Particulate Matter Filtration Research Articles

A multi-layer antimicrobial cellulose filter with electrostatic adsorption properties prepared by coating cellulose with chitosan and CuO

The health impacts of air pollution such as particulate matter (PM) and bioaerosols have prompted a focus on the utilization of personal protective filters. Traditional filters pose environmental concerns due to their non-biodegradable composition, while cellulose presents a promising alternative for biodegradable air filtration applications. This research involved the development of cellulose filter substrates with a customizable pore structure by adjusting the nanofiber content in cellulose filters and employing a simultaneous freeze-drying method. By integrating chitosan and CuO nanoparticles, the filters gained electrostatic adsorption capabilities, leading to a substantial enhancement in filtration efficiency, as well as imparting moisture resistance and durable antimicrobial properties to the filter. Subsequently, a three-layer cellulose filter integrated with chitosan and CuO (abbreviated as Int-Cs&CuO) was constructed based on the generalized Murray’s law to enable multi-stage PM filtration. The Int-Cs&CuO cellulose filter demonstrated filtration efficiencies of 99.2 % for non-oily PM0.3 and 99.5 % for oily PM0.3, with a low pressure drop of 49.5 Pa. Under humid conditions, the filtration efficiency of the Int-Cs&CuO cellulose filter against PM0.3 particles was minimally impacted, showcasing a decrease of only 1.3 %. Notably, the filter exhibited complete biodegradation in composted soil within approximately 2 months.

High-throughput production of low-cost hydrophobic and oleophilic mullite fiber sponges for high-temperature PM filtration

Particulate matter (PM) from high-temperature emissions like chemical plants, coal stoves and vehicle exhausts poses a gravel challenge to human health. To address this issue, researchers have explored various fiber filters, yet the bulk struggle to withstand high temperatures. In this study, mullite fiber sponges were developed utilizing low-cost materials and Kármán vortex solution blow spinning, using surfactants to improve the spinnability of the sol. Optimized sponges demonstrate ultralight (19 mg cm−3), temperature-resistant reversible compressibility (50% strain) and a water contact angle of 135°. These sponges exhibited exceptional thermal insulation (thermal conductivity: 0.0256 W m−1 K−1) and performed well in high-temperature air filtration. At 800 °C, the mullite sponge with a base weight of 35 mg cm−2, achieved an average filtration efficiency of 98.18 % and 99.57 % for PM2.5 and PM2.5−10, respectively, with a quality value of 0.98 Pa-1 at a wind speed of 4 cm s−1. This low-cost mullite fiber sponge offers a promising avenue for designing high-performance filtration materials.

Influence of coconut and castor oil coating on engine intake non-woven filter performance

PurposeThis research focuses on the development and characterization of oil-wetted spun-bonded polypropylene (PP) non-woven filters for improved air intake systems in automobiles. The study aims to enhance engine performance, durability, fuel economy and emission reduction by addressing key aspects such as contaminants filtration efficiency, loading capacity, pressure drop, temperature performance and longevity.Design/methodology/approachThe research methodology involves the utilization of textile fabrics, particularly oil-wetted spun-bonded PP non-woven filters, renowned for their effective particle collection capability from intake air. Experiments were conducted using a Box–Behnken design with three variables – oil concentration, areal density and dust quantity – each at three different levels to establish correlations with the filter’s dust holding capacity (DHC) and pressure drop.FindingsThe findings indicate that immersing particles in oil-coated medium significantly enhances the filter’s DHC. Notably, castor oil as a coating demonstrates remarkable results, with a 97.53% increase in DHC and a high particulate matter filtration efficiency of 94.12%.Originality/valueThis study contributes to the originality of research by emphasizing the importance of oil density in determining the filter’s DHC and filtration efficiency. Furthermore, it highlights the superiority of castor oil over coconut oil-coated filter media, advancing air intake and/or filter systems for automotive engines.

