scholarly journals Fractionation of solid component of welding aerosol

Author(s):  
A.A.-A. Ennan ◽  
V.I. Vishnyakov ◽  
S.A. Kiro ◽  
M.V. Oprya

The design of portable filtration device with electrostatic filter and description of its work, which provides the trapping efficiency about 99.5% and fractionation of the polydisperse aerosol to four fractions via particles’ electrical mobility, are presented. The samples of aerosol particles’ fractions are obtained under usual welding regimes by welding wire Св08Г2С in CO2 and their specific surface area, element and phase compositions, phase ratio and crystallite sizes are determined. The correlation between fraction’s element composition and its specific surface area is demonstrated – the iron content is decreased, and manganese and silicon contents are increased when specific surface area is increased. The polyphase content (Fe3O4, FeO, FeMn2O4 и a-Fe are determined) and presence of the monocrystal nanosized magnetite particles, wustite and iron-manganese spinel in the fraction samples are confirmed by the X-ray analysis. The silicon compounds in particles are in amorphous state. The possibility of utilization of the nanostructured aerosol particles are proposed as a result of experimental data analysis.

NANO ◽  
2017 ◽  
Vol 12 (02) ◽  
pp. 1750020
Author(s):  
Chuan Zhou ◽  
Dachuan Zhu ◽  
Daji Wang

After mechanochemical reaction of hydrous cerium (III) chloride and citric acid with a little of ethanol followed by a subsequent calcination process at different temperature, cerium dioxide nanoparticles with fluorite structure were successfully prepared. Then the obtained ceria powders were characterized by means of X-ray diffractometer, specific surface area analyzer, scanning electron microscope, transmission electron microscopy and laser particle analyzer. It was found that the degree of particle aggregation passed through a minimum with the calcination temperature rising from 400[Formula: see text]C to 800[Formula: see text]C, accompanied with growth of particle size. The ceria powders calcined at 500[Formula: see text]C had an average aggregated particle size of 59.8[Formula: see text]nm with uniform spheroidal morphology, while their crystallite sizes ranged from 10[Formula: see text]nm to 20[Formula: see text]nm. Yet the product calcined at 400[Formula: see text]C had the maximum specific surface area of 109.6[Formula: see text]m2/g. In polishing experiment, the ceria powders calcined at 500[Formula: see text]C showed great polishing performances.


2006 ◽  
Vol 317-318 ◽  
pp. 705-708 ◽  
Author(s):  
K. Sato ◽  
Sawao Honda ◽  
T. Nishikawa ◽  
Hideo Awaji

Porous NiZrO2 has been widely used as anode in SOFC. However, it has been reported that there was reduction in cell performance at high temperature since Ni grains in the porous Ni ZrO2 sintered during cell operation. In this study, NiOZrO2 composite powders in which NiO powder were covered with ZrO2 particles were prepared with controlled microstructure of porous NiZrO2 which can prevent sintering of Ni grains during cell operation. NiOZrO2 composite powders (HNZ) were prepared using NiO powder of high specific surface area and ZrO2 sol of average particle size of 50 nm by ball milling (sol-coating method). SEM and EPMA analysis of prepared NiOZrO2 composite powders showed that NiO particles were covered with ZrO2 particles. The crystallite phases, crystallite sizes, BET specific surface area of NiOZrO2 composite powders and porosities of fabricated porous NiZrO2 were characterized. SEM and EPMA analysis showed that ZrO2 was distributed around Ni of a few μm range in the porous Ni ZrO2 (HNZ) fabricated by the sol-coating method. Mechanical properties of porous NiZrO2 (HNZ) are required to be improved.


