Non-thermal Plasma Technology Research Articles

Environment pollutants removal with non-thermal plasma technology

Abstract In recent years, non-thermal plasma technology has gained considerable attention. It can produce highly reactive hydroxyl radicals and other strong oxidants, which is promising in environment pollutants removal. This article mainly reviews the recent advances in environment contaminants removal with several well-known non-thermal plasma technologies. We first introduce non-thermal plasma technology and its development, then summarize their applications for air purification organic wastewater treatment and sludge organic crack and prospect their further development in the future.

Bactericidal efficacy of non-thermal plasma activation against Aeromonas hydrophila and immunological responses of koi (Cyprinus carpio haematopterus)

In the aquaculture industry, an efficient and safe water purification system is important to prevent mass mortality by virulent pathogens. As extensive use of traditional methods (e.g.: povidone-iodine, ozone, ultraviolet irradiation, formalin, and chlorine dioxide) have adverse effects on cultured fish, an appropriate and alternative water purification method is vital for the sustainability of the industry. Non-thermal plasma technology has been successfully used for various biomedical purposes (e.g: food sterilization, medical device disinfection, wound healing, cancer therapy, etc.) and has great potential to be used as a sterilizing system. However, few studies have been conducted on its usefulness in the aquaculture industry. In this study, we investigated the bactericidal efficacy of plasma-activated water induced by non-thermal plasma and its histopathological as well as immunological adverse effects on koi. A highly virulent Aeromonas hydrophila SNU HS7, which caused massive mortality of koi, was used for this study. Non-thermal plasma was applied for 10 min to the fish tanks with 1.2 × 109 CFU/mL SNU HS7 using PLMB-20 system to confirm the sterilization efficacy and to observe the survival and immunological reaction of koi for 14 days. As a result, gross pathological, histopathological, and immunological investigations did not reveal any significant adverse effects in fish as compared to the control groups. To the best of our knowledge, this is the first study showing that non-thermal plasma can be used for sterilization of rearing water without giving significant physiological damage to the fish, even under the assumption of extreme situations. As plasma can effectively sterilize not only bacteria but also other unknown pathogens, the results of this study are showing a promising future in purifying water in aquaculture practice.

Effects of non-thermal atmospheric plasma on protein.

Currently, the advancement in non-thermal atmospheric plasma technology enables plasma treatments on some heat-sensitive targets, including biological substances, without unspecific damage caused by thermal effect. The significant effects of non-thermal atmospheric plasma modulating biological events have been demonstrated by considerable studies. Protein, one of the most important biomolecules, participates in the majority of the life-sustaining activities in all organisms, whose functions are derived from the diverse biochemical properties of amino acid compositions and four-tiered protein structure hierarchy. Therefore, the knowledge of how non-thermal atmospheric plasma affects protein greatly benefits the understanding and application of the non-thermal atmospheric plasma's effect in biological area. In this review, we summarize recent research progress on the effects of non-thermal atmospheric plasma, particularly its reactive species, on biochemical and biophysical characteristics of proteins at different structural levels that leads to their functional changes. Moreover, the physiological effects of non-thermal atmospheric plasma at cellular or organism level driven by the manipulations on protein and their relative application prospects are reviewed. Despite the exceptional application potential, the exploration of the non-thermal atmospheric plasma's effect on protein still confronts with difficulties due to the limited knowledge of the underlying mechanisms and the complexity of non-thermal atmospheric plasma operation systems, which requires further studies and standardization of non-thermal atmospheric plasma treatments.

Atmospheric pressure nonthermal pin to plate plasma system for the microbial decontamination of oat milk

