scholarly journals Acetone-Sensitive Thin Films Comprising Coal Fly Ash Na-X Zeolites and Sol–Gel Nb2O5 Matrix

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2399
Author(s):  
Katerina Lazarova ◽  
Silviya Boycheva ◽  
Marina Vasileva ◽  
Denitza Zgureva-Filipova ◽  
Biliana Georgieva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
Sol Gel ◽  
Optical Quality ◽  
Film Deposition ◽  
Reflectance Spectra ◽  
Raw Material ◽  
X Zeolites

In this study, thin composite films of a sol–gel Nb2O5 matrix doped with coal fly ash Na-X zeolites were deposited by the spin-coating method. Fly ash of lignite coal collected from the electrostatic precipitators of one of the biggest TPPs in Bulgaria was used as a raw material for obtaining zeolites. Zeolite Na-X was synthesized by ultrasonic-assisted double stage fusion-hydrothermal alkaline conversion of coal fly ash. In order to improve the optical quality and sensing properties of the deposited thin films, synthesized zeolites were wet-milled for 60, 120, and 540 s prior to film deposition. The surface morphology of zeolite powders was studied both by scanning electron microscopy and transmission electron microscopy, while their porosity was investigated by N2-physisorption. Refractive index, extinction coefficient, and thickness of the films were determined through fitting of their reflectance spectra. The sensing ability of thin films towards acetone vapors was tested by measuring the reflectance spectra prior to and during exposure to the analyte, and the change in the reflection coefficient ∆R of the films was calculated. The influence of milling time of zeolites on the sensing and optical properties of the films was assumed and confirmed.

scholarly journals Effect of Milling Time on the Sensing Properties of Fly Ash Zeolite Composite Thin Films

2021 ◽  
Vol 6 (1) ◽  
pp. 55
Author(s):  
Katerina Lazarova ◽  
Silviya Boycheva ◽  
Marina Vasileva ◽  
Denitza Zgureva ◽  
Tsvetanka Babeva
Keyword(s):  
Thin Films ◽  
Fly Ash ◽  
Milling Time ◽  
Sol Gel ◽  
Optical Quality ◽  
Sensing Properties ◽  
Liquid Adsorption ◽  
Coating Method ◽  
Ultrasonic Assisted ◽  
Zeolite Composite

Thin films, consisting of a sol–gel Nb2O5 matrix doped with zeolite Na-X synthesized from fly ash through ultrasonic-assisted double-stage fusion-hydrothermal alkaline activation, were deposited by the spin-coating method. In order to improve the optical quality and sensing properties of the thin films, zeolites were wet milled for 60, 120 and 540 s prior to incorporation in the film. The liquid adsorption ability of thin films was tested by measuring the reflectance spectra prior to and after exposure to liquid acetone and the change in the reflection coefficient ∆R of the films was calculated. The influence of milling time of zeolites on the sensing and optical properties of the films was studied.

scholarly journals Recovery of Cenospheres and Fine Fraction from Coal Fly Ash by a Novel Dry Separation Method

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3576
Author(s):  
Jan Wrona ◽  
Witold Żukowski ◽  
Dariusz Bradło ◽  
Piotr Czupryński
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Fine Fraction ◽  
Free Fall ◽  
Raw Material ◽  
Fluidised Bed ◽  
Air Chamber ◽  
Pneumatic Separation ◽  
Bed Separation ◽  
Separation Product

Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications due to their low density. Currently, there is no efficient and ecologically rational method of cenosphere recovery from fly ash. A combination of dry methods for the recovery of both fine ash particles and aluminosilicate microspheres from coal fly ash is presented. It is comprised of fluidised bed separation followed by screening and pneumatic separation in a free-fall air chamber. Fluidised bed separation was assisted by a mechanical activator to prevent agglomeration. This step reduced the portion of material that required further treatment by 52–55 wt.%, with the recovery of microspheres exceeding 97%. Then, the concentrates were individually subjected to pneumatic separation. The final separation product for the fly ash containing 0.64 wt.% cenospheres was a cenosphere concentrate that constituted about 17 wt.% of the initial fly ash. The recovery of cenospheres was around 81%. Usage of a combination of dry methods allowed for maintaining almost 83 wt.% of the raw material in its dry form. Furthermore, the produced fly ash grain fractions could be used for different industrial purposes.

Synthesis and Film Investigation of Titania

2013 ◽  
Vol 832 ◽  
pp. 128-131
Author(s):  
Sharipah Nadzirah ◽  
Uda Hashim
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Electron Microscopy ◽  
Titanium Dioxide ◽  
Sol Gel ◽  
Titanium Butoxide ◽  
Before And After ◽  
Scanning Electron ◽  
Spin Coater

Titania or titanium dioxide (TiO2) thin film has been synthesized via sol-gel method with monoethanolamine (MEA) as a catalyst. The mixing of titanium butoxide as a precursor, ethanol as a solvent and MEA were stirred using magnetic stirrer under ambient temperature [. The TiO2solution prepared then was deposited on SiO2substrates using spin-coater and the coated films were annealed at 600°C. Finally, both before and after annealed TiO2thin films were characterized using Field Emission Scanning Electron Microscopy (FESEM). The obtained results show the different TiO2particles formation before and after annealed.

