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In recent years, there has been a large demand for processing technologies that are environmentally safe, energy efficient, and that generate low levels of waste byproduct. For these reasons, and due to their versatility, plasma-based technologies have come to the forefront of material processing and fabrication in both research and industry. At its core, plasma is a gas that has been excited to the next state of matter, which contains an abundance of free radicals, free electrons, ions, neutral atoms, and UV radiation. This cocktail of chemistries can be generated at, or close to, room temperature and is therefore known as "cold plasma". As such, it has become a preferred method of surface modification as these generated species can be used for both chemical and physical alterations, without interfering with the bulk properties of the material. Cold plasma systems have been used for over a decade from assisting in material process modifications to surface patterning at the nanoscale. This review summarizes the recent advances made in the development and utilization of key nonthermal plasma technologies. State-of-the-art plasma systems, such as microbubble and pin-to-plate reactors, are discussed in detail. Furthermore, the use of plasma in surface modification, water treatment, micro-organism decontamination, and food treatment applications are explored in depth. Despite recent developments and methodologies, current plasma systems still have many challenges, such as processing time, scalability, material suitability, and limited theoretical understanding of the dynamics present at each interface present in the treatment process. These factors need to be addressed before plasma-based technologies can be fully integrated at an industrial scale and in more fields of application. [Display omitted] • A summarized view of plasma treatments is presented. • Different strategies to plasma treatment reactors and their functionalities are detailed. • Promising applications of plasma in material synthesis are discussed in detail. • Challenges and future perspectives of plasma treatments are presented. [ABSTRACT FROM AUTHOR]

Plasma reforming is a promising technology to transform tars from biomass gasification into valuable fuels and chemicals. However, the key performance (tar conversion, gas yield and energy efficiency) of the plasma tar reforming process can be significantly influenced by operating conditions such as the gas composition. In this study, the effect of CO 2 , steam and O 2 on the plasma reforming of toluene, a model tar compound, was investigated in a gliding arc (GA) reactor. Compared to the plasma reforming of toluene with N 2 , the presence of oxidative gases (CO 2 , H 2 O and O 2) can generate a highly reactive plasma environment, thus creating new reaction pathways in the plasma conversion of toluene. The optimal content of CO 2 , H 2 O and O 2 to balance the toluene conversion, syngas yield and energy efficiency in the plasma reforming was 2 vol%, 4 vol% and 2 vol%, respectively, suggesting that the presence of an appropriate amount of oxidative gas (CO 2 , H 2 O and O 2) is important to maximize the key performance of the plasma reforming process. The highest toluene conversion of 78.3%, syngas yield of 73.9% and energy efficiency of 69.5 g/kWh were achieved simultaneously in the plasma reforming of toluene containing 4 vol% steam. The reaction pathways in the plasma reforming of toluene have been proposed through the analysis of gas and liquid products coupled with optical emission spectroscopic diagnostics. [Display omitted] • Gliding arc plasma reforming of toluene as a tar model compound was performed. • The content of different oxidative gases on the plasma reforming of toluene was investigated. • The optimal content of CO 2 , H 2 O and O 2 was found to maximize the plasma reforming performance. • The highest toluene conversion of 78.3% and energy efficiency of 69.5 g/kWh were achieved. [ABSTRACT FROM AUTHOR]

This work provides an insight into the generation of excited nitrogen species by allowing noble gases to interact both with one another and ambient air. He and Ar were utilized to generate the optimum selectivity process to create reactive nitrogen species. An optimum setting for the generation of excited molecular nitrogen species, based on their excited energy levels, was obtained when using a mixture of Ar‐He at a ratio of 10:1. At that point, when a voltage of 27 kV is applied to the system, it reached the maximum efficiency for selectivity processes to occur which allowed for a greater non‐radiative transfer of energy through the mixture of noble gas atoms and into the molecular nitrogen present in ambient air. [ABSTRACT FROM AUTHOR]

The potential of cold plasma as a food processing aid has been demonstrated for a range of processes and products. The potential applications of plasma technology are extensive and include microbial decontamination, pest control, toxin elimination, food and package functionalisation and many others. However, studies reported to date have principally been at laboratory scale. This paper discusses the status and challenges of transferring the technology to the industry. The major challenges discussed for adoption of atmospheric plasma as a food processing tool by industry are (1) demonstration of product/process specific efficacies; (2) development of process compatible technology designs and scale‐up; (3) effective process control and validation; (4) regulatory approval; and (5) consumer acceptance. [ABSTRACT FROM AUTHOR]

