Development of Ecofriendly Filters from Local Plant Byproducts

Abstract

Filters used in face masks or in devices (such as HEPA filters) are essential tools against airborne pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or Covid-19), and adsorbing hazardous gases. The various components of a face mask include an air filter, nose adapter, and elastic ear loops. Each component is constructed of different materials, such as polypropylene or polyester for the filter, aluminum for the nasal adapter, and elastane for the elastic loops. According to recent studies, over 129 billion face masks are used globally every month due to the Covid-19 pandemic. The manufacturing of masks and filters necessitates a large consumption of fossil-based materials and the generation of large amounts of toxic waste, both of which can result in environmental pollution, infection, and ozone layer depletion. The objective of this research is to contribute to environmental sustainability through extraction of cellulose from sugarcane bagasse (SCB) and banana midrib (BMR) by treating them (SCB and BMR) with ethanol and sodium hydroxide, followed by formic and acetic acid, then performic and peracetic acid, and finally hydrogen peroxide to fabricate eco-friendly filters. The resulting materials were purified to remove impurities (such as lignin and hemicellulose) and were then characterized using scanning electron microscope (SEM), universal testing machine (UTM), capillary flow porometer, condensation particle counter, and thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) analysis after each treatment to assess fiber type, mechanical property, pore size, filtration efficiency, flow resistance, thermal properties and chemical composition. The SEM analysis showed the microstructure of the cellulose membrane extracted from SCB and BMR which varied from aggregated cellulose structures to a fibrous mesh depending on the treatment. The thermogravimetric analysis showed the presence of impurities in the specimen, or lack thereof. The FTIR analysis further confirmed that the extracted membrane from SCB and BMR are cellulose by matching the resonance frequencies of the functional groups with literature. The mean and bubble pore diameter of the cellulose membranes ranged from 2.05 to 57.67µm, with mean and bubble point pressure of 4.32 to 0.31KN/m2. The filtration efficiency of the bleached cellulose membrane ranged from 35 to 57% with flow resistance 16.2 to 51.3 mm.H2O. Analysis of the contact angle showed that the membrane is highly hydrophilic regardless of treatment. The cell culture experiment showed that the filtered membranes after each treatment were biocompatible, non-toxic to cells and the membranes can be used as scaffolds for tissue engineering applications. Overall, cellulose extracted from SCB and BMR have great properties which makes them potential polymers for producing eco-friendly filters that can be used for face masks and also as scaffolds for tissue engineering. The extraction and fabrication processes are safe and will also contribute to environmental sustainability.