2019 ◽  
Vol 33 (31) ◽  
pp. 1950391
Author(s):  
G. H. Zhu ◽  
H. C. Li ◽  
I. Underwood ◽  
Z. H. Li

Physico-chemical instability is commonly associated with the amorphous state, and the understanding of instability mechanisms (e.g. the glass transition) involved is essential in designing pharmaceutical products. The glass transition of bulk water might occur at 210 K [Oguni et al., J. Phys. Chem. B 115 (2011) 14023] but it was recently proposed the glass transition of water could happen around 121 K [C. R. Hill et al., Phys. Rev. Lett. 116 (2016) 215501]. Note that molecular self-inclusions in a glassy water show relaxation features that are characteristically different from those observed in thermodynamically stable, crystalline solids with inclusions. Here we point out some doubtful results and calculations in Hill et al.’s work [C. R. Hill et al., Phys. Rev. Lett. 116 (2016) 215501] which was based on the small-angle neutron scattering (SANS) measurements. We also made some remarks about the possible mistakes in their previous works [C. Mitterdorfer, Phys. Chem. Chem. Phys. 16 (2014) 16013] considering the calculation of the specific surface area. The latter is crucial to the doubtful fixing of the glass transition temperature in Hill et al.’s work [C. R. Hill et al., Phys. Rev. Lett. 116 (2016) 215501].


2012 ◽  
Vol 468-471 ◽  
pp. 1353-1358
Author(s):  
Quan Xiao Liu ◽  
Wen Cai Xu

In this paper silica are made in the production line and its properties are investigated. It shows that the content of SiO2 of BSZ1 is 90.24%, its specific surface area of BET is 204.70m2/g, its CTAB is 240m2/g, its oil absorption value of DBP is 2.82cm3/g, and its particle size of D50 is 5.71μm. The content of SiO2 of BSZ2 is 94.16%, its specific surface area of BET is 245.07m2/g, its CTAB is 212m2/g, its oil absorption value of DBP is 2.86cm3/g, and its particle size of D50 is 2.82μm. The content of SiO2 of BSZ3 is 92.43%, its specific surface area of BET is 355.90m2/g, its CTAB is 273m2/g, its oil absorption value of DBP is 2.70cm3/g, and its particle size D50 is 5.71μm. BSZ2 and BSZ3 are amorphous state with silanol groups on their surfaces, and they are the spherical particle with some irregular granules. BSZ1 and BSZ2 are good application in rubber as reinforcing agent.


2017 ◽  
Vol 35 (7-8) ◽  
pp. 668-676 ◽  
Author(s):  
J Skubiszewska-Zięba ◽  
B Charmas ◽  
H Waniak-Nowicka

Mechanochemical and microwave-assisted hydrothermal (MicroWave Treatment [MWT]) procedures were applied to prepare crystalline CaCO3. Mechanochemical process was carried out at different speeds of rotation (500 or 850 rpm/min), different duration times (30 or 60 min) and in the aqueous suspensions or in dry state. MWT synthesis was conducted in a saturated water vapour or under the layer of water. The crystalline and porous structures of the prepared samples as well as their morphology were investigated using N2 adsorption, X-ray diffraction and scanning electron microscopy methods. As a result, the calcium carbonate samples in the form of calcite were obtained. The materials prepared by the mechanochemical route performed in the aqueous suspension are characterized by smaller crystallite sizes as compared to those obtained without the addition of water. The samples obtained hydrothermally have the largest size of crystallites. Powders prepared by energetical milling possess higher values of specific surface area in relation to the parameter for those synthesized hydrothermally. In the process of hydrothermal treatment, macroporous structure of the prepared materials is created. With the increasing specific surface area of the sample, the size of the crystallites decreased.


