Gas-phase particle size distributions and lead loss during spray pyrolysis of (Bi,Pb)–Sr–Ca–Cu–O

1995 ◽  
Vol 10 (7) ◽  
pp. 1644-1652 ◽  
Author(s):  
Abhijit S. Gurav ◽  
Toivo T. Kodas ◽  
Jorma Joutsensaari ◽  
Esko I. Kauppincn ◽  
Riitta Zilliacus
Keyword(s):  
Particle Size ◽  
Spray Pyrolysis ◽  
Gas Phase ◽  
Phase Particle ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Processing Temperature ◽  
Average Particle ◽  
Size Distributions ◽  
Particle Size Distributions

Gas-phase particle size distributions and lead loss were measured during formation of (Bi,Pb)-Sr-Ca-Cu-O and pure PbO particles by spray pyrolysis at different temperatures. A differential mobility analyzer (DMA) in conjunction with a condensation particle counter (CPC) was used to monitor the gas-phase particle size distributions, and a Berner-type low-pressure impactor was used to obtain mass size distributions and size-classified samples for chemical analysis. For (Bi,Pb)-Sr-Ca-Cu-O, as the processing temperature was raised from 200 to 700 °C, the number average particle size decreased due to metal nitrate decomposition, intraparticle reactions forming mixed-metal oxides and particle densification. The geometric number mean particle diameter was 0.12 μm at 200 °C and reduced to 0.08 and 0.07 μm, respectively, at 700 and 900 °C. When the reactor temperature was raised from 700 and 800 °C to 900 °C, a large number (∼107 no./cm3) of new ultrafine particles were formed from PbO vapor released from the particles and the reactor walls. Particles made at temperatures up to 700 °C maintained their initial stoichiometry over the whole range of particle sizes monitorcd; however, those made at 800 °C and above were heavily depleted in lead in the size range 0.5–5.0 μm. The evaporative losses of lead oxide from (Bi,Pb)-Sr-Ca-Cu-O particles were compared with the losses from PbO particles to gain insight into the pathways involved in lead loss and the role of intraparticle processes in controlling it.

44 O 03 Gas-phase particle size distributions of (Bi,Pb)-Sr-Ca-Cu-O superconducting powders made via spray pyrolysis

1993 ◽  
Vol 24 ◽  
pp. S571-S572
Author(s):  
J. Joutsensaari ◽  
E.I. Kauppinen ◽  
J.K. Jokiniemi ◽  
A.S. Gurav ◽  
T.T. Kodas
Keyword(s):  
Particle Size ◽  
Spray Pyrolysis ◽  
Gas Phase ◽  
Phase Particle ◽  
Size Distributions ◽  
Particle Size Distributions

Determination of Latex Particle Size Distributions by Fractional Creaming with Sodium Alginate

1961 ◽  
Vol 34 (2) ◽  
pp. 433-445 ◽  
Author(s):  
E. Schmidt ◽  
P. H. Biddison
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Sodium Alginate ◽  
Mass Distribution ◽  
Average Particle Size ◽  
Average Particle ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions

Abstract Knowledge of mass distribution of particle sizes in latex is very important to the latex technologist. Therefore, it is desirable to have available a simple method for the determination of mass distribution of particle sizes. This paper presents a method, based on fractional creaming of latex with sodium alginate, which can be used in any laboratory without special equipment. The method is particularly advantageous for analyzing latexes of very wide particle size distributions. When analyzed with an electron microscope, these latexes require counting a very large number of particles. McGavack found that partial creaming of normal hevea latex with ammonium alginate gives concentrates of larger average particle size than the original latex. He found that the average particle size in the cream approaches that of the original latex as the amount of creaming agent is increased. In a previous paper from this laboratory, Schmidt and Kelsey demonstrated that the phenomenon of fractionation according to particle size with increasing amounts of creaming agent is applicable in a wide variety of anionic latex systems and in colloidal silica. Their results indicated also the existence of a quantitative relationship, independent of the nature of the dispersed particles, between the concentration of creaming agent and size of creamed particles. Maron confirmed fractionation with respect to particle size as a consequence of partial creaming with alginate. He showed that the mass average particle sizes of fractions, determined optically, cumulate to that of the original latex. Although the previous paper by Schmidt and Kelsey implied the basic concept of a method of determining particle size distribution by fractional creaming, it was not exploited at that time. In order to adapt the fractional creaming phenomenon to a quantitative method for particle size determination, we required a more precise knowledge of the relation between creaming agent concentration and size of particles creamed. It was proposed to establish this relationship with the aid of the electron microscope. Various factors influencing the creaming of latex, such as polymer concentration, electrolyte, soap content, and variability of the creaming agent, had to be considered in standardizing the creaming procedure.

