The use of cold atmospheric plasma in agriculture is limited due to its potential toxic effect. The properties of cold plasma and its effect on plants can vary depending on the type of device used, treatment conditions, and the physiological characteristics of the treated object. This study provides a comparative analysis of the growth and physiological parameters of Hordeum vulgare L. seedlings after root and leaf treatment with cold atmospheric plasma. Using hyperspectral technology, infrared spectroscopy, and fluorescence imaging, it was shown that 1 s plasma exposure (generated by a coaxial system with a dielectric barrier discharge, a power of 40 W, and Ar flow rate of 142 L/h) of the roots increased leaf reflectance, transpiration and CO2 assimilation rates, while photosynthetic electron flows remained unchanged. These seedlings showed enhanced dry matter content and primary leaf length compared to control plants. Foliar treatment of Hordeum vulgare L. seedlings with the same plasma did not affect stomatal conductance, but increased chlorophyll and carotenoid content, activated cyclic electron transport around photosystem I, and enhanced the proton gradient across the thylakoid membrane. With this type of plasma impact, increased leaf length was recorded 3 days after treatment. The obtained data demonstrated the growth-promoting effect of cold atmospheric plasma using the tested treatment methods.
The concentration of alkaline-earth metal ions in aqueous solutions is measured using the method of atmospheric pressure discharge plasma emission spectroscopy with a liquid cathode. Rubidium atoms added as RbCl serve as the actinometer component in the plasma. A known concentration of this reference cation is added to the analyzed solution. Magnesium, calcium, and barium chloride solutions with concentrations ranging from 10− 4 to 0.1 g/L are analyzed. It is demonstrated that the addition of background electrolytes to the solution affects the emission intensity of the metal atomic lines. However, using the ratio of the emission intensity of the analyzed component to that of the actinometer component effectively compensates for this matrix effect, ensuring accurate quantitative analysis.
Graphene and other sp2-hybridized carbon nanostructures are highly sought for their large surface area, novel electrical and optical properties, and potential applications for energy conversion/storage. Atmospheric pressure plasmas offer a scalable route to carbon nanoparticle synthesis, but controlling the carbon allotrope formation is a major challenge because methane plasmas can lead to a large variety of non-graphitic nanostructures such as amorphous carbon nanospheres. Here we report on a gas flow-and-composition-based selectivity window for few-layer-graphene synthesis using an atmospheric pressure radiofrequency plasma reactor. Our key finding is that selecting for wrinkled few-layer graphene nanoparticle formation as opposed to other allotropes of carbon nanoparticles can be achieved by solely adjusting methane concentration and flowrate. This result establishes that atmospheric pressure plasmas can go beyond general carbon nanoparticle synthesis and enable selective control over allotrope formation.
The widespread use of antibiotics in aquaculture and livestock production has contributed to the dissemination of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) in aquatic environments. In this study, submerged spark plasma systems were evaluated for the removal of rifampicin, rifampicin-resistant Escherichia coli O157:H7, and ARG-associated DNA in different water matrices using a 40 mL single-spark reactor and a 1000 mL multiple-spark reactor. The single-spark system achieved 99.43
Pentafluoropropanol (PFP; C3H3F5O) and hexafluoroisopropanol (HFIP; C3H2F6O) were investigated as low global warming potential (GWP) alternatives to the conventional perfluorocarbon, C4F8, for the plasma etching of SiO2 using an inductively coupled plasma system. The PFP/Ar and HFIP/Ar plasmas exhibited substantially higher SiO2 etch rates than C4F8/Ar plasma across all bias voltage conditions, which was attributed to the generation of O radicals that suppress fluorocarbon deposition and the higher production of F radicals. The radical generation tendencies measured using optical emission spectroscopy were consistent with the bond dissociation energy predictions. X-ray photoelectron spectroscopy indicated that the steady-state fluorocarbon film on SiO2 was thinner in PFP/Ar and HFIP/Ar plasmas than in C4F8/Ar plasma, with lower fluorine-to-carbon ratios due to defluorination by H radicals. The PFP/Ar plasma demonstrated superior etch selectivity for SiO2 with respect to the amorphous carbon layer, and the most anisotropic etch profile in 200-nm-diameter contact holes. Fourier-transform infrared analysis of exhaust gases showed that PFP/Ar and HFIP/Ar plasmas predominantly produced low-GWP byproducts, reducing the million metric tons of carbon equivalent values by approximately 72
This study presents the structure and properties of the muscovite mica natural powder that was melted by plasma jet and collected as solidified microspheres after rapid cooling in air. The heating of mica material in plasma induces its dehydroxylation, i.e. the removal of the structurally bound water. The pore size distribution curves reveal that the plasma-spheroidized powder contained ultrafine pores, whereas the natural mica powder contained predominantly coarser pores. Flowability characteristics of natural mica powder were substantially improved after plasma spheroidization. The amorphous component strongly prevailed in the plasma spheroidized mica powder. The monitoring of chemical changes in powder was discussed in a common manner, i.e. element concentrations expressed as simple oxides contents. We saw a trend matching the content of each oxide with its melting point.
