Particulate Matter Removal Efficiency Research Articles

Evaluation of the performance of the cross/updraft type gasification technology with the sliding bed over a circular grate

In this article, a novel, pilot-scale gasification technology is closely described from the technological and design points of view. The construction of the fuel bed within the reactor is circular, operating according to the sliding bed principle, equipped with a tangential oxidiser intake. The technology combines principles of cross-draft and updraft gasification reactor type in an autothermal regime. In the model process with softwood pellets (spruce wood) as source fuel, the LHV of the producer gas reached 4.3 MJ·m−3, with the overall conversion ratio reaching 80.3%. These results were obtained in a 709 ± 10 °C environment with the fuel feed rate equal to exactly 30 kg·h−1 while the flow rate of the oxidising media was 17 ± 1 m3∙h−1.The gas quality in terms of its content is a major factor to be considered. The purity of the producer gas is crucial for most final-use technologies. Thus, the question of polluting agents and undesired substances is analysed and discussed in this article. The custom-made cleaning track of hereby described scientific technology can operate with 99.9% particulate matter removal efficiency, while tar compounds within the producer gas are kept as low as 9.7 g·m−3.This article summarises a detailed description of a specific pilot-scale gasification unit where results of an experimental analysis are depicted along with real-time values and detailed schematic descriptions and illustrations, providing a base for comparison with conventional technology designs.

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.

Experimental study on particulate matter removal using packed-bed dielectric barrier discharge plasma reactor

In this study, a packed-bed dielectric barrier discharge (DBD) reactor was developed for particulate matter (PM) removal. The effects of operating conditions such as the packing materials, applied power, and discharging gap were systematically investigated. The results revealed that Zeolite 13X exhibited the highest PM removal efficiency based on its high electrostatic adsorption capacity. A narrow discharge gap (2.4 mm) and increased power density resulted in an enhancement of the PM removal efficiency in the system. Further, these operating conditions increased the electric field strength, which was proportional to the current density in the system. The energy yield decreased with an increase in the specific energy input into the packed-bed DBD reactor. Among the tested operating parameters, maintaining a narrow discharging gap was determined to be the most important for achieving high energy efficiency and PM removal in the system. Moreover, an air cleaning procedure was applied for the regeneration of the packing materials, resulting in a high recovery rate of over 80%.

Four-in-one multifunctional air filter using copper coordination polymer particle decorated fibre for efficient pathogen removal and indoor air treatment

This paper introduces a multifunctional air filter with a strong ability to trap and disinfect pathogens and absorb particulate matter (PM), the volatile organic compound (VOC), and CO2. This study demonstrates a facile and eco-friendly synthesis of copper coordination polymer particle (Cu-CPP)-decorated non-woven fibre filters (Cu-CPP/NWF) via an in situ growth dip-coating method. Their multifunction potentials in air pollution treatment are also assessed. The Cu-CPP/NWF filter media showed a remarkable performance for air treatment, with 100% disinfection efficiency against airborne E. coli bacteria (2 × 106 CFU mL−1) in 45 min, superior PM removal efficiency (quality factor 0.299 Pa−1), excellent p-xylene adsorption capacities (1.19 mmol/g) and high potential CO2 uptake capacities (19.81 cm3/g). A Cu-CPP can work as an antibacterial agent and an adsorbent component, thus offering many applications. The rational integration of Cu-CPP can substantially enhance the filtration efficiency via electrostatic interaction, while most commercial air purifiers rely on dense fibrous filters. This study provides valuable insight into developing a multifunctional and reusable air filter proven to be a life-saving product for public health protection.

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.

