Particulate Matter Removal Research Articles

Electrospun carboxylated MWCNTs modified PMIA tree-like nanofibrous membrane with excellent thermal stability and chemical resistance for efficient particulate matter removal

The aim of this study is to fabricate nanofibrous membranes with excellent filtration and mechanical properties for application in the field of flue gas purification. Carboxylated Multiwalled carbon nanotubes (MWCNTs-COOH) were used to enhance the performance of PMIA nanofibrous membranes. The results showed that the average particle size D50 of MWCNTs-COOH in the PMIA electrospining solution was significantly reduced from 644 nm to 361 nm, the stability and dispersibility of MWCNTs-COOH were significantly enhanced. The resultant membranes exhibit a tree-like structure with a bimodal distribution of diameters and interconnected bonding points, where the trunk nanofibers exhibit an average diameter of 134.80 nm, while the branch nanofibers demonstrate an average diameter of 27.19 nm. The MWCNTs-COOH/PMIA nanofibrous membranes exhibited a filtration efficiency of 99.98 % for the most penetrating particle size (MPPS), while maintaining a tensile strength of 46.736 MPa. Notably, they retained significant strength even under harsh conditions, e.g. 56.46 % at 250 °C, 58.26 % with 30 wt% H2SO4, and 82.71 % with 10 wt% NaOH. The filtration efficiency remained at approximately 88.97 % even at 250 °C. These findings expand PMIA's application to harsh environments and offer insights for designing high-performance filters for high-temperature settings.

Bio‐inspired hierarchical bamboo‐based air filters for efficient removal of particulate matter and toxic gases

AbstractAir pollution is caused by the perilous accumulation of particulate matter (PM) and harmful gas molecules of different sizes. There is an urgent need to develop highly efficient air filtration systems capable of removing particles with a wide size distribution. However, the efficiency of current air filters is compromised by controlling their hierarchical pore size. Inspired by the graded filtration mechanisms in the human respiratory system, microporous ZIF‐67 is in situ synthesized on a 3D interconnected network of bamboo cellulose fibers (BCFs) to fabricate a multiscale porous filter with a comprehensive pore size distribution. The macropores between the BCFs, mesopores formed by the BCF microfibers, and micropores within the ZIF‐67 synergistically facilitate the removal of particulates of different sizes. The filtration capabilities of PM2.5 and PM0.3 could reach 99.3% and 98.6%, respectively, whereas the adsorption of formaldehyde is 88.7% within 30 min. In addition, the filter exhibits excellent antibacterial properties (99.9%), biodegradability (80.1% degradation after 14 days), thermal stability, and skin‐friendly properties (0 irritation). This study may inspire the research of using natural features of renewable resources to design high‐performance air‐filtration materials for various applications.

Removal Efficiency of Bottom Ash and Sand Mixtures as Filter Layers for Fine Particulate Matter.

Permeable pavement is a technology that allows rainwater to infiltrate into the pavement. Permeable pavements not only help reduce surface runoff by allowing rainwater to infiltrate into the pavement, but also improve water quality with the filter layer that removes particulate matter pollutants. This study evaluated the particulate matter removal efficiency of bottom ash-sand mixtures as filter layers for removing fine (≤10 μm) or ultrafine (≤2.5 μm) particulate matter in the laboratory. Five filter media were tested: silica sand, bottom ash, and bottom ash-sand mixtures with 30:70, 50:50, and 70:30 ratios. The mixed filters exhibited more consistent and stable particulate matter removal efficiency over time than either the uniform sand or bottom ash filter. The 50:50 bottom ash-sand mixture demonstrated removal rates of 58.05% for 1.8 μm particles, 93.92% for 10 μm particles, and 92.45% for 60 μm particles. These findings highlight the potential of bottom ash-sand mixtures as effective filter media for removing PM10 road dust, although field validation with actual pavement systems is necessary.

Sansevieria trifasciata's specific metabolite improves tolerance and efficiency for particulate matter and volatile organic compound removal

Phytoremediation has become famous for removing particulate matter (PM) and volatile organic compounds (VOCs), but the ability is affected by plant health. Lately, the priming technique was a simple approach to studying improving plant tolerance against abiotic stress by specific metabolites that accumulated, known as “memory”, but the mechanism underlying this mechanism and how long this “memory” was retained in the plant was a lack of study. Sansevieria trifasciata was primed for one week for PM and VOC stress to improve plant efficiency on PM and VOC. After that, the plant was recovered for two- or five-weeks, then re-exposed to the same stress with similar PM and VOC concentrations from cigarette smoke. Primed S. trifasciata showed improved removal of PMs entirely within 2 h and VOC within 24 h. The primed plant can maintain a malondialdehyde (MDA) level and retain the “memory” for two weeks. Metabolomics analysis showed that an ornithine-related compound was accumulated as a responsive metabolite under exposure to PM and VOC stress. Exogenous ornithine can maintain plant efficiency and prevent stress by increasing proline and antioxidant enzymes. This study is the first to demonstrate plant “memory” mechanisms under PM and VOC stress.

