Dielectric Barrier Discharge Treatment Research Articles

Effect of dielectric barrier discharge (DBD) plasma treatment on physicochemical and 3D printing properties of wheat starch

In recent years, the focus has shifted towards carbohydrate-based hydrogels and their eco-friendly preparation methods. This study involved an investigation into the treatment of wheat starch using dielectric barrier discharge (DBD) plasma technology over varying time gradients (0, 2, 5, 10, 15, and 20 min). The objective was to systematically examine the impact of different treatment durations on the physicochemical properties of wheat starch and the suitability of its gels for 3D printing. Morphology of wheat starch remained intact after DBD treatment. However, it led to a reduction in the amylose content, molecular weight, and crystallinity. This subsequently resulted in a decrease in the pasting temperature and viscosity. Moreover, the gels of the DBD-treated starch exhibited superior 3D printing performance. After a 2-min DBD treatment, the 3D printed samples of the wheat starch gel showed no significant improvements, as broken bars were evident on the surface of the 3D printed graphic, whereas DBD-20 showed better printing accuracy and surface structure, compared to the original starch without slumping. These results suggested that DBD technology holds potential for developing new starch-based gels with impressive 3D printing properties.

The synergistic effect of dielectric barrier discharge plasma and phycocyanin on shelf life of Oncorhynchus mykiss rainbow fillets

This study aimed to evaluate the efficacy of dielectric barrier discharge treatment (DBD) combined with phycocyanin pigment (PC) in extending the shelf life of Oncorhynchus mykiss rainbow fillets stored at 4 ± 0.1 °C. Microbiological, physicochemical, sensory and antioxidant properties were assessed over an 18-day storage period. The combined DBD and PC treatment significantly inhibited total viable counts and Psychrotrophic bacteria counts compared to the rest of the samples throughout storage. While Total Volatile Nitrogen concentrations remained below international standard until day 18, they exceeded this threshold in control sample by day 9. DBD treatment notably reduced Trimethylamine levels compared to controls (p < 0.05). PC and DBD combined inhibited DPPH and ABTS radical scavenging capacities by 80% and 85%, respectively, while demonstrating heightened iron-reducing antioxidant activity compared to controls. Analysis of 24 fatty acids indicated that PC mitigated DBD’s adverse effects, yielding superior outcomes compared to controls. The ratio of n-3 to n-6 fatty acids in all samples met or fell below international standard. Thus, the combined use of DBD and PC shows promise in extending fillet shelf life by over 15 days at 4 °C.

Study on the treatment of oily wastewater with non equilibrium plasma synergistic catalysts

Petroleum is currently a highly demanded power fuel, but oil fields produce oily wastewater during production. If not treated in a timely manner, it can cause serious ecological problems. To solve this issue, this article utilizes the non-equilibrium plasma generated by Dielectric Barrier Discharge (DBD) technology to treat diesel simulated oily wastewater under the synergistic effect of AC/Mn + TiO2 catalyst. The results indicate that: After 180 min of DBD treatment, the degradation rates of diesel and Tween-80 were 60.9% and 53.2%, respectively; after 180 min of synergistic DBD treatment with AC/Mn + TiO2 catalyst, the degradation rates of diesel and Tween-80 were 76.0% and 71.7%, respectively, with a significant increase in degradation rates. The SEM characterization of the catalyst before and after the reaction was compared, and it was found that the surface of the crystal after the reaction was smooth. XPS characterization showed that Mn electron migration leads to the generation of positively charged holes on the valence band of TiO2. These all demonstrate that the synergistic effect of DBD and catalyst promotes the degradation of oily wastewater.