Particulate matter capturing over manganese dioxides with different crystal structures

Particulate matter (PM) is the main contributor to air pollution, and filtration has been reported to be promising for PM capturing. Considering the complexity of polluted air (volatile organic compounds (VOCs) and ozone are likely concomitant with PM particles) and in view of the versatility of MnO2 for the degradation of VOCs and ozone, the feasibility of MnO2 materials as PM filtering media was investigated in this study, and the effect of crystal structure on PM filtration was clarified. Compared with the layered δ-MnO2, the MnO2 with tunnel structure (including 1 × 2-, 2 × 2- and 3 × 3-MnO2) exhibited greatly enhanced PM removal efficiencies, and particularly, the 3 × 3-MnO2 possessed not only significant activity for adsorbing PM particles but also high utilization efficiency of the active surface. Physicochemical properties of the adsorbents were studied by XRD, ATR, isothermal N2 adsorption, SEM and (HR)TEM. The correlation between pore characteristics and particle elimination activity demonstrates that the most developed mesoporous structure of the 3 × 3-MnO2 sample played an important role in strengthening the PM adsorption capability. Further comparison of the surface properties of the fresh and spent samples reveals that with respective to the occasion of δ-MnO2, the structure of 3 × 3-MnO2 was robust enough to resist collapse after PM capturing and the great accommodation of the inorganic and organic PM substances in the voluminous pores induced strong affinity between PM particles and 3 × 3-MnO2. Thereby, a higher particle filtration ability was retained.

Commuter exposures to in-transit PM in an urban city dominated by motorcycle: A case study in Vietnam

Exposure to in-transit particulate matter (PM) has negatively affected human health but is barely reported in an urban area dominated by motorcycles. This study aimed to investigate the personal exposure and inhaled dose of PM for commuting modes in Ho Chi Minh City (HCMC), Vietnam. To do this, we conducted simultaneously sampled trips between on motorcycle without and with facemasks, car, and bus. Measurements were performed using portable PM monitors across representing routes in HCMC. In total, we conducted 1086 km in length of paired mode trips. The result shows that motorcyclist was exposed to the highest PM concentrations followed by bus and car commuters. A facemask worn by a motorcyclist while riding was consistent in reducing the in-transit PM exposures (e.g., ∼33–43% lower in PM2.5), and surgical facemask had higher PM removal efficiency than that of cloth facemask (p < 0.01). Ratios (I/O) for PM1 ranged from 0.31 for car/motorcycle to 0.77 for motorcycle-cloth facemask/motorcycle, and PM10 tend to have the lowest ratios. However, bus/motorcycle ratios show the opposite trend with the highest ratio obtained for PM10 due to the effect of a stop-and-go pattern during bus trips. Compared to ambient PM2.5 concentration, in-transit PM2.5 concentration on motorcycle has a good correlation with those measured at the urban station. In conclusion, our work suggests that motorcycle should be urgently restricted in megacities (like HCMC) to protect human health. Policy makers should also pay attention to in-transit PM exposure in public transport mode for future urban transport planning.

Insight into Nanoparticle-Number-Derived Characteristics of Precharged Biodiesel Exhaust Gas in Nonthermal Plasma State.

The utilization of biodiesel as an alternative partial replacement of diesel fuel was shown to improve exhaust emissions from diesel engines. Waste cooking oil biodiesel (WCO) has also gained more attention due to edible biofuel supply and the environment. In this study, a nonthermal plasma (NTP) technique was applied to be equipped into the after-treatment system of a four-cylinder diesel engine at medium- and high-load conditions. The exhaust gases in the NTP state from the combustion of WCO and diesel (D100) fuels were partially drawn by spectrometers and nanoparticle-number-derived characteristics were analyzed. The particle number, area, and mass concentrations were in log-normal distribution over equivalent diameters, and they were higher at high load. The concentration of the particulate matter (PM) was lower but was larger in size when the NTP charger was activated due to coagulation principally owing to WCO’s number and surface area. The total particle masses were lower for WCO at the two load conditions tested. During NTP charger activation, the mass mean diameters were increased by maximum values of 24.0% for D100 and 5.5% for WCO. The PM removal efficiencies were maximized by 10.8% for D100 and 16.7% for WCO when the NTP charger was in use, and the WCO exhaust was dominantly seen to simultaneously reduce NOx and PM emissions.

