scholarly journals STUDY OF THE COAGULATION OF AEROSOL PARTICLES IN THE SCRUBBER ULTRASOUND CHAMBER

2021 ◽  
pp. 162-167
Author(s):  
А.А. Антонникова
Keyword(s):  
Mass Concentration ◽  
Sound Pressure ◽  
Aerosol Particles ◽  
Ammonium Phosphate ◽  
Initial Mass ◽  
Particle Coagulation ◽  
Radiation Frequency ◽  
Monoammonium Phosphate ◽  
Coagulation Process

В данной работе представлены результаты исследования процесса коагуляции частиц аэрозоля моноаммонийфосфата в модельной ультразвуковой (УЗ) камере скруббера. Изучено поведение аэрозольных частиц внутри камеры на расстоянии 100 мм и 400 мм от ультразвукового излучателя с частотой излучения 22 кГц. Представленные результаты показывают практически отсутствие коагуляции частиц при интенсивности звукового давления 140 dB и процесс активной коагуляции при интенсивности звукового давления 150 dB для выбранного образца. Начальная массовая концентрация фосфата аммония в камере составляла 1 г/м3. Измерения дисперсного состава аэрозоля внутри камеры показали, что более интенсивно коагуляция проходила в области 400 мм. Через 30 минут воздействия значение среднего объемно-поверхностного диаметра частиц аэрозоля в камере изменилось на 238,4 %. This paper presents the results of the study of the coagulation of the monoammonium phosphate aerosol particles in the model ultrasonic scrubber chamber. The behavior of aerosol particles inside the chamber is studied at the distance of 100 mm and 400 mm from the ultrasonic emitter with 22 kHz of the radiation frequency. The presented results show almost complete absence of particle coagulation at the sound pressure intensity of 140 DB and the active coagulation process at the intensity of 150 dB for the selected sample. The initial mass concentration of ammonium phosphate in the chamber was 1 g / m3. Measuring the dispersed composition of the aerosol showed that coagulation proceeds more intensively in the region of 400 mm. After 30 minutes of exposure the value of the average surfactant diameter of the aerosol particles in the chamber has changed by 238.4%.

scholarly journals Synergistic effect of water-soluble species and relative humidity on morphological changes of aerosol particles in Beijing mega-city during severe pollution episodes

2018 ◽  
Author(s):  
Xiaole Pan ◽  
Baozhu Ge ◽  
Zhe Wang ◽  
Yu Tian ◽  
Hang Liu ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Synergistic Effect ◽  
Mass Fraction ◽  
Mass Concentration ◽  
Morphological Changes ◽  
Aerosol Particles ◽  
Water Soluble ◽  
Coarse Mode ◽  
Heavy Pollution ◽  
Soluble Species

Abstract. Depolarization ratio (δ) of backscattered light from aerosol particle is an applicable parameter for real-time distinguishing spherical and non-spherical particles, which has been widely adopted by ground-based Lidar observation and satellite remote sensing. From November 2016 to February of 2017, it consecutively suffered from numbers of severe air pollution at Beijing with daily averaged mass concentration of PM2.5 (aerodynamic diameter less than 2.5 μm) larger than 150 μg/m3. We preformed concurrent measurements of water-soluble chemical species and depolarization properties of aerosol particles on the basis of a continuous dichotomous Aerosol Chemical Speciation Analyzer (ACSA-14) and a bench-top optical particle counter with a polarization detection module (POPC). We found that δ value of ambient particles generally decrease as mass concentration of PM2.5 increased at unfavorable meteorological condition. Ratio of mass concentration of nitrate (NO3−) to that of sulfate (SO42−) in PM2.5 was 1.5 ± 0.6, indicating of great importance of NOx in the formation of heavy pollution. Mass concentration of NO3− in PM2.5 (fNO3) was generally an order of magnitude higher than that in coarse mode (cNO3) with a mean fNO3 / cNO3 ratio of 14 ± 10. Relatively high allocation (fNO3/cNO3 = 5) of NO3− in coarse mode could be partially attributed to hygroscopic growth/coagulation of nitrate-rich fine mode particles under higher relative humidity condition. As a result, δ values of particles with Dp = 2 μm (δDp = 2) and 5 μm (δDp = 5) decreased evidently as the mass fraction of water-soluble species (NO3− and SO42−) increase in both PM2.5 and PM2.5–10, respectively. In particular, due to synergistic effect of RH, δDp = 5 value could decrease by 50 % as mass fraction of NO3− in PM2.5–10 increased from 8 % to 23 %. It suggested that alteration of non-sphericity of mineral dust particles was evident owing to coating with pollutants and heterogeneous reactions on the surface of the particle during heavy pollution period. This study brings the attention to great variability of morphological changes of aerosol particles along the transport, which have great complex effects in evaluating their climate and health effect.