Tailoring the structural, morphological, surface wettability and hardness features of Makrofol HS for surface applications: effect of DBD treatment

ABSTRACT In current research, Makrofol HS polymeric films have been utilized to evaluate the alterations in the surface properties under an atmospheric-pressure dielectric barrier discharge (DBD) plasma source. Upon DBD plasma exposure with various exposure durations ranging from 10 min to 120 min, the structural, surface wettability, surface free energy, surface roughness, and hardness features of Makrofol HS films have been studied and analyzed using different techniques. The FTIR spectra demonstrated that small changes in the band intensities correspond to the C-O-C as well as C=O bonds. Further, the changes in the absorption bands are correlated to the treatment time, leading to two critical processes, degradation, and crosslinking. The results of surface wettability displayed that the liquids' contact angle decreased from 84 ± 3o, 77 ± 3o and 62 ± 2o for water, glycerol, and dimethyl to 45 ± 1o, 42 ± 1o, and 36 ± 1o for untreated and treated samples at the highest treatment time, respectively. Also, the surface free energy significantly amended with increasing plasma exposure time. This modification in the treated surface indicates the increase in the polar groups on the treated surfaces, which then become hydrophilic surfaces. The samples' surface roughness parameters Ra, Rq, and Rz increased from 0.057 ± 0.003, 0.084 ± 0.004 and 0.366 ± 0.02 mm for untreated samples to 1.463 ± 0.073, 1.707 ± 0.085, and 6.839 ± 0.34 mm for treated samples at the highest treatment time, respectively. The Vickers hardness measurements showed an increase in the Vickers hardness from 12.31 ± 0.61 kgf/mm2 for the untreated sample to 44.89 ± 2.24 kgf/mm2 for the treated sample at the highest duration.

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.

Feasibility and mechanism of removing Microcystis aeruginosa and degrading microcystin-LR by dielectric barrier discharge plasma

Harmful cyanobacterial bloom is one of the serious environmental problems worldwide. Microcystis aeruginosa is a representative harmful alga in cyanobacteria bloom. It is of great significance to develop new technologies for the removal of Microcystis aeruginosa and microcystins. The feasibility and mechanism of removing microcystis aeruginosa and degrading microcystins by dielectric barrier discharge (DBD) plasma were studied. The suitable DBD parameters obtained in this study are DBD (41.5 W, 40 min) and DBD (41.5 W, 50 min), resulting in algae removal efficiency of 77.4% and 80.4%, respectively; scanning electron microscope and LIVE-DEATH analysis demonstrate that DBD treatment can disrupt cell structure and lead to cell death; analysis of elemental composition and chemical state indicated that there are traces of oxidation of organic nitrogen and organic carbon in microcystis aeruginosa; further intracellular ROS concentration and antioxidant enzyme activity analysis confirm that DBD damage microcystis aeruginosa through oxidation. Meanwhile, DBD can effectively degrade the microcystin-LR released after cell lysis, the extracellular microcystin-LR concentration in the DBD (41.5 W) group decreased by 88.7% at 60 min compared to the highest concentration at 20 min; further toxicity analysis of degradation intermediates indicated that DBD can reduce the toxicity of microcystin-LR. The contribution of active substances to the inactivation of microcystis aeruginosa is eaq− >•OH > H2O2 > O3 > 1O2 >•O2− >ONOO−, while on the degradation of microcystin-LR is eaq− >•OH > H2O2 > O3 >•O2− >1O2 > ONOO−. The application of DBD plasma technology in microcystis aeruginosa algae removal and detoxification has certain prospects for promotion and application.

Effect of atmospheric dielectric barrier discharge treatment on the triboelectric charging properties of brominated Polyethylene granules

This paper aims to investigate the effect of dielectric barrier discharge (DBD) plasma treatment on the triboelectric charging properties of granular materials containing brominated flame retardants (BFRs). This work focuses on the impact of treatment time and the applied voltage frequency. Experiments were carried out on Polyethylene (PE) particles containing 40000 ppm of bromine (PE 4.6 % of Hexabromobenzene) and BFR-free PE. The DBD treated particles were then charged by triboelectric effect in a multi-cylinder device. The triboelectric charge acquired by each sample was quantified using a Faraday cage connected to an electrometer. The humidity of the ambient air ranged between 51 % and 60 % and the temperature varied from 16.5 °C to 19 °C during the experiments. Results show the significant influence of DBD treatment time on the triboelectric charging of brominated and non-brominated PE granules. In case of brominated PE, the particles acquire less charge than the non-brominated ones. Furthermore, it was found that the charge of DBD-treated particles is influenced by the applied voltage frequency. The observed variation in triboelectric behavior may be attributed to the changes in the roughness and wettability of the polymer surface caused by DBD.