• CO 2 reforming of CH 4 was performed in DBDs with different dielectric layers. • More intensified filamentary microdischarges were displayed in DBD-SD. • DBD-SD exhibited higher reactant conversion and liquid product selectivity. • Higher gas product selectivity and stable carbon balance were achieved in DBD-DD. • Higher energy efficiency for plasma reforming process was obtained in DBD-SD. CO 2 reforming of CH 4 in a non-thermal plasma process (e.g., dielectric barrier discharge, DBD) possesses dual benefits for our environment and energy needs. However, this process is strongly influenced by the dielectric structure of the DBD. Here, plasma CO 2 reforming of CH 4 has been performed in both single-dielectric and double-dielectric DBD (DBD-SD and DBD-DD) reactors under atmospheric pressure. Electrical and optical characterization, along with temperature measurements are performed to understand the influence of the DBD-SD and DBD-DD designs. Reactor performance for reforming is compared under different discharge powers. The results show that CO 2 /CH 4 discharges in both DBD-SD and DBD-DD display typical filamentary microdischarges. Compared with the DBD-DD, the DBD-SD reactor exhibits a larger number and higher intensity of current pulses, which leads to a higher electron density and formation of reactive species. The highest conversion of CO 2 (24.1 %) and CH 4 (49.2 %) are achieved in the DBD-SD at a high discharge power (75 W). Moreover, higher selectivities of gaseous products are obtained in the DBD-DD, while the DBD-SD reactor shows a higher selectivity for liquid products, mainly including methanol and acetic acid. The highest energy efficiencies for reactant conversion (0.34 mmol/kJ), gaseous and liquid production formation (0.26 mmol/kJ and 0.015 mmol/kJ) are achieved in the DBD-SD reactor at a low discharge power (22 W), resulting from the low energy loss to the environment. However, the carbon deposited on the inner electrode surface in the DBD-SD would have an adverse influence on the reactor's performance. Further research on the optimization of the DBD reactor to establish an efficient plasma-catalysis system is required for industrial applications. [ABSTRACT FROM AUTHOR]

The use of plastics has spanned across almost all aspects of day to day life. Although their uses are invaluable, they contribute to the generation of a lot of waste products that end up in the environment and end up polluting natural habitats such as forests and the ocean. By treating low-density polyethylene (LDPE) samples with non-thermal plasma in ambient air and with an addition of ≈4% CO2, the biodegradation of the samples can be increased due to an increase in oxidative species causing better cell adhesion and acceptance on the polymer sample surface. It was, however, found that the use of this slight addition of CO2 aided in the biodegradation of the LDPE samples more than with solely ambient air as the carbon bonds measured from Raman spectroscopy were seen to decrease even more with this change in gas composition and chemistry. The results show that the largest increase of polymer degradation occurs when a voltage of 32 kV is applied over 300 s and with a mixture of ambient air and CO2 in the ratio 25:1. [ABSTRACT FROM AUTHOR]

The study examined the effect of non-thermal plasma (NTP) on the total viable count and lipid oxidation of two common sushi products: nigiri and hosomaki. Sushi samples were treated with NTP using a dielectric barrier discharge system with 70 and 80 kV of potential differences for 5 min. The samples were stored at 4 °C for 11 days and analysed for total aerobic count, moisture and protein content, TBA index and fatty acids composition. Although the effect of NTP on the total aerobic counts was not statistically significant, a tendency in log reduction could be observed, with 1–1.5 log cfu/g reduction. Moisture and protein content, as well as fatty acids composition of sushi was not affected by the treatment. The TBA index of treated samples increased significantly by 0.4–1.5 mg/kg, with hosomaki reaching higher TBA index than nigiri. Although NTP in the studied conditions can, to a limited degree, increase the microbiological quality of the sushi samples, it also increases the oxidation rate. [ABSTRACT FROM AUTHOR]

Plasma-enabled liquefaction (PEL) is an emerging technology to transform renewable biomass into value-added fuels and chemicals through the plasma-induced highly-reactive chemical reactions. However, biomass dramatically ranges in the feedstock content in terms of hemicelluloses, cellulose, lignin, and ash, strongly affecting the liquefaction performance. Here, we performed the liquefaction of three typical lignocellulosic materials (sawdust, corncob and rice straw) with different feedstock contents in a PEL system. The influence of the catalyst content and the reaction time on the degradation of each biomass was investigated to understand the effect of the feedstock content on liquefaction yield. The results confirmed that the chemical contents of the lignocellulosic biomass especially the amount of lignin and ash significantly affected the liquefaction yield, the quality of liquid products and the distributions of the chemicals obtained. Compared with the PEL performance of corncob and rice straw, the higher energy yield (liquid fuels) was achieved in the PEL of sawdust, owing to higher content of lignin and less ash inside. Moreover, possible reaction pathways of lignocellulose biomass liquefaction were deduced based on the chemical analysis. Overall, this work demonstrated that the proposed PEL strategy could be a promising approach for rapid biomass conversion with high energy efficiencies. • Fast liquefaction of biomass was performed in a low temperature plasma reactor. • Corncob was completely liquefied in 3 min during the plasma liquefaction process. • Distribution of liquid products of different biomass were symmetrically analysed. • Higher lignin content in the feedstock resulted in higher energy yield. • Higher liquefaction rate and energy efficiency were achieved in the PEL process. [ABSTRACT FROM AUTHOR]