This study investigates the potential of a pin to plate atmospheric plasma on the microbial decontamination of oat milk along with the changes in the physicochemical, rheological, functional, and particle morphology. As cold plasma comprises reactive species, and free radicals tend to rupture the microbial cells, microbial reduction in the oat milk is expected. Extracted oat milk (14.03 ± 0.67% solids) is treated with plasma input voltages of 170–230 V for an exposure time of 5–15 min. The treated milk is analyzed for the effect of plasma treatment on microbial reduction, physicochemical properties (total soluble solids [TSS], pH, titratable acidity [TA], color, and total protein content), viscosity, sedimentation index (SI), and the particle morphology. The highest microbial log reduction of 2.18 and 1.47 in bacteria and yeast and molds, respectively, is obtained at the intensive plasma treatment of 230 V and 15 min. With plasma treatment, TSS, TA, and SI are increased, whereas pH, total protein content, and viscosity are reduced. The modifications in the oat constituents and aggregate formations are the major causes of the observed results. This proves that cold plasma is a prospective decontamination technique for a plant-based milk analog. Novelty impact statement Microbial decontamination of oat-milk through nonthermal cold plasma technology has never been explored. The physicochemical alteration, color, and rheological parameters have been extensively studied in the current study. Microbial reduction of up to 2 logs was obtained at 230 V treatment of 15 min without changing the fluidity of the oat milk.

Non-thermal plasma removal of naphthalene as tar model compound from biomass gasification

Gasification of biomass is an industrial process utilized to produce product gas that can be used in electrical power generation with internal combustion engines. However, there remain huge challenges with regards to tar and other pollutants, thus their removal before further use is necessary. Non-thermal plasma method can be considered as a novel and efficient way for treatment of tar from product gas. In this work, a laboratory-scale, reverse vortex flow gliding arc plasma reactor was developed and tested for the removal of tar model compound using naphthalene as surrogate. Effects of total gas feed rate in the range of 20–60 L/min, applied voltage in the range of 50–220 V, hence, power input in the range of 300–460 W with initial naphthalene concentration of 610 ± 50 mg/m3 on removal and energy input were investigated. It was found the tar removal efficiency increased with increasing applied voltage. Maximum naphthalene removal efficiency of 85% was achieved at applied high voltage of 15 kV and specific energy input of 0.13 kWh/m3 with energy utilization efficiency of about 4.60 g/kWh. From the findings, non-thermal plasma technology appeared to offer great potential in the removal of biomass tar from gasification. The technology may be promising for possible application to real biomass tar cracking and upgrading of product gas from gasification.

Review on inactivation of airborne viruses using non-thermal plasma technologies: from MS2 to coronavirus.

Although several non-thermal plasmas (NTPs) technologies have been widely investigated in air treatment, very few studies have focused on the inactivation mechanism of viruses by NTPs. Due to its efficiency and environmental compatibility, non-thermal plasma could be considered a promising virus-inactivation technology. Plasma is a partly or fully ionized gas including some species (i.e., electrons, free radicals, ions, and neutral molecules) to oxidize pollutants or inactivate harmful organisms. Non-thermal plasmas are made using less energy and have an active electron at a much higher temperature than bulk gas molecules. This review describes NTPs for virus inactivation in indoor air. The different application processes of plasma for microorganism inactivation at both laboratory and pilot-scale was also reviewed This paper reports on recent advances in this exciting area of viral inactivation identifying applications and mechanisms of inactivation, and summarizing the results of the latest experiments in the literature. Moreover, special attention was paid to the mechanism of virus inactivation. Finally, the paper suggests research directions in the field of airborne virus inactivation using non-thermal plasma.

Enhancing Interface Reactions by Introducing Microbubbles into a Plasma Treatment Process for Efficient Decomposition of PFOA.

Efficient destruction of perfluoroalkyl compounds in contaminated waters remains a challenge because of highly stable C-F bonds. In this study, mineralization of perfluorooctanoic acid (PFOA) with high concentration (∼30 mg/L) was realized in a needle-plate pulsed discharge reactor integrated with a water jet (NPDW) to which microbubbles (MBs) with different carrier gases (air, N2, and Ar) were introduced to enhance interfacial reactions. MBs effectively enrich dispersed PFOA from a bulk solution to a liquid surface to allow enhancing contact with reactive species and also expanding the plasma discharge area and channels. The PFOA removal efficiency in air and Ar discharge reached 81.5 and 95.3% in 2 h, respectively, with a defluorination ratio of no less than 50%. Energy requirements (EE/O) ranged from 216.49 to 331.95 kWh/m3. Aside from fluoride, PFOA was degraded to a range of short-chain perfluoroalkyl acids and, to a minor extent, at least 20 other fluorinated transformation products. PFOA degradation mechanisms were proposed, including decarboxylation, hydroxylation, hydrogenation reduction, and defluorination reactions. Real water matrices (groundwater, tap water, wastewater effluent, and surface water) showed moderate impact on treatment outcomes, demonstrating the robustness of the treatment process. The study demonstrated an environmentally friendly nonthermal plasma technology for effective PFOA degradation.