Amino functionalized zeolitic imidazolate framework-8 coated cellulose aerogel for enhanced air purification

Human activities generate large quantities of air pollutants, and particulate matter (PM) in the air poses a serious threat to public health. Nanofiber filters with surface-loaded metal–organic frameworks (MOFs) are promising materials for the capture of PM. Herein, this work creatively fabricated an air filter by anchoring amino-functionalized ZIF-8 on the surface of cellulose aerogel (NZCA) by in situ growth approach. The excellent compatibility between ZIF and cellulose was demonstrated by XRD, FT-IR, SEM and XPS characterization techniques. The functionalized ligand introduces –NH2, and the polar –NH2 group enhances the electrostatic interaction between ZIF-8-NH2 and PM, resulting in NZCA with superior PM filtration performance (filtration efficiency and quality factor: PM2.5: 92%, 0.054; PM10: 96%, 0.068) compared to ZCA without sacrificing the pressure drop. Furthermore, ZIF-8-NH2 modified cellulose filters were easy to regenerate and exhibited excellent reusability. This work paves the way for the rational design of ligand-modified MOF/cellulose filters for the efficient removal of PM from air, which has important implications for solving environmental problems and energy crises.

Polylactic acid-based composite filter with multi-gradient structure developed for high-efficiency particulate matter filtration and NH3 purification

Particulate matter (PM), ammonia (NH3) and other polluted gases emitted from animal feeding operations have emerged as significant risks to workers, surrounding residents, and the regional environment. Therefore, the development of air filters capable of simultaneously filtering PM and adsorbing toxic gases is particularly important. In this study, a three-layer gradient structure nanofiber filter was prepared by electrospinning technology, consisting of fluorinated Polylactic acid (PLA)/SiO2 as the outer layer, PLA nanofibers as the middle layer, and PLA/UiO-66-NH2 as the inner layer. This gradient structure of composite filter featured gradually decreasing pore sizes, exhibited optimal air filtration performance compared to PLA filter and commercial glass fiber filter. At 5.3 cm/s flow rate, the composite nanofiber filter achieved high filtration efficiency (99.15 % for PM0.5) and low pressure drop (89.65 Pa). Furthermore, the composite nanofiber filter exhibited highest dust holding capacity, indicating longer service life. It also featured excellent self-cleaning capabilities, allowing for reuse after simple water rinsing. Additionally, the results of ammonia (NH3) adsorption tests demonstrated the prepared composite filter’s highest adsorption capacity for NH3. Therefore, this work enhanced the application potential of high-performance air filters in the removal of PM pollution and hazardous gases.

Slot-structured catalytic membrane for sustained oily particulate matter removal with a low pressure drop

Oily particulate matter (PM) filtration faces the problems of high pressure drop and difficult regeneration. Herein, vertical arrays of MnO2 nanosheets was assembled on Zr doped TiO2 (Zr-TiO2) nanofibers to construct a core–shell structure MnO2@Zr-TiO2 (CSMT-x) catalytic membranes for highly efficient oily PM filtration and decomposition. The confining effect of the ultrathin MnO2 nanosheets enhances PM capture efficiency, and the increase of effective contact area between MnO2 and oily PM accelerate the decomposition of oily PM. The optimized CSMT-3 catalytic membrane exhibited high gas permeability and redox capacity, outperforming the Zr-TiO2 (Bare T) membrane with over 99.97 % PM filtration efficiency and a low pressure drop at the temperatures of 25–425 °C. The catalytic decomposition of PM prevented the accumulation of particles on the membrane surface, which inhibited the formation of cake layer. Therefore, the CSMT-3 membrane exhibited a slight increase in pressure drop (less than 120 Pa) even after 120 h long-term filtration. This work may contribute to the development of advanced multifunctional membranes for purification of oily PM.

