Experimental and Modeling Studies on the Filtration of SiO2 Nanoparticles Aerosolized from Different Solvents.

The filtration performance of a fibrous filter in removing nano-SiO2 aerosols atomized using different solvents including methanol, ethanol, 1-propanol, water, and the ethanol/water mixture has been investigated. Through discrete element method (DEM) simulation and filtration experiments, the efficiency variation caused by the combinative interaction of the particle-filter adhesion and interparticle attraction has been analyzed and verified. The adhesion force between the solvent-coated nanoparticles and the filter is considered as the key factor to influence their initial filtration efficiency and can be balanced by their interparticle interaction. The stronger the adhesion, the higher the initial filtration efficiency. Primary aggregate is formed through the particle-fiber interaction, and further agglomerate is caused by particle migration on the fibers, i.e. secondary aggregate. Hydrogen bonding interaction is considered as the main factor causing interparticle secondary agglomeration, and plenty of OH groups existing in the nano-SiO2 aerosols yielded from alcohol promotes the particle secondary aggregation. As a result, the Brown diffusion capture of the filter is significantly abated, and the as-formed agglomerate is scraped off the filter surface by the alcohol molecules, causing the filtration efficiency decreases. This study highlights the surface affinity properties of nanoaerosols and their balance between particle-particle and particle-fiber interactions in the filtration process.