Quantification of reactive species generated in pulsed electrical discharge plasma reactor and its application for 17α-ethinylestradiol degradation in different water matrices

The degradation of a synthetic female hormone, a typical endocrine disruptor i.e., 17α-ethinylestradiol (EE2), in water was studied using pulsed electrical discharge plasma reactor with multiple pin-plate electrode configuration at atmospheric pressure and room temperature. Various liquid phase reactive oxygen species generated in the system were also quantified to understand the scenario in depth. The effect of different operating parameters such as initial concentration of EE2, solution pH, presence of scavenger, purging of air and reactor overhead gases, different water matrices, humic acid (HA) and different ions on the removal kinetics of the reactor was probed in detail. The complete removal of EE2 was achieved in 15 sec of treatment time at concentration of 100 µg L-1 and the corresponding electrical energy per order and direct electricity cost were 2.43 kWh m−3 and ~ 0.16 US$ m−3, respectively. The plausible degradation pathways of EE2 in the reactor have also been proposed through the identification of intermediates. Further, algal acute toxicity test of all the treated samples revealed complete removal of toxicity. Thus, these findings demonstrated the promise of non-thermal pulsed plasma technology for degradation of EE2 at environmentally relevant concentrations.

Anti-Bacterial Action of Plasma Multi-Jets in the Context of Chronic Wound Healing

This work is a contribution to the development and implementation of non-thermal plasma technology for decontamination in the perspective of nosocomial and chronic wound innovative therapies. Multi jets devices based on Plasma Gun® technology in static and scanning operation modes and bacterial lawns inoculated with resistant and non-resistant bacterial strains were designed and used. A pilot toxicity study exploring plasma treatment of wound bearing patients, performed with a low voltage plasma applicator, is documented as a first step for the translation of in vitro experiments to clinical care. Bacterial inactivation was demonstrated for Staphylococcus aureus, Pseudomonas aeruginosa and drug resistant S. aureus, P. aeruginosa and Escherichia Coli strains collected from patient wounds at Orleans (France) hospital. A few square centimeter large contaminated samples were inactivated following a single plasma exposure as short as one minute. Samples inoculated with a single but also a mix of three resistant pathogens were successfully inactivated not only right after their contamination but for mature lawns as well. Similar bactericidal action was demonstrated for antibiotic-resistant and non-resistant P. aeruginosa. The time exposure dependent increase of the inhibition spots, following multi jets exposure, is discussed as either the accumulation of reactive species or the likely combinatory action of both the reactive species and transient electric field delivery on inoculated samples.

Regeneration of an aged hydrodesulfurization catalyst: Conventional thermal vs non-thermal plasma technology

This study compares the regeneration efficiency of an aged industrial hydrodesulfurization catalyst (CoMoP/Al2O3) by conventional and alternative routes: thermal oxidation versus non-thermal plasma technology (NTP). Spent, partially, and fully regenerated catalysts have been characterized by XRD, XPS, and toluene hydrogenation to measure hydrogenating activity. Complete regeneration of the HDS catalyst via NTP requires the heating of the dielectric barrier discharge plasma reactor. Total removal of coke is obtained from 250 °C by applying only 8.6 W/gcatalyst, against 400 °C by conventional thermal treatment. The hydrogenation activity of the regenerated catalyst by NTP assisted by temperature is higher than that obtained by traditional thermal regeneration practiced industrially. Plasma treatment mitigates the oxide sintering but leads to the formation of cobalt oxide species preventing Co of fully playing its role as MoS2 slabs promoter. HDS catalyst regeneration using non-thermal plasma assisted by low temperature appears as a promising alternative to thermal combustion.

