Improved non-woven surgical masks with nanostructured cellulosic reinforcement from sugarcane bagasse waste

The COVID-19 pandemic has brought concerns about the efficacy of respiratory protection equipment, primarily due to their widespread usage during this period. Among the various types of face masks, the N95, PFF3, and PFF2 surgical masks have gained great prominence due to their efficiency, despite the discomfort they may cause. Therefore, thinking of a cost-effective and more comfortable solution, this work aimed to reinforce non-woven face masks with cellulose nanofibrils (CNFs), to improve their filtration efficiency. For this, CNFs were produced using the mechanical processing of sugarcane bagasse (SCB) residues, which underwent plain alkaline pretreatment (CNF-PA) or alkaline pretreatment followed by enzymatic pretreatment (CNF-AE). It was observed that the CNF-AE films developed better characteristics regarding the contact angle, density, porosity, transmittance and transparency as well as vapor permeability compared to the CNF-PA films. The application of CNF on non-woven masks was performed using the spray technique. Bacterial filtration analysis showed filtration efficiency of 99.68% and 99.80% for masks that were coated with CNF-PA and CNF-AE, respectively. Whereas uncoated masks presented a filtration efficiency below 95%, which is the minimum required value. The masks obtained breathability values of 79.75 Pa/cm2 and 106.00 Pa/cm2 for CNF-AE and CNF-PA, respectively, whereas the uncoated masks showed values below 30.00 Pa/cm2. This work shows that the CNF obtained from SCB present good barrier capabilities and should be used for this purpose, especially on protective masks.