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The constant growth in the share of renewable electricity and the need to reduce CO2 emissions create prospects for the development of non‐thermal plasma (NTP) pyrolysis of heavy oil. NTP pyrolysis requires only electricity and does not require heating of raw materials to high temperatures, which significantly reduces the carbon footprint during processing. This paper investigates the characteristics of NTP pyrolysis of vacuum gas oil under the action of electric microsecond discharges in the liquid phase, depending on the voltage of the current source 300–700 V to optimize energy consumption, conversion of raw materials, and increase the yield of commercial demand products. [ABSTRACT FROM AUTHOR]

Fundamental and applied research on plasma‐treated liquids for biomedical applications was boosted in the last few years, dictated by their advantages with respect to direct treatments. However, often, the lack of consistent analysis at a molecular level of these liquids, and of the processes used to produce them, have raised doubts of their usefulness in the clinic. The aim of this article is to critically discuss some basic aspects related to the use of plasma‐treated liquids in medicine, with a focus on their chemical composition. We analyze the main liquids used in the field, how they are affected by non‐thermal plasmas, and the possibility to replicate them without plasma treatment. [ABSTRACT FROM AUTHOR]

The efficient removal of toluene by plasma catalytic system (PCS) requires catalysts that can generate strong synergetic effect with discharge to oxidize toluene while promoting CO2 selectivity and suppressing the formation of harmful byproducts. We report that application of an Ag/CeO2/Al2O3 catalyst into PCS enables high conversion of toluene to CO2 and H2O with the low concentration of ozone and nitrogen oxides. The Ag nanoparticles dispersed on CeO2 surface transforms the filamentary discharge to a relatively uniform discharge with high‐efficiency, facilitates surface oxygen activation and organic intermediates oxidation, thus, enhances toluene removal efficiency. At 1800 J L−1, toluene conversion and CO2 selectivity reached maximum at 93% and 71%, respectively, whereas the removal process exhibited a good stability during a 5‐h test. [ABSTRACT FROM AUTHOR]

The current and potential applications of atmospheric pressure plasmas in medicine generate an increasing need to develop safe and reliable plasma devices for patient treatment. This paper shows how the estimation of safety risks, the stability of the generated plasma, and the effectiveness in the aimed application can orientate the design process of a specific atmospheric pressure plasma device intended for clinical use. A promising plasma jet device operated with air is optimized, leading to a configuration with a more advanced design that reduces the temperature of the effluent, prevents the material degradation and improves the isolation of the high voltage components. The effects of the plasma jet treatment are investigated by chemical analysis of demineralized water and inactivation tests on E. coli cultures. [ABSTRACT FROM AUTHOR]

The paper presents the effects of plasma treatment on agricultural seeds. Cucumber and pepper seeds, widely used in agriculture, were treated using the Diffuse Coplanar Surface Barrier Discharge (DCSBD) at atmospheric pressure in ambient air. The plasma treatment (4 s for pepper, 20 s for cucumber) led to an improvement of germination and germinating power. XPS confirmed chemical changes on the seed surface. The surface morphology of the plasma treated seeds showed no evidence of structural damage. The conclusion is that DCSBD proves to be able to reduce some of the microorganisms and pathogens affecting the seeds. Thanks to their technical simplicity and easy scaling‐up, DCSBD plasma sources open new opportunities for atmospheric pressure plasma application in the agricultural industry. [ABSTRACT FROM AUTHOR]

We review new trends of agricultural applications of atmospheric‐pressure plasmas for decontaminating agricultural products and enhancing seed germination and growth of plants and beneficial microorganisms. We classify the decontamination techniques into three kinds of treatments, which are gas‐phase, in‐liquid, and plasma‐activated liquid treatments, and introduce recent studies mainly after 2010, discussing the inactivation mechanism of microorganisms in each treatment. Likewise, we categorize the enhancement techniques into the same three kinds of treatments, and introduce the growth enhancements in detail, discussing the mechanisms and future prospects. [ABSTRACT FROM AUTHOR]

The paper presents experimental results concerning pre‐sowing stimulation of Thuringian Mallow (Lavatera thuringiaca L.) seeds with non‐thermal plasma generated in GlidArc reactor (dry nitrogen, atmospheric pressure) and its effect on the germination process. Five groups of seeds characterized by different exposure times were used. The effect of cold plasma on seeds was analyzed by investigation of microscopic pictures of carbon coated seed surfaces registered by means of electron scanning microscope. Visible changes in the seed surface structure could enhance the formation of micro‐pores which may be involved in water absorption, thus facilitating faster seed germination. Pre‐sowing plasma stimulation of seeds improved germination parameters such as germination capacity and germination energy for all tested groups, relative to control. The highest germination parameters were obtained for seeds stimulated with plasma for the exposure times of 2 and 5 min. [ABSTRACT FROM AUTHOR]

