High Particulate Matter Removal Efficiency Research Articles

A Study on the Particle Removal Efficiency and Durability According to the Material of the Ionizer of the Fiber Brush Type Electric Precipitator

In this study, we investigated the particulate matter (PM) removal efficiency and durability of the two-stage electrostatic precipitator (ESP) different materials of brush-typed ionizers (non-metal: carbon fiber/metal: stainless steel (SUS) fiber). The PM removal efficiency was reduced when the average diameter and number of fibers of the brush-typed ionizer increased due to thin and multi-edge in a large number of fibers, which decreased the average electric field, resulting in lower PM removal efficiencies. In contrast with the carbon fiber ionizer, when the SUS fiber ionizer was used, the PM removal efficiency was maintained for a long time, due to its lower electrical resistivity (∼6.9 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−7</sup> Ω * m) of the SUS fiber compared with the carbon fiber (∼5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> Ω * m), which prevents the positive ions to be stacked on the fiber. Therefore, the present research showed the potential use to apply SUS fiber ionizers as two-stage ESPs for a future air pollution control technology with high PM removal efficiency and durability without ozone emission and additional maintenance.

Preparation and Characterization of Electrospun PAN-CuCl2 Composite Nanofiber Membranes with a Special Net Structure for High-Performance Air Filters.

The growing issue of particulate matter (PM) air pollution has given rise to extensive research into the development of high-performance air filters recently. As the core of air filters, various types of electrospun nanofiber membranes have been fabricated and developed. With the novel poly(acrylonitrile) (PAN)-CuCl2 composite nanofiber membranes as the filter membranes, we demonstrate the high PM removal efficiency exceeding 99% and can last a long service time. The nanoscale morphological characteristics of nanofiber membranes were investigated by scanning electron microscopy, transmission electron microscopy, and mercury intrusion porosimeter. It is found that they appear to have a special net structure at specific CuCl2 concentrations, which substantially improves PM removal efficiency. We anticipate the PAN-CuCl2 composite nanofiber membranes will be expected to effectively solve some pressing problems in air filtration.

High-performance electrospun particulate matter (PM) filters embedded with self-polarizable tetragonal BaTiO3 nanoparticles

This study developed a novel transparent filter with a high particulate matter (PM) removal efficiency and low airflow resistance for use in windows. The main idea of this filter is to combine the ability of electrospun nanofiber (NF) structures to minimize airflow resistance with the unique self-polarizability of tetragonal BaTiO3 (t-BTO) nanoparticles, which enables the capture of PM through electrostatic interactions. Density functional theory (DFT) calculation predicted the self-polarization of t-BTO, and the presence of static electricity on the NF filters with t-BTO was confirmed by Kelvin probe force microscopy and electrostatic force measurement. Their PM removal efficiency and airflow resistance were dependent on the t-BTO loading and filter transparency. The filter with 20% t-BTO and 90% transparency exhibited a high PM removal efficiency (∼99.1% for PM10–2.5 and ∼98.9% for PM2.5) and a pressure drop of <70 Pa, indicating an extremely low airflow resistance. Moreover, its quality factor value reached ∼0.79 Pa−1, which far exceeds those of previously reported air filters (∼0.2 Pa−1). Further, accelerated long-term experiments for verifying the filter’s durability revealed that it exhibited a high PM removal performance and maintained a low airflow resistance despite a slight reduction in its performance. To enable the commercialization of our filter, the filter’s properties will be optimized based on the results of a field test under actual environments.

ZIF-8/PI Nanofibrous Membranes With High-Temperature Resistance for Highly Efficient PM0.3 Air Filtration and Oil-Water Separation.

Air and water pollution poses a serious threat to public health and the ecological environment worldwide. Particulate matter (PM) is the major air pollutant, and its primary sources are processes that require high temperatures, such as fossil fuel combustion and vehicle exhaust. PM0.3 can penetrate and seriously harm the bronchi of the lungs, but it is difficult to remove PM0.3 due to its small size. Therefore, PM0.3 air filters that are highly efficient and resistant to high temperatures must be developed. Polyimide (PI) is an excellent polymer with a high temperature resistance and a good mechanical property. Air filters made from PI nanofibers have a high PM removal efficiency and a low air flow resistance. Herein, zeolitic imidazolate framework-8 (ZIF-8) was used to modify PI nanofibers to fabricate air filters with a high specific surface area and filtration efficiency. Compared with traditional PI membranes, the ZIF-8/PI multifunction nanofiber membranes achieved super-high filtration efficiency for ultrafine particles (PM0.3, 100%), and the pressure drop was only 63 Pa. The filtration mechanism of performance improvement caused by the introduction of ZIF-8/PI nanofiber membrane is explored. Moreover, the ZIF-8/PI nanofiber membranes exhibited excellent thermal stability (300 C) and efficient water–oil separation ability (99.85%).

