scholarly journals Kinetic Analysis of the Thermal Decomposition of a Synthetic Mercury Jarosite

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 200 ◽  
Author(s):  
Mizraim Flores ◽  
Iván Reyes ◽  
Elia Palacios ◽  
Francisco Patiño ◽  
Julio Juárez ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Thermal Decomposition ◽  
Environmental Concern ◽  
Frequency Factor ◽  
X Ray Diffraction ◽  
Thermal Decomposition Process ◽  
X Ray ◽  
The Third ◽  
Mercury Oxide

Jarosites are widely used in the hydrometallurgical industry of zinc to eliminate iron and other impurities contained in the concentrates. However, these compounds can also incorporate elements of significant environmental concern such as Tl+, Hg2+, Pb2+, Cd2+, Cr(VI), and As(V). In this work, the characterization of a synthetic mercury jarosite and its thermal decomposition kinetics are reported. XRD and FTIR analyses confirm that a mercury jarosite—Hg0.40(H3O)0.2]Fe2.71(SO4)2.17(OH)4.79(H2O)0.44—was successfully synthesized. Four mass loss events were observed by thermogravimetric analysis at 290 °C, 365 °C, 543 °C, and 665 °C. The third event corresponds to mercury decomposition into mercury oxide, whilst the forth is related to the jarosite to hematite transformation determined by X-ray diffraction starting at around 600 °C. According to the kinetic parameters (activation energy and frequency factor) of the thermal decomposition process, the fourth stage required the highest energy (Ea = 234.7 kJ∙mol−1), which corresponds to elimination of sulfur and oxygen from the jarosite lattice. Results show that jarosite-type compounds have the capability to incorporate heavy metals into their structure, retaining them even at high temperatures. Therefore, they can be used as a remediation strategy for heavy metals, such as mercury and others elements of environmental concern.

Research on the Thermal Decomposition Process of K-Feldspar-CaSO4-CaO System

2013 ◽  
Vol 734-737 ◽  
pp. 916-920 ◽  
Author(s):  
Jing Xia Chao ◽  
Ju Pei Xia ◽  
Chao Qin Yang ◽  
Zhao Shu Zhang ◽  
Xue Jiao Ren
Keyword(s):  
Thermal Decomposition ◽  
Calcium Sulfate ◽  
Xrd Analysis ◽  
Operating Conditions ◽  
Decomposition Process ◽  
Complex Reaction ◽  
X Ray Diffraction ◽  
Thermal Decomposition Process ◽  
X Ray

The thermal decomposition process of K-feldspar-CaSO4-CaO system was studied by X-ray diffraction (XRD) analysis of the product which calcined at 1473K. The results show that KAlSi3O8 firstly is decomposed into KAlSi2O6 and released the SiO2, then has a complex reaction between KAlSi2O6 and CaO, which generated intermediates-K2SiO3 under the operating conditions. K2SiO3 is unstable and reacted with calcium sulfate to generate K2SO4. When the CaO amount is insufficient, the main products are KAlSi2O6 and 2CaOAl2O3SiO2, the potassium existed as K2S2O8; when n (CaO) / n (KAS6) 12:1, the products will further transfer into CaOSiO2 and 2CaO SiO2 and the potassium existed as K2SO4.

Synthesis and Characterization of Co Nanoparticles by Solventless Thermal Decomposition

2007 ◽  
Vol 119 ◽  
pp. 71-74 ◽  
Author(s):  
Yan Li ◽  
Xiao Li Zhang ◽  
Young Hwan Kim ◽  
Young Soo Kang
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Synthesis And Characterization ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Of Nanoparticles ◽  
Co Nanoparticles

Co nanoparticles were synthesized via a solventless thermal decomposition of Co2+-oleate2. The crystalline structure is strongly affected by the thermal treatment of the Co nanoparticles. Further, the annealing also results in the decomposition of surfactant around Co particles. The size of nanoparticles was confirmed by transmission electron microscopy (TEM). The crystal structure of nanoparticles was characterized by X-ray diffraction pattern (XRD). The magnetic properties were characterized by vibrating sample magnetometer (VSM).