Nickel (Ni) nanoparticles have been synthesized from the dissociation of nickelocene (Ni(Cp)2) in an argon‐hydrogen (Ar‐H2) low pressure continuous‐flow non‐thermal plasma. The influence of process parameters on the synthesized Ni nanomaterial structure, size, size‐dispersion, and carbon content has been characterized by EDS and TEM analysis. The role of hydrogen dilution and plasma input power on material throughput is carefully discussed. These data, in combination with the prediction of the electron affinity and ionization potential of Ni(Cp)2 by DFT calculations, supports the hypothesis that the material loss‐mechanism to the reactor walls is due to the inherent ambipolar diffusion present in this synthesis technique. This study suggests that precursors should be screened with care when attempting to produce nanoparticle via a low pressure, continuous flow plasma reactor. [ABSTRACT FROM AUTHOR]

O2 and CO2 Dielectric Barrier Discharges (DBD) were studied at elevated (i.e., above atmospheric) pressure regimes (1-3.5 bar). It was demonstrated that these operational conditions significantly influence both the discharge dynamics and the process efficiencies of O2 and CO2 discharges. For the case of the O2 DBD, the pressure rise results in the amplification of the discharge current, the appearance of emission lines of the metal electrode material (Fe, Cr, Ni) in the optical emission spectrum and the formation of a granular film of the erosion products (10-300 nm iron oxide nanoparticles) on the reactor walls. Somewhat similar behavior was observed also for the CO­2 DBD. The discharge current, the relative intensity of the CO Angstrom band measured by Optical Emission Spectroscopy (OES) and the CO2 conversion rates could be stimulated to some extent by the rise in pressure. The optimal conditions for the O2 DBD ( P = 2 bar) and the CO2 DBD ( P = 1.5 bar) are demonstrated. It can be argued that the dynamics of the microdischarges (MD) define the underlying process of this behavior. It could be demonstrated that the pressure increase stimulates the formation of more intensive but fewer MDs. In this way, the operating pressure can represent an additional tool to manipulate the properties of the MDs in a DBD, and as a result also the discharge performance. [ABSTRACT FROM AUTHOR]

This article reports the use of innovative diagnostics to monitor toluene adsorption and oxidation on CeO2 surface under non-thermal plasma (NTP) exposure. Two plasma-catalytic configurations are explored, namely: post-plasma catalysis (PPC) and in-plasma catalysis (IPC). Since heterogeneous processes are pointed out as key steps of the plasma-catalyst coupling, the catalyst surface has been monitored by two complementary in situ diagnostics: (i) diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) and (ii) transmission fourier transform infrared spectroscopy using Sorbent track (ST) device. Dielectric barrier discharges (DBD) are used in both PPC and IPC configurations to induce adsorbed toluene oxidation. Toluene in dry air is first adsorbed on the selected catalytic surface: ceria (CeO2). Subsequently, the plasma is switched on. During the experiment, the ceria surface is monitored by infrared to study toluene adsorption and oxidation mechanisms. The adsorption capacity of toluene on ceria is, respectively, measured in the configurations of PPC and IPC by DRIFTS and ST. The oxidation of toluene by plasma follows a first-order reaction regardless of plasma configuration and injected power and IPC is more effective for the toluene removal than PPC. Intermediates of toluene (benzyl alcohol, benzaldehyde and benzoic acid) are also identified on the surface and their respective temporal evolutions as a function of the plasma exposure are studied. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysis is of great importance in chemical industries. Hence, various approaches are studied to improve catalyst characteristics with the purpose of promoting catalytic reactions. Among them, non-thermal plasma treatment has attracted more attention due to its low temperature operation, simplicity, and shorter processing time. An extensive review has been performed for better understanding of various aspects of this technique. Unanimously, it is reported that plasma method leads to higher conversion, lower temperature activity and better coke suppression. In light of the investigated literature, application of plasma seems to have potential of starting a revolution in chemical processes. However, it necessitates more works to promote this technology toward industrial application. [ABSTRACT FROM AUTHOR]