It was shown that the action of a DC discharge (discharge current is 50 mA) in air at atmospheric pressure on a mixture of iron nitrate (III) and nickel nitrate (II) salts located on the cathode leads to the formation of nickel ferrite. The composition of the ferrite (Ni1.43Fe1.7O4) and the size of the crystallinity region ( 29 nm) were determined using XRD and EDX analysis. It was found that the synthesized substance is a soft magnetic material with a saturation magnetization of 27 emu/g (293 K), a BET specific surface area of 21 m2/g, and a pore volume of 0.044 cm3/g.
An indoor air decontamination system combining a dielectric barrier discharge (DBD), UV-C lamps, and a TiO₂ photocatalyst, is investigated for the simultaneous removal of two volatile organic compounds (VOCs) — formaldehyde and methanol — at a high flow rate of 300 L·min⁻¹. The contributions of each component are evaluated independently and in combination, showing a strong synergistic effect between DBD and UV-C, particularly for formaldehyde removal, reaching up to 50
Integrating CO₂ capture and conversion within a single material platform offers an attractive route to reduce process complexity in carbon utilization technologies. Here, we investigate KOH-activated carbon foams as triple-functional electrodes that simultaneously adsorb CO₂, provide a reactive carbon surface for plasma-assisted CO formation, and serve as the discharge electrode in a DC corona reactor, enabling direct plasma–solid contact at the carbon interface. KOH-activated carbon foams were prepared across a systematic activation parameter space, with Fourier Transform Infrared Spectroscopy revealing a non-monotonic dependence of oxygen-containing surface functional groups on activation temperature and impregnation ratio. CO₂ breakthrough measurements and gas-phase mass spectrometry confirm material-dependent capture and CO conversion behavior, with the 4:1–750 °C condition exhibiting the most favorable uptake and transport kinetics. While Optical emission spectroscopy (OES) and zero-dimensional plasma chemistry modeling are individually well-established, their combined use to probe how electrode surface chemistry alone modifies plasma fragmentation pathways under otherwise identical discharge conditions has received little attention. Addressing this gap, OES is employed as a diagnostic tool, revealing condition-dependent shifts in CN, CO, CO⁺, and OH emission intensities. A custom-built zero-dimensional plasma chemistry model reproduces key qualitative features of the emission spectra and identifies the heterogeneous Boudouard reaction as the kinetically dominant CO production pathway under the experimental conditions examined. Across all diagnostics, CO formation is surface-reaction-limited rather than plasma-energy-limited, and the 4:1–750 °C condition consistently establishes the most productive plasma–surface interaction regime. These findings demonstrate that electrode surface chemistry is an active and tunable variable in plasma-driven CO₂ conversion.
Real time discharge dynamics in a pulse-driven cold atmospheric pressure plasma (CAP) device has been probed directly via ultra-high-speed imaging (480000 frames per second). CAP is driven by a variable frequency power source in the kHz range.While a detailed analysis of the discharge mechanism has been presented for 17 kHz, the key features of the discharges have also been presented at higher excitation frequencies (30 kHz, and 60 kHz). Observed charge buildup forming apparently stable strange structures in the discharge zone has been probed further by numerically subtracting the intensities of the consecutive images. Some of the novel mechanisms explored include specific stepwise buildup of ion density in the discharge zone leading to massive breakdown (avalanche), increased emission of secondary electrons via auto-enhanced ion accelerating voltages, reduction in potential through depletion of the ion cloud via recombination at higher frequencies, formation of strange but apparently stable discharge structures in the discharge zone, and oscillating electron current followed by relatively prolonged steady ion current after collection of the electrons. Measured steady electron current for few microseconds, immediately after the avalanche allowed a rough estimation of the electron density and electron mobility, which corroborate fairly well with the values reported in literature.
