Thermogravimetric analysis of Ontario limestones and dolomites. II. Reactivity of sulfur dioxide with calcined samples

1970 ◽  
Vol 48 (19) ◽  
pp. 2979-2982 ◽  
Author(s):  
R. K. Chan ◽  
K. S. Murthi ◽  
D. Harrison
Keyword(s):  
Thermogravimetric Analysis ◽  
Sulfur Dioxide ◽  
Grain Boundaries ◽  
Temperature Region ◽  
Room Temperature ◽  
Intermediate Temperature ◽  
Controlled Atmosphere ◽  
Absorption Region ◽  
Fast Absorption

Thermogravimetric analysis was done for representative calcined samples of Ontario limestones and dolomites in a 5% SO2 controlled atmosphere. The SO2 absorption vs. temperature curves showed three distinct regions. (i) A unimolecular chemisorption of SO2 at room temperature. (ii) An intermediate temperature region between 200–450 °C where absorption of SO2 was due to increased rate of SO2 diffusion into the interior of CaO via grain boundaries. When the surfaces of these internal spaces were almost fully occupied the rate of SO2 absorption decreased. Further absorption was due to diffusion of SO2 into CaO lattice, which was a much slower process. (iii) A fast absorption region between 500–700 °C, where a disproportionation of CaSO3 into CaSO4 and CaS took place which effectively broke down the original CaO structure to expose fresh layers of CaO. The amount of SO2 absorption after 1 h at 745 °C corresponded to approximately 80% conversion of CaO to mainly CaSO4 and CaS and smaller amount CaSO3.Finally, the calculations showed that the reaction of SO2 with CaO was more exothermic than the reaction of SO2 with MgO, which accounted for the faster rate of the former.

The Reactivity of Different Active Forms of Sodium Carbonate with Respect to Sulfur Dioxide

1992 ◽  
Vol 57 (11) ◽  
pp. 2302-2308
Author(s):  
Karel Mocek ◽  
Erich Lippert ◽  
Emerich Erdös
Keyword(s):  
Thermal Decomposition ◽  
Liquid Phase ◽  
Sulfur Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Sodium Carbonate ◽  
Room Temperature ◽  
Active Form ◽  
The Other ◽  
Kinetics Of

The kinetics of the reaction of solid sodium carbonate with sulfur dioxide depends on the microstructure of the solid, which in turn is affected by the way and conditions of its preparation. The active form, analogous to that obtained by thermal decomposition of NaHCO3, emerges from the dehydration of Na2CO3 . 10 H2O in a vacuum or its weathering in air at room temperature. The two active forms are porous and have approximately the same specific surface area. Partial hydration of the active Na2CO3 in air at room temperature followed by thermal dehydration does not bring about a significant decrease in reactivity. On the other hand, if the preparation of anhydrous Na2CO3 involves, partly or completely, the liquid phase, the reactivity of the product is substantially lower.

Deformation Twins Formed in Nanocrystalline Materials

2006 ◽  
Vol 503-504 ◽  
pp. 125-132 ◽  
Author(s):  
Yuntian T. Zhu
Keyword(s):  
Grain Boundaries ◽  
Nanocrystalline Materials ◽  
Partial Dislocation ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Nucleation And Growth ◽  
Analytical Models ◽  
Partial Dislocations ◽  
Deformation Twins ◽  
Low Strain Rate

Deformation twins have been oberved in nanocrystalline (NC) Al synthsized by cryogenic ball-milling and in NC Cu processed by high-pressure torsion under room temperature and at a very low strain rate. They were found formed by partial dislocations emitted from grain boundaries. This paper first reviews experimental evidences on deformation twinning and partial dislocation emissions from grain boundaries, and then discusses recent analytical models on the nucleation and growth of deformation twins. These models are compared with experimental results to establish their validity and limitations.