High-performance filter membrane composed of oxidized Poly (arylene sulfide sulfone) nanofibers for the high-efficiency air filtration

In this study, a novel, oxidized poly (arylene sulfide sulfone) (O-PASS) nanofibrous membrane filter was successfully fabricated for the effective removal of particulate matter. PASS was electrospun into a nanofibrous membrane with an average nanofiber diameter of 0.31 µm and basis weight of 3 g/m2. These specifications were chosen as they showed high particulate matter removal efficiency (99.98%), low pressure drop (68 Pa), and high quality factor QF (0.125 Pa−1). In addition, the filtration mechanism of the PASS nanofibrous membrane was intuitively revealed by simulating the intercepted particular distributions and motion paths of particles. After a simple oxidation treatment, the O-PASS nanofibrous membrane was successfully built up. The microstructure and morphology showed little change compared with the PASS nanofiber, but the oxidation treatment significantly improved the mechanical properties of the membrane from 1.51 MPa to 4.92 MPa. More importantly, the O-PASS nanofibrous membrane still exhibited high removal efficiency after high temperature, acid, alkali, or organic solvent treatments. Overall, O-PASS nanofibrous membranes are promising high-performance filter materials with high temperature and corrosion resistance.

Facile synthesis of porous organic polymers (POPs) membrane via click chemistry for efficient PM2.5 capture

Global environmental problems are facing serious challenges, especially the harm of air pollution to human health. It is meaningful to capture harmful particulate matter (PM) in the air. In this work, we report for the first time the facile synthesis of porous organic polymers (POPs) with macroporous structure, which were synthesized using 1,4-benzenedithiol, 1,4-diethynylbenzene and 1,3-benzenedithiol via click chemistry, for efficient PM capture. PM filtration measurement was simulated by the release of particulate pollutants from cigarette smoke. The test results of porous composite membranes (PCMs) show a high PM removal efficiency for PM2.5 (≥99.80 ± 1.58%) and PM10 (≥99.89 ± 0.89%) in 30 h. The PCMs based on kapok fiber not only has good mechanical properties, but also can be made into membranes of different sizes depending on the size of the substrate. Taking advantage of their simple one-step synthesis via click chemistry with great potentials for scale-up under mild conditions, such PCMs may find useful applications in PM capture.

Seeds embedded epitaxial growth strategy for PAN@LDH membrane with Mortise-Tenon structure as efficient adsorbent for particulate matter capture

Fabrication of highly efficient and low-resistance membranes for particulate matter (PM) capture has attracted wide attention. We reported herein a new “Seeds Embedded Epitaxial Growth” (SEEG) strategy for the preparation of novel PAN@LDH (PAN: polyacrylonitrile; LDH: layered double hydroxide) inorganic-organic composite membranes with unique “Mortise-Tenon” structures. Among the as-prepared PAN@LDH membranes, the PAN@60%LDH exhibited excellent removal efficiency for PM10 and PM2.5 of 99.29 ± 0.56%, 99.03 ± 0.82%, respectively, under extreme hazardous air condition with PM >3000 μg m-3. In particular, the PAN@60%LDH membrane showed outstanding removal efficiency for PM0.3–0.5 of 95.29 ± 1.95% too. Moreover, such a membrane can be renewed easily and remain high PM removal efficiency. The diffusion effect, the inertance effect, the electrostatic interactions between PM and LDH contributed significantly to PM capture. As such, the PAN@LDH membranes can be a very promising and environmental-benign material for industrial applications in environmental purification.

Hierarchical Ceramic Foams with 3D Interconnected Network Architecture for Superior High-Temperature Particulate Matter Capture.