PET/TiO2 fabric shows durable UV protection across the UVA-UVC range with a low TiO2 concentration. Popular delustered PET/TiO2 fabrics made using a simple and eco-friendly technique. Plasma selective etching boosts roughness, exposing TiO2 for low UV transmittance, high abrasion, and high UPF. Exposed TiO2 micro/nanoparticles stayed on the fiber surface after 50 washes. This sparks research into novel, sustainable, and clean textile techniques. A recent focus on environmental principles and ultraviolet (UV) screening covering the long-wavelength (UVA) the shortest wavelength (UVC) range has driven extensive research for a novel and clean textile technique. In this work, the most popular delustered PET/TiO2 fabrics were applied through a facet and green plasma selective etching to create a rough fiber surface with exposed nanoparticles of TiO2. Durable anti-ultraviolet protection covering the UVA-UVC range was displayed for PET/TiO2 fabric, even with a low concentration of TiO2 nanoparticles. The UV-absorption intensity increased obviously with etching time. The ultraviolet protection factor (UPF) of the etched PET/TiO2 samples increased by more than 2 times and maintained an acceptable UPF even after 5 washing cycles. The surface morphology, chemical composition, and UV properties before and after various washing cycles were studied using Field Emission Scanning Electron Microscopy (FE-SEM), X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD), and UV-vis Spectroscopy. The results indicated that the exposed nanoparticles and etched pattern remained stable, and the ratios of [O]/[C] and [Ti]/[C] did not decrease too much after washing. Moreover, increased roughness and exposed TiO2 micro/nanoparticles by plasma selective etching were responsible for the large UV screening range with low UV transmittance and high UV absorption. Thus, this study opened an opportunity towards utilizing cheap materials which could be applicable in industry to make the sun safety delustered PET fabrics and reduce skin cancer infections.
Today, most hydrogen production is associated with significant greenhouse gas emissions. Given hydrogen’s growing importance across various sectors (mainly fertilizer synthesis, steel production and transportation), there is increasing interest in alternative, low-emission production routes. One promising route is conversion of methane under non-oxidative conditions, which yields hydrogen and carbonated byproducts. In this work, we investigate methane conversion using non-thermal plasma, specifically dielectric barrier discharges. The investigation focuses on the influence of different high voltage signal durations, ranging from milliseconds pulses (pulsed AC, burst mode) to microsecond (µSP) and nanosecond pulses (NSP), on the energy cost (EC). To ensure a valid comparison between modes, a similar specific energy input (5–11 kJ L− 1) is used across different experiments, which are all performed in the same reactor. Results indicate that µSP and NSP present a lower EC (4200–5000 kJ mol− 1) for methane conversion than the burst mode (6000–7000 kJ mol− 1). The burst mode showed no clear improvement compared to AC operation under the explored SEI range. Rotational temperature (Trot) measurements reveal that discharge temperature was higher in the case of the NSP (700–1000 K) compared to the burst mode (500–650 K). Trot for the NSP was correlated with pulse power rather than total dissipated energy, showing that tuning a NSP can effectively control the discharge temperature.
Cold atmospheric plasmas offer promise for the treatment of water contaminated by per- and polyfluoroalkyl substances (PFAS). One approach to improve these treatments combines plasma with various heterogeneous materials, searching for new catalytic routes or for benefits associated to physical phenomena like sorption. Here a 32-pin electrode was used to generate pulsed (M-SPD, Multipin-Self Pulsing Discharge) and corona (MCD, Multipin Corona Discharge) discharges, and test them in combination with graphene oxide (GO), reduced graphene oxide (rGO) and boron-doped reduced graphene oxide (B-rGO). Preliminary tests on the degradation of perfluorooctanoic acid (PFOA) in water, identified beneficial effects by these materials, the M-SPD/B-rGO system being the most effective one. Further research focussed on this system, to evaluate the effect of B-rGO on the velocity and products of plasma-induced PFOA degradation, using argon or air as plasma feed gas. The amount of PFOA adsorbed on the material during the treatment was also determined. Both with argon and air plasma, significantly lower concentrations of residual PFOA were found in the presence of catalyst than with plasma only. For example, after 5 min treatment of a 1∙10− 6 M PFOA solution, residual PFOA with and without catalyst was, respectively, 32
Atmospheric pressure plasmas (APPs) can efficiently activate liquids by simultaneous delivery of electrons, ions, photons, and excited neutral species to the liquid surface. With the goal of controlling APP-liquid interactions, the impact of operational parameters on the formation and development of surface ionization waves (SIWs) was investigated with a two-dimensional numerical model, including the effects of the: (i) applied voltage pulse; (ii) liquid thickness (capacitance); (iii) liquid conductivity; and (iv) Ar/He gas mixture ratio. These parameters can be used to control the type and flux of reactive species arriving at the liquid surface, providing a means to tune the plasma-initiated chemistry. Higher voltages, thinner liquids, higher liquid conductivities, and helium-rich mixtures shift the system towards charge-dominated interfacial reactivity, whereas lower voltages, thicker liquids, lower conductivities, and argon-rich mixtures enhance photon-driven pathways. The ability to control reactivity delivered to the surface was applied to an investigation of APP destruction of per- and polyfluoroalkyl substances (PFAS) in water. Since long-chain PFAS preferentially accumulate at the gas–liquid interface, APPs that generate SIWs provide a targeted means of delivering reactive fluxes directly to these contaminants.
