Removal Efficiency Of PM2 Research Articles

Evaluation of the effectiveness of various pollution removal mechanisms of indoor air purifiers in removing suspended particles

This study comprehensively investigated the efficacy of five distinct air purifiers in the removal of both particulate matter and gaseous pollutants. The analysis was conducted within a consistent test environment, employing a standardized benchmark to ensure accurate and comparable results. A rigorous methodology was devised to evaluate the efficiency of each air purification mechanism. The experimental setup involved placing the air purifiers inside a controlled test chamber, carefully designed to replicate typical indoor conditions. The focus of the analysis was on the removal efficiency of PM2.5, and the evaluation utilized the Clean Air Delivery Rate (CADR) values, measured in cubic feet per minute (ft³/min or CFM). Importantly, the study maintained uniform specifications, including unit filter area and unit electrostatic volume, to facilitate a fair and meaningful comparison of the removal efficiency for each purification mechanism. The CADR values served as a quantitative metric to assess the air purifiers’ effectiveness in removing PM2.5 particles. This standardized approach allowed for a direct comparison of their performance under identical conditions. By considering unit filter area and electrostatic volume, the study aimed to provide insights into the relative merits of each mechanism, enabling consumers to make informed decisions based on the specific removal capabilities of the air purifiers. In summary, the research established a robust methodology for evaluating air purifier performance, facilitating a thorough analysis of their effectiveness in removing particulate matter and gaseous pollutants within a controlled environment. The use of CADR values and standardized specifications ensures a reliable basis for comparing the efficiency of different air purification mechanisms.

Effect of charged spray evaporation of desulfurization wastewater on fine particle removal efficiency of electrostatic precipitator

The removal of fine particles from coal-fired power plants and the zero-discharge treatment of desulfurization wastewater (DW) from wet desulfurization are critical issues. In this study, we propose a charged droplet evaporation technology of DW for efficient electrostatic dust removal, aiming to achieve zero discharge of DW and effectively remove fine particles. We experimentally studied the effect of charged DW droplet evaporation on the dust removal efficiency of an electrostatic precipitator (ESP) and analyzed the internal mechanism. The results revealed that the removal efficiency of fine particles by ESP was affected by electrode voltage, atomization pressure, DW volume flow, and Cl− concentration. The main internal mechanisms that improved the removal efficiency of fine particles were agglomeration and pre-charging of the particles. Increasing the electrode voltage proved to be the most effective method in enhancing the removal efficiency of fine particles. Specifically, when the electrode voltage was increased from 0 to 12 kV, the removal efficiency of PM2.5 by ESP demonstrated an increase of greater 14 %. The removal efficiency in the penetrating window exhibited an increase of greater than 8 %. Furthermore, augmenting the atomization pressure and DW volume flow also contributed to the improvement in fine particle removal by ESP. In contrast, increasing the Cl− concentration had a detrimental effect on the removal process.

A Novel Sustainable Semiconductor/Metal-organic Framework Coated Electret Filter for Simultaneous Removal of PM2.5 and VOCs

A MIL-125-NH2 metal-organic framework (MOF) coated electret filter, named E-MOFilter, was previously developed to simultaneously remove PM2.5 (particulate matter less than 2.5 mm in aerodynamic diameter) and volatile organic compounds (VOCs, e.g., toluene). This E-MOFilter captures toluene primarily through physical adsorption, however, degradation of the adsorbed VOCs is desired for increasing the service life of the filter. In this study, photocatalytic nanosheets Bi2WO6/BiOCl (p-BWO) were synthesized, grafted on the MIL-125-NH2 to be p-BWO@MIL, and then coated to the electret filter to form a new filter named PE-MOFilter. The physical characterizations, including size, morphology, crystal structure, optical properties, and surface area for the semiconductor p-BWO nanosheets, p-BWO@MIL and PE-MOFilter were first examined to find out the optimal p-BWO to MIL ratio and coating wt% of p-BWO@MIL particles on the electret filter. Results demonstrated that the p-BWO nanosheets were successfully coated on the surface of MIL and the p-BWO@MIL retained the surface area and micropore volume of the MIL-125-NH2. The capability of the PE-MOFilter on adsorption and degradation of VOCs and the removal efficiency of PM2.5 was examined. The results showed that this novel PE-MOFilter not only captured but also effectively photodegraded VOC pollutants via the synergistic action of adsorption and photocatalytic oxidation (PCO). The photodegradation efficiency was found to be as high as 68.7% and it depended on the ratio of p-BWO to MIL. The PM2.5 removal efficiency also demonstrated that the coating of p-BWO@MIL particles had a negligible influence on the degradation of fiber charge. This research sheds light on the development of semiconductor@MOF coated electret media to simultaneously remove particulate and gaseous pollutants to improve indoor air quality with low energy consumption.

