Sustainable ammonia production using water and air through the coupling of plasma-driven intermediary NOx generation and their electrocatalytic conversion.

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Aims: This study aimed to compare the efficacy of plasma-activated water (PAW) generated by two novel plasma reactors against pathogenic foodborne illness organisms. Methods and results:The antimicrobial efficacy of PAW produced by a bubble spark discharge (BSD) reactor and a dielectric barrier discharge-diffuser (DBDD) reactor operating at atmospheric conditions with air, multiple discharge frequencies and Milli-Q and tap water, was investigated with model organisms Listeria innocua and Escherichia coli in situ. Optimal conditions were subsequently employed for pathogenic bacteria Listeria monocytogenes, E. coli and Salmonella enterica. DBDD-PAW reduced more than 6-log of bacteria within 1 min. The BSD-PAW, while attaining high log reduction, was less effective. Analysis of physicochemical properties revealed that BSD-PAW had a greater variety of reactive species than DBDD-PAW.Scavenger assays designed to specifically sequester reactive species demonstrated a critical role of superoxide, particularly in DBDD-PAW.Conclusions: DBDD-PAW demonstrated rapid antimicrobial activity against pathogenic bacteria, with superoxide the critical reactive species. Significance and impact of study: This study demonstrates the potential of DBDD-PAW produced using tap water and air as a feasible and cost-effective option for antimicrobial applications, including food safety.

In this study, we demonstrate that atmospheric air plasma bubbles are an effective, energy‐efficient, residue‐free alternative to current decontamination techniques. Five to fifteen minutes of plasma‐bubble treatments of inoculated chicken skin led to a significant reduction in colony‐forming units (CFUs). We show that the activation efficiency is dependent on the plasma discharge frequency, with a higher one (2,000 Hz) leading to a higher CFU reduction (1.4 log) as compared with a lower (0.3 log) reduction at 1,000 Hz. Scanning electron microscopy pictures of treated bacteria reveal damage to the cells. An evaluation of the physicochemical properties of the generated plasma‐activated water revealed an increase in conductivity and in ozone, nitrite, nitrate, hydroxyl, and peroxide concentrations with higher frequencies, all contributing to the observed antimicrobial effect.