Efficient simultaneous removal of diesel particulate matter and hydrocarbons from diesel exhaust gas at low temperatures over Cu–CeO2/Al2O3 coupling with dielectric barrier discharge plasma

Diesel particulate matter (DPM) and hydrocarbons (HCs) emitted from diesel engines have a negative affect on air quality and human health. Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem. In this study, Cu-doped CeO2 loaded on Al2O3 coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs. Removals of DPM and HCs at 200 °C using the catalyst were as high as 90% with plasma but below 30% without plasma. Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process. It was found that Cu–CeO2 can promote the formation of adsorbed oxygen ( – ) and terminal oxygen (M=O), which can react with DPM to form carbonates that are easily converted to gaseous CO2. Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.

Atmospheric particulate matter deposition in herbaceous species on a university campus in Colombia

Atmospheric particulate matter (PM) is one of the most harmful atmospheric pollutants with implications for human health. Plants have been used as an alternative for the removal of atmospheric PM in urban environments. The removal of PM depends on different plant morphological traits, including trichomes and epicuticles evaluated on trees. However, leaf traits for herbaceous plants commonly used in urban gardens have not been fully explored. This study used filtering to quantify the PM deposition and to describe leaf morphological traits throughout optical devices on 20 leaves from six herbaceous species –Calathea rufibarba, Calathea zebrina, Heliconia psittacorum, Heliconia rostrata, Philodendron sp. and Dieffenbachia sp. Our results suggest that structures such as trichomes –C. rufibarba– and epicuticle –H. psittacorum– play a role in PM deposition. On the other hand, large leaf size did not influence the deposition of PM per leaf unit area. Therefore, for improving city air quality, our study suggests selecting species with epidermal traits independent of leaf area. This is the first study focusing on ornamental herbaceous species ability for PM deposition in urban environments in Medellín, Colombia.

Microalgal biochar assisted simultaneous removal of particulate matter, formaldehyde, and total volatile organic compounds (TVOC's) from indoor air

Biochar-based materials for air treatment have gained significant attention for removing health-detrimental volatile organic compounds (VOCs) and particulate matter (PM) in indoor air settings. However, high turnaround time, multiple pretreatment processes involved, and high pore size and low surface area (>10 μm, <100 m2 g−1) of lignocellulosic feedstocks demand alternative biochar feedstock material. Considering this, we designed a simple first-of-its-kind indoor air scrubbing material using diatoms-enriched microalgae biochar. In the present study, the microalgae were cultivated on waste anaerobic digestate (biogas slurry) and were pyrolyzed at three different temperatures: 300 °C (BC300), 500 °C (BC500), and 700 °C (BC700). The BC500 and BC700 showed the highest removal efficiencies (99 %) for total volatile organic carbons (TVOCs) and formaldehyde (HCHO) at concentrations of 1.22 mg m−3 HCHO and 8.57 mg m−3 TVOC compared to 50% efficiency obtained with commercially available surgical, cloth, and N95 masks. The biochar obtained showed a high Brunauer–Emmett–Teller (BET) surface area of 238 m2 g−1 (BC500) and 480 m2 g−1 (BC700) and an average pore size of 9–11 nm due to the mesoporous characteristic of diatom frustules. The comparatively poor performance of BC300 was due to lower surface area (150 m2 g−1) arising from incomplete organic removal, as evidenced by FESEM-EDX and FTIR. The high removal efficiencies in BC500 and BC700 were also attributed to the presence of reactive functional groups such as –OH and R–NH2. Concurrently, the average particulate matter (PM10, PM2.5, and PM1) removal efficiency for BC500 and BC 700 ranged between 66 and 82.69 %. The PM removal performance of BC500 and BC700 was lower (15–20%) than commercially available masks. Overall, the present study highlights the importance of diatoms (reactive Si) present inside the pores of microalgal biochar for enhanced removal of PM, TVOCs, and HCHO at temperatures above 500 °C. This complete approach signifies a step towards establishing a self-sustainable and circular process characterized by minimal waste generation for indoor air treatment.