Conductivity and Permittivity Studies in the Diluted Perovskite System [(NH3)(CH2)6(NH3)]FexZn1-xCl4, x=1, 0.8, 0.5, and 0

2002 ◽  
Vol 57 (11) ◽  
pp. 897-908 ◽  
Author(s):  
M. F. Mostafa ◽  
M. M. AbdelKader ◽  
S. S. Arafat
Keyword(s):  
Temperature Region ◽  
Room Temperature ◽  
Conduction Mechanism ◽  
High Temperature Region ◽  
Frequency Dependent ◽  
Arrhenius Relation ◽  
Zn Addition ◽  
Series Type ◽  
Type Conduction ◽  
Band Type

The dielectric permittivity and AC conductivity of the perovskite-like system [(NH3)(CH2)6(NH3)]FexZn1-xCl4 (HDAFxZ1-x), where x=1, 0.8, 0.5 and 0, were measured at different frequencies in the temperature range 100 K<T<430 K. At temperatures below 273 K, for x=1 the material exhibits a transition at (245±1) K, while for x=0 transitions at (155±5) K, (220±4) K and (255±2) K were found. A rotational-type transition in the range 295 - 305 K was found for the Fe-containing materials. Ferroelectric transitions were observed in the high temperature region for all four concentrations. Differential thermal scanning confirmed the existence of the phase transitions above room temperature. The conductivity decreases with Zn addition, an the conduction mechanism varies with the temperature and concentration. Extrinsic conduction prevails for T<150 K for all concentrations. At intermediate temperatures an Arrhenius relation with frequency dependent activation energy (ΔE=0.46 - 0.06 eV) is observed for Fecontaining materials. The frequency dependent conductivity for all materials has a linear response following the power law: σac=A(T) ·ωS(T) with the exponent s varying with temperature and composition. At high temperatures, for Zn-rich materials series type conduction with s ∼ 0.6±0.1 is identified, while for Fe-rich materials band type conduction prevails. In the low temperature region ionic hopping prevails.

scholarly journals Syntheses, Structures, and Characteristics of Three Metal Complexes Constructed Using Hexacarboxylic Acid

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4431 ◽  
Author(s):  
Lingshu Meng ◽  
Lun Zhao ◽  
Guanlin Guo ◽  
Xin Liu ◽  
Zhijun Liang ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Thermogravimetric Analysis ◽  
Coordination Polymers ◽  
Electrochemical Behavior ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Hexadentate Ligand ◽  
Xrd Techniques

In this study, three new 3D coordination polymers (CPs), {[Cd3(L)(H2O)6]·H2O}n (1), {[Cu1.5(L)0.5(bimb)1.5]·5H2O·DMF}n (2), and {[Mn1.5(H3L)(bibp)0.5(H2O)2]·3H2O}n (3) (bimb= 1,3-bis(imidazol-1-yl)benzene, bibp= 1,4-bis((4-imidazol-1-yl)benzyl)piperazine), were prepared under solvothermal or hydrothermal conditions based on a hexadentate ligand (1,3,5-triazine-2,4,6-triamine hexa-acetic acid (H6L)). Structural elucidations were carried out by IR spectra along with single-crystal X-ray diffraction analysis, while thermogravimetric analysis (TGA) (dynamic and isothermal) and XRD techniques were used for property evaluations of the polymers. Furthermore, the fluorescence properties and detection of the Fe3+ ions in 1 were tested at room temperature, and the electrochemical behavior of 2 is also stated in this article.

A metal-free route to alkynyl sulfones under photoinduced conditions with the insertion of sulfur dioxide

2020 ◽  
Vol 22 (6) ◽  
pp. 1906-1910 ◽  
Author(s):  
Xinxing Gong ◽  
Min Yang ◽  
Jin-Biao Liu ◽  
Fu-Sheng He ◽  
Xiaona Fan ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Room Temperature ◽  
Light Irradiation ◽  
Metal Free

A metal-free route to alkynyl sulfones under photoinduced conditions is accomplished, starting from 4-alkyl Hantzsch esters, sulfur dioxide, and alkynyl bromides under visible light irradiation at room temperature.

THE POLARIZATION OF LIQUIDS AND THEIR SATURATED VAPORS IN THE CRITICAL TEMPERATURE REGION

1936 ◽  
Vol 14b (3) ◽  
pp. 90-95
Author(s):  
J. Marsden ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Methyl Ether ◽  
Temperature Region ◽  
Room Temperature ◽  
Saturated Vapor ◽  
Dielectric Constants

The values of the so-called polarization of methyl ether (liquid and saturated vapor) and propylene (liquid and saturated vapor), from room temperature to the critical temperature, are given. In both liquids this polarization is independent of the temperature to within a few degrees of the critical temperature. Calculations show that the polarizations of a liquid and its saturated vapor may be equal above the critical temperature, even though the dielectric constants of the liquid and its saturated vapor, as well as their densities, are different.

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