SiO2ZrO2 Thin Films as Low Temperature NO2 and O3 Sensors

2015 ◽  
Vol 1088 ◽  
pp. 81-85 ◽  
Author(s):  
T.N. Myasoedova ◽  
Victor V. Petrov ◽  
Nina K. Plugotarenko ◽  
Dmitriy V. Sergeenko ◽  
Galina Yalovega ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Operating Temperatures ◽  
Scanning Electron

Thin SiO2ZrO2films were prepared, up to 0.2 μm thick, by means of the sol–gel technology and characterized by a Scanning electron microscopy and X-ray diffraction. It is shown the presence of monoclinic, cubic and tetragonal phases of ZrO2in the SiO2matrix. The crystallites sizes depend on the annealing temperature of the film and amount to 35 and 56 nm for the films annealed at 773 and 973 K, respectively. The films resistance is rather sensitive to the presence of NO2and O3impurity in air at lower operating temperatures in the range of 30-60°C.

Sol-gel processing of nanocrystalline haematite thin films

1997 ◽  
Vol 12 (6) ◽  
pp. 1441-1444 ◽  
Author(s):  
L. Armelao ◽  
A. Armigliato ◽  
R. Bozio ◽  
P. Colombo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Single Particles ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Processing

The microstructure of Fe2O3 sol-gel thin films, obtained from Fe(OCH2CH3)3, was investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Samples were nanocrystalline from 400 °C to 1000 °C, and the crystallized phase was haematite. In the coatings, the α–Fe2O3 clusters were dispersed as single particles in a network of amorphous ferric oxide.

Fabrication of Nanoporous Ceramic Thin Films: De-alloying and Self-organized Template Formation Onamorphous Substrates

2002 ◽  
Vol 17 (1) ◽  
pp. 115-126 ◽  
Author(s):  
Maggie Paulose ◽  
Oomman K. Varghese ◽  
Craig A. Grimes
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Sol Gel ◽  
Oxide Ceramic ◽  
Porous Network ◽  
Self Organized ◽  
Ceramic Thin Films ◽  
Transmission Electron ◽  
Amorphous Substrate ◽  
Drying Conditions

Sol-gel-derived metal oxide ceramic thin films deposited onto amorphous iron-rich substrates were found to form self-organized nanoporous structures dependent upon the extent to which the substrate is de-alloyed, a function of the substrate alloycomposition, acid concentration of the sol, and film drying conditions. Field emission scanning electron microscopy, transmission electron microscopy, and x-ray energy dispersive analysis were used to investigate details of the porous structure formation.Our studies showed the more electrochemically active elements in the amorphous substrate are de-alloyed by the sol in high-humidity environments, whereupon the liberated elements form oxides replicating the de-alloyed substrate matrix resulting in athree dimensional porous network structure.

Thermal Behavior of Celsian Ceramics Synthesized from Coal Fly Ash

2012 ◽  
Vol 1373 ◽  
Author(s):  
Jorge López-Cuevas ◽  
David Long-González ◽  
Carlos A. Gutiérrez-Chavarría
Keyword(s):  
Fly Ash ◽  
Thermal Behavior ◽  
Coal Fly Ash ◽  
Thermal Analyses ◽  
Linear Thermal Expansion ◽  
Raw Material ◽  
Synthesis Conditions ◽  
Calcination Step ◽  
Heating Microscopy ◽  
The Mean

ABSTRACTCelsian with a chemical composition of Ba0.75Sr0.25Al2Si2O8, is synthesized by using coal fly ash (byproduct of a Mexican coal-burning power plant, composed mainly by SiO2 and Al2O3) as main raw material. The thermal behavior of the synthesized material is evaluated by differential (DTA) and gravimetric (TGA) thermal analyses as well as by heating microscopy; its coefficient of linear thermal expansion (CTE) is also determined. Heating microscopy shows that cylinders of compacted powdered Celsian start sintering at ∼1140 ºC, which is associated with a considerable contraction occurring up to 1500 ºC. The mean CTE value of the material in the temperature range of 30-1100ºC is slightly affected by the synthesis conditions employed. Synthesis at 1400 or 1300 ºC during 10 h, with a pre-calcination step at 900 ºC/5h in both cases, produce mean CTE values of 5.15 x 10-6 and 5.43 x 10-6 ºC-1, respectively. On the other hand, Celsian synthesized at 1400 ºC/10 h, without the pre-calcination step, has a mean CTE value of 5.25 x 10-6 ºC-1. Lastly, the DTA/TGA analysis of the synthesized material shows that a slight weight gain takes place from room temperature to 1100ºC, which is followed by a slight weight loss up to 1300ºC. This is attributed to oxidation and evaporation of some of the impurities present in the material.

Sol-Gel Synthesis and Characterization of BiFeO3-PbTiO3 Thin Films

2007 ◽  
Vol 997 ◽  
Author(s):  
Ashish Garg ◽  
Soumya Kar ◽  
Anju Dixit ◽  
D C Agrawal
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Electron Microscopy ◽  
Sol Gel ◽  
Grazing Incidence ◽  
Synthesis And Characterization ◽  
Sol Gel Synthesis ◽  
Polycrystalline Form ◽  
Scanning Electron

AbstractIn this work, we report on the synthesis and characterization of thin films of (BiFeO3)1−x (PbTiO3)x (BFPT) solid solutions of compositions around morphotropic phase boundary (MPB) grown on platinized silicon (111) Pt/TiO2/SiO2/Si substrate by sol-gel based spin coating technique. The films were post-annealed at 700 and 750°C for 1 h in air. Morphological analysis of the films was carried out by scanning electron microscopy. Grazing incidence X-ray diffractometry revealed the perovskite structure of the films and peaks suggested the presence of rhombohedral structured pure BFPT phase in polycrystalline form. Scanning electron microscopy suggested that films annealed at 750degC had a denser microstructure as compared to those at 700°C. The room temperature dielectric constant of the films with composition of BF:PT :: 75:25 was measured to be ∼1200 at a frequency of 100 kHz.

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