Maintaining the PM Removal Efficiency of a Two-Stage ESP With External Ion-Injection Discharge via a Water Film on the Collection Plate and Cleaning of the Ionizer

A two-stage electrostatic precipitator (ESP) with a reduced footprint, external ion-injection discharge, and water film on the collection plate was developed for long-term operation. For optimal particulate matter (PM) removal efficiency, the ionizer of the external ion injection system was fixed at a distance of 5 mm from the bias plate. Under these operating conditions, the 0.3- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m PM (PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.3</sub> ) removal efficiency was reduced to approximately 70% due to low migration velocity. The application of an additional collection plate extended the residence time of the charged particles in the electric field, which resulted in a removal efficiency exceeding 95%. However, long-term operation (675 min) of the two-stage ESP with external ion-injected discharge resulted in spark generation due to contamination of the ionizer, and the PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.5</sub> and PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> removal efficiencies decreased linearly from 80.4% to 62.2% and 87.7% to 68.2%, respectively. Changing the ionizer to a pin shape with electrical specifications similar to those of carbon fibers resulted in water film formation on the collection plate. The PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.5</sub> and PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> removal efficiencies remained at their initial levels for 120 min. The two-stage ESP with external ion-injected discharge operating with a water film is likely suitable for long-term operation in an industrial setting.

A Novel Multi-Gradient Pass Nanofibrous Membranes with Outstanding Particulate Matter Removal Efficiency and Excellent Antimicrobial Property

A Novel Multi-Gradient Pass Nanofibrous Membranes with Outstanding Particulate Matter Removal Efficiency and Excellent Antimicrobial Property

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%).

Triboelectrification-based particulate matter capture utilizing electrospun ethyl cellulose and PTFE spheres

Air pollution associated with particulate matter (PM) has become one of the most serious environmental problems of the decade. Fibrous filters and electrostatic precipitators are usually employed to the indoor PM removal. In case of fibrous filter, if PM is smaller than the hole of filter, removal efficiency decreases considerably whereas, electrostatic precipitator has fatal drawback of producing unwanted O3. In this study, triboelectric PM capture system was introduced by utilizing integrated mechanical filtration attributed to structural characteristic of electrospun ethylcellulose (EC) and the electrostatic filtration induced by the direct triboelectrification between electrospun EC and polytetrafluoroethylene (PTFE) spheres. The electrospun EC was reinforced by heating above glass transition temperature (Tg) to improve mechanical strength. Further, the triboelectrification between EC and PTFE achieved 100% PM removal efficiency and can eliminate the drawback of mechanical filtration without production of any hazardous substances. The improvement of PM removal efficiency by the triboelectrification were +6.68%, +6.89% and +5.47%, corresponding to PM1, PM2.5 and PM10 respectively. More importantly, it was observed that the triboelectric contribution was much higher for small PM which benefits overall system.

Modelling and optimisation of a wire-plate ESP for mitigation of poultry PM emission using COMSOL

Particulate matter (PM) emissions constitute a major air pollution concern for commercial poultry production facilities. Recently, the electrostatic precipitator (ESP) has emerged as a promising technology for mitigation of poultry PM. However, further optimisation of ESP design, operation scale, and operating parameters is necessary for improved PM removal efficiencies and practical applications in poultry facilities. In this study, a comprehensive model of the poultry PM collection process in a simulated ESP module was developed using COMSOL software. The model simulated airflow characteristics, electric field and space charge development, particle charging, and particle trajectory tracking of both PM10 and PM2.5. Wire-plate ESP configurations with varying design parameters, such as number of wire electrodes and plate separation distance, were simulated using the COMSOL model at an inlet air velocity of 2.0 m s−1 to identify the optimal configuration for development of ESP physical prototypes. The model was validated by laboratory testing of a prototype ESP within a wind tunnel under three sets of ventilation conditions representing hot, warm, and cold weather, respectively. The prototype ESP exhibited PM10 collection efficiencies of 90.8%, 97.1%, and 99.0% in hot, warm, and cold weather conditions, respectively. The observed PM2.5 collection efficiencies under these respective conditions were 86.9%, 94.4%, and 97.8%. This COMSOL model can be used as an inexpensive alternative to developing physical prototypes when evaluating ESP designs for PM mitigation in poultry facilities.

