At present, reports on the arc interruption and decomposition behavior of a C ₄ F ₇ N/air gas mixture especially the biosafety of its by‐products are limited. Herein, a 57% C ₄ F ₇ N/43% air gas mixture was employed as an arc‐quenching medium to conduct 200 breaking tests on a load switch (630 A/24 kV). The arc interruption and decomposition behavior of the gas mixture were evaluated, and the biosafety of the decomposition products was assessed based on an acute inhalation toxicity test. It was found that the average arcing time of the 200 breakings was about 10.1 ms and that breakings were basically completed at the zero‐crossing of the second or third current half‐cycle. The gas mixture after breaking decomposed dramatically (the C ₄ F ₇ N content decreased by 75.6%), generating a large number of gaseous by‐products (CO, CF ₄ , C ₂ F ₆ , C ₃ F ₈ , CF ₃ CN, C ₄ F ₈ , CO ₂ , C ₄ F ₁₀ N ₂ , C ₃ F ₆ , C ₂ N ₂ , etc.) as well as solid by‐products (carbon particles). The lethal concentration of 50% (LC50, 4 h) of C ₄ F ₇ N/air after 200 breakings was 31 ppm (male mice) and 34 ppm (female mice), respectively, and the toxicity was classified as Grade 1. In general, C ₄ F ₇ N has an arc interruption capability, albeit weaker than that of SF ₆ under the same conditions. After breaking, the C ₄ F ₇ N gas mixture has a relatively high acute inhalation toxicity, and relevant safety protection measures for research or operation personnel are strictly needed.

This study deals with paracetamol degradation in water using a non-thermal plasma (NTP) created by a dielectric barrier discharge (DBD). The effects of the NTP operating conditions on the degradation were studied, showing that the treatment efficiency of the process was highly dependent on the electrical parameters and working gas composition in the reactor containing the aqueous solution. A conversion rate higher than 99% was reached with an energy yield of 12 g/kWh. High resolution mass spectrometry (HRMS) measurements showed that the main species produced in water during the process were nitrogen compounds, carboxylic acids and aromatic compounds.

In order to remediate the very poor mineralization of paracetamol in water, even when well degraded by using a Non-Thermal Plasma (NTP) process at a very low dissipated power, a plasma-catalyst coupling process was tested and investigated. A homemade glass fiber supported Fe³⁺ catalyst was immersed in the liquid to be treated in a Dielectric Barrier Discharge plasma reactor. The plasma-catalysis process, at the same low dissipated power, achieved a mineralization rate of 54% with a full conversion rate of paracetamol at 25 mg L⁻¹ in initial concentration after 60 min treatment, thanks to Fenton-like effects. The synergetic effects of the plasma-catalysis coupling process also improved the Energy Yield by a factor of two. The catalyst before and after use for treatment was characterized by Brunauer-Emmett-Teller and Thermogravimetric analysis. High-Performance Liquid Chromatography was used to measure the concentration of treated solution and to investigate the intermediates. Two of them, namely 1,4-hydroquinone and 1,4-benzoquinone, were formally identified. Some intermediates are presented in this paper as a function of treatment time and their UV absorbance spectra. NTP processes with and without catalyst coupling were compared in terms of acidity, conductivity, and nitrate concentrations in the treated solution.