One of the major environmental challenges in the oil industry is the accumulation of heavy asphaltene-rich residues, which are difficult to process and are often underutilized as carbon resources. In this study, asphalt obtained as a by-product of the solvent deasphalting (SDA) process was converted into graphitized carbon materials by vacuum-free direct-current arc-discharge plasma treatment. The plasma route enabled rapid transformation of the asphaltene-rich feedstock into carbon products containing graphite-like domains, nanoonions, and polyhedral graphite particles. Comprehensive physicochemical characterization confirmed substantial dehydrogenation, deoxygenation, and structural ordering of the initial organic matrix, together with high thermal stability and measurable porosity in the resulting carbon material. The obtained carbon was further evaluated as a precursor for carbide synthesis under vacuum-free arc conditions. X-ray diffraction analysis confirmed the formation of cubic silicon carbide SiC (with carbide phase is 56 wt
Most plasma-based waste-treatment gasification systems employ arc plasma torches, in which the arc is usually stabilized either by a water vortex or by a swirling gas flow. Hybrid water–gas torches integrate both stabilization mechanisms. In current practice, argon is frequently selected as the stabilizing medium due to its strong arc-stabilizing capability; however, its presence in the produced synthesis gas is undesirable. This drawback motivates the search for alternative stabilizing gas compositions. Hydrogen has been proposed as a potential substitute for argon and may offer improved plasma-processing performance. In this study, we present thermophysical property calculations for argon–steam and hydrogen–steam plasmas, including enthalpy, electrical conductivity, thermal conductivity, and net emission coefficients. In addition, we introduce parameters derived from a simplified integral model of the arc column to characterize the influence of the stabilizing gas on arc-column behavior. The parameters were benchmarked against a more detailed one-dimensional numerical model of the central part of the plasma discharge. The results indicate that hydrogen increases the thermal conductivity and enthalpy of the plasma compared to argon, while the electrical conductivity is slightly larger for argon at relevant temperatures. The examined parameters suggest that hydrogen stabilization leads to higher arc voltages, although with increased heat losses to the torch walls. Relative to argon–steam, hydrogen–steam plasmas are expected to exhibit lower bulk temperatures while transporting higher enthalpy, which may translate into improved overall efficiency and supports the feasibility of hydrogen as an effective stabilizing gas for hybrid torches.
Per- and polyfluoroalkyl substances (PFAS) are resistant to degradation by typical treatment methods. Various technologies utilizing non-equilibrium plasma, including gliding arc plasma (GAP) discharge, show promise for degrading PFAS in water. This study investigated the mechanism by which air GAP discharge degrades PFAS in water. Experiments scavenging aqueous plasma species indicated that hydrated electrons (e− aq) are important to degradation, but do not play a significant role in mineralization, while reactive oxygen and nitrogen species (RONS) appeared to play a negligible role. On the other hand, experiments that scavenged gas-phase charged particles decreased PFAS degradation and completely inhibited mineralization. Based on these results, degradation products, and previous literature on PFAS degradation pathways and GAP treatment of PFAS-contaminated water, several significant pathways for PFAS degradation during GAP treatment were hypothesized: (1) thermal mineralization driven by gas-phase charged particles, (2) H/F exchange driven by free electrons (e−) at the plasma-water interface or e− aq at the plasma-water interface and in the bulk liquid, and (3) fragmentation via charge transfer from gas-phase charged particles. While the significance of gas-phase charged particles to PFAS degradation in water during non-equilibrium plasma treatment has been previously hypothesized and modeled, this study provides the first experimental evidence of their role.
The study evaluated two different treatments for nonthermal plasma devices, namely diffuse coplanar surface barrier discharge (DCSBD) and point-to-ring discharge (PTR) in cucumber plants against the severity of Meloidogyne incognita infestation. Plants were evaluated as intensity of infestation (Zeck scale), shoot height, compared to the infected control (IC) (nontreated seeds with M. incognita) and negative control (NC) (no infestation with treatment and no M. incognita). DCSBD 5s reduced the infestation by 22.9