Net particulate matter removal ability and efficiency of ten plant species in Beijing

Particulate matter (PM) removal is a major component of ecosystem services provided by urban green infrastructure. The annual PM removal service of plant species has generally been determined based on net PM removal ability. However, little is known about the leaf surface area normalized net PM mass removal abilities and efficiencies of different species. Net PM removal ability is the PM removed from the atmosphere by leaf surface during a period. We evaluated the net PM removal abilities and efficiencies of ten species based on quantitative leaf surface PM 1 day after and 21 days after a rainfall event. Net PM removal ability differed between plant species during the study period, and the net PM removal abilities were strongly correlated with the leaf surface PM 21 days after the rainfall, and this relationship weakened with the decrease of PM diameter. Plant species had significantly different net PM removal efficiencies except for large PM, and net PM removal efficiency was lower for coniferous trees and higher for species with high self-cleaning ability during our study period. Species differed in net PM removal ability and efficiency, and there were greater differences in the net removal ability of fine and coarse PM compared with large PM; therefore, care should be taken when species are selected for fine and coarse PM mitigation.

Effect of upflow and downflow baffle configuration on particulate matter removal in a mirror-symmetrical multi-compartment scrubber

Control over particulate matter (PM) emission from grilling is required for improving public health and air quality. The performance of mirror-symmetrical multi-compartment scrubbers with an upflow (U-type) and downflow baffle (D-type) configuration was evaluated for PM emission control from grilling at a flow rate of 30 m3 min−1. The PM removal efficiency of the U-type scrubber was the highest when the water level was 8 cm (95.6%), and the pressure drops recorded at the water levels of 6, 8 and 10 cm were 103, 122 and 153 mmH2O, respectively. Although PM removal efficiency of the D-type scrubber was over 91.0% at the water levels of 8, 10 and 12 cm, the pressure drops were 124, 142 and 185 mmH2O, respectively. A comprehensive evaluation of the water volume, pressure drop and PM removal performance, as well as device size, revealed that the U-type scrubber with a PM removal efficiency of 92% or higher and a pressure drop of 122 mmH2O or lower at the water levels of 6–8 cm was more economical for removing PM from grilling gas than the D-type scrubber.

Removal of Particulate Matter from Meat-Grilling Fumes Using a Mirror-Symmetrical Multicompartment Scrubber

In megacities and urban areas, grilling restaurants have been recognized as major sources of particulate matter (PM) with an aerodynamic diameter under 2.5 μm (PM2.5). To reduce PM emissions from grilling fumes, we developed and evaluated the performance of both multicompartment (M-type) and mirror-symmetrical multicompartment (MSM-type) scrubbers. M-type scrubbers exhibited a PM removal efficiency of 95.7%±3.7% at a fume flow rate of 6 m3/min and a water level of 10 cm, whereas the PM removal efficiency of MSM-type scrubbers was 95.3%±32.5% at a gas flow rate of 12 m3/min and a water level of 10 cm. The design parameters for the M-type and MSM-type scrubbers were compared with the parameters for conventional single-type (S-type) scrubbers. Each design parameter for each scrubber was calculated so that the PM in the grilling fumes at a flow rate of 30 m3/min could be removed at a >95%rate. The equipment volumes were 2.02, 0.54, and 0.47 m3 for the S-type, M-type, and MSM-type scrubbers, respectively. The MSM-type scrubber pressure drop was the lowest (141 mm H2O), followed by the M-type scrubber (162 mm H2O), and, finally, the S-type scrubber (220 mm H2O). These results demonstrate that the MSM-type scrubber represents a promising technology for PM reduction from grilling fumes thanks to its compact design, simple operation, and satisfactory PM removal performance.