Atmospheric–pressure DBD plasma modifying photoemission, optical and electrical properties of polycarbonate films

In this study, the DBD plasma reactor has been constructed, characterized, and tested to be employed in material treatment for use in different applications. A neon power source with an output of 10 kV, 30 mA, with a frequency of 20 kHz is used to drive the DBD reactor in an atmospheric-pressure environment. The investigation covered the analysis of many parameters of the dielectric barrier discharge (DBD) reactor, including its discharge voltage, current, capacitance, consumption energy, and the light emission of the produced plasma. Also, to examine the generated DBD plasma effect, the photoemission, optical, and electrical characteristics of untreated/treated polycarbonate films were investigated using photoluminescence spectroscopy, UV/Vis spectroscopy, and electrical spectroscopy. The results demonstrated the appearance of two modes in the DBD discharge: filamentary and homogeneous. Moreover, the DBD reactor's power consumption has been measured to be 20 mW at a supplied voltage of 6.5 kV peak-to-peak, operated in atmospheric–pressure. The photoluminescence emission results emphasized that the treated films are modified particularly with increasing DBD treatment time. The UV–Vis spectra demonstrated a notable displacement of the absorption edge towards higher wavelengths as the duration of DBD exposure increased. This is indicative of the reduction of the band gap energy, thus improving the electric conductivities. The optical parameters of the treated polycarbonate films were enhanced in comparison to the untreated sample. Through the used frequency range, measurements of dielectric loss, dielectric constant, as well as AC electrical conductivity, are sensitive parameters to the modifications in electrical behaviors due to DBD plasma treatment.

Lc-ms-based lipidomics analyses revealed changes in lipid profiles in Asian sea bass (Lates calcarifer) with dielectric barrier discharge (DBD) atmospheric plasma treatment

A comprehensive LC-MS-based lipidomics analysis of Asian sea bass (Lates calcarifer) muscle after dielectric barrier discharge (DBD) atmospheric plasma treatment was performed. Through the analysis, 1500 lipid species were detected, phosphatidylcholine (PC, 27.80%) was the most abundant lipid, followed by triglyceride (TG, 20.50%) and phosphatidylethanolamine (PE, 17.10%). Among them, 125 lipid species were detected and identified as differentially abundant lipids in Asian sea bass (ASB). PCA and OPLS-DA showed that ASB lipids changed significantly after DBD treatment. Moreover, glycerophospholipid metabolism was key metabolic pathways, as PC, PE, and lysophosphatidylcholine (LPC) were key lipid metabolites. The findings concerning fatty acids revealed that the saturated fatty acids (SFA) content of ASB after DBD treatment increased by 8.54%, while the content of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decreased by 13.77% and 9.16%, respectively. Our study establishes a foundation for the lipid oxidation mechanism of ASB following DBD treatment.