Image based analytical approaches for study of particulate matter (PM) in air

Particulate matter (PM) stands as a predominant pollutant in developing countries, demanding effective source identification and remediation strategies. This review centers on the scanning electron microscopy (SEM) image-based methodology for PM analysis, particularly emphasizing the passive technique of utilizing plant leaves for PM capture. The SEM-image-based approach serves as a powerful tool for unraveling the morphological characteristics of PM, crucial for source identification. Additionally, SEM, when equipped with energy dispersive spectroscopy (EDS), enables chemical and mineralogical characterization, providing insights into the origin of PM. The first part of the review describes the plant as the best bio-sampler for PM. In this context, removal of PM from the environment through plant-based interventions is described. Subsequently, the application of SEM for size-based analysis using ImageJ and morphological analysis for source identification of PM is detailed. Following this, the PM chemical and mineralogical composition for source identification are described based on EDS analysis. Image-based techniques play a pivotal role in selecting the most effective plant species for PM removal from the air. The review comprehensively outlines the morphological, chemical, and mineralogical attributes utilized for PM source identification and their subsequent remediation by plants. Finally, the benefits of SEM-image-based techniques for PM analysis are elucidated. This review offers a holistic understanding of the SEM-EDS and plant-based approach, presenting a promising avenue for addressing PM pollution and enhancing environmental quality.

Solar Chimney Power Plants for Sustainable Air Quality Management Integrating Photocatalysis and Particulate Filtration: A Comprehensive Review

Urban air pollution has become a pressing challenge in recent times, demanding innovative solutions. This review delves into the potential of Solar Chimney Power Plants (SCPPs) as a sustainable approach to mitigating air pollution. The idea of mitigation of pollution may be an added advantage to the use of SCPPs in practice. Recent advancements, such as the integration of photocatalytic reactors (PCRs) for the elimination of greenhouse gases (GHGs), emphasizing the importance of addressing non-CO2 GHGs like CH4 and N2O are analyzed. The novelty of this review is that it not only focuses on the shifting and removal of particulate matter but also on the removal of greenhouse gases. Numerous case studies, ranging from filter-equipped SCPPs to Solar-Assisted Large-Scale Cleaning Systems (SALSCSs), are reviewed, providing a comprehensive understanding of their design, performance, and potential benefits. This review serves as a guide for researchers and policymakers, emphasizing the need for multifaceted approaches to address the intricate nexus of air pollution, renewable energy generation, and climate change mitigation.

Effectiveness of intranasal saline cleansing methods for removal of particulate matter

Effectiveness of intranasal saline cleansing methods for removal of particulate matter

Advancing urban agriculture and air quality in edge computing environments through integrated small-scale plant-based filtration systems

This paper introduces the integrated Small-Scale Plant-Based Air Filtration (SPAF) system, a novel integration of air filtration and urban agriculture, specifically designed for edge computing free cooling in urban environments. The SPAF's modular design enables extensive customization to meet various air quality requirements and agricultural needs. Through evaluation across different scenarios, the system has proven its effectiveness in particulate matter reduction, with a single unit showcasing substantial initial filtration efficiency, and even greater performance when multiple units are utilised in series. Beyond its air filtration capabilities, the SPAF system also contributes to urban agriculture, expanding planting areas and supporting the growth of local produce, thereby aligning with global sustainability objectives. Despite its promising applications, challenges such as the variability in filtration performance across different plant species, external climates, and the inability to ensure complete particulate matter removal, underscore the need for further research and potential integration with other purification technologies.

The Behavior and Removal of Condensable Particulate Matter in Flue Gas in a Multi-Field Force: A Modeling and Experimental Study

Condensable particulate matter (CPM) is different from filterable particulate matter (FPM), which could escape from air pollution control devices (APCDs) and pose a great threat to the environment and human health. Thus, modeling and experimental studies were conducted on CPM particle behavior and removal, in a cold electrode electrostatic precipitator (CE−ESP) coupled with a electric field, temperature field and concentration field. A multi−field force coupling model was then established that was based on the mechanical behavior of particles inside the CE−ESP. The results showed that temperature field was beneficial to depositing small size particles and that, the greater the temperature gradient, the higher CPM’s removal efficiency. While the electric field tended to gather larger size particles, the greater the voltage provided, the higher the removal efficiency for CPM and FPM. In the multi−field, the augmented coagulation and the removal efficiencies of both CPM and FPM increased significantly, reaching 89% and 98%, respectively. Subsequently, experiments were conducted by a self−made CE−ESP device, which showed the removal efficiencies of CE−ESP of a CPM in a multi−field were 91% and 81% for a coal−fired power plant and a waste incineration plant, respectively. This research could make a great contribution to CPM condensation, aggregation and removal.

