Air filtration by interception—Theory and experiment

Brown, Richard C. D.; Wake, D.

doi:10.1016/0021-8502(91)90026-e

Cited by 29 publications

(16 citation statements)

References 6 publications

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“…The system is composed of an atomizer (aerosol generator), a diffusion dryer, a charge neutralizer, a filter holder and a condensation particle counter. In detail, the essential features of the test method are as follows: monodisperse aerosols are passed in turn through the filter under test and through an identical balanced empty line; the air flow is kept constant by computer control, while the test particle size is varied automatically; and particles in the filtered and the unfiltered aerosol are counted optically, yielding date on the filtration performance of the membranes. The collection efficiency of a fibrous filter medium is calculated as follows

η = [1 - \frac{C_{downstream}}{C_{upstraem}}] \times 100 %

where η is the collection efficiency and C downstream and C upstream are the aerosol concentrations after and before passing through the air filtration membranes, respectively.…”

Section: The Electrospinning Processmentioning

confidence: 99%

Electrospun Nanofibers Membranes for Effective Air Filtration

Zhu

Han

Wang

et al. 2016

Macromol. Mater. Eng.

500

352

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In modern society, traffic and transportation and the manufacturing industry and construction industries continuously release large amounts of dust and particles into the atmosphere, which can cause heavy air pollution, leading to health hazards. The haze disaster, a serious problem in developing countries such as China and India, has become one of the main issues of global environmental pollution in recent decades. Many air filtration technologies have been developed. Air filtration using electrospun fibers that intercept fine particles/volatile organic gases/bacterium is a relatively new, but highly promising, technique. Due to their interconnected nanoscale pore structures, highly specific surface areas, fine diameters, and porous structure as well as their ability to incorporate active chemistry on a nanoscale surface, electrospun fibers are becoming a promising versatile platform for air filtration. In this review, following a short introduction concerning the need for air filtration and filtration theory and mechanism, electrospun nanofibers membranes for air filtration have been highlighted, including the preparation (electrospinning process) and the parameters relevant to filtration efficacy. Additionally, various types (function) of the electrospun air filtration membranes have been classified in detail. Furthermore, their potential in the filtration of fine particles and chemical pollutants has been discussed. Finally, the challenges of their practical application and the future prospects have been summarized. Given that some advanced electrospun air filtration nanofibrous membranes exist for treating different contaminants from various types of polluted atmosphere, it is believed that they should make a significant contribution in protection against air pollution.

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η = [1 - \frac{C_{downstream}}{C_{upstraem}}] \times 100 %

where η is the collection efficiency and C downstream and C upstream are the aerosol concentrations after and before passing through the air filtration membranes, respectively.…”

Section: The Electrospinning Processmentioning

confidence: 99%

Electrospun Nanofibers Membranes for Effective Air Filtration

Zhu

Han

Wang

et al. 2016

Macromol. Mater. Eng.

500

352

View full text Add to dashboard Cite

show abstract

“…The FE of a dry fiber can be calculated using theory developed previously by Brown and Wake, Stechkina and Fuchs, and Lee and Liu. 23 − 27 Details of the calculation of E F and Δ P are shown in the Supporting Information eqs S1–S10. The FE and Δ P of a filter are a balance of D f , α, L , and flow rate where changes in one term that increase FE can be offset by changes in other terms.…”

Section: Resultsmentioning

confidence: 99%

Hydration of Hydrophilic Cloth Face Masks Enhances the Filtration of Nanoparticles

Zangmeister

Radney

Staymates

et al. 2021

ACS Appl. Nano Mater.

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Under high humidity conditions that mimic respiration, the filtration efficiency (FE) of hydrophilic fabrics increases when challenged with hygroscopic nanoparticles, for example, respiratory droplets containing SARS-CoV-2. The FE and differential pressure (Δ P ) of natural, synthetic, and blended fabrics were measured as a function of relative humidity (RH) for particles with mobility diameters between 50 and 825 nm. Fabrics were equilibrated at 99% RH, mimicking conditions experienced when worn as a face mask. The FE increased after equilibration at 99% RH by a relative percentage of 33 ± 12% for fabrics composed of two layers of 100% cotton when challenged by 303 nm-mobility-diameter NaCl aerosol. The FE for samples of synthetics and polyester/cotton blends was unchanged upon equilibration at 99% RH. Increases in FE for 100% cotton fabrics were a function of particle size with a relative increase of 63% at the largest measured particle size (825 nm). The experimental results are consistent with increased particle capture due to H 2 O uptake and growth as the particles traverse the fabric.

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“…[1][2][3][4] For particles >0.5 μm, they can be captured by filter fibers via interception or inertial impaction. 13 For ultrafine particles (≤0.3 μm) that move around in Brownian motion, trapping occurs due to a concentration gradient of particles between the air and the filter fiber surface, driving small particles towards the fiber surface and binding to them by van der Waals forces. 14 Electrostatic interactions with charged fibers can further aid in the particle filtration, especially at low air flow velocities.…”

Section: Introductionmentioning

confidence: 99%

“…14 Electrostatic interactions with charged fibers can further aid in the particle filtration, especially at low air flow velocities. 13,[15][16][17] However, particulates in the intermediate 0.1-0.4 μm size range are the most difficult to filter. 18 Materials currently used for air filtration have various limitations.…”

Section: Introductionmentioning

confidence: 99%

Efficient and Robust Metallic Nanowire Foams for Deep Submicrometer Particulate Filtration

et al. 2021

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The on-going COVID-19 pandemic highlights the severe health risks posed by deep submicron sized airborne viruses and particulates in the spread of infectious diseases. There is an urgent need for the development of efficient, durable and reusable filters for this size range. Here we report the realization of efficient particulate filters using nanowire-based low-density metal foams which combine extremely large surface areas with excellent mechanical properties. The metal foams exhibit outstanding filtration efficiencies (>96.6%) in the PM0.3 regime, with potentials for further improvement. Their mechanical stability and light weight, chemical and radiation resistance, ease of cleaning and reuse, and recyclability further make such metal foams promising filters for combating COVID-19 and other types of airborne particulates.

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Air filtration by interception—Theory and experiment

Cited by 29 publications

References 6 publications

Electrospun Nanofibers Membranes for Effective Air Filtration

Electrospun Nanofibers Membranes for Effective Air Filtration

Hydration of Hydrophilic Cloth Face Masks Enhances the Filtration of Nanoparticles

Efficient and Robust Metallic Nanowire Foams for Deep Submicrometer Particulate Filtration

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