Rational designed ZIF-8@PDA@PDMS composite sponge for efficient and sustainable particulate matter filtering under harsh environment

Particulate matter (PM) is a significant danger to both environment and human health. Despite the development of a series of air filters, they do not work well in harsh environment such as high temperature, high humidity or long-time filtration. To make a three-dimensional (3D) particle capture device, a sacrificial template approach was used to manufacture polydimethylsiloxane (PDMS) sponge, and then zeolite imidazole framework-8 (ZIF-8) was grown in situ on the 3D network of PDMS sponge. The removal efficiency of PM2.5 or PM10 is greater than 99.8% because of the high specific surface area and porous network structure of PDMS sponge, as well as the large number of metal sites of ZIF-8. In addition, the sponge filter has long-term filtration stability and still achieves excellent performance after 65 h of filtration. The composite sponge can adapt to harsh environments such as high temperature (250 °C) and high humidity (90% RH). Composite sponge filter has a regular shape, and it may be customized to any shape as required. This study provides a new idea for designing 3D high-efficiency air filters that can adapt to harsh environments.

Highly efficient removal of PM and VOCs from air by a self-supporting bifunctional conjugated microporous polymers membrane

Efficient removal of pollutants in the atmosphere is of great significance to human health and environmental restoration. Herein, we report the preparation of a self-supporting conjugated microporous polymers (CMPs) membrane (SS-CMPs-M) synthesized by Sonogashira-Hagihara (S–H) cross-coupling reaction using KBr tables as a template. The intrinsic hydrophobic chemical composition made it good hydrophobicity and lipophilicity, e.g., the water contact angles (WCA) for SS-CMPs-M were measured to be 113°. The aromatic building blocks of CMPs make SS-CMPs-M exceptionally stable physicochemical properties, i.e., the membrane exists stably below 300 °C, and they were insoluble in organic solvents. Additionally, the as-resulted SS-CMPs-M-1 which also presents mesoporous architecture shows effectively captures performance for particulate matter (PM) with different particle sizes in the air, the removal efficiency of PM2.5 and PM10 are 99.7% and 99.9%, respectively. For volatile organic compounds (VOCs) vapor in the air, the SS-CMPs-M-1 shows an excellent purification effect, the removal efficiency of formaldehyde in the simulated air is above 97%, and the AQI value of the filtered gas (>500) is reduced to 50. Taking advantage of its simple and scalable manufacture, the SS-CMPs-M-1 may have great potential as an advanced membrane for the separation and elimination of PM in different environments.

Electrospun polyetherimide/zeolitic imidazolate framework nanofibrous membranes for enhanced air filtration performance under high temperature and high humidity conditions

Efficient filtration of particulate matter (PM) is the major goal for various air cleaning technologies. However, most existing air filters are conducted at room temperature with a relative humidity (RH) of around 45%, ignoring the fact that many operate under high temperature and RH above 90%. Herein, we report the successful fabrication of a polyetherimide (PEI)/zeolitic imidazolate framework-67 (PEI/ZIF-67) nanofibrous membranes using electrospinning technology, which showed steady and high efficiency PM filtration performance under a high temperature of 200 °C and RH of 90%. Compared with pure PEI nanofibrous membranes, the resultant nanofibrous membranes containing 2 wt% of ZIF-67 showed an increase of 112% and 109% in removal efficiency of PM2.5 and PM10, respectively, which are attributed to synergistic effects of enhanced surface roughness, strengthened electrostatic interaction and small pore size by the introduction of the ZIF-67. More importantly, after operating under a high RH of 90% over 70 h, the removal efficiency of such PEI/ZIF-67 nanofibrous membranes remained almost unchanged. Density functional theory calculations suggested that the ZIF could efficiently reduce water adsorption and thereby avoid the PEI being damaged by water. Such a finding demonstrated that the ZIFs should be promising candidates for designing highly stable nanofibrous membranes under extremely high RH and high temperature conditions.

Inertial Separation of Particles Escaped from Electrostatic Precipitators.