scholarly journals Aerosol effective density measurement using scanning mobility particle sizer and quartz crystal microbalance with the estimation of involved uncertainty

2015 ◽  
Vol 8 (12) ◽  
pp. 12887-12931
Author(s):  
B. Sarangi ◽  
S. G. Aggarwal ◽  
D. Sinha ◽  
P. K. Gupta
Keyword(s):  
Quartz Crystal Microbalance ◽  
Mass Concentration ◽  
Quartz Crystal ◽  
Aerosol Particles ◽  
Particle Mass ◽  
Effective Density ◽  
Substantial Contribution ◽  
New Delhi ◽  
Scanning Mobility Particle Sizer ◽  
Particle Sizer

Abstract. In this work, we have used scanning mobility particle sizer (SMPS) and quartz crystal microbalance (QCM) to estimate the effective density of aerosol particles. This approach is tested for aerosolized particles generated from the solution of standard materials of known density, i.e. ammonium sulfate (AS), ammonium nitrate (AN) and sodium chloride (SC), and also applied for ambient measurement in New Delhi. We also discuss uncertainty involved in the measurement. In this method, dried particles are introduced in to a differential mobility analyzer (DMA), where size segregation was done based on particle electrical mobility. At the downstream of DMA, the aerosol stream is subdivided into two parts. One is sent to a condensation particle counter (CPC) to measure particle number concentration, whereas other one is sent to QCM to measure the particle mass concentration simultaneously. Based on particle volume derived from size distribution data of SMPS and mass concentration data obtained from QCM, the mean effective density (ρeff) with uncertainty of inorganic salt particles (for particle count mean diameter (CMD) over a size range 10 to 478 nm), i.e. AS, SC and AN is estimated to be 1.76 ± 0.24, 2.08 ± 0.19 and 1.69 ± 0.28 g cm−3, which are comparable with the material density (ρ) values, 1.77, 2.17 and 1.72 g cm−3, respectively. Among individual uncertainty components, repeatability of particle mass obtained by QCM, QCM crystal frequency, CPC counting efficiency, and equivalence of CPC and QCM derived volume are the major contributors to the expanded uncertainty (at k = 2) in comparison to other components, e.g. diffusion correction, charge correction, etc. Effective density for ambient particles at the beginning of winter period in New Delhi is measured to be 1.28 ± 0.12 g cm−3. It was found that in general, mid-day effective density of ambient aerosols increases with increase in CMD of particle size measurement but particle photochemistry is an important factor to govern this trend. It is further observed that the CMD has good correlation with O3, SO2 and ambient RH, suggesting that possibly sulfate secondary materials have substantial contribution in particle effective density. This approach can be useful for real-time measurement of effective density of both laboratory generated and ambient aerosol particles, which is very important for studying the physico-chemical property of particles.

scholarly journals EXPERIMENTAL INVESTIGATION OF ACOUSTIC FIELD INFLUENCE FOR AEROSOLS PARTICLES / AKUSTINIO LAUKO ĮTAKOS AEROZOLIO DALELIŲ KOAGULIACIJAI EKSPERIMENTINIAI TYRIMAI

2016 ◽  
Vol 7 (6) ◽  
pp. 609-612
Author(s):  
Ina Tetsman ◽  
Irina Grinbergienė
Keyword(s):  
Experimental Investigation ◽  
Acoustic Field ◽  
Sound Pressure ◽  
Particle Diameter ◽  
Particle Coagulation ◽  
Experimental Stand ◽  
Coagulation Of Particles ◽  
Field Excitation ◽  
Field Sound ◽  
Field Influence

There were made tests of particulate matter (aerosol), of coagula-tion efficiency, depending on the acoustic field sound pressure and frequency. It is described experimental stand that is used to do researches and methodology of experiments performance. It is used two sound generators for acoustic field excitation: piezoe-lectric and aero-acoustic. It was determined after researches, that increasing the frequency of the acoustic field, it is increased rate of particle coagulation when particle diameter not greater than 1 μm. Effectively coagulation of particles up to 1 μm in diameter must subsonic acoustic field frequencies, as the particles over 1 μm in diameter must be lower than the frequency of ultrasonic acoustic field. Atlikti labai mažo skersmens kietųjų dalelių koaguliacijos efektyvumo, priklausomai nuo akustinio lauko garso slėgio ir dažnio, tyrimai. Aprašytas tyrimams atlikti naudotas eksperimentinis stendas ir eksperimentų atlikimo metodika. Akustiniam laukui žadinti naudoti du garso generatoriai: pjezoelektrinis ir aeroakustinis. Atlikus tyrimus nustatyta, kad, didėjant akustinio poveikio dažniui, dalelių koaguliacijos greitis didėja, kai dalelių skersmuo neviršija 1 μm. Efektyviausiai dalelių iki 1 μm skersmens koaguliacijai reikia ultragarsinių dažnių, didesnio nei 1 μm skersmens dalelėms reikia žemesnio dažnio už ultragarsinį.