Developing new filters for the effective removal of high-temperature particulate matter is of great importance but still remains a challenge. Herein, we demonstrate a novel and facile strategy for producing hierarchical ceramic foams with three-dimensional interconnected porous architecture via the combination of chemical grafting of pore-forming agent and polyurethane foaming technique. Carbamate groups are directly grafted onto carbon black surface to enhance its dispersion. Abundant micrometer-sized pores are generated on the cell walls of porous frameworks to form three-dimensional interconnected porous architectures, resulting in the mullite foam with high particulate matter removal efficiency and relatively low pressure drop. The optimized mullite foam exhibits integrated properties of high particulate matter removal efficiency (96.7%), ultralow pressure drop (35 Pa), and outstanding recyclability. Our results open new opportunities for fabricating efficient particulate matter filters used in high-temperature environmental fields.

Transparent Antibacterial Nanofiber Air Filters with Highly Efficient Moisture Resistance for Sustainable Particulate Matter Capture.

SummaryParticulate matter (PM) pollution has posed great threat to human health. This calls for versatile protection or treatment devices that are both efficient and easy to use. Herein, we have rationally designed a novel reusable bilayer fibrous filter consisting of electrospun superhydrophobic poly(methylmethacrylate)/polydimethylsiloxane fibers as the barrier for moisture ingression and superhydrophilic chitosan fibers for a PM capture efficiency of over 96% at optical transmittance of 86%. Furthermore, it could realize a high-level PM2.5 capture efficiency (>98.23%) even after 100-h test during extremely hazardous air environment (PM2.5 > 3,000 μg m−3) and retain a high PM removal efficiency (PM2.5 > 98.39%) after five washing cycles. Besides, such membranes possessed high antibacterial activity at 96.5% for E. coli and 95.2% for Staphylococcus aureus. As a proof-of-concept study, continuous particle removing has been successfully demonstrated on a window screen to prevent particle pollution.

Hierarchical porous ceramics with 3D reticular architecture and efficient flow-through filtration towards high-temperature particulate matter capture

Porous ceramics with high porosity and extensive interconnected pores have great application potential in fields ranging from dye removal to high-temperature particulate matter (PM) capture. However, constructing these materials to achieve efficient filtration is extremely challenging. Herein, a novel strategy to create hierarchical-structured porous alumina ceramics (PACs) with three-dimensional (3D) reticular architecture is reported based on polyurethane (PU) foaming method. To ensure the efficient flow-through filtration, carbamate-grafted carbon black is used as the pore-forming agent and assembled into the porous PU framework. Submicron and micron-sized pores on the cell walls are observed in hierarchical-structured PACs. This unique structure enables a high PM removal efficiency (94.1%) at an ultralow pressure drop (20 Pa). Our work has demonstrated great application potentials of as-prepared PACs as an efficient high-temperature PM filter and provided new insights to develop highly effective filter.

Removal of fine particulate matter (PM2.5) via atmospheric humidity caused by evapotranspiration

Reduction of particulate matter (PM) has emerged as one of the most significant challenges in public health and environment protection worldwide. To address PM-related problems and effectively remove fine particulate matter (PM2.5), environmentalists proposed tree planting and afforestation as eco-friendly strategies. However, the PM removal effect of plants and its primary mechanism remains uncertain. In this study, we experimentally investigated the PM removal performance of five plant species in a closed chamber and the effects of relative humidity (RH) caused by plant evapotranspiration, as a governing parameter. On the basis of the PM removal test for various plant species, we selected Epipremnum aureum (Scindapsus) as a representative plant to identify the PM removal efficiency depending on evapotranspiration and particle type. Results showed that Scindapsus yielded a high PM removal efficiency for smoke type PM2.5 under active transpiration. We examined the correlation of PM removal and relative humidity (RH) and evaluated the increased effect of RH on PM2.5 removal by using a plant-inspired in vitro model. Based on the present results, the increase of RH due to evapotranspiration is crucial to the reduction of PM2.5 using plants.

Transparent thermoplastic polyurethane air filters for efficient electrostatic capture of particulate matter pollutants