Author(s):  
И.О. Шаповалова ◽  
А.В. Вураско ◽  
М.А. Агеев

Дана оценка влияния свойств природного и синтезированного на технической целлюлозе из рисовой и овсяной шелухи диоксида кремния на каталазную активность диоксидсодержащих материалов. Техническую целлюлозу из шелухи получали окислительно-органосольвентным способом. Закрепление диоксида кремния на целлюлозе проводили золь-гель методом с применением тетраэтоксисилана. Свойства полученных диоксидсодержащих материалов оценивали: рентгеноструктурным анализом, методом тепловой десорбции азота, эмиссионным спектральным анализом с индукционно-связанной плазмой. Каталазную активность диоксидсодержащих материалов оценивали по модельной реакции разложения Н2О2. В ходе работы получены образцы целлюлозы: из рисовой шелухи с содержании зольного остатка от 0,3 до 33,5%; из овсяной и рисовой шелухи без содержания минеральных компонентов. Золь-гель методом получены материалы с содержанием синтетического диоксида кремния от 0 до 47,2% на основе рисовой шелухи и от 0 до 44,3% на основе овсяной шелухи. Установлено, что количество закрепленного диоксида кремния золь-гель методом не зависит от природы технической целлюлозы. Диоксид кремния остающийся в технической целлюлозе находится в аморфном состоянии. Максимум удельной поверхности (20,4 м2/г) достигается при предельном содержанием диоксида кремния (30,3%). Синтезированный на технической целлюлозе золь-гель методом диоксид кремния находится в кристаллическом состоянии, при этом максимальная удельная поверхность составляет для диоксидсодержащего материала на основе ОШ 18,5 м2/г, а для диоксидсодержащего материала на основе РШ 15,7 м2/г); Выявлено, что каталазной активностью обладает диоксидсодержащий материал с природным диоксидом кремния. Такой каталазный эффект можно объяснить наличием примесей в виде металлов, которые накапливаются в минеральном компоненте растительного сырья при вегетации. Образцы целлюлозы с синтезированным диоксидом кремния каталазной активностью не обладают, независимо от удельной поверхности и содержания SiO2. The influence of the properties of natural and synthesized silicon dioxide on technical cellulose from rice and oat husks on the catalase activity of dioxidecontaining materials is estimated. Technical cellulose from the husk was obtained by the oxidative-organosolvent method. The fixation of silicon dioxide on cellulose was carried out by the sol-gel method using tetraethoxysilane. The properties of the obtained dioxide-containing materials were investigated by X-ray diffraction analysis, nitrogen thermal desorption method, inductively coupled plasmaemission spectroscopy. The catalase activity of the dioxide-containing materials was evaluated by the model reaction of Н2О2 decomposition. In the course of the work, the following samples of cellulose were obtained: one from rice husks with an ash content of 0.3 to 33.5%; one from oat and rice husks without mineral components. The sol-gel method was used to obtain materials with a content of synthetic silicon dioxide from 0 to 47.2% based on rice husk and from 0 to 44.3% based on oat husk. It was established that the amount of fixed silicon dioxide by the sol-gel method does not depend on the origin of the technical cellulose. The silicon dioxide remaining in the technical cellulose is in an amorphous state. The maximum specific surface area (20.4 m2/g) is achieved at the limiting silicon dioxide content (30.3%). The silicon dioxide synthesized on technical cellulose by the sol-gel method is in a crystalline state, with the maximum specific surface area being 18.5 m2/g for a dioxide-containing material based on OH, and 15.7 m2/g for a dioxide-containing material based on RH; It was found that dioxide-containing material with natural silicon dioxide possesses the catalase activity. This catalase effect can be explained by the presence of impurities in the form of metals, which are accumulated in the mineral component of plant raw materials during the vegetation. Cellulose samples with synthesized silicon dioxide do not have catalase activity, independently from specific surface area and SiO2 content.


2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Phuong Thu Nguyen ◽  
Xuyen Thi Nguyen ◽  
Trang Van Nguyen ◽  
Thom Thi Nguyen ◽  
Thai Quoc Vu ◽  
...  

Apatite ore from Lao Cai (Vietnam) has large reserves and low prices. Its main component is fluorapatite. The purification and modification of apatite ore can produce a material that can be used as an absorbent for heavy metals with high efficiency. The molecular structure, phase component, specific surface area, element component, and morphology of modified apatite ore from Lao Cai province, Vietnam, were characterized by IR, XRD, BET, EDX, and SEM methods. The IR and XRD results show that the modified process transformed apatite ore from fluorapatite to nanohydroxyapatite. The specific surface area of modified apatite ore (100.79 m2/g) is much higher than the original ore (3.97 m2/g). The modified apatite ore was used to adsorb Cd2+ and Cu2+ ions in water. The effect of adsorbent mass, pH, contact time, and initial concentration of Cd2+ and Cu2+ on the adsorption efficiency and capacity was investigated. Besides, the isotherm adsorption model was determined using Freundlich and Langmuir theories.


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