Effects of size and shape on filtration of TiO₂ nanoparticles

Abstract

Titanium dioxide (TiO 2 ) is one of the most widely used nanoscale materials to date and could result in human exposures. The main objective of this study was to perform detailed characterization of TiO 2 agglomerate particles and how these properties influence particle penetration in a screen filter. Transmission electron microscope (TEM) photos showed compact agglomerates of nanoscale primary particles. The projected area diameter was close to the mobility diameter, where the length was about 25% larger than the mobility diameter. The mean aspect ratio of TiO 2 agglomerate was constant between 1.39 and 1.55. Using the tandem differential mobility analyzer-aerosol particles mass analyzer (DMA-APM) technique, we were able to measure aerodynamic diameter, mass, and fractal dimension. The value of fractal dimension based on mass and mobility diameter was 2.8. Penetration of classified TiO 2 particles through a screen filter was measured. Penetration increased with increasing mobility diameter and flow rate indicating that diffusion and interception were the main filtration mechanism. The measured physical dimensions, mobility diameter, and aerodynamic diameter were used in a single-fiber filtration theory for the fan model filter to predict the penetration of TiO 2 particles. The interception parameter was the key to estimate the penetration. Experimental penetration data were in best agreement with the model in which the maximum length was used to calculate the interception model. This result was consistent with the assumption that the rotation time of a non-spherical particle of small aspect ratio was much less than the transport time for the particle to pass through the filter fiber.

Effects of Size and Morphology of TiO2 and SiO2 Airborne Nanoparticles on their Filtration through Chemical Protective Clothing

“…The first parameter to be studied was the size of the airborne nanoparticles. Numerous studies, conducted with screen and nonwoven filters, report an increase in penetration as the electrical mobility diameter is increased, with a Most Penetrating Particle Size (MPPS) greater than 300 nm [25], [26]. In the present work, minimum penetration was reached at 24% for nSiO2-30 nm and 26% for nSiO2-300 nm (Figure 4).…”

“…He concluded that the filtration efficiency is higher for agglomerates than for spheres. On the other hand, Chang and Zhou (2017) evaluated and modeled the effect of size and shape of 25 nm-TiO2 nanoparticles on the filtration through a screen filter (solidity 0.345 and face velocities at 2.92 and 5.85 cm/s) [26]. Their conclusion confirmed Kim's work.…”

Anions influence the extraction of rutile nanoparticles from synthetic and lake water

“…The total interactive energy likely has a stronger inuence than the particle size on the stability of NPs in aquatic environments. 48 The variations indicate that aggregation and agglomeration are constant processes during the settling period, and even though the size of the particles may change, the average size distribution remains between 100 nm and 300 nm ( Fig. 4).…”

Sol-Gel Spin Coating Synthesis of TiO<sub>2</sub> Nanostructure and Its Optical Characterization

“…The grain size of the synthesized TiO 2 nanostructure was calculated using the intercept technique [8].…”