Impact of the mercury removal system using modified fly ash on particulate matter emission

This study examines the impact of adding a mercury removal system which uses modified fly ash on particulate matter (PM) emissions from a coal-fired power plant. The modified fly ash injection technology has been demonstrated and was installed in a commercial power plant and reached 91.9% mercury removal efficiency. An important consideration was that the emission limitation for PM –5 mg/Nm3, should not be exceeded due to the addition of 0.2% (by mass) of modified fly ash to untreated fly ash fed to a coal boiler unit. Thus, the effect of modified fly ash injection on the PM emissions was studied at different locations in the power plant: before and after the Electrostatic Precipitator (ESP), after the Flue Gas Desulphurization (FGD) unit. Measurements were also made at the stack. The results showed that after the modified fly ash was injected into the flue gas stream from the boiler, the mass concentration of particulate matter leaving the particulate emission control device (PECD) was slightly increased. However, the distribution of PM10, PM2.5, PM1 and PM0.2 was not significantly changed due to the addition of 0.2% (by mass) of modified fly ash. The results indicated that the total PM removal efficiency of the PECD was still around 99.1 ~ 99.9% for the case of mass concentration and 98.6 ~ 99.7% for number concentration. The mass emission concentration of PM10 with modified fly ash injection were 2.46 and 1.96 mg/m3 at 100% and 50% load, respectively.

Ionic Salts@Metal-Organic Frameworks: Remarkable Component to Improve Performance of Fabric Filters to Remove Particulate Matters from Air.

The elimination of particulate matters (PMs) from the air is very important for our sustainability. In this study, highly porous metal-organic frameworks (MOFs) like MIL-101 and UiO-67 were first modified, coated onto cotton, and applied in PM removal via filtration. Ionic salts (ISs) like CaCl2 and LiCl, after loading onto the MOFs, remarkably increased the PM removal efficiency. For example, CaCl2(20)@MIL-101/cotton shows 5.7 times the quality factor (QF, which is the most important parameter in filtration) of that of bare cotton and has the most competitive performances in PM removal (with the highest QF of 0.085 Pa-1) compared to any filter modified with porous materials or commercial filters. The noticeable performances of ISs@MOFs can be explained by the contribution of charge separation (that is effective for electrostatic interactions with PMs) of ISs and the high porosity of MOFs. Moreover, how MOFs with small pores of a few nanometers or less can remove large PMs with sizes in the micron range could be explained. Finally, loading ISs onto highly porous materials can be a promising strategy to improve the performances of filters to remove PMs from the air.

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.

Laminated polyacrylonitrile nanofiber membrane codoped with boehmite nanoparticles for efficient electrostatic capture of particulate matters

Particulate matters (PMs) air pollution is identified as the major threat to public health and climate. High-performance air filter technology based on various electrospun nanofibers is considered as an effective strategy to eliminate the effects of PMs air pollution. However, to date, nearly all the existing micro-/nanofibers are hard to meet both requirements of high PMs removal efficiency and long service life. In this work, we reported the production of laminated polyacrylonitrile(PAN)-boehmite nanoparticles (BNPs) nanofiber structured membrane by the electrospinning process. The dimension of PAN-BNPs nanofiber can be tunable from (0.09 ± 0.03) μm to (0.81 ± 0.11) μm by controlling the PAN and BNPs concentrations in precursors. The optimized PAN-BNPs nanofiber air filter with a basis weight of 1 g m−2 demonstrates the attractive attributes of high PM2.5 removal efficiency up to 99.962% and low pressure drop of 58 Pa. Most importantly, after introducing the BNPs as electret, the removal efficiency is very stable under the air flow rate of 6 l min−1. This PAN-BNPs nanofiber with a long electrostatic duration time offers an approach for fabricating future high-performance air filters.