Efficient degradation and mineralization of aniline in aqueous solution by new dielectric barrier discharge non-thermal plasma

Aniline is a priority pollutant that is unfavorable to the environment and human health due to its carcinogenic and mutagenic nature. The performance of the dielectric barrier discharge reactor was examined based on the aniline degradation efficiency. Different parameters were studied and optimized to treat various wastewater conditions. Role of active species for aniline degradation was investigated by the addition of inhibitors and promoters. The optimum conditions were 20 mg/L initial concentration, 1.8 kV applied voltage, 4 L/min gas flow rate and a pH of 8.82. It was observed that 87% of aniline was degraded in 60 min of dielectric barrier discharge treatment at optimum conditions. UV–Vis spectra showed gradual increase in the treatment efficiency of aniline with the propagation of treatment time. Mineralization of AN was confirmed by TOC measurement and a decrease in pH during the process. To elicit the aniline degradation route, HPLC and LC-MS techniques were used to detect the intermediates and byproducts. It was identified that aniline degraded into different organic byproducts and was dissociated into carbon dioxide and water. Comparison of the current system with existing advanced oxidation processes showed that DBD has a remarkable potential for the elimination of organic pollutants.

An application of dielectric barrier discharge treatment to control gray mold growth on cut rose flowers

Cold atmospheric pressure plasma irradiation is an efficient method for decontaminating fruits and vegetables. The present study evaluates the effect of dielectric barrier discharge (DBD) cold plasma treatment on controlling gray mold (Botrytis cinerea Pers.), a destructive pathogen of cut roses (Rosa hybrida L. cv. Samurai). The ion leakage, relative water content (RWC), proline, chlorophyll, carotenoid, anthocyanin content, and discoloration of treated rose petals were measured. Experimental observation showed significant changes in ion leakage, RWC, and chlorophyll content at 20 kV for 8 min compared to the control. The same treatment induced significant changes in the proline content of the rose petals, but no statistical difference was observed in their anthocyanin and carotenoid contents compared to the control. The results indicated that gray mold growth was entirely suppressed by plasma irradiation at 20 kV for 4, 6, and 8 min and 15 kV for 8 min. Plasma at 10 kV for 8 min and 15 kV for 6 min suppressed 90% and 70% of the gray mold growth, respectively. It is noteworthy that plasma irradiation at 20 kV for just 4 min and at 15 kV for 6 min suppressed 100 and 70% of B. cinerea growth, respectively; however, plasma irradiation did not change the quality indices of rose petals. Overall, it can be said that cold plasma treatment by DBD has the potential to increase the shelf life of cut roses by suppressing gray mold development.

Prediction of CO2 and ethylene produced in‐packaged apricot under cold plasma treatment by machine learning approach

AbstractIn this study, the fresh and in‐packaged apricots were treated with dielectric barrier discharge (DBD) cold plasma for 5, 10, and 15 min and then stored at 21°C for 12 days to simulate the shelf life of the apricot. The effects of DBD treatment on the main quality attributes of apricot such as physicochemical traits (mass loss, pH, soluble solid content, titratable acidity, and skin color), mechanical properties (Young's modulus, tangent modulus, and bioyield stress), in‐package gas composition and ethylene production were investigated during the storage time. In addition, the bruise susceptibility (BS) of control and treated samples at the microscale was evaluated by using pendulum test and scanning electron microscopy. The results of the mass loss, pH, soluble solid content, titratable acidity, skin color, and bioyield stress have been applied for input parameters of the developed artificial neural network (ANN) and support vector regression (SVR) models to predict the CO2 and ethylene production. The statistical data showed the performance of the developed ANN to predict the CO2 (R2 = 0.983, root mean square error [RMSE] = 0.486) and ethylene production (R2 = 0.933, RMSE = 5.376) was superior to SVR (CO2: R2 = 0.894, RMSE = 6.077 and ethylene: R2 = 0.759, RMSE = 14.117). These results indicated that intelligent methods are effective and robust tools for predicting the quality parameters of fresh fruits in the postharvest process.Practical ApplicationsAdvancement of technology and artificial intelligence leads to the tendency of many food industry engineers and researchers in the R&amp;D department to use this technology to classify and predict various food industry processes. In the process of packaging products, there are challenges such as the amount of produced carbon dioxide and ethylene inside the package, which affects the shelf life of fresh agricultural products. In this research, artificial neural networks and support vector machine methods have been used to predict the two mentioned parameters. This approach can be used for the digitalization of the packaging process of agricultural and horticultural products and reduce the number of experimental activities. In addition, it is possible to improve the digitalization process by the fusion of smart sensors with machine learning methods.