Atmospheric-pressure nonthermal plasma was used to synthesize ammonia from nitrogen and hydrogen over ruthenium catalysts. Formation of NH3 in a N2-H2 mixture altered the plasma characteristics due to the low ionization potential of NH3 (10.15 eV). The optimum gas ratio was found at N2:H2 = 4:1 by volume (i.e., N2-rich conditions). When plasma was operated at a temperature below 250 °C, the NH3 concentration increased linearly with increasing specific input energy (SIE). For the Ru(2)-Mg(5)/γ-Al2O3 catalyst at 250 °C, pulse energization was four times more efficient than the AC energization case. The presence of RuO2 was found to be beneficial for the NH3 synthesis via plasma-catalysis. The addition of a small amount of O2 was found to be effective for the in situ regeneration of the deactivated catalyst. The effect of metal promoters was in the order of Mg > K > Cs > no promoter. [ABSTRACT FROM AUTHOR]

This article reports the use of innovative diagnostics to monitor toluene adsorption and oxidation on CeO2 surface under non-thermal plasma (NTP) exposure. Two plasma-catalytic configurations are explored, namely: post-plasma catalysis (PPC) and in-plasma catalysis (IPC). Since heterogeneous processes are pointed out as key steps of the plasma-catalyst coupling, the catalyst surface has been monitored by two complementary in situ diagnostics: (i) diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) and (ii) transmission fourier transform infrared spectroscopy using Sorbent track (ST) device. Dielectric barrier discharges (DBD) are used in both PPC and IPC configurations to induce adsorbed toluene oxidation. Toluene in dry air is first adsorbed on the selected catalytic surface: ceria (CeO2). Subsequently, the plasma is switched on. During the experiment, the ceria surface is monitored by infrared to study toluene adsorption and oxidation mechanisms. The adsorption capacity of toluene on ceria is, respectively, measured in the configurations of PPC and IPC by DRIFTS and ST. The oxidation of toluene by plasma follows a first-order reaction regardless of plasma configuration and injected power and IPC is more effective for the toluene removal than PPC. Intermediates of toluene (benzyl alcohol, benzaldehyde and benzoic acid) are also identified on the surface and their respective temporal evolutions as a function of the plasma exposure are studied. [ABSTRACT FROM AUTHOR]

Results of simulation of streamers propagating along atmospheric-pressure air plasma jets formed by pulsed discharges in thin dielectric tubes are presented. The specific feature of these jets is substantial gas heating by the discharges. The hot gas, emerging from the tube, is cooled at mixing with surrounding air. The streamers are guided along the jet axis, the channel with reduced gas density. Spatial profiles of various plasma parameters inside the jet are calculated. The densities of produced oxygen and nitrogen atoms near the jet axis are one-two orders larger, while the widths of radial profiles of these species are several times smaller than those in typical helium plasma jets. [ABSTRACT FROM AUTHOR]

Based on the comparison of simulative and experimental data, an approach is presented for the design and optimization of processes assisted by low power atmospheric pressure Radio Frequency (RF) thermal plasmas. High Speed Imaging (HSI), Schlieren Imaging (SI), and temperature measurement on the surface of the substrate are performed to characterize the effect of the interaction of the RF torch effluent with a substrate placed downstream of the torch outlet. The related processes are simulated in 2-D axisymmetric and 3-D domains for different operating conditions, for the plasma generation region and for the downstream region, respectively. The comparison of numerical and experimental results is used to in depth characterize and investigate the behavior of the effluent of the RF torch. [ABSTRACT FROM AUTHOR]

The modelling of a gliding arc discharge (GAD) is studied by means of the quasineutral (QN) plasma modelling approach. The model is first evaluated for reliability and proper description of a gliding arc discharge at atmospheric pressure, by comparing with a more elaborate non-quasineutral (NQN) plasma model in two different geometries - a 2D axisymmetric and a Cartesian geometry. The NQN model is considered as a reference, since it provides a continuous self-consistent plasma description, including the near electrode regions. In general, the results of the QN model agree very well with those obtained from the NQN model. The small differences between both models are attributed to the approximations in the derivation of the QN model. The use of the QN model provides a substantial reduction of the computation time compared to the NQN model, which is crucial for the development of more complex models in three dimensions or with complicated chemistries. The latter is illustrated for (i) a reverse vortex flow (RVF) GAD in argon, and (ii) a GAD in CO2. The RVF discharge is modelled in three dimensions and the effect of the turbulent heat transport on the plasma and gas characteristics is discussed. The GAD model in CO2 is in a 1D geometry with axial symmetry and provides results for the time evolution of the electron, gas and vibrational temperature of CO2, as well as for the molar fractions of the different species. [ABSTRACT FROM AUTHOR]

