Bio-based ionic liquid filter with enhanced electrostatic attraction for outside filtration and inside collection of viral aerosols

Hazardous biological pathogens in the air pose a significant public environmental health concern as infected individuals emit virus-laden aerosols (VLAs) during routine respiratory activities. Mask-wearing is a key preventive measure, but conventional filtration methods face challenges, particularly in high humidity conditions, where electrostatic charge decline increases the risk of infection. This study introduces a bio-based air filter comprising glycine ionic liquids (GILs) and malleable polymer composite (GILP) with high polarity and functional group density, which are wrapped around a melamine-formaldehyde (MF) resin skeleton, forming a conductive, porous GIL functionized ionic network air filter (GILP@MF). When subjected to low voltage, the GILP@MF composite efficiently captures VLAs including nanoscale virus particles through the enhanced electrostatic attraction, especially in facing high humidity bioaerosols exhaled by human body. The filtration/collection efficiency and quality factor can reach 98.3% and 0.264 Pa-1 at 0.1 m s-1, respectively. This innovative filter provides effective VLA protection and offers potential for non-invasive respiratory virus sampling, advancing medical diagnosis efforts.

A theoretical study on the filtration efficiency and dust holding performance of pleated air filters

Filter media composed of electrostatically charged nonwovens is the key device in an air purifier. Pleated filters are constructed from a cardboard frame with lattice faces containing a filter media reinforce by an expanded support grid, which have more surface area for trapping contaminants and capture airborne contaminants more effectively than non-pleated air filters. The aim of this work is to investigate the dominant factors on the filtration efficiency and dust holding performance of pleated filter by using a modified numerical model. It is found that geometric parameters of pleated filter play important roles to efficiency of the air purifier based on particle loading and filtration efficiency. The stable structural parameters include bending angle of pleated filter material in the range of 0∼60° and the ratio of bending portion less than 0.5. Lower filling degree and shorter length of pleated filter unit exhibit similar stability of efficiency, indicating that the change of structural parameters has little effects on the filtration performance. The knowledge obtained in this work provides concrete reference for the design of high-performance air-cleaner element.

Evolution of pressure drop across electrospun nanofiber filters clogged by solid particles and its influence on indoor particulate air pollution control

Because of the relatively low pressure drop and high particle removal efficiency, nanofiber filter media can be potentially used for indoor particulate air pollution control. However, the influence of particle loading on the long-term performance of nanofiber filters in indoor particle control has not been well studied. This study first experimentally investigated the relationship between the pressure drop and solid particle loading mass for 42 nanofiber filter samples under various face velocities. The results show that the air resistance coefficient increased with the solid particle loading mass for the nanofiber filter media. Furthermore, the air resistance coefficient was positively associated with the face velocity, as a higher air velocity tended to make the particle cake tighter with higher resistance. Based on the experimental data, a semi-empirical equation was developed for predicting the pressure drop under different particle loading masses and face velocities. The developed semi-empirical model was then used to assess the long-term performance of an air cleaner equipped with nanofiber filter media in indoor PM_2.5 control. The case study demonstrated that an air cleaner equipped with nanofiber filter media could effectively control indoor PM_2.5, but the lifetime of the nanofiber filter was shorter than that of traditional HEPA filters.