Study of the variability of physicochemical characteristics of surface aerosol in Moscow under atypical weather conditions in 2019

2020 ◽  
Author(s):  
Dina Gubanova ◽  
Andrey Skorokhod ◽  
Nikolai Elansky ◽  
Vyacheslav Minashkin ◽  
Mikhail Iordanskii
Keyword(s):  
Air Temperature ◽  
Atmospheric Aerosols ◽  
Mass Concentration ◽  
Aerosol Particles ◽  
Weather Conditions ◽  
Lower Atmosphere ◽  
Anthropogenic Sources ◽  
Model Assessment ◽  
Calculated Concentration ◽  
Microphysical Parameters

<p>In recent years, interest in studying the physicochemical parameters of atmospheric aerosols, which is associated with their active influence on the air pollution, optical characteristics of the atmosphere and the Earth’s climate has increased. Climatic changes cause the occurrence of atypical weather conditions and dangerous meteorological phenomena that affect changes in the properties of aerosol particles. In large industrial megacities frequent atypical meteorological situations change aerosols behavior and complicate the predictive model assessment of the air quality and thermal regime of the atmosphere.</p><p>We consider the results of studies of the daily and seasonal variability of the chemical composition, microphysical parameters, and mass concentration of surface aerosols in Moscow under atypical weather conditions prevailing in summer (June 10-July 10) and in autumn (October 10-November 7) of 2019. In the second half of June 2019, strong cyclonic activity was observed, and air masses of Arctic origin dominated, bringing intense rainfall, cleansing the atmosphere of contaminants and significant decrease in air temperature. October was characterized by air temperature above the climatic norm, insignificant precipitation and frequent strong gusts of wind of western direction.</p><p>Under such conditions, abnormally low aerosol PM<sub>2.5</sub> and PM<sub>10</sub> concentrations were found, and in the summer average monthly concentrations were 1.5 times lower than in the autumn period what is untypical for aerosols. Usually aerosols annual course is characterized by broad maximum in summer, and by minimum in October-November. In addition, comparison with the results of observations of previous years showed that in 2019 aerosol concentration was 3-5 times lower during both summer and autumn. In particular, the average monthly calculated concentration of  submicron fraction in the study period was: 273 particles/cm<sup>3</sup> in the summer and 405 particles/cm<sup>3</sup> in the autumn; mass concentration of PM<sub>2.5</sub> particles: 3.9 and 5.4 μg/m<sup>3</sup>, respectively. For comparison, multiyear average mass concentrations of PM<sub>2.5</sub> are 15-30 μg/m<sup>3</sup>. The day-to-day variability and weekly cyclicity of atmospheric aerosols also underwent changes as a result of synoptic and meteorological factors. Under these conditions, the contribution of urban anthropogenic sources, including traffic leveled, in particular, due to such intensive processes as leaching and weathering of aerosols from the atmosphere.</p><p>Simultaneously with the measurement of microphysical parameters, the elemental composition of aerosol samples was determined by inductively coupled plasma mass spectrometry. It showed that atmospheric aerosol particles are characterized by a high content of sulfur, heavy metals (Cd, Cu, Zn, Mo, W, Ti, Au, Hg, Pb, Ag, Mn, Fe, Co, As), and metalloids (Bi, Sb, B, P, As, Sn), mainly of anthropogenic nature. Such harmful substances are accumulated in the fine fractions of particles that are part of the PM<sub>2.5</sub> aerosol and most dangerous for human health.</p><p>Large amplitudes of variations in the disperse composition and concentration of aerosol particles in the atmospheric surface layer, recorded during seasonal observations under atypical weather conditions, characterize strong inhomogeneities of aerosol parameters in space and time, which can significantly affect the chemical and optical properties of aerosols, as well as lower atmosphere state in general.</p><p>The reported study was funded by RFBR, projects ## 05-19-00352 and 05-19-50088.</p>

scholarly journals Microphysical properties of carbonaceous aerosol particles generated by laser ablation of a graphite target

