Electron beam processing for decomposition treatment of gaseous formaldehyde after sterilization

Shimada, Akihiko; Hakoda, Teruyuki; Kojima, Takuji

Electron beam (EB) suitable for decomposition of dilute organic pollutants in high-flow rate air was applied to the treatment of formaldehyde (HCHO)/air mixture for purification in the clean room after sterilization. Air mixtures containing 90-1230 ppmv of HCHO with and without 30-340 ppmv of methanol (CHOH), which are commonly used for sterilization, were irradiated by EB to the absorbed doses of 5-80 kGy (=kJ/kg). The dose required for decreasing initial HCHO concentration to 10 ppmv was examined as a function of initial HCHO concentration (ppmv) in the air mixture ([HCHO]) with and without CHOH. The following relations were obtained: =-4.210[HCHO]+1.210[HCHO]-1.2 and =-3.810[HCHO]+1.010 [HCHO]-1.0, respectively, where (kGy) is dose. According to these results, the treatment completion time of HCHO/air mixture with CHOH using EB was simulated considering the conceptual processing. This EB processing can be applicable, e.g. the clean rooms at the food packaging factories, and contributes to improve the operation efficiency of the factories.