the separation efficiency of hydrogen isotopes in CD. As the equilibrium reaction temperature decreases, a larger proportion of HD, HT, and DT decomposes into H2, D2, and T2, which enhances the performance of the equilibrator. While Pt/Al2O3 catalyst exhibits high activity at 303 K in the H2-D2 equilibrium reaction, it is almost inactive at 77 K. Non-thermal plasma (NTP) technology offers a promising and attractive alternative to conventional catalytic technology. In this study, H2-D2 equilibrium reaction was carried out without catalysts in a dielectric barrier discharge (DBD) reactor, achieving efficient conversion of HD even at 77 K. In the single-electrode DBD plasma reactor (S-P-Reactor), with an input power of 50 W, the conversion efficiency of HD was found to be 99.5% at 303 K, 99.5% at 273 K, and 99.2% at 77 K. To further optimize the energy efficiency of the S-P-Reactor, the reactor structure was enhanced, leading to the development of a multi-high-voltage DBD reactor (M-P-Reactor). The input power of the M-P-Reactor was reduced by approximately 10 W compared to the S-P-Reactor, while maintaining a conversion efficiency of over 95% for HD. The energy density of the reactor was calculated using the Q-V Lissajous graphic method, demonstrating that the M-P-Reactor exhibited superior energy conversion efficiency compared to the S-P-Reactor. Furthermore, the yield of HD was solely determined by the energy density and temperature. At a specific energy density, the yield of HD remained consistent for the same temperature. However, generating HD at lower temperatures required more energy due to the lower reactant activity. These results illustrate the potential application of NTP technology in improving hydrogen isotope separation performance in the cryogenic distillation process for fusion applications.

Efficient toluene degradation using Bacillus subtilis biofilm-supported Mn–Ce/zeolite catalysts

This study investigated a new approach for synthesizing Bacillus subtilis biofilm-supported Mn–Ce/zeolite catalysts for the degradation of gaseous toluene. Four different metal oxide nano-catalysts (ZMn, ZMnCe-10%, ZMnCe-20%, and ZMnCe-30%) were synthesized with varying ratios of manganese (Mn) and cerium (Ce) on zeolite nanoparticles. TEM, SEM, XRD, BET, XPS, and EDX mapping were used to examine these four samples, as well as simple zeolite. Based on these analyses, the catalytic activity of the prepared samples ZMn, ZMnCe-10%, ZMnCe-20%, and ZMnCe-30% for the complete oxidation of toluene and toluene intermediate products were tested with Non-thermal plasma (NTP) technology in a dielectric barrier discharge (DBD) reactor. Among all, ZMnCe-20% showed the highest toluene degradation efficiency (89%) at low concentrations (200 ​ppm) and humidity (>50%). Later, highly efficient and hydrophobic nano-biocatalysts were prepared by combining B. subtilis biofilm wild-type (WT) and engineered B. subtilis biofilm EPS with ZMnCe-20% catalyst. EPS is the main component found in biofilm matrix and plays a key role in influencing properties such as biofilm stability, electron transfer, surface roughness and hydrophobicity. Compared to WT B. subtilis biofilm, EPS overexpressed B. subtilis biofilm showed stronger growth and development on ZMnCe-20% nanocatalyst. Moreover, the NTP system packed with ZMnCe-20%/biofilm (EPS+) nano-biocatalyst exhibited the highest toluene degradation activity (99%) with (83%) CO2 selectivity, (up to 50%) reduction in NOx concentration and complete ozone decomposition at (250 ​ppm) toluene concentrations and increased humidity (>90%). High-energy electrons generated in the NTP system break the C–H and C–C bond between the rings of the toluene molecule, forming several byproducts which are later reacted with active radical species such as O, OH, and O3 and further converted into final degradation products (CO2 and H2O). The results demonstrated successful biofilm development and growth on the ZMnCe-20% catalyst with advanced features such as superhydrophobicity, H2O resistance, improved surface roughness, and electron generation. In short, the study's approach combines bioengineering and material science to develop sustainable nano-biocatalysts for removing VOCs in industrial and environmental settings.

Emerging Food Processing and Preservation Approaches for Nutrition and Health

This comprehensive review critically evaluates contemporary and emergent food processing and preservation technologies with a primary focus on enhancing nutrition and promoting health. The discourse delves into a spectrum of innovative methodologies, encompassing high pressure processing, pulsed electric field processing, oscillating magnetic field processing, nonthermal plasma, ultrasound processing, and avant-garde thermal technologies. A detailed analysis is provided, shedding light on the manifold impacts of these technologies on diverse facets such as food quality, sensory attributes, nutrient preservation, shelf-life augmentation, and the effective inactivation of pathogens. Furthermore, the document accentuates recent applications that exemplify the successful enhancement of nutritional profiles across a gamut of food products. The review not only scrutinizes the advantages but also delineates the challenges associated with the implementation of these cutting-edge technologies. An insightful exploration of potential future opportunities is incorporated, offering a forward-looking perspective on the evolving landscape of food processing and preservation. By expanding the discourse on these pivotal technologies, this review serves as a valuable resource for researchers, practitioners, and stakeholders interested in advancing nutrition and health outcomes through state-of-the-art food processing and preservation approaches.

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 (&gt;90 W) with a Lab Unit generating plasma-activated water, a shorter activation time (&lt;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.