Investigation on the long‐term bactericidal effect and chemical composition of radical‐activated water

Abstract

Abstract We treat deionized water using an atmospheric‐pressure radical source to investigate the role of neutral radicals in the bactericidal efficacy of radical‐activated water (RAW). The bactericidal efficacy of RAW is investigated using a colony‐forming unit assay with Escherichia coli . Both the bactericidal efficacy and reactive oxygen and nitrogen species (RONS) concentration in stored RAW are investigated over a period of a month. E. coli was completely sterilized even in RAW stored for 7 days, indicating the strong bactericidal effect. However, deterioration of the bactericidal efficacy of RAW stored for 14 days is confirmed, which does not have a clear correlation with the time evolution of the RONS concentration. This result becomes a strong evidence that RAW has long‐term bactericidal efficacy.