Mapping the constituent preference of tree species for capturing particulate matter on leaf surfaces using single-particle mass spectrometry and supervised machine learning

Respiratory health is negatively influenced by the dimensions and constituents of particulate matter (PM). Although mass concentration is widely acknowledged to be key to assessing dust retention by urban trees, the role of plant leaves in filtering PM from the urban atmosphere, particularly regarding the particle dimensions and chemical constituents of retained PM on the leaf, remains elusive. Here we combined single-particle aerosol mass spectrometry and a particle resuspension chamber to investigate how urban tree species capture PM constituents. Results indicate that leaves are efficient in capturing relatively larger particles (1.0–2.0 μm). Compositionally, airborne particles were mostly composed of elemental carbon (EC, 20%), organic carbon (OC, 17%), and secondary reaction products (13%). However, leaf surfaces revealed a preference for retaining crustal species, comprising 55% of captured particulates. Notably, specific tree species demonstrated varied affinities for different PM constituents: Osmanthus fragrans Lour. predominantly captured levoglucosan (LEV), indicative of its efficiency against biomass burning particles, whereas Cinnamomum camphora (L.) J.Presl and Sabina chinensis var. kaizuca W.C.Cheng & W.T.Wang were more effective in capturing heavy metals (HMs). XGBoost modelling identified indicator ions, e.g., CN−, NO3−, NO2−, PO3−, with SHAP values surpassing 0.035, suggesting a preferential adsorption of these ions among different tree species. These findings demonstrate that the particulate capture efficiency of urban tree species varies with species-specific leaf properties, particularly in their ability to selectively adsorb particles containing hazardous constituents such as LEV and HMs. This study provides a scientific basis for the strategic selection of tree species in urban forestry initiatives aimed at improving air quality and public health.

Engineering electrospun PAN/PCL blend for high-performance and eco-friendly particulate matter filtration

Particulate matter (PM) is an air pollutant that poses a significant threat to human health. Efficient air filters are crucial for reducing PM pollution. However, several existing filtration materials fail under vigorous motion, such as twisting or stretching by high-velocity airflows, owing to their poor mechanical properties. In this study, we designed and fabricated a highly stretchable and biodegradable PM filtration membrane using electrospun polyacrylonitrile (PAN)/polycaprolactone (PCL) blended nanofibers. Our study incorporated polymer blend theory, particularly Hansen's solubility theory, to determine an optimal composition that not only provides particle absorption properties (minimizing PAN content without compromising absorption performance), but also significantly improves stretchability and biodegradability (maximizing PCL content). The resulting PAN/PCL air filters exhibited 100-times-enhanced stretchability and high filtration efficiency for PM2.5 (99.95%) and PM10 (99.89%), with a simultaneous low-pressure drop (121 Pa, only <1% of atmospheric pressure) under a high gas flow velocity (5 L/min ≈ face velocity of 0.3 m/s). Moreover, the 50/50 wt% PAN/PCL air filter demonstrated biodegradability, showing weight loss of up to 40% after 72 h of enzymatic degradation. Our highly efficient and biodegradable air filter, fabricated using PAN/PCL-blended nanofibers, offers new perspectives for the design and preparation of high-performance filtration materials. Moreover, it has potential applications in air pollution control and environmental protection.

Botanical Impact on Air Quality: Analyzing Particulate Matter Filtration by Plants and Health Effects

Botanical Impact on Air Quality: Analyzing Particulate Matter Filtration by Plants and Health Effects

Efficient capture of particulate matter with composite air filters comprising bamboo-derived nanofiber and base paper

Particulate-matter (PM) air filters comprising chemically synthesized polymers and petroleum-based materials are not environmentally sustainable because they do not biodegrade, causing secondary environmental pollution. To overcome this problem, we synthesized and analyzed the PM-capturing performance of composite sandwich-structured air filters containing bamboo-derived lignocellulose nanofibers and lignocellulose base paper. Bamboo pulp was produced through an organosolv process, and lignocellulose nanofibers and lignocellulose base paper were manufactured via electrospinning and paper processes, respectively. The manufacturing process was not only optimized via a rheological analysis of the precursor solution with different mixed solvent composition (6:4, 5:5, and 4:6 of 1-ethyl-3-methylimidazolium acetate:dimethylformamide) and different lignocellulose weight percent (3.3, 4.0, and 4.6 wt%), but also via nanofiber characterization, including electrospinnability, diameter distribution, and basis weight. The base paper condition was optimized based on analyses of the air permeability, PM filtration efficiency, and strength according to the paper thickness of 0.38 ± 0.05 and 0.10 ± 0.05 mm. As the lignocellulose nanofibers and base paper effectively captured particles smaller and larger than 2.5 μm, respectively, the structure of their composite sandwich-structured air filter was optimized to improve its PM-capturing performance. The study results provide new insights into the manufacturing of highly efficient PM air filters suitable for practical applications with diverse PM size distributions.

