Preparation and characterization of air nanofilters based on cellulose nanofibers

One of the most important environmental issues in the world today is the problem of air pollution, which includes particulate matter (PM) and greenhouse gases (mainly CO₂). The production of efficient sustainable filters to overcome this concern as well as to provide an alternative to synthetic petroleum-based filters remains a demanding challenge. The purpose of this research was to first produce novel cellulose nanofibers (CNF) based nanofilter from a combination of CNF and chitosan (CS) and then evaluate its applicability for air purification. A number of structural and chemical properties as well as CO₂ and PM adsorption efficiency of the modified CNF, were determined using advanced characterization techniques. After pretests, we determined the optimum loading for the CS was 1 wt%, and upon producing the samples, the CNF loadings (1, 1.5, and 2 wt%) were chosen as one variable. For particle absorption, the PM sizes (0.1, 0.3, 0.5, and 2.5 μm) were kept as other variables. Based on SEM results, we concluded the higher the concentration of CNF the higher the specific surface area and the lower the porosity and the diameter of the pores, which was confirmed by the BET test. Furthermore, the results showed that increasing the concentration of modified CNFs increases the adsorption rate of CO₂ and PM and that the highest adsorption of CO₂ and PM belonged to the 2% modified CNF.