Gas-phase particle size distributions during vapor condensation of fullerenes

1994 ◽  
Vol 4 (5) ◽  
pp. 491-496 ◽  
Author(s):  
A.S. Gurav ◽  
T.T. Kodas ◽  
L.M. Wang ◽  
E.I. Kauppinen ◽  
J. Joutsensaari
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Phase Particle ◽  
Vapor Condensation ◽  
Size Distributions ◽  
Particle Size Distributions

Numerical study on key issues in the Eulerian-Eulerian simulation of fluidization with wide particle size distributions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yang Liu ◽  
Haigang Wang ◽  
Yinqiang Song ◽  
Haiying Qi
Keyword(s):  
Particle Size ◽  
Numerical Study ◽  
Particle Diameter ◽  
Flow Characteristics ◽  
Average Particle ◽  
Size Distributions ◽  
Particle Phase ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Eulerian Approach

Abstract Gas-particle flows in circulating fluidized beds (CFB) with wide particle size distributions were simulated using the Eulerian-Eulerian approach to analyze the effects of the particle phase division and the applicability of the particle-particle drag model. The results indicate that the simulation is not accurate by just using a single average particle diameter when the particle size distribution includes a critical particle diameter. A binary particle phase division criterion was then developed to establish two particle phases representing two types of particles with different flow patterns. Coupling the Eulerian-Eulerian approach with the new criterion enabled accurate predictions of the pressures, particle volume fractions, and particle mass circulation rates that were in agreement with experimental data. The influences of different particle-particle drag models were also investigated to show that the simulation using the Syamlal model was not accurate due to the overestimated particle-particle drag, while the results without particle-particle drag and with the Manger model were similar and much more accurate. Moreover, the flow mechanism for the non-uniformity of particle circulation rates in the parallel circulating loops of the CFB boiler was revealed. This study improves the Eulerian-Eulerian simulations of fluidization with wide particle size distributions and further deepens the understanding of flow characteristics in CFB.

scholarly journals Synthesis of MgO Nanoparticles by Solvent Mixed Spray Pyrolysis Technique for Optical Investigation

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
K. R. Nemade ◽  
S. A. Waghuley
Keyword(s):  
Particle Size ◽  
Spray Pyrolysis ◽  
Spray Pyrolysis Technique ◽  
Average Particle Size ◽  
Band Gap Energy ◽  
Average Particle ◽  
Optical Investigation ◽  
X Ray Diffraction ◽  
Mgo Nanoparticles ◽  
Electron Microscope Analysis

Solvent mixed spray pyrolysis technique has attracted a global interest in the synthesis of nanomaterials since reactions can be run in liquid state without further heating. Magnesium oxide (MgO) is a category of the practical semiconductor metal oxides, which is extensively used as catalyst and optical material. In the present study, MgO nanoparticles were successfully synthesized using a solvent mixed spray pyrolysis. The X-ray diffraction pattern confirmed the formation of MgO phase with an excellent crystalline structure. Debye-Scherrer equation is used for the determination of particle size, which was found to be 9.2 nm. Tunneling electron microscope analysis indicated that the as-synthesized particles are nanoparticles with an average particle size of 9 nm. Meanwhile, the ultraviolet-visible spectroscopy of the resulting product was evaluated to study its optical property via measurement of the band gap energy value.

scholarly journals Preparation of Polyetherimide Nanoparticles by a Droplet Evaporation-Assisted Thermally Induced Phase-Separation Method

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1548
Author(s):  
Peng Zhu ◽  
Huapeng Zhang ◽  
Hongwei Lu
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Phase Separation ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Droplet Evaporation ◽  
Average Particle ◽  
Thermally Induced Phase Separation ◽  
Thermally Induced ◽  
Pei Nanoparticles

The droplet evaporation effect on the preparation of polyetherimide (PEI) nanoparticles by thermally induced phase separation (TIPS) was studied. PEI nanoparticles were prepared in two routes. In route I, the droplet evaporation process was carried out after TIPS. In route II, the droplet evaporation and TIPS processes were carried out simultaneously. The surface tension and shape parameters of samples were measured via a drop shape analyzer. The Z-average particle diameter of PEI nanoparticles in the PEI/dimethyl sulfoxide solution (DMSO) suspension at different time points was tested by dynamic light scattering, the data from which was used to determine the TIPS time of the PEI/DMSO solution. The natural properties of the products from both routes were studied by optical microscope, scanning electron microscope and transmission electron microscope. The results show that PEI nanoparticles prepared from route II are much smaller and more uniform than that prepared from route I. Circulation flows in the droplet evaporation were indirectly proved to suppress the growth of particles. At 30 °C, PEI solid nanoparticles with 193 nm average particle size, good uniformity, good separation and good roundness were obtained. Route I is less sensitive to temperature than route II. Samples in route I were still the accumulations of micro and nanoparticles until 40 °C instead of 30 °C in route II, although the particle size distribution was not uniform. In addition, a film structure would appear instead of particles when the evaporation temperature exceeds a certain value in both routes. This work will contribute to the preparation of polymer nanoparticles with small and uniform particle size by TIPS process from preformed polymers.