Particulate matter (PM) air pollution has been established as a significant threat to public health and a destructive factor to the climate and eco-systems. In order to eliminate the effects of PM air pollution, various air filtering strategies based on electrospun nanofibers have recently been developed. However, to date, almost none of the existing nanofibers based air filters can meet the requirements of high-performance air PM filtering, including high PM removal efficiency, low resistance to airflow, and long service life, etc. For the first time, we report a fabrication process using the electrospinning method for air filters based on thermoplastic polyurethane (TPU) nanofibers. The average diameters of TPU nanofibers are tunable from 0.14 ± 0.06 μm to 0.82 ± 0.22 μm by changing the TPU concentrations in polymeric solutions. The optimized TPU nanofibers based air filters demonstrate the attractive attributes of high PM2.5 removal efficiency up to 98.92%, good optical transparency of ∼60%, low pressure drop of ∼10 Pa, high quality factor of 0.45 Pa−1, and long service life under the flow rate of 200 ml min−1, which is ground-breaking compared with the existing nanofibers based air filters. These TPU nanofibers based air filters, with the excellent filtration performance and light transmittance, will shed light on the future research of nanofibers for various filtration applications and greatly benefit the public health by reducing the effects of PM air pollution.

Preparation and Properties of sc-PLA/PMMA Transparent Nanofiber Air Filter.

Particulate matter (PM) pollution is a serious concern for the environment and public health. To protect indoor air quality, nanofiber filters have been used to coat window screens due to their high PM removal efficiency, transparency and low air resistance. However, these materials have poor mechanical property. In this study, electrostatic induction-assisted solution blowing was used to fabricate polylactide stereocomplex (sc-PLA), which served as reinforcement to enhance the physical cross-linking point to significantly restrict poly(methyl methacrylate) (PMMA) molecular chain motion and improve the mechanical properties of sc-PLA/PMMA nanofibers. Moreover, the introduction of sc-PLA led to the formation of thick/thin composite nanofiber structure, which is beneficial for the mechanical property. Thus, sc-PLA/PMMA air filters of ~83% transparency with 99.5% PM2.5 removal and 140% increase in mechanical properties were achieved when 5 wt % sc-PLA was added to PMMA. Hence, the addition of sc-PLA to transparent filters can effectively improve their performance.

Effect of Pulsed Power on Particle Matter in Diesel Engine Exhaust Using a DBD Plasma Reactor

Nonthermal plasma (NTP) treatment of exhaust gas is a promising technology for both nitrogen oxides $({\rm NO}_{\rm X})$ and particulate matter (PM) reduction by introducing plasma into the exhaust gases. This paper considers the effect of NTP on PM mass reduction, PM size distribution, and PM removal efficiency. The experiments are performed on real exhaust gases from a diesel engine. The NTP is generated by applying high-voltage pulses using a pulsed power supply across a dielectric barrier discharge (DBD) reactor. The effects of the applied high-voltage pulses up to 19.44 kVpp with repetition rate of 10 kHz are investigated. In this paper, it is shown that the PM removal and PM size distribution need to be considered both together, as it is possible to achieve high PM removal efficiency with undesirable increase in the number of small particles. Regarding these two important factors, in this paper, 17-kVpp voltage level is determined to be an optimum point for the given configuration. Moreover, particles deposition on the surface of the DBD reactor is found to be a significant phenomenon, which should be considered in all plasma PM removal tests.

Exposure levels of particulate matter in long-distance buses in Taiwan

This study investigated the passenger exposure to particulate matter (PM) in long-distance buses in Taiwan. PM and CO(2) were measured in thirty buses traveling between Taipei and Tainan. The results indicated that average in-cabin PM levels were below the guidelines or standards suggested by Taiwan and other countries. Cigarette smoking revealed no effect on in-cabin PM2.5 level. However, since only one cigarette was lit per journey, the effect might be different if more cigarettes were lit in bus cabins. Opening windows was found to affect in-cabin PM2.5 and PM2.5/PM10 ratios may be elevated. Moreover, the PM10 level from air monitoring stations did not reflect the true passenger exposure to PM10. This study concludes that PM levels in long-distance buses is lower than those in other studies of urban buses, as a result of faster driving speed, non-stop driving pattern, and highway surroundings. Keeping windows closed on long-distance buses can minimize passenger exposure to PM2.5. Conversely, high in-cabin CO(2) levels may occur if opening window is minimized when air change rate is low. This study suggests that long-distance buses should increase their air exchange rates to reduce CO(2) levels and install particle filters with high removal efficiency to lower in-cabin PM levels. The PM levels in the long-distance buses running on highways are lower than those observed in city buses. Opening window in the long-distance buses would result in higher in-cabin PM levels but may effectively reduce in-cabin CO(2) levels, which accumulate over the journey of long hours. Increase of air exchange rate and installation of filters with high PM removal efficiency in ventilation system are suggested to improve air quality in the cabin of long-distance buses.