Electron Beam Processing for Decomposition Treatment of Gaseous Formaldehyde after Sterilization

Abstract

An electron beam (EB) suitable for decomposition of dilute organic pollutants in high-flow rate air was applied to the treatment of a formaldehyde (HCHO)/air mixture for purification in a clean room after sterilization. Air mixtures containing 90–1230 ppmv of HCHO with and without 30–340 ppmv of methanol (CH₃OH), 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 the initial HCHO concentration to 10 ppmv was examined as a function of the initial HCHO concentration (ppmv) in the air mixture ([HCHO]₀) with and without CH₃OH. The following relations were obtained: D = –4.2 × 10^–5[HCHO]₀² + 1.2 × 10^–1[HCHO]₀ – 1.2 and D = –3.8 × 10^–5[HCHO]₀² + 1.0 × 10^–1[HCHO]₀ – 1.0, respectively, where D [kGy] is the dose. According to these results, the treatment completion time of the HCHO/air mixture with CH₃OH using EB was simulated considering the conceptual processing. This EB processing can be applicable, to the clean rooms at food packaging factories, for example, and contributes to improve the operation efficiency of the factories.