For particles that escape from electrostatic precipitators (ESPs), inertial recapture is used to improve the efficiency of dust removal. A rod-grid inertial separator was designed. The electrostatic and fluid flow particle tracking modules were selected in the model established by the COMSOL software, and the dust removal efficiency of the proposed dust separator was evaluated. When the flue gas velocity was 20 m·s–1, the diameter of the round rod was 8 mm, and the spacing of the pipes was 15 mm, the removal efficiency of PM2.5 and PM10 reached 27.8 and 84.6%, respectively. Experiments were performed under laboratory conditions and actual working conditions in a coal-fired power plant flue. Results showed that an inertial separator can achieve more than 60% efficiency in recapturing fly ashes that have escaped from ESPs. It can effectively remove fine particles and aerosol pollutants represented by PM2.5 and PM10.

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.

Freestanding MoS2@carbonized cellulose aerogel derived from waste cotton for sustainable and highly efficient particulate matter capturing

Particulate matter (PM) has been the main contributor to air pollution that has posed a serious threat to human health. Here we designed an environmentally-friendly conductive air filter for sustainable and highly efficient PM particle capturing under the assistance of an electrostatic field. Waste cotton fibers were used as the raw materials to prepare carbonized cellulose aerogel. Then molybdenum disulfide was vertically grown on the aerogel surface. Due to the high specific surface area, excellent electrical conductivity of the carbonized aerogel, and the strong electrostatic force between the air filter and PM particles, the removal efficiency of PM2.5 and PM10 is over 99.91% and 99.95%, respectively. The high efficiency can be maintained for up to 600 min demonstration (PM2.5 > 98.6%, PM10 > 99.1%). This composite air filter also exhibited excellent reusability: the adsorption efficiency was greater than 97.80% after 5 cycles, and regeneration can be simply realized by washing. The current work not only provides a new strategy to designing more efficient PM filter, but also suggests an avenue to recycle waste cotton fibers.

Effect of water microdroplet size on the removal of indoor particulate matter

The effective removal of indoor particulate matter (PM) has received considerable attention due to the harmful effects of airborne PM on human health. Although various techniques have been introduced to remove indoor PM, no impeccable method has been established. In this study, we proposed the use of microscale water droplets produced by the ultrasonic module of a commercial household ultrasonic humidifier (UH) for effective PM removal. Water droplet size was regulated using micropinholes. The effect of water microdroplet size on the removal of indoor PM was experimentally investigated. Normalized PM concentration, PM removal efficiency and PM deposition constant were assessed by analyzing the measured temporal variations in PM concentration inside a test chamber. The PM deposition constants measured in this study were compared with those of other previous studies. Deposition events were quantitatively visualized by using a high-speed camera attached with a long-distance microscope. The increase in the deposition rate of surface area and the PM collection ratio were analyzed using digital image processing to examine the interactions between PM particles and water microdroplets with different droplet sizes. As a result, the removal efficiency of PM2.5 particles reaches up to 56.2% when water droplets of d = 2 μm are used. The PM10 removal efficiency is also increased by 73.9% within the initial 30 min. The deposition constant for the smallest water droplets of d = 2 μm is drastically increased. In addition, the increasing rate of the deposition surface area is exponentially increased, as the size of water droplets decreases. The small microscale water droplets generated by a commercial UH attached with a micropinhole are found to be effective for the removal of indoor PM.

Experimental study on production and emission characteristics of PM2.5 from industrial fluidized bed boilers

Particle size distributions, concentrations, morphological characteristics, and elemental compositions of eight fluidized bed boilers with different capacities and different dust collectors were determined experimentally. The PM2.5 particle concentration and mass concentration were monitored in real-time before and after the boiler dust collector by electric low pressure impactor, and the physical and chemical properties of PM2.5 were analyzed by membrane sampling. We found that the PM2.5 particle concentration produced by industrial fluidized bed boilers displayed bimodal distributions, peaking at 0.2 ?m and 0.76 ?m, the formed mechanism of these two parts particles is vaporization-condensation of mineral matter and residual ash particles and the adsorbent wear or tear. Mass concentration exhibits a single peak characteristic with a peak at 0.12 ?m. The removal efficiency for PM2.5 of dust collectors varies with different dust removal mechanisms. The electrostatic precipitator and bag filter have high dust removal efficiency, and the water film dust collector has low dust removal efficiency. The normal operation of the bag filter has a great influence on the dust removal efficiency. The physical and chemical properties of PM2.5 showed that the single-particle morphology was mainly composed of irregular particles, containing a small amount of solid spherical particles and more agglomerates. The content of Si and Al in PM2.5 elemental analysis is the highest, which decreases after a dust collector. Some fluidized bed boilers use desulfurization in the furnace, which has great influence on the mass concentration of Ca and S elements, and the lowest Hg content in trace elements, about a few ppm. <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/TSCI200901242E">10.2298/TSCI200901242E</a><u></b></font>