• HDP reactor formed plasma discharges in both electrodes with a single power source. • PAW was generated with high energy efficiency and a very fast inactivation rate. • Decreasing the orifice diameter of the HPD reactor increased the energy efficiency. • Increasing salinity enhanced the energy efficiency to 0.181 mol·kW−1·h−1. • 5.18-log 10 reduction of Escherichia coli inactivation was achieved in 30 s. Plasma-activated water (PAW), an emerging and cost-effective disinfectant produced from the interaction between non-thermal plasma and water, was generated with a newly designed hybrid plasma discharge (HPD) reactor. The HPD reactor produces two simultaneous plasma discharges within one power source, one from the high-voltage electrode above the liquid surface, and the other from the ground electrode enclosed in a quartz tube, allowing the air to flow through the side of the ground electrode and injecting plasma bubbles into the liquid. The simulated distributions of electric field indicated that high electric fields were induced around both the high voltage and ground electrodes, at high input voltages, explaining the plasma discharges observed on both electrodes. The PAW generated via the HPD reactor achieved a high RONS energy efficiency of 1.81 × 10-1 mol·kW−1·h−1 and a high inactivation against Escherichia coli of 5.18-log 10 reduction in 30 s of contact time, outperforming reported literature studies, which require minutes or hours to achieve similar inactivation. The effect of the number and size of orifices in the bubble column of the HPD reactor was studied, as well as the effect of the liquid volume (from 0.5 to 2 L), and salinity (from 0 to 8 mM NaCl). The Escherichia coli in PAW was further analysed by TEM and DNA leakage showing that PAW damaged the cell membrane. This hybrid plasma discharge reactor can be the base of producing disinfectant PAW in larger volume for the agriculture, biomedical, food and water treatment industries. [ABSTRACT FROM AUTHOR]

Antibiotics have been extensively used as pharmaceuticals for diverse applications. However, their overuse and indiscriminate discharge to water systems have led to increased antibiotic levels in our aquatic environments, which poses risks to human and livestock health. Non-thermal plasma water. However, the issues of process scalability and the mechanisms towards understanding the plasma-induced degradation remain. This study addresses these issues by coupling a non-thermal plasma jet with a continuous flow reactor to reveal the effective mechanisms of amoxicillin degradation. Four industry-relevant feeding gases (nitrogen, air, argon, and oxygen), discharge voltages, and frequencies were assessed. Amoxicillin degradation efficiencies achieved using nitrogen and air were much higher compared to argon and oxygen and further improved by increasing the applied voltage and frequency. The efficiency of plasma-induced degradation depended on the interplay of hydrogen peroxide (H 2 O 2) and nitrite (NO 2 −), validated by mimicked chemical solutions tests. Insights into prevailing degradation pathways were elucidated through the detection of intermediate products by advanced liquid chromatography-mass spectrometry. [Display omitted] • New amoxicillin degradation method using nitrogen, argon, air, and oxygen plasmas. • First-time revealed order of degradation efficiency: nitrogen＞air＞argon＞oxygen. • New mechanism of amoxicillin degradation based on plasma reactive nitrogen species. • Advanced mass spectrometry related intermediates to degradation pathways. • Scalable approach for plasma deactivation of amoxicillin in wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Underwater plasma bubbles were used to degrade cefixime in water. • Complete cefixime degradation with high-energy yield of 1.5 g/kWh. • Degradation of cefixime was conducted by reactive species, especially short-lived OH radicals. • Degradation pathways of cefixime were proposed by intermediates identified by LCMS. • Plasma treatment leads to the loss of antibacterial activity and cytotoxicity of cefixime. Excessive use and indiscriminate discharge of antibiotics inevitably lead to their accumulation in the environment, posing significant ecological and physiological risks. Non-thermal plasma (NTP) is receiving increasing attention as a sustainable technology for the efficient breakdown of these antibiotics as well as other contaminants. However, implementation of NTP technology still faces several hurdles, particularly the maximization of the reactive plasma effects and the practical scaling approaches. In this study, we generated NTP inside forming bubbles with enlarged gas-liquid interfacial areas for efficient delivery of reactive plasma species to target cefixime antibiotic molecules in aqueous solution. The degradation of cefixime was largely dependent on the different number of microholes, air flow rate, discharge power, plasma exposure time and solution properties. Results show that a high-performance degradation was achieved in the 10-microhole reactor with an energy yield of 1.5 g/kWh, after 30 min of plasma treatment. Based on LC-MS analysis, an NTP-initiated cefixime degradation pathway was proposed. Cytotoxicity studies demonstrated that the antibiotic activity of cefixime was effectively and wholly deactivated by the plasma process, and that no toxic effects of the 30 min-treated water were observed toward human cell lines. Furthermore, considering that air was employed as the inducer gas, which results in the formation of reactive nitrogen species in the water, the treated water was able to enhance seedling growth, further contributing to the societal and economic benefits of this plasma-based antibiotic degradation strategy. [ABSTRACT FROM AUTHOR]