Self-synthesis and performance analysis of a Cu-Fe composite ZSM-5 zeolitic catalyst for NOx reduction and particulate matter removal using NH3 SCR

The NH3-SCR has gained widespread usage due to its exceptional denitrification efficiency. It achieves high nitrogen oxides (NOx) reduction rates within the temperature range of 300⁰C to 400℃. Nonetheless, most of the catalyst have a limited temperature range for effective NOx removal applications. For sustainable utilization of common combustion units, it has become essential to develop a catalyst which can provide a broader spectrum of temperature range for NOx reduction. This study is thus aimed to enhance the structure of ZSM-5 zeolite molecular sieves using tetrapropylammonium bromide. Copper and iron ions (total 3% weight) were incorporated to boost the reaction at temperatures of 180⁰C, 250⁰C and 320⁰C. The overall efficiency of NOx removal was above 81%, highest being 97.6%. The carrier significantly impacts the NOx conversion rate with increased copper ion content in the samples at medium and low temperatures. The Particulate Matter removal efficiency ranged from 90.1% to 93.1%.

Nature-Inspired Regenerative Fine-Dust-Catching Coatings to Improve Air Quality.

Increased particulate matter (PM) concentrations in our ambient air are the cause of various life-threatening diseases and consequently need to be reduced to nonhazardous levels. The natural PM removal capabilities of leaves inspired the development of a low-cost coating technology that exploits natural weather phenomena for its PM catching and removal processes. The herein presented coating is based on microparticle-filled silicone with optimized chemical and physical surface properties. Its surface roughness was tuned using differently sized spray-dried particles, and its surface contact angle was adjusted through silicone tensides, polar ether groups incorporated in the silicon backbone, and the used amount of spray-dried particles. In such a way, optimized silicone coatings showed in laboratory experiments improved catching abilities (>300% relative to glass surfaces), a full retention of adsorbed PM during wind events, and the formation of large PM aggregates. Upon (simulated) rain events, these coatings were regenerated, and the content of harmful PM of various sizes dispersed in water was reduced between ∼73 and 100%. Furthermore, an outdoor test over 100 days showed the functioning of the coating under real-world conditions. These regenerative coatings are readily applicable on diverse surfaces and do not require any further technical infrastructure. Thus, they present an extension of the toolbox for PM reduction technologies.

Preliminary Indications on an Atmospheric Particulate Matter and Rainwater Chemistry in Colombo, Sri Lanka: A Study During Southwestern Monsoon

The atmospheric cleansing nature of rainfall, specifically in the removal of particulate matter, is a determinant of rainwater quality. This study investigated the relationship between atmospheric particulate matter (PM10) concentration and rainwater quality in Colombo during the southwest monsoon period in 2023. The rainwater samples were collected using a manually prepared high- density polyethylene collector and analysed for pH, electrical conductivity (EC), water-soluble cations (Na+, K+, Ca2+, Mg2+, and NH4+), and anions (Cl-, NO3–, and SO42–). The concentration of atmospheric PM10 was obtained from the ambient air quality monitoring station (AQMS) at Battaramulla. The measured data were analysed using multivariate statistical techniques, including principal component analysis and Pearson correlation analysis, to identify relationships between the concentration of atmospheric PM10 and rainwater quality. The atmospheric PM10 showed an insignificant positive correlation with southwest monsoon rainfall (r=0.14, p&gt;0.05). The concentration of atmospheric PM10 increased the total concentration of water-soluble ions (r=0.30) and decreased the pH (r=-0.42) and electrical conductivity (r=0.07) of rainwater samples. The concentration of Na+, K+ and Ca2+ displayed moderate positive correlation, while Mg2+, NH4+, Cl-,&#x0D; NO3- and SO42- showed a weak positive correlation of rainwater samples in the atmospheric PM10.&#x0D; This study contributes valuable insights into the variations of PM10 in the atmosphere and its potential implications on rainwater quality in southwest monsoon, underscoring the importance of comprehensive analyses for a more nuanced understanding of the intricate relationships between atmospheric components and rainwater chemistry.&#x0D; &#x0D; Keywords: Atmospheric chemistry, Correlation analysis, Particulate matter, Rainwater quality, Southwest monsoon&#x0D;

Photothermal-driven flow with water droplets for effective removal of indoor fine particulate matters

