Evaluation of the sterilization effect of a new mercury-free UVC light source

Abstract

So far, short-wave UV produced by low-pressure mercury lamps has been widely applied in sterilization, wastewater treatment, and bioassays, which could be due to its low cost, high conversion efficiency, and small size. However, metal pollution is caused by the evitable releasing of mercury. In this study, a new mercury-free lamp was developed, which generated UV light by the electron beam excitation (EBE) of YPO 4 :Bi 3+ under vacuum conditions. Such lamps emit light at 241 nm and possessed a photoelectric effect. Excellent sterilization effect was obtained in Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, in the absence of ozone. These effects positively correlated with the treatment distances and time. Furthermore, oxidative stress was found to play a major role in the sterilization process of our light sources, since no production of ozone was detected during each treatment. After all, EBE lamps could be a promising tool for sterilization, and our results provided the theoretical basis for its microorganism-killing effects.