The effect of pulse voltage rise rate on the polypropylene surface hydrophilic modification by ns pulsed nitrogen DBD

The nanosecond (ns) pulsed nitrogen dielectric barrier discharge (DBD) is employed to enhance the hydrophilicity of polypropylene (PP) surface and improve its application effect. The discharge characteristics of the ns pulsed nitrogen DBD with different pulse rise times (from 50 to 500 ns) are investigated by electrical and optical diagnostic methods and the discharge uniformity is quantitatively analyzed by image processing method. To characterize the surface hydrophilicity, the water contact angle (WCA) is measured, and the physical morphology and chemical composition of PP before and after modification are analyzed to explore the effect of plasma on PP surface. It is found that with increasing pulse rise time from 50 to 500 ns, DBD uniformity becomes worse, energy efficiency decreases from 20% to 10.8%, and electron density decrease from 6.6 × 1011 to 5.5 × 1011 cm−3. The tendency of electron temperature is characterized with the intensity ratio of N2/N+ 2 emission spectrum, which decreases from 17.4 to 15.9 indicating the decreasing of T e with increasing pulse rise time from 50 to 500 ns. The PP surface treated with 50 ns pulse rise time DBD has a lower WCA (∼47°), while the WCA of PP treated with 100 to 500 ns pulse rise time DBD expands gradually (∼50°‒57°). According to the study of the fixed-point WCA values, the DBD-treated PP surface has superior uniformity under 50 ns pulse rise time (3° variation) than under 300 ns pulse rise time (8° variation). After DBD treatment, the increased surface roughness from 2.0 to 9.8 nm and hydrophilic oxygen-containing groups on the surface, i.e. hydroxyl (−OH) and carbonyl (C=O) have played the significant role to improve the sample’s surface hydrophilicity. The short pulse voltage rise time enhances the reduced electric field strength (E/n) in the discharge space and improves the discharge uniformity, which makes relatively sufficient physical and chemical reactions have taken place on the PP surface, resulting in better treatment uniformity.

A high-efficiency solar desalination biomass material prepared by DBD plasma

Biomass materials for interfacial evaporation with solar energy have obvious advantages and potentials in the field of desalination. In this work, plasma technology is first used to prepare biomass materials for seawater desalination. The plasma carbonized film (PCF) is obtained from poplar chips treated by dielectric barrier discharge (DBD) plasma. The whole preparation process can be quickly achieved in one step without any chemical reagent or carrier gas. After DBD treatment, the original water channels of the xylem are preserved ensuring efficient water transport and high salt resistance. The hydrophobic nature of the evaporator surface makes it self-floating. Under sunlight irradiation, photons are captured by the black PCF surface converting solar energy into heat energy, and fresh water can be continuously and stably obtained from salt water. The evaporation rate under one sunlight by PCF in water and 3.5 wt% NaCl solution can reach 1.70 kg m−2 h−1, and 1.63 kg m−2 h−1, respectively. PCF has abundant micron-sized holes and low-distortion channels making the material form a 3D interconnection structure. Therefore, PCF has a solar-steam conversion efficiency as high as 91%. Besides, the tolerance test shows that PCF can still maintain a high evaporation rate and self-clean after long-term work.

