Al-Coated Conductive Fibrous Filter with Low Pressure Drop for Efficient Electrostatic Capture of Ultrafine Particulate Pollutants

Abstract

Here, we demonstrate a new strategy of air filtration based on an Al-coated conductive fibrous filter for high efficient nanoparticulate removals. The conductive fibrous filter was fabricated by a direct decomposition of Al precursor ink, AlH{O(CH)}, onto surfaces of a polyester air filter via a cost-effective and scalable solution-dipping process. The prepared conductive filters showed a low sheet resistance (<1.0 Ω sq), robust mechanical durability and high oxidative stability. By electrostatic force between the charged fibers and particles, the ultrafine particles of 30-400 nm in size were captured with a removal efficiency of ∼99.99%. Moreover, the conductive filters exhibited excellent performances in terms of the pressure drop (∼4.9 Pa at 10 cm s), quality factor (∼2.2 Pa at 10 cm s), and dust holding capacity (12.5 μg mm). After being cleaned by water, the filtration efficiency and pressure drop of the conductive filter was perfectly recovered, which indicates its good recyclability. It is expected that these promising features make the conductive fibrous filter have a great potential for use in low-cost and energy-efficient air cleaning devices as well as other relevant research areas.

Moisture Effect on Particulate Matter Filtration Performance using Electro-Spun Nanofibers including Density Functional Theory Analysis

“…Guidelines were established to limit average exposure to a maximum of 10 μg/m 3 of PM 2.5 per year, and a maximum of 25 μg/m 3 over a 24-h period 6,7 . Consequently, many studies have been conducted on the capture and removal of PM such as electric precipitators 8 , catalytic filters 9 , cyclonic separators 10 , wet scrubbers 11 , and fabric filters 12–15 . Among them, nanofiber (NF)-based air-purification (or filtration) technology has attracted particular interest in recent years owing to its high performance (low pressure drop, high filtration efficiency, and dust-holding capacity), durability (service life, high-temperature stability, and flexibility), and high productivity (large-area production and mass production) 16,17 .…”

High-performance particulate matter including nanoscale particle removal by a self-powered air filter

“…However, for NPs with diameters smaller than the pore size, some particles may follow the gas streamline and pass through the purification material, resulting in a less effective filtration performance 18,19 . To resolve this limitation, a series of functional materials and production technologies based on top-down fibre manufacturing processes have been developed [20][21][22][23] , of which Brownian diffusion was surmised to be a dominant mechanism [24][25][26] . For instance, the Wang group reported creating a rotating triboelectric nanogenerator-enhanced polyimide nanofibre air filter by electrospinning 21 .…”

“…However, the method requires independent units of a nanogenerator and fibre membrane, which is inconvenient for fabricating portable devices. Lee's group applied an Al-coated conductive fibrous filter to capture NPs by strong electrostatic forces in the fibres 23 , which realized a high efficiency of over 99.99%. However, the specialized instrument and ultra-high voltage may consume large amounts of energy and ionize air, thus producing ozone and leading to further health risks.…”

Al-Coated Conductive Fiber Filters for High-Efficiency Electrostatic Filtration: Effects of Electrical and Fiber Structural Properties

“…Figure 1a presents a schematic diagram of the SD process that involves two steps: (i) a catalytic treatment by titanium isopropoxide (Ti(O- i -Pr) 4 ) and (ii) dip-coating into the Al precursor ink AlH 3 {O(C 4 H 9 ) 2 } chemically synthesized by an ethereal reaction of aluminum chloride (AlCl 3 ) with lithium aluminum hydride (LiAlH 4 ) in dibutyl ether (O(C 4 H 9 ) 2 ). More detailed fabrication procedures for the Al precursor ink and ALCF filter are explained in our previous work 22 , 30 . The top-right and bottom-right images shown in Fig.…”

“…If a fibrous filter has high electrical conductivity, the ESP technology can be applied directly to the filter. Recently, our group introduced an Al-coated conductive fiber (ALCF) filter fabricated by the reaction of the direct decomposition of Al onto the fibers of a polyester (PET) nonwoven filter using an Al precursor ink AlH 3 {O(C 4 H 9 ) 2 } 22 . The ALCF filter yielded high electrostatic PM removal rates of >99% for particles sizes ranging from 30 to 410 nm while showing low pressure drops in the region of ~4.9 Pa at an airflow velocity of 10 cm/s.…”