Natural Cellulose-Based Multifunctional Nanofibers for the Effective Removal of Particulate Matter and Volatile Organic Compounds

Abstract

Multifunctional nanofibers for particulate matter (PM) and volatile organic compounds (VOCs) removal from the indoor atmospheric environment were manufactured from eco-friendly natural cellulose materials via electrospinning using an optimized solvent system containing 1-ethyl-3-methylimidazolium acetate (EmimAC) and dimethylformide (DMF) in a 3:7 volume ratio. EmimAC improved the cellulose stability, whereas DMF improved the electrospinnability of the material. Various cellulose nanofibers were manufactured using this mixed solvent system and characterized according to the cellulose type, such as hardwood pulp, softwood pulp, and cellulose powder, and cellulose content ranging from 6.0-6.5 wt%. The correlation between the precursor solution alignment and electrospinning properties indicated an optimal cellulose content of 6.3 wt% for all cellulose types. The hardwood pulp-based nanofibers possessed the highest specific surface area and exhibited high efficiency for eliminating both PM and VOCs, with a PM_2.5 adsorption efficiency of 97.38%, PM_2.5 quality factor of 0.28, and toluene adsorption of 18.4 mg/g. This study will contribute to the development of next-generation eco-friendly multifunctional air filters for indoor clean-air environments.

Keywords: air filter; cellulose; ionic liquid; nanofiber; toluene adsorption.

Figure 1

(a) Schematics of the cellulose dissolution mechanism in mixed solvents. (b) Viscosity and solubility characteristics of cellulose precursor solutions as a function of EmimAC and DMF mixing ratio.

Figure 2

(a) Viscosity and solubility characteristics of H-6.3Pulp as a function of mixing time. (b) Schematic of the morphology conditions of the cellulose precursor solutions and cellulose nano-fibers. TEM images of (c) the cellulose precursor solution at a mixing time of 60 min and (d) the cellulose nanofibers.

Figure 3

(a) SEM images of the H-NF, S-NF, and P-NF systems with various cellulose contents. (b) Ternary phase diagrams illustrating the suitable composition range for the production of the desired cellulose nanofibers.

Figure 4

(a) Schematic diagrams of the PM removal mechanism by cellulose nanofibers. (b) SEM images of the H-NF, S-NF, and P-NF systems with various cellulose contents after PM_2.5 adsorption.

Figure 5

(a) Schematic of toluene adsorption on the cellulose nanofibers. Characteristics of toluene adsorption on the cellulose nanofibers: (b) adsorption breakthrough curves; (c) adsorption amount; and (d) FT-IR spectra before and after toluene adsorption.