Non-thermal plasma activated peroxide and percarbonate for tetracycline and oxytetracycline degradation: Synergistic performance, degradation pathways, and toxicity evaluation

Tetracycline (TC) and Oxytetracycline (OTC) are common antibiotics increasingly detected in the environment, posing a potential risk to human and aquatic lives. Although conventional methods such as adsorption and photocatalysis are used for the degradation of TC and OTC, they are inefficient in removal efficiency, energy yield, and toxic byproduct generation. Herein, a falling-film dielectric barrier discharge (DBD) reactor coupled with environmentally friendly oxidants (hydrogen peroxide (HPO), sodium percarbonate (SPC), and HPO + SPC) was applied, and the treatment efficiency of TC and OTC was investigated. Experimental results showed that moderate addition of the HPO and SPC exhibited a synergistic effect (SF > 2), significantly improving the antibiotic removal ratio, total organic removal ratio (TOC), and energy yield by more than 50%, 52%, and 180%, respectively. After 10 min of DBD treatment, the introduction of 0.2 mM SPC led to a 100% antibiotic removal ratio and a TOC removal of 53.4% and 61.2% for 200 mg/L TC and 200 mg/L OTC, respectively. Also, 1 mM HPO dosage led to 100% antibiotic removal ratios after 10 min of DBD treatment and a TOC removal of 62.4% and 71.9% for 200 mg/L TC and 200 mg/L OTC, respectively. However, the DBD + HPO + SPC treatment method had a detrimental effect on the performance of the DBD reactor. After 10 min of DBD plasma discharge, the removal ratios for TC and OTC were 80.8% and 84.1%, respectively, when 0.5 mM HPO + 0.5 mM SPC was added. Moreover, principal component and hierarchical cluster analysis confirmed the differences between the treatment methods. Furthermore, the concentration of oxidant-induced in-situ generated ozone and hydrogen peroxide were quantitatively determined, and their indispensable roles during the degradation process were established via radical scavenger tests. Finally, the synergetic antibiotic degradation mechanisms and pathways were proposed, and the toxicities of the intermediate byproducts were evaluated.

Insights into catalyst-free, highly effective degradation of pharmaceutical contaminant in aqueous solution by a dielectric barrier discharge system

The emerging pharmaceutical wastewater including non-steroidal anti-inflammatory drugs has posed a serious threat to the ecological environment and human health, and therefore effective treatment technologies are being urgently needed. Herein, a novel horizontal continuous-flow dielectric barrier discharge (DBD) system without catalyst was developed for the highly effective degradation of diclofenac in aqueous solution. The degradation efficiency of 10 mg/L diclofenac reached about 90% in 14 min, and the corresponding energy efficiency was 0.181 g/kWh. Furthermore, the treated water quality was evaluated in terms of TOC, BOD5/COD and toxicity. The biodegradability rapidly improved with the increasing of DBD treatment time as be expected, although the mineralization efficiency of diclofenac was still low. To gain insight into the degradation mechanism, short-lived transient and long-lived species have been identified during DBD process, in which transient species (·OH, ·O2–) were the major contribution to the oxidation of diclofenac. Furthermore, based on the intermediates identified by LC-MS, a possible degradation pathway of diclofenac by DBD system in aqueous solution was proposed. Therefore, the novel DBD reactor with horizontal continuous-flow appears to be more promising for the treatment of pharmaceutical wastewater in practical applications.

Subcellular damages of pathogenic fungi combined with gene expression analysis reveals mechanisms that cold plasma controlling apricot disease

Dielectric barrier discharge (DBD) plasma technology has proven effective in controlling postharvest fungus in fruits and vegetables. However, its mechanism of action is rarely reported. In this study, DBD technology was investigated to inhibit apricot diseases under the conditions of shelf simulation, and its mechanism was analysed. Apricot fruits and pathogenic fungal spores were treated with DBD of different voltage intensities（fruits: 80 kV, 90 kV, 100 kV; spores: 80 kV, 100 kV, 120 kV). Experimental data showed that DBD plasma treatment significantly reduced the microbial biomass on the surface of apricot fruit and inhibit Rhizopus oryzae and Alternaria tenuissima. Rhizopus oryzae and Alternaria tenuissima's spore germination decreased by 74.7% and 82.0%, respectively, after 40 s of processing with 100 kV DBD treatment. To investigate DBD plasma's antibacterial mechanism, deoxyribonucleic acid damage and the morphological characteristics of fungal spores were determined; this indicated that DBD plasma treatment resulted in nuclear degradation and cell deformation. In addition, DBD treatment enhanced apricots' expression of phenylalanine ammonia-lyase 1 (PAL1), aldehyde dehydrogenase 2B7 (ALDH2B7) and GDP-L-galactose phosphorylase (VTC2), delayed disease and improved quality under shelf storage conditions. The results demonstrated that DBD plasma treatment could control the primary diseases of apricot fruit and enhance the quality by destroying microbial spores and activating the disease-resistant genes of the fruit.