Minimum Particle Diameter of the Vanadium/Iron Co-Doped Nano TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 989-994 ◽  
pp. 611-614
Author(s):  
Ling Li ◽  
Wen Ming Zhang ◽  
Hua Yan Zhang ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Ferric Nitrate ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Vanadium Iron ◽  
Co Doped

Vanadium/iron co-doped nanoTiO2 transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, ferric nitrate, ammonium metavanadate, etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, EDS, nanolaser particle size analyzer, and UV-Vis spectrophotometer. The photocatalytic properties of V/Fe doped TiO2 were studied through degrading acid 3R dye, and the results show that when the content of V/Fe was 0.5%, the degradation rate reached more than 96% under irridation for 60 min.

The ATAL and its aerosol microphysical properties in the Asian Monsoon Anticyclone

2020 ◽  
Author(s):  
Christoph Mahnke ◽  
Stephan Borrmann ◽  
Ralf Weigel ◽  
Francesco Cairo ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Particle Size ◽  
Asian Monsoon ◽  
Extreme Values ◽  
Monsoon Season ◽  
Measurement Techniques ◽  
Potential Temperature ◽  
Particle Diameter ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Microphysical Properties

<p>During the StratoClim 2017 measurement campaign in Nepal, within the Asian Monsoon Anticyclone (AMA), measurements of the aerosols’ microphysical properties up to UT/LS altitudes were successfully completed with a modified version of the commercially available (Droplet Measurement Technologies Inc.) aerosol spectrometer UHSAS-A. Technical rearrangements of parts of the UHSAS-A were developed and implemented, which improve the instrument’s measuring performance and extend its airborne application range from around 12 km altitude to the extreme ambient conditions in the stratosphere at heights of 20 km. The measurement techniques used for this purpose were characterized by laboratory experiments.</p><p>Within the AMA region, extreme values of the particle mixing ratio (PMR) ranging between 6 mg<sup>-1</sup> and about 10000 mg<sup>-1</sup> were found with the UHSAS-A (particle diameter range: 65 nm to 1000 nm). The median of the PMR for all research flights was about 1300 mg<sup>-1</sup> close to the ground. Within tropospheric altitudes, the PMR was highly variable and median values between 70 mg<sup>-1</sup> and 400 mg<sup>-1</sup> were observed.  At levels of 370 K potential temperature, the median PMR maximally reaches about 700 mg<sup>-1 </sup>while the 1 Hz resolved measurements show values up to about 10000 mg<sup>-1</sup>. Between 450 K and 475 K, median PMR between 40 mg<sup>-1</sup> and 50 mg<sup>-1</sup> were observed. The aerosol size distributions (measured by the UHSAS-A) were extended by an additional diameter size bin obtained from the 4-channel Condensation Particle counting System (COPAS), i.e. for aerosol diameter between 10 nm and 65 nm.</p><p>The UHSAS-A measured aerosol particle size distributions were compared with balloon-borne measurements (by T. Deshler et al., Dep. of Atmospheric Science, University of Wyoming, USA) at altitudes of up to 20 km. These show that the size distributions measured during the StratoClim 2017 campaign fit well within the range of the balloon-borne measurements during the Asian Monsoon season over India (Hyderabad) in 2015 and the USA (Laramie) in 2013. Further analyses of measured particle size distributions by means of backscatter ratio show remarkable consistency with CALIOP satellite observations of the ATAL during the StratoClim mission period.</p>

scholarly journals The Use of Inorganic Packing Materials during Methane Biofiltration

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Josiane Nikiema ◽  
Michèle Heitz
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Average Particle Size ◽  
High Specific Surface Area ◽  
Packing Material ◽  
Average Particle ◽  
Packing Materials ◽  
Clay Particles ◽  
Good Surface ◽  
Methane Elimination

The objective behind this study is to select a suitable inorganic packing material for methane biofiltration. Three packing materials are to be compared: two rock materials (average particles' sizes: 2 and 5 mm) and one porous clay particles (average particle size of 7 mm). The main parameter used to assess the efficiency of the packing material is the methane elimination capacity. The study reveals that the rock material having an average particle size around 2 mm is to be preferred. This result is probably due to its high specific surface area and to its good surface properties as compared to the other 2 tested porous materials. The influence of the nonirrigation with the nutrient solution of the biofilter is also investigated. It has been found that nonirrigation of biofilter causes the biofilter performance to decrease significantly (e.g., 45% decrease in 1 week) even with the humidification of the gas phase prior to its introduction into the biofilter.

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