Airborne particulate matter (PM) causes hazardous problems in human health, and water droplets have been utilized for PM removal in the air. However, since conventional wet scrubbing techniques mostly rely on mechanically generated water droplets, they have intrinsically limited in collection efficiencies of a single droplet. In addition, PM capturing strategies for removal of fine PM need to be established to enhance PM removal performance based on flow dynamics. Here, we propose a steam flow of water droplets generated by a photothermal membrane for air purification. The generated flow captures PM efficiently by the aid of the coupled effects of water droplets and hydrodynamic flow. The flow achieves high and sustainable deposition constants of 0.458 and 0.472 h−1 for PM1.0 and PM2.5 within 1 h at 4 solar intensity, which is 2.20 and 2.24 times higher than those of without solar irradiation, respectively. The deposition constants of PM using steam flow were higher than that of previous wet scrubbing methods despite a low volume of water usage. Our photothermal-driven flow with water droplets could be utilized as effective indoor air purification system that is low cost, energy-efficient, and environmentally-friendly.

Development of biodegradable nanofiber filters based on surface-modified cellulose nanofibers with graphene oxide for high removal of airborne particulate matter

Airborne particulate matter is a pressing environmental and public health concern globally. This study aimed to develop sustainable filtration materials from cellulose nanofibers (CNFs) modified with graphene oxide (GO) to capture fine particulates from air effectively. CNFs were extracted from α-cellulose via mechanical grinding and modified with 0.5–1.5 wt% GO solution by ultrasonication to produce CNF-GO nanocomposites. These were freeze-dried into highly porous, lightweight aerogels for air filtration applications. Fourier transform infrared spectroscopy (FT-IR) confirmed GO incorporation through hydroxyl group interactions. Field emission scanning electron microscopy (FE-SEM) revealed a porous 3D network with reduced porosity after GO addition due to pore blocking. X-ray diffraction analysis showed the cellulose I crystal structure was retained after modification. Brunauer-Emmett-Teller (BET) measurements indicated increased density but decreased surface area and pore volume with GO loading. The thermogravimetric analysis demonstrated improved thermal stability with GO incorporation due to oxidative reactions and a barrier effect. The particulate absorption efficiency markedly increased from 86.37 % to 99.98 % for CNFs modified with 1.5 wt% GO due to the high surface area, surface oxygen functionalities, and nanoplatelet morphology of GO. The nanofiber filters with 1.5 wt% GO exhibited a maximum absorption efficiency of 99.98 % and a quality factor of 0.0912 Pa−1. Although GO reduced biodegradability, substantial degradation occurred under soil conditions. Overall, the sustainable, high-efficiency CNF-GO air filters developed in this work demonstrate immense promise for controlling air pollution and protecting human health.

Impacts of reduced graphene oxide modified air purification filters on removal of particulate matter from Ambient Air

Impacts of reduced graphene oxide modified air purification filters on removal of particulate matter from Ambient Air

Graphene and its derivatives for air purification: A mini review

Acceleration of industrialization causes an increase in concentration of greenhouse gases (GHGs), particularly CO2, as well as particulate matter in the air. Therefore, it is necessary to develop strategies for the elimination of GHGs. Graphene and its derivatives were reported to be excellent candidates for CO2 adsorption and also for the removal of particulate matter by air filtration. For the fabrication of air filtration membranes, by using graphene/graphene derivatives, they were incorporated with certain polymers such as polyacrylonitrile and made into nanofibrous membranes. Electrospun nanofibrous membranes are characterised by high porosity, small pore size and excellent connectivity, have been found to be a promising candidate for air filtration. The review article focuses on two aspects of air purification, first part discuss the use of graphene/graphene derivatives for CO2 adsorption and the second part discuss the use of graphene based electrospun nanofibrous membranes for particulate matter removal. The factors influencing the efficiency of filtration has been discussed in detail.

Removal pattern of particulate matter from condensing heat exchanger after wet desulfurization of coal-fired unit

The flue gas after wet desulfurization of coal-fired units still contains a large amount of particulate matter. Flue gas condensing heat exchangers are often used to further remove particulate matter. However, current research focuses on the overall removal effect of the heat exchangers, but ignores the difference of pollutant removal ability of the inner tube bundle along the flue gas-flow direction. This paper studied the correlation between pollutant removal and operating parameters of condensation heat exchanger, so as to make the removed amount of pollutants as large as possible. A field experimental platform was built on a 3 ? 350 MW supercritical circulating fluidized bed coal-fired unit. The total amount of pollutants removed between the 3rd and 6th rows of tube bundles from the inlet of the heat exchanger was the largest. The removal of particulate matter near the outlet of the heat exchanger was the smallest. The highest removal rate of filterable particulate matter reached 76 %. The proportion of condensable particulate matter in the total removal of particulate matter reached around 90%. The mass ratio of both H2SO4 and SO3 to the removed condensable particulate matter were more than 9 %.