Urban meadow—a recipe for long-lasting anti-smog land cover

This study evaluates for the first time whether 33 species of annual and perennial herbaceous plants originating from a moderate climate continue to be capable of air filtration of particulate matter (PM) at the end of the growing season. Research was undertaken in November in two urban meadows located in trafficked areas of Białystok (Poland). The study reveals that despite the lateness in the season, tested species remained capable of PM accumulation. Deposition of total PM exceeding 100 μg·cm−2 was found on S. vulgaris, S. latifolia, T. pratense, E. vulgare, and A. officinalis. The finest and most toxic fraction was accumulated most effectively by S. latifolia, E. vulgare, and L. vulgare (>12 μg·cm−2). Taraxacum officinale and M. sylvestris retained c. 60% of PM in their epicuticular wax. A slight significant correlation was found between rosette growth pattern and deposition of total PM on foliage, while the accumulation of the finest fraction was correlated with a simple leaf shape. These results support the usefulness of urban meadows as long-lasting air bio-filters provided that their composition includes species that have a confirmed, prolonged PM accumulation capacity and that the meadow is not mown in autumn.

Lumped model for evaluating dynamic filtration and pressure drop behaviour in diesel particulate filters

Particulate matter (PM) emitted from diesel vehicles poses significant risks to the global climate, environment, and human health. Diesel particulate filters (DPF) are currently the only effective aftertreatment device for PM emissions reduction, and it is important to reflect the DPF filtration and pressure drop performance by numerical method. This study established and validated a lumped model based on the spherical packed bed theory and Darcy’s law. The model described the dynamic PM filtration process in DPF, predicting real-time characteristics such as wall porosity, soot load, and pressure drop with improved accuracy. The effects of channel characteristics, monolithic size, and exhaust conditions on filtration and pressure drop performance were also investigated. The results showed that an increase in cell density, wall thickness, DPF length, and diameter is beneficial for increasing filtration efficiency, while DPF inlet temperature and exhaust mass flow rate have adverse effects. Besides, wall thickness, DPF diameter and exhaust flow rate have a more significant impact on total pressure drop. The results improve the dynamic performance prediction in the PM filtration process and provide a theoretical basis for DPF structural optimization.

A cellulose composite filter with multi-stage pores had high filtration efficiency, low pressure drop, and degradable properties

The increasing air pollution has drawn attention to the importance of using protective masks. The non-biodegradable nature of conventional disposable masks can have a significant ecological impact. Cellulose materials have great potential in degradable filters. In this study, a three-layer cellulose pore structure was designed for an antimicrobial integrated cellulose filter (Int-CF&Z/C) based on the generalized Murray's law. Int-CF&Z/C was constructed using cellulose nanofibers to create cellulose filter layers with three different pore sizes. The three-layer pore-size gradient of Int-CF&Z/C not only enables Multiple filtration of particulate matter (PM) but also enhances dust capacity and reduces pressure drop. Then, the binary composite of ZIF-8 and CuO was added to the cellulose filter layer with the smallest pore size. This addition aims to improve the filtration performance, moisture resistance, and antimicrobial properties of the filter. The Int-CF&Z/C had a filtration efficiency of 97.7 % for non-oily PM0.3 and 98.5 % for oily PM0.3, with a pressure drop of only 74 Pa. Furthermore, the filtration performance of the filter exhibited a significantly lower decline compared to that of an N95 filter when utilized in prolonged periods in humid environments. Importantly, the filter could completely degrade in compost soil within approximately two months.

One-Step Fast Fabrication of Electrospun Fiber Membranes for Efficient Particulate Matter Removal.

