Sterilization Ability by Microwave UV-ozone Generator

Abstract

The 253.7 nm UV light emitted from mercury lamps is known as germicidal radiation. Additionally, it emits UV light with a shorter wavelength of 184.9 nm. This UV wavelength can generate ozone (O3) from oxygen molecules (O2) in the air. Ozone has been shown to effectively inactivate various pathogenic microorganisms. However, they must decompose quickly because they are harmful to the human body. Methods for decomposing ozone include a thermal decomposition method, a chemical cleaning method, an activated carbon method, and the like. However, there is no practical or efficient treatment method. Ozone generation methods include the silent discharge method, electrolytic method, photochemical reaction method, high-frequency discharge method, and radiation method. The most efficient method is silent discharge, which is concerned with nitrogen oxide (NOX) generation caused by nitrogen molecules in the air, and deterioration of the electrodes during use is problematic. Furthermore, nitrogen oxides react with water in the gaseous phase to produce nitric acid. Nitric acid reacts with several metals to form nitrates. A sterilization device using highconcentration ozone has not been put to practical use because of the lack of an efficient method for decomposing ozone and the corrosion of metals. The UV-ozone generation method using microwave plasma used in this study can generate UV light by applying 2.45 GHz microwaves to a quartz electrodeless bulb filled with mercury. By changing the glass material and emitting UV light at different wavelengths, it is possible to develop a UV-ozone generator that can selectively generate and decompose ozone. Furthermore, since 184.9 nm UV specifically acts on oxygen molecules, NOX is not generated. Additionally, 253.7 nm UV, which is emitted at the same time as 184.9 nm UV, can easily decompose ozone into O2