Most thermal plasma applications involve interactions between the plasma and solid or liquid surfaces. Computational models of thermal plasma applications typically consider the influence of the plasma on the surface, but often neglect the effect of the surface on the plasma. In many cases, however, it is not possible to accurately model the plasma process without taking the two-way interactions into account. This is demonstrated using examples from arc welding, plasma cutting, plasm­a-particle interactions, such as occur in plasma spheroidization, plasma nanoparticle production and plasma spraying, and high- and low-voltage circuit breakers. Vaporization of metal, ceramic and polymer surfaces, transfer of heat and momentum from the plasma to particles and droplets, and changes in the surface shape are all shown to affect the properties of the plasma. [ABSTRACT FROM AUTHOR]

This work presents a review of expanding thermal plasma - chemical vapour deposition (ETP-CVD) of Al-doped ZnOtransparent conducting oxides (TCOs), alongside new results providing insights into the role of the plasma chemistry on film microstructure. Standard growth conditions generate high resistivities (>10−3Ω · cm) at low film thicknesses (<300 nm) as a result of a high grain boundary and void density. Microscopy studies of the early growth stage reveal that a high nucleation probability and strong <0002>-texture are the causes of this microstructure. We investigate how the precursor feed composition (diethylzinc-to-O2 flow rate ratio) can be utilised to modify the growth mechanism and consequently reduce film resistivity (∼10−4Ω · cm), focussing on the role that this flow rate ratio has on the plasma chemistry developing in the downstream region of the expanding plasma (as supported by Langmuir probe and mass spectrometry measurements). [ABSTRACT FROM AUTHOR]

In the present work, ZrO2 nanoparticles loaded on glass wool (GW) were employed for catalytic and plasma-catalytic decomposition of ethylene. Unlike ZrO2 pellets, nanosized ZrO2 was found to exhibit catalytic activity for the decomposition of ethylene. Some carbon-containing by-products like CH4, C2H2, and HCHO were detected under room-temperature operation of the reactor. The formations of such unwanted by-products were suppressed and the conversion into CO2 was enhanced when the ZrO2 catalyst was combined with non-thermal plasma at high temperatures. The nanosized ZrO2 exhibited a stable decomposition performance during 80-h continuous operation, suggesting that it is able to withstand deactivation without substantial loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various topics within the issue including article on "Numerical Modelling of Low-Temperature Plasmas for Various Applications" and modellingapproaches for thermal plasmas.

Non‐thermal plasma treatment is one of the promising options for local anti‐neoplastic treatment of dysplastic lesions and early intraepithelial cancer. Primarily, the antiproliferative properties are driven through the generation of reactive oxygen and nitrogen species. In this study, we investigated the amount and distribution of reactive species generated by a non‐thermally operated electrosurgical argon plasma source using electron spin resonance (ESR) spectroscopy. During the plasma treatment of both, aqueous solution and solid human preputial tissue an increasing amount of different oxygen‐ and carbon‐centered radicals was detected. However, and most probably due to spin trap degradation by the high energy input and the increase of reactive components in aqueous solution, the ESR signal decreased after treatment times exceeding 10 s. Non‐thermally operated electrosurgical argon plasma sources reveal a potent emergence of reactive species and may be suitable for usual cold atmospheric plasma applications in plasma medicine. The vigorous generation of reactive plasma components of these plasma sources, being the main trigger for plasma related cell phenomena, may enable efficient treatment of precancerous and cancerous lesions. [ABSTRACT FROM AUTHOR]

The interest of fructose production arises from its sweetening character used in application such as food and pharmaceutic industries. Fructose formation is achieved by the short treatment of inulin by non thermal plasma at atmospheric pressure, under air, using a dielectric barrier discharge (DBD) configuration. Promising results were observed as a total conversion of inulin was achieved within 10 min of treatment (18 kV, 2 kHz), without the addition of solvent, nor catalyst and at room temperature. Additionally to fructose (32%), fructooligosaccharides of higher degrees of polymerization were produced. The mechanism underlying the depolymerization process appears to start with the oxidation of inulin followed by the cleavage of the β‐glycosidic bond and eventually ring opening of the monomer. Depolymerization of inulin into fructose is achieved by non thermal plasma treatment at atmospheric pressure. The gas chemical nature is a key parameter for the reaction. Depolymerization into fructo‐oligosaccharides depends on treatment time and local temperature. These products can be valorized various applications. [ABSTRACT FROM AUTHOR]