Rapid social and industrial development has resulted in an increasing demand for fossil fuel energy, which increases particulate matter (PM) pollution. In this study, we employed a simple one-step electrospinning technique to fabricate polysulfone (PSF) fiber membranes for PM filtration. A 0.3 g/mL polymer solution with an N,N-dimethylformamide:tetrahydrofuran volume ratio of 3:1 yielded uniform and bead-free PSF fibers with a diameter of approximately 1.17 μm. The PSF fiber membrane exhibited excellent hydrophobicity and mechanical properties, including a tensile strength of 1.14 MPa and an elongation at break of 116.6%. Finally, the PM filtration performance of the PSF fiber membrane was evaluated. The filtration efficiencies of the membrane for PM2.5 and PM1.0 were approximately 99.6% and 99.2%, respectively. The pressure drops were 65.0 and 65.2 Pa, which were significantly lower than those of commercial air filters. Using this technique, PSF fiber membrane filters can be easily fabricated over a large area, which is promising for numerous air filtration systems.

An efficient atmospheric pollution control using hierarchical porous nanofibers containing zeolitic-imidazolate-frameworks and hydroxyapatite nanoparticles

Air pollution due to contaminants such as particulate matter (PM) and bacteria has become a global atmospheric pollution issue. Identifying effective methods for removing PM and other contaminants such as bacteria is an important challenge, and several efforts are being made to resolve it. In this study, we introduced a polystyrene (PS) hierarchical porous nanofiber (HAP/ZIF-8 @PS HPNF) containing a zeolitic imidazolate framework (ZIF-8) and hydroxyapatite (HAP) for PM (PM2.5, PM10) filtration and antibacterial applications. HAP/ZIF-8 @PS HPNF was manufactured by electrospinning of ZIF-8, which has a synergistic effect on the adsorption of PM and HAP that have antibacterial properties. The modified nanofibers improved the filtration performance and antibacterial activity by adsorbing PM (efficiency = 96.68% for PM2.5 and 96.98% for PM10) and reducing microbial populations (S. aureus and E. coli.). Thus, the well-dispersed ZIF-8 and HAP on the nanofibers, the multifunctional nanofibers are appropriate for use in environments with harmful PM as well as bacteria.

3D printed monolithic microfluidic device with an integrated porous filter: Application to pH measurement of water

Despite the available 3D printing technologies, fabrication of miniaturized analytical systems with integrated functional components is still one of the largest impediments. Here, we integrate a permeable porous filter into a 3D printed fluidic device capable of withstanding moderate hand pressure for in-field colorimetric pH measurements. The pH indicator is loaded and dried into the device, and the pH determined from converting images taken by a smartphone camera to a chromaticity diagram in International Commission on Illumination (CIE) 1931 color space and compared to calibration standards. The portable miniaturized device was fabricated with an integrated porous structure using a PolyJet 3D printer. One hundred and thirty-six devices could be printed in a single run (136 min), with cost of $0.6 per device. The 3D printed devices are capable of filtering particulate matter from the sample before mixing with an indicator avoiding optical interferences. Different environmental samples with a wide pH range (3–10) can be measured rapidly within 1 min.

Size-resolved particulate matter filtration efficiency of macroporous asymmetric SiC ceramic filters

Controlling particulate matter (PM) emissions to the atmosphere in industrial processes is critical for a safe and healthy environment. Because of its high strength and thermal stability, silicon carbide (SiC) is among the best materials for producing hot gas filters to be coupled to sugarcane bagasse-fired boilers in Brazil and India. In this study, we evaluated the performance of asymmetric SiC-based filters of different features for removing fine PM with particle sizes ranging from 90 to 3000 nm. The collection efficiency of the asymmetric filter made of SiC/mullite support with no pore former, porosity of 31–33 %, and permeability of (0.17–0.30) × 10−11 m2 with a coating thickness of 109–138 μm, effective pore size of 19–26 μm, and effective collector diameter of 64–86 μm was higher than 99 % for PM with size greater than 0.60 μm. The SiC formulation with mullite and pore former also presented promising performance. The resulting pressure drop remained within the range reported for commercial hot gas filters. Over 99 % of the mass of soot and fly ash particles generated during sugarcane bagasse combustion exceeds the MPPS range found for filters, which was between 0.16 and 0.36 μm. Therefore, the SiC asymmetric filters presenting mullite in their formulation are anticipated to meet current international emission standards.