Effect of Aged Lubricating Oil on the Regeneration of Diesel Particulate Filters and Ash Physical Characteristics with Non-Thermal Plasma Technology

Effect of Aged Lubricating Oil on the Regeneration of Diesel Particulate Filters and Ash Physical Characteristics with Non-Thermal Plasma Technology

Post Harvest Applications of Cold Plasma Technology: A Review

Plasma is the fourth state of matters which have a wide application in food processing and post harvest technology. Plasma when applied over crops has tremendous effects in improvement in the quality and other post harvest attributes. Application of cold plasma technology could effectively induce desirable changes in its overall quality and diverse physiology. The following review would discuss the application of non-thermal plasma technology to disinfect and decontaminate processed food product and fresh horticultural crops. Horticultural crops which are treated with plasma technology do not show any loss in nutrients. The packaging materials can also be sterilized by using plasma technology. Similarly, the food packed inside a package can also be sterilized without harming the package integrity. Beside that it can also be used to reduce the enzymatic activity of fresh fruits and vegetables and help to modify the food properties. Cold plasma technology can penetrate fungal biofilm and destroy resting fungal spores. This technology can also be harnessed to remove residual toxic pesticide from food products and fresh fruits and vegetables. However, the technology might sound a bit expensive but have a long future in terms of utility.

Experimental Investigation of Ozone Decomposition in Diesel Particulate Filter Regeneration with Non-Thermal Plasma Technology

Experimental Investigation of Ozone Decomposition in Diesel Particulate Filter Regeneration with Non-Thermal Plasma Technology

Combined effect of silicon and non-thermal plasma treatments on yield, mineral content, and nutraceutical proprieties of edible flowers of Begonia cucullata

Edible flowers are becoming popular as a nutraceutical and functional food that can contribute to human nutrition with high antioxidant molecules and mineral elements. While comparative studies between different flower species have been performed, less is known about the best agronomical practices to increase yield and nutraceutical proprieties of blooms. Silicon stimulates plant resistance against stress and promotes plant growth while non-thermal plasma (NTP) technology has been applied for the disinfection and decontamination of water, as well as for increasing plant production and quality. The application of silicon and NTP technology through nutrient solution and spraying was investigated in edible flowers given that the combination of these treatments may play a role in promoting their nutritional and nutraceutical proprieties. The treatments were applied on two varieties of Begonia cucullata Willd. (white and red flowers) to explore their effects on different flower pigmentations. Plants with red flowers showed higher nutraceutical proprieties than the white ones but yielded a lower flower number. While the NTP treatment did not improve flower yield and quality, the silicon treatment increased anthocyanins and dry weight percentage in red flowers. NTP treatment increased zinc concentration, while it decreased potassium, magnesium, and manganese, and increased silicon concentration in white flowers. The combination of silicon and NTP showed negative effects on some nutraceutical proprieties of red flowers thus highlighting that the two treatments cannot be combined in edible flower production. In conclusion, the positive effect of silicon use in edible flower production has been demonstrated while the NTP technology showed contrasting results and its use should be explored in greater depth, including a consideration of its role in biotic attack prevention and reduced chemical input.

Non-Thermal Plasma-Assisted Catalytic Reactions for Environmental Protection

“Non-thermal plasma technology” (NTP) has notably increased [...]

Recent Progress in Applications of Non-Thermal Plasma for Water Purification, Bio-Sterilization, and Decontamination

Various reactive oxygen and nitrogen species are accompanied by electrons, ultra-violet (UV) radiation, ions, photons, and electric fields in non-thermal atmospheric pressure plasma. Plasma technology is already used in diverse fields, such as biomedicine, dentistry, agriculture, ozone generation, chemical synthesis, surface treatment, and coating. Non-thermal atmospheric pressure plasma is also considered a promising technology in environmental pollution control. The degradation of organic and inorganic pollutants will be massively advanced by plasma-generated reactive species. Various investigations on the use of non-thermal atmospheric pressure plasma technology for organic wastewater purification have already been performed, and advancements are continuing to be made in this area. This work provides a critical review of the ongoing improvements related to the use of non-thermal plasma in wastewater control and outlines the operational principle, standards, parameters, and boundaries with a special focus on the degradation of organic compounds in wastewater treatment.

Non-Thermal Plasma Treatment Influences Shoot Biomass, Flower Production and Nutrition of Gerbera Plants Depending on Substrate Composition and Fertigation Level.

