Increased sanitization potency of hydrogen peroxide with synergistic O₃ and intense pulsed light for non-woven...

Supplies of respiratory masks have recently become a concern due to the onset of the SARS-CoV-2 pandemic. Sanitization and reuse of masks can alleviate high mask consumption and production stresses. In the present work, improved sanitization potency of vaporous hydrogen peroxide (VHP) treatment of resilient bacterial spores while retaining polymeric filter performance was explored. A batch fumigation chamber with hydrogen peroxide (H₂O₂) vapor and ozone (O₃) is featured, followed by intense pulsed light (IPL) flash treatments. A resilient bacterial indicator, Geobacillus stearothermophilus (G. stearothermophilus), was utilized to compare the efficacy of various H₂O₂ concentrations in combination with O₃ and IPL. It was found that exposure to 30 minutes of 4.01 L min^-1 0.03% H₂O₂ aqueous vapor and 3 g h^-1 O₃ followed by 10 IPL flashes per side completely inactivated G. stearothermophilus. The xenon sourced IPL irradiation was found to synergistically enhance radical production and strengthen the complementary biocidal interaction of H₂O₂ with O₃. Due to the synergistic effects, H₂O₂ was able to sanitize at a diluted concentration of 0.03% H₂O₂. The physical properties, such as surface potential, tensile strength, hydrophobicity, and filtration efficiency of >300 nm saline water aerosol of fibrous polypropylene (PP) sheets, were maintained. In addition, no residue of sanitizers was detected, thus confirming the biosafety and applicability of this method to disposable masks. Performance was benchmarked and compared with commercially available processes. The synergistic regime was found to achieve sterilization of G. stearothermophilus at drastically reduced H₂O₂ concentrations and in ambient conditions relative to commercial methods.