Effective destruction of Escherichia coli (E. coli) bacteria has been obtained in a flowing N 2 -O 2 microwave post-discharge reactor. The sterilizing agents are the O atoms and the UV emissions of NOβ which are produced by N and O atoms recombination in the reactor. In the following plasma conditions: pressure 5 Torr, flow rate 1 L n min −1 , microwave power of 100 W in a quartz tube of 5 mm, an O atom density of 2.5 × 10 15 cm −3 is measured by NO titration in the post-discharge reactor with UV emission in a N 2 -(5%)O 2 gas mixture. Full destruction of 10 13 cfu ml −1 E. coli is observed after a treatment time of 25 min.

Summary: It is demonstrated here that the sterilization process using a flowing N2‐O2 post discharge reactor involves a specific heating of the bacteria metal holder produced by heterogeneous O and N atoms recombination. Such heating increases with N and O‐atom concentrations, which can be varied with the microwave discharge power. It also depends on the metallic material of the holder: a brass support can reach a maximum surface temperature of 120 °C while the surface temperature of the stainless steel holder increases to 60–70 °C after 40 min of exposure to a N2‐5% O2 post discharge at 0.6 kPa (5 Torr), 1 Ln · min−1 and 100 W. It is demonstrated that the E. coli destruction efficiency increases with N and O atom density at a constant temperature (60 °C) of the stainless steel support and with the support temperature (up to 60 °C) at constant N and O atom densities. A cumulative effect was also found with increasing N and O atom density and of the support temperature.

No abstract

No abstract