2015 ◽  
Vol 8 (3) ◽  
pp. 1207-1215 ◽  
Author(s):  
T. Ajtai ◽  
N. Utry ◽  
M. Pintér ◽  
G. Kiss-Albert ◽  
R. Puskás ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Mass Concentration ◽  
Aerosol Particles ◽  
Comprehensive Analysis ◽  
Carbonaceous Aerosol ◽  
Graphite Target ◽  
Graphite Sample ◽  
Microphysical Properties ◽  
Optical Responses ◽  
Transmission Electron

Abstract. In this work various microphysical properties including mass concentration, size distribution and morphology of aerosol particles generated by laser ablation of a high purity graphite sample were investigated in detail. Supplementary chemical analysis of the generated particles including microstructure investigation by high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy were also made. These measurements proved that the proposed method can be used to model the real atmospheric carbonaceous particulate under various climate relevant conditions regarding its specific properties investigated here. However, to introduce the presented methodology as a novel BC surrogate, further improvement and investigation including simplification in experimental setup, comprehensive analysis of thermochemical refractiveness and optical responses of the generated particles as well as comparative study with the presently available concurrent surrogates are required. The related results of these issues are planned to be demonstrated in other studies.

scholarly journals MECHANOCHEMICAL HYDROPHOBIZATION OF MONOAMMONIUM PHOSPHATE

2021 ◽  
Vol 64 (2) ◽  
pp. 87-94
Author(s):  
Alexey V. Kunin
Keyword(s):  
Silicon Dioxide ◽  
Moisture Absorption ◽  
Ammonium Phosphate ◽  
Water Repellency ◽  
Shear Loading ◽  
Raw Material ◽  
Monoammonium Phosphate ◽  
Active Centers ◽  
Hydrophobic Properties ◽  
Main Component

Here, we investigated the influence of mechanical treatment on hydrophobization of monoammonium phosphate (MAP) with organosilicon liquid and silicon dioxide in order to obtain the main component of multipurpose fire extinguishing powders. We estimated hydrophobic properties of mixtures of various compositions. Based on the obtained results, the optimal content of hydrophobizing agents for obtaining monoammonium phosphate with the best hydrophobic properties was established. It is shown that the use of only organosilicon liquid for mechanochemical hydrophobization of MAP is not enough to achieve required values for water repellency, tendency to aggregation, bulk density and particle size distribution. According to GOST R 53280.4-2009, the ability to repel water (powders should not completely absorb water droplets) should be at least 120 min; the tendency to caking (mass of the formed aggregates) should not exceed 2% of the total mass of the sample; the apparent density of uncompacted and compacted powders should be at least 700 and 1000 kg/m3, respectively. It was found that in order to achieve the specified parameters, the mechanochemical hydrophobization of monoammonium phosphate should include modification of the mixture which contains 95 wt. % ammonium phosphate, 4.5 wt. % silicon dioxide and 0.5 wt. % hydrophobizing organosilicon liquid (HOL) in a mill with shock-shear loading at an input energy of 100-110 J/g. The absence of moisture in the raw material (preliminary drying of MAP particles) allows us to obtain a finer-grained product with a low tendency to moisture absorption. The process of mechanochemical hydrophobization of MAP can be described in the following way. During grinding hydrophobized silicon dioxide covers the particles of monoammonium phosphate, resulting in blocking active centers of adsorption and creating a structural and mechanical barrier that prevents particle aggregation.

scholarly journals Regularities of new particle formation and evolution of existing atmospheric aerosol particles in a large (3200 m<sup>3</sup>) isolated volume

2020 ◽  
Author(s):  
Nikolay Romanov ◽  
Alexey Paley ◽  
Yuri Andreev ◽  
Sergey Dubtsov ◽  
Oleg Ozols ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Mass Concentration ◽  
Tap Water ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Galactic Cosmic Rays ◽  
Size Spectrum ◽  
New Particle Formation ◽  
Outdoor Air