INFLUENCE OF DIELECTRIC BARRIER DISCHARGE ON BEET SEEDS GERMINATION

The effect of dielectric barrier discharge (DBD) treatment on the germination of beet seeds under different conditions was investigated. The emission spectra of the DBD plasma were measured under various operating conditions. It is shown that the main components of the emission spectra are nitrogen (N2) bands. The rotational (Tr) and vibrational (Tv) temperatures of the DBD plasma are determined from the N2 bands under different operating conditions. The dependences of the germination percentage of beet seeds at different time intervals of DBD treatment were obtained. The optimal time for treating beet seeds was determined.

Supported bimetallic hydrogenation catalysts treated by non-thermal plasmas

Non-thermal plasma (NTP) may be an effective and clean way for enhancing catalyst performance. The paper aims to treat the surface of catalysts by different NTP techniques. Here, radio-frequency (RF) plasma jet, dielectric barrier discharge (DBD), and spark discharge are used to treat supported bimetallic hydrogenation catalysts (i.e., Mo-Ni sulfide/γ-Al2O3 and Mo-Co oxide/γ-Al2O3) in ambient air. Surface representations of the virgin and NTPs treated catalysts show that the surface morphology, chemical states and functional groups change remarkably after NTPs treatment. The catalyst’s surface become smoother after RF plasma jet treatment, but rougher after DBD or spark discharge treatment, compared with the virgin case. The heavy particles (i.e., Ar metastable states) in RF plasma jet, high-energy electrons in DBD, and heat in spark discharge play major roles in the plasma-catalyst interactions, respectively. The evident promotion of Mo chemical valence by the oxidation of O atoms happens after DBD treatment, which indicates that DBD may be an effective way to regulate Mo chemical valence. The MoS2 layers of the Mo-Ni sulfide/γ-Al2O3 catalyst are severely destroyed as the MoS2 Raman spectrum disappear after RF plasma jet treatment. The paper provides guidance for structure regulation of catalyst surfaces by NTPs.

Dielectric barrier discharge based defect engineering method to assist flash sintering

Oxygen vacancy plays an important role in the flash sintering (FS) process. In defect engineering, the methods to create oxygen vacancy defect include doping, heating, and etching, and all of them often have complex process or equipment. In this study we used dielectric barrier discharge (DBD) as a new defect engineering technology to increase oxygen vacancy concentration of green billet with different ceramics (ZnO, TiO₂ and 3 mol% yttria-stabilized zirconia (3YSZ)). With a 10 kHz AC power supply, the low-temperature plasma was generated and the specimen could be treated in different atmosphere. The effect of DBD treatment was influenced by atmosphere, treatment time, and voltage amplitude of power supply. After DBD treatment, the oxygen vacancy defect concentration in the ZnO samples increased significantly, and the resistance test showed that the conductivity of the samples increased by 2–3 orders of magnitude.&nbsp; Moreover, the onset electric field of ZnO FS decreased from 5.17 kV/cm to 0.86 kV/cm at room temperature, while in the whole FS the max Power dissipation decrease from 563.17 W to 27.94 W. The defect concentration and conductivity of the green billets for TiO₂ and 3YSZ also changed by DBD, and then the FS process was modified. It is a new technology to treat green billet of ceramic in very short time, applicable to other ceramics, and beneficial to regulate the FS process.