The social justice issues of smoke im/mobilities

ABSTRACT In 2014, the Hazelwood mine fire burned for 45 days. Local communities were impacted by smoke and ash, and there were reports of raised carbon monoxide levels. Local news and social media reported residents experiencing numerous physical symptoms of smoke inhalation, including bleeding noses, coughing, wheezing and chest tightness. Paper masks to filter particulate matter were made available to residents to wear outside. The dust and ash constantly seeped into homes and offices, which required cleaning daily and sometimes multiple times during the day. Smoke was free to move across physical and bodily boundaries while those most vulnerable were hampered by lack of movement: pregnant women, the elderly and children were advised to leave the area. However, this suggestion to ‘simply’ move ignored the context of a community disproportionately impacted through years of economic decline and societal change. This paper explores the unequal mobilities of smoke and people that arose as a result of this event and draws on concepts of mobility justice (Sheller 2018) and emergency mobilities (Adey 2016) to reflect on the political dimensions of uneven mobility in times of crisis.

Biodegradable Nanofiber/Metal-Organic Framework/Cotton Air Filtration Membranes Enabling Simultaneous Removal of Toxic Gases and Particulate Matter.

The typical filters that protect us from harmful components, such as toxic gases and particulate matter (PM), are made from petroleum-based materials, which need to be replaced with other environmentally friendly materials. Herein, we demonstrate a route to fabricate biodegradable and dual-functional filtration membranes that effectively remove PM and toxic gases. The membrane was integrated using two layers: (i) cellulose-based nanofibers for PM filtration and (ii) metal-organic framework (MOF)-coated cotton fabric for removal of toxic gases. Zeolitic imidazolate framework (ZIF-8) was grown from the surface of the cotton fabric by the treatment of cotton fabric with an organic precursor solution and subsequent immersion in an inorganic precursor solution. Cellulose acetate nanofibers (NFs) were deposited on the MOF-coated cotton fabric via electrospinning. At the optimal thickness of the NF layer, the quality factor of 18.8 × 10-2 Pa-1 was achieved with a filtration efficiency of 93.1%, air permeability of 19.0 cm3/cm2/s, and pressure drop of 14.2 Pa. The membrane exhibits outstanding gas adsorption efficiencies (>99%) for H2S, formaldehyde, and NH3. The resulting membrane was highly biodegradable, with a weight loss of 62.5% after 45 days under standard test conditions. The proposed strategy should provide highly sustainable material platforms for practical multifunctional membranes in personal protective equipment.

Bicomponent spunbond filters doped with polytetrafluoroethylene nanoparticles for long-term efficient fine particle removal

Electret fiber-based air filtration materials find extensive applications in various fields, including particulate matter filtration, indoor purification, and epidemic prevention. However, achieving high-efficiency filtration with low resistance and long-term stability remains a challenge. In this study, we present a novel approach to fabricate sheath-core bicomponent spunbond filters (BCSFs) doped with polytetrafluoroethylene nanoparticles (PNPs) using bicomponent spunbond, through-air bonding, and corona charging techniques. This strategy enables the filtration material to possess low air resistance, long-term stable filtration efficiency, and a high dust holding capacity. The resulting BCSFs-PNPs exhibit remarkable filtration performance, with a filtration efficiency of 99.25% and a dust holding capacity of up to 11.48 g m−2, while maintaining a pressure drop as low as 37.87 Pa. Notably, the filtration efficiency of BCSFs-PNPs only experienced a slight decrease of 3.58% over a period of 180 days, demonstrating excellent long-term stability. The successful preparation of BCSFs-PNPs using corona charging technology holds great promise and offers valuable insight for the design and application of advanced air filtration materials.