Abstract. The paper reports on an investigation of nanometre-sized new particles formation (NPF) in aerosol-free outdoor air. This phenomenon was observed after filling of Large Aerosol Chamber (LAC) RPA Typhoon with the volume of 3200 m3 with outdoor air, passed through HEPA 13 class filter (H13). During the summer-autumn period of 2018, even in the full darkness and in presence ionizing radiation only in the shape of secondary galactic cosmic rays, new particle formation with the particle size greater than 15 nm starts 0.5–1 hour after the end of LAC filling. During the 2018–2019 winter periods the NPF event was not observed once only. Approximately one day after NPF narrow bell-shaped spectra with number concentration up to 104 cm−3 and mass concentration up to 0.6 µg per m3 are formed. During the next five or more days, these size distributions evolve due to coagulation, while their asymptotic shape remains constant with relative breadth σc ≈ 0.28, and relative asymmetry ras ≈ 2 (ras = skewness/σc). The value ras ≈ 2 defines the analytical description of the size distribution as the gamma-distribution. During additional purification of newly formed particles with the inner H13 filter, aerosol particles concentration in LAC decreases down to a few particles per cm3. This concentration remained constant for more than a week. This demonstrates that new aerosol particles are formed by homogeneous gas-to-particle conversion of gaseous precursors, which passed through the external H13 filter. The mass concentration of newly formed particles depends on the concentration of precursors. It was found that after filling LAC with outdoor unfiltered air, approximately after 10 hours the left-hand side of aerosol particle size distribution below 15 nm disappears, and after several days there forms an asymptotic bell-shaped size spectrum with σc ≈ 0.4–0.5 and ras = 2–3. The modal diameter becomes about 150 nm after five days, while the size distribution greater than 200 nm remains unchanged. This allows concluding that aerosol particles greater than 200 nm have a life-time of more than five days, while particles smaller than 15 nm, not more than five hours. The observed regularities of NPF and pre-existing aerosol spectra evolution may contribute significantly to understanding the processes of the formation of atmospheric aerosols, which are responsible for cloud and precipitation formation. They also should be considered during the design of purification methods for facilities and living spaces. During the investigation of size distribution evolution of aerosol particles generated by the spraying of tap water, it was found that this aerosol particles size distribution transforms from a power law to a bell-shaped distribution in five days with σc ≈ 0.4 and ras ≈ 2. These results may be used for the development of aerosol evolution models.

scholarly journals Aerosol effective density measurement using scanning mobility particle sizer and quartz crystal microbalance with the estimation of involved uncertainty

2016 ◽  
Vol 9 (3) ◽  
pp. 859-875 ◽  
Author(s):  
Bighnaraj Sarangi ◽  
Shankar G. Aggarwal ◽  
Deepak Sinha ◽  
Prabhat K. Gupta
Keyword(s):  
Quartz Crystal Microbalance ◽  
Mass Concentration ◽  
Quartz Crystal ◽  
Aerosol Particles ◽  
Particle Mass ◽  
Effective Density ◽  
Substantial Contribution ◽  
New Delhi ◽  
Scanning Mobility Particle Sizer ◽  
Particle Sizer

Abstract. In this work, we have used a scanning mobility particle sizer (SMPS) and a quartz crystal microbalance (QCM) to estimate the effective density of aerosol particles. This approach is tested for aerosolized particles generated from the solution of standard materials of known density, i.e. ammonium sulfate (AS), ammonium nitrate (AN) and sodium chloride (SC), and also applied for ambient measurement in New Delhi. We also discuss uncertainty involved in the measurement. In this method, dried particles are introduced in to a differential mobility analyser (DMA), where size segregation is done based on particle electrical mobility. Downstream of the DMA, the aerosol stream is subdivided into two parts. One is sent to a condensation particle counter (CPC) to measure particle number concentration, whereas the other one is sent to the QCM to measure the particle mass concentration simultaneously. Based on particle volume derived from size distribution data of the SMPS and mass concentration data obtained from the QCM, the mean effective density (ρeff) with uncertainty of inorganic salt particles (for particle count mean diameter (CMD) over a size range 10–478 nm), i.e. AS, SC and AN, is estimated to be 1.76 ± 0.24, 2.08 ± 0.19 and 1.69 ± 0.28 g cm−3, values which are comparable with the material density (ρ) values, 1.77, 2.17 and 1.72 g cm−3, respectively. Using this technique, the percentage contribution of error in the measurement of effective density is calculated to be in the range of 9–17 %. Among the individual uncertainty components, repeatability of particle mass obtained by the QCM, the QCM crystal frequency, CPC counting efficiency, and the equivalence of CPC- and QCM-derived volume are the major contributors to the expanded uncertainty (at k = 2) in comparison to other components, e.g. diffusion correction, charge correction, etc. Effective density for ambient particles at the beginning of the winter period in New Delhi was measured to be 1.28 ± 0.12 g cm−3. It was found that in general, mid-day effective density of ambient aerosols increases with increase in CMD of particle size measurement but particle photochemistry is an important factor to govern this trend. It is further observed that the CMD has good correlation with O3, SO2 and ambient RH, suggesting that possibly sulfate secondary materials have a substantial contribution in particle effective density. This approach can be useful for real-time measurement of effective density of both laboratory-generated and ambient aerosol particles, which is very important for studying the physico-chemical properties of particles.

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