Non-thermal plasma (NTP) appears a promising strategy for supporting crop protection, increasing yield and quality, and promoting environmental safety through a decrease in chemical use. However, very few NTP applications on containerized crops are reported under operational growing conditions and in combination with eco-friendly growing media and fertigation management. In this work, NTP technology is applied to the nutrient solution used for the production of gerbera plants grown in peat or green compost, as an alternative substrate to peat, and with standard or low fertilization. NTP treatment promotes fresh leaf and flower biomass production in plants grown in peat and nutrient adsorption in those grown in both substrates, except for Fe, while decreasing dry plant matter. However, it causes a decrease in the leaf and flower biomasses of plants grown in compost, showing a substrate-dependent effect under a low fertilization regime. In general, the limitation in compost was probably caused by the high-substrate alkalinization that commonly interferes with gerbera growth. Under low fertilization, a reduction in the photosynthetic capacity further penalizes plant growth in compost. A lower level of fertilization also decreases gerbera quality, highlighting that Ca, Mg, Mn, and Fe could be reduced with respect to standard fertilization.

Effect of Plasma Activated Water (PAW) on Fruits and Vegetables

In recent time, the consumption of fruits and vegetables has raised, the variety of pathogens of fresh fruits and vegetables has enhanced, and it's believed that pathogens are capable to resisting the stress conditions that are major causes of fresh produce related food-borne ill health. In order to ensure microbial safety and reduce nutrient loss, non-thermal plasma technology has received increasing attention in food preservation applications. Non-thermal plasma has high reactivity and has potential applications in food safety, nutritional quality and environmental safety. Plasma activated water (PAW) abundant source of reactive oxygen species (ROS) and reactive nitrogen species, which can inactive the microorganisms. In addition to its bactericidal activity, it can also be used to degrade pesticide residues and antibiotic residues in water and packaging materials. Non-thermal plasma is applied to water to generate plasma-activated water, potentially applied in fruits and vegetables in recent years. PAW has been successfully applied as washing agent or disinfect agent in fruits and vegetables. In addition, it can inactivate food-borne pathogens on fruit and vegetable contact surfaces and on fruits and vegetables without adverse effect on the environment and human health. Reported findings indicates that plasma activated water has the least affect the sensory parameters and quality of fruits and vegetables. Therefore, it can be potentially applied in fruits and vegetables industry as substitute of traditional washing agent i.e. chlorinated water, quaternary ammonium salts etc. Furthermore, High bactericidal ability and easy to produce plasma activated water function can be used in every food field, such as meat, dairy products, fruits and vegetables and grains. However, the chemistry of PAW is taken into account to be extraordinarily complicated, and controlling the reaction is one in all the challenges for future analysis. Furthermore, it also requires from regulatory agencies to generally recognize as a safe (GRAS) status.

Nonthermal Plasma Induced Fabrication of Solid Acid Catalysts for Glycerol Dehydration to Acrolein

The feasibility of fabricating better solid acid catalysts using nonthermal plasma (NTP) technology for biobased acrolein production is demonstrated. NTP discharge exposure was integrated in catalyst fabrication in air or argon atmosphere. The fabricated catalysts were characterized by Brunauer–Emmett–Teller surface area analysis, temperature-programmed desorption of ammonia, X-ray powder diffraction and Fourier-transform infrared spectroscopy of pyridine adsorption, in comparison to regularly prepared catalysts as a control. Further, kinetic results collected via glycerol dehydration experiments were compared, and improvement in acrolein selectivity was displayed when the catalyst was fabricated in the argon NTP, but not in the air NTP. Possible mechanisms for the improvement were also discussed.

Non-thermal atmospheric plasma reactor design for fine powder processing and starch modification

In this article, non-thermal plasma technology at atmospheric pressure for fine powder processing was investigated. A common potato starch was modified within Argon plasma to produce a commercial well-known modified starch known as HT drilling starch. A theoretical model was developed for possible future scale-up of the designed suitable plasma reactor in the emerging field of plasma modification of starch. The model predicts the incipient condition for full fluidization of the solid particles within the plasma fluid. This condition led to maximum interaction between the plasma species and the starch granules. The predicted incipient full fluidization velocity in the model was in consistent with required experimental flow conditions for producing the desired modified starch. Since the plasma modified starch was used as an adhesion additive, the known characteristics in the oil & gas-well drilling fluid such as Fluid-Loss (F.L) and viscosity were reduced more than 30% and 10%, respectively.