Hierarchical micro/nanofibrous filter for effective fine-particle capture

Hierarchical micro/nanofibrous filters are fabricated by blending electrospun polyurethane (PU) nanofiber with polyethylene terephthalate (PET) microfibers followed by spunlace reinforcement. PET microfibers mainly act as a skeletal framework and PU nanofiber is employed for capturing fine particles. The incorporation of PU nanofiber optimizes inner structures and improves filtration properties of hybrid filters. The mean pore size decreases and pore size distribution shifts to smaller pore sizes with the increased content of PU nanofiber. When the PU nanofiber accounts for 1.87%, the composite filter exhibits a high filtration efficiency (76.63%) for PM0.26 and low pressure drop (17.3 Pa) under an airflow velocity of 5.3 cm/s. This composite filter exhibits a high quality factor of 0.084 Pa−1. Furthermore, the removal efficiency for PM2.5 reaches to 99.93% with a low terminal pressure drop of 26.3 Pa. The composite filters with excellent filtration performances prepared can be applied to industrial production and commercial applications.

Experimental and DFT studies of PM2.5 removal by chemical agglomeration

Fine particles are significantly harmful to the human body and the atmospheric environment. However, the electrostatic precipitator (ESP) removal efficiency for PM2.5 is low, therefore chemical agglomeration technology, which uses various chemical agents to induce particle agglomeration, improving the efficiency of ESP seems to be a promising pretreatment technology. In the present contribution a combination of experimental and DFT calculations has been used to study this technique. We used water, pectin and sodium alginate solutions as agglomeration agents. Experimental results showed that sodium alginate solutions is most effective, the particle diameter increased from 0.1 μm to 1 μm and the ESP removal efficiency of number concentration increased above 20% with chemical agglomeration technology. In theoretical studies we simulated various molecular clusters consisting of water, pectin and sodium alginate in combination with simple model silica particles (TOS) by using DFT calculations to explore the internal interactions in ESP system at molecular level. In our results, water, pectin and sodium alginate interacted with TOS by hydrogen bond, with interaction energy of 4.0 kcal/mol, 6.7 kcal/mol and 7.4 kcal/mol, respectively. Finally, according to the experimental and theoretical results, the chemical agglomeration models were put forward.

Heterogeneous condensation coupled with partial gas circulation for fine particles abatement

The removal efficiency of PM2.5 is very low in traditional dust removal devices, especially for the particles range from 0.1 to 1μm, which can decreases to 25% and pretreatment must be conducted before fine particles enter into these devices. Vapor condensation on fine particles can improve the PM2.5 removal efficiency of traditional devices. Therefore, a novel process was proposed for heterogeneous condensation on fine particles of water vapor with partial gas circulation in this paper. The essential supersaturation was established by adding hot water into cooled saturated gas, and the application of partial gas circulation technique in this process made the required supersaturation level decreasing. The fine particles were enlarged by the heterogeneous condensation and the collision-coalescence of droplet and particle in the partial gas circulation growth tube (PGCGT). The results indicated that the enlargement of fine particles in the PGCGT was more efficient than that in the conventional growth tube (CGT). The performance of fine particles enlargement by this process was influenced by many factors, such as circulation point at the growth tube, gas circulation proportion, supersaturation and initial particle concentration in the gas flow. Under the optimum conditions, the arithmetic mean diameter of the submicron particles could be enlarged to 6.156μm. Moreover, the different growth pathways of particle enlargement in the PGCGT were elucidated.

Emission of particulate matter 2.5 (PM2.5) and elements from municipal solid waste incinerators

To determine the concentration and behavior of fine particulate matter (PM2.5) from municipal solid waste incineration, size-classified dust samples were collected from four incineration facilities using cascade impactors. The total dust and PM2.5 concentrations were 1.7–236 and 0–104 μg/Nm3, respectively, in the flue gas sampled from the stacks. The total dust concentration in the flue gas was 1/50 or less of the concentrations measured previously in the same facilities with the operation of an electrostatic precipitator. Each air pollution control device used in the facilities was evaluated from the perspective of PM2.5 removal. A bag filter, activated carbon tower and selective catalytic reduction were all considered to be effective. The removal efficiency of PM2.5 was more than 99.99 %. Analysis of the particle size distributions of the dust identified two peaks around 1 and 10 μm at the inlet of the BF. Based on the results of an elemental analysis of the dust, the particle size distributions of each element were also calculated. As a result, the emission of PM2.5 as primary particles from a state-of-the-art municipal solid waste incinerator was estimated to be very low.