Reusing Face Covering Masks: Probing the Impact of Heat Treatment

Abstract

The COVID-19 pandemic resulted in imminent shortages of personal protective equipment such as face masks. To address the shortage, new sterilization or decontamination procedures for masks are quickly being developed and employed. Dry heat and steam sterilization processes are easily scalable and allow treatment of large sample sizes, thus potentially presenting fast and efficient decontamination routes, which could significantly ease the rapidly increasing need for protective masks globally during a pandemic like COVID-19. In this study, a suite of structural and chemical characterization techniques, including scanning electron microscopy (SEM), contact angle, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman were utilized to probe the heat treatment impact on commercially available 3M 8210 N95 Particulate Respirator and VWR Advanced Protection surgical mask. Unique to this study is the use of the synchrotron-based In situ and Operando Soft X-ray Spectroscopy (IOS) beamline (23-ID-2) housed at the National Synchrotron Light Source II at Brookhaven National Laboratory for near-edge X-ray absorption spectroscopy (NEXAFS).

Structure, Morphology, and Surface Chemistry of Surgical Masks and Their Evolution up to 10 Washing Cycles

“…This oxidation would also explain the broadening of the C 1s peak at 285 eV due to the presence of bonds between C and O. Such a broadening has been reported in ref and was related to oxidation induced by a dry heating at 100 °C.…”

Methine initiated polypropylene-based disposable face masks aging validated by micromechanical properties loss of atomic force microscopy

“…This indicates that the C = C bond plays a dominant role in the early aging stages (0-24 h), and the C=O bond takes a second role. Besides, a very low-density signal is observed in the O 1 s spectra of the pristine DFM on account of the absorption of molecular water, adsorb oxygen( Yan et al, 2021 ), and oxidation (Table S8). The corresponding O 1 s peak was fitted by adsorption oxygen (531.33 eV), O - H (531.48 eV), O = C (532.71 eV), H 2 O (532.68 eV), O-C (533.35 eV), and chemical adsorption oxygen (534.64 eV).…”

Post-Pandemic: Investigation of the Degradation of Various Commercial Masks in the Marine Environment

“…Taking both the changes of surface chemistry and physical structures into considerations, saliva and sweat CAs on the surfaces varied slightly. 49 Some (e.g., N95, surgical layers, and silk) were increased, mainly dominated by the microparticles observed from the SEM imaging as the microstructures make the hydrophobic surface with larger CAs; 50 however, others (e.g., PU, PET, and nylon) were decreased a little bit mainly due to the changes of the surface species. 51 Since the pandemic, face masks have exacerbated plastic pollution significantly, especially the microplastics with their degradation posing a threat to marine species, even humans.…”

“…However, both outer layers are hydrophobic to prevent the transmission of droplets farther, with the saliva CAs of 140 ± 0.89° and 139 ± 2.50°. Taking both the changes of surface chemistry and physical structures into considerations, saliva and sweat CAs on the surfaces varied slightly . Some (e.g., N95, surgical layers, and silk) were increased, mainly dominated by the microparticles observed from the SEM imaging as the microstructures make the hydrophobic surface with larger CAs; however, others (e.g., PU, PET, and nylon) were decreased a little bit mainly due to the changes of the surface species …”