Characterization of Three 'Active' Rhodium(III) Hydroxides

1995 ◽  
Vol 48 (3) ◽  
pp. 557 ◽  
Author(s):  
SJ Crimp ◽  
L Spiccia
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Infrared Spectroscopy ◽  
Ion Exchange ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
X Ray Diffraction ◽  
X Ray

Pure solutions of [ Rh (H2O)6]3+, dimer [Rh2(μ-OH)2(H2O)8]4+ and trimer [Rh3(μ-OH)4(H2O)10]5+ have been converted into their respective 'active' hydroxides by dropwise addition to an imidazole solution. These 'active' hydroxides have been analysed by a variety of techniques including rhodium determination, infrared spectroscopy, thermal analysis and powder X-ray diffraction. Purity determinations using ion-exchange chromatography showed that the three hydroxides consist primarily of the neutral forms of the starting aqua ion (>96%) with small amounts of species with higher nuclearity. Rhodium analysis and thermogravimetric measurements confirmed the composition of these hydroxides to be Rh (OH)3(H2O)3.H2O, Rh2(μ-OH)2(OH)4(H2O)4 and Rh3(μ-OH)4(OH)5(H2O)5.5H2O. A scheme for the thermal decomposition of each of the hydroxides has been proposed on the basis of the t.g . and d.t.a . data and the knowledge that the final product in each case is α-Rh2O3. Heating of the hydroxides in air resulted in oxidation of RhIII to RhIV (temperature 250-300°C) forming RhO2 which on further heating decomposed to α-Rh2O3 and dioxygen.

Probing the thermal decomposition process of layered double hydroxides through in situ 57Fe Mössbauer and in situ X-ray diffraction experiments

2006 ◽  
Vol 42 (2) ◽  
pp. 534-538 ◽  
Author(s):  
Daniel X. Gouveia ◽  
Odair P. Ferreira ◽  
Antonio G. Souza Filho ◽  
M. G. da Silva ◽  
J. A. C. de Paiva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Layered Double Hydroxides ◽  
Decomposition Process ◽  
X Ray Diffraction ◽  
Thermal Decomposition Process ◽  
X Ray ◽  
57Fe Mössbauer ◽  
Double Hydroxides

Synthesis and characterization of the barium oxalates BaC2O4·0.5H2O, α-BaC2O4 and β-BaC2O4

2002 ◽  
Vol 58 (5) ◽  
pp. 808-814 ◽  
Author(s):  
Axel Nørlund Christensen ◽  
Rita Grønbæk Hazell ◽  
Ian Charles Madsen
Keyword(s):  
Thermal Decomposition ◽  
Ammonium Oxalate ◽  
Barium Chloride ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Weak Hydrogen Bonds ◽  
Made In

The synthesis of BaC2O4·0.5H2O and its thermal decomposition to α-BaC2O4 and β-BaC2O4 was investigated. BaC2O4·0.5H2O is precipitated at room temperature from aqueous solutions of barium chloride and ammonium oxalate. The deuterated compound BaC2O4·0.5D2O was made in analogy with D2O as the solvent. The compounds were characterized by X-ray and neutron diffraction analysis. Single-crystal X-ray diffraction of BaC2O4·0.5H2O measured at 120 K gave the triclinic cell a = 8.692 (1), b = 9.216 (1), c = 6.146 (1) Å, α = 95.094 (3), β = 95.492 (3), γ = 64.500 (3)°, space group P\bar 1, Z = 4. Two independent Ba atoms are each coordinated to nine O atoms at distances from 2.73 (1) to 2.99 (1) Å. One of the two oxalate ions deviates significantly from planarity. The water molecule does form weak hydrogen bonds. In situ X-ray powder diffraction was used to study the thermal decomposition of BaC2O4·0.5H2O and the formation of α-BaC2O4. The X-ray powder pattern of α-BaC2O4 measured at 473 K was indexed on a triclinic cell with a = 5.137 (3), b = 8.764 (6), c = 9.006 (4) Å, α = 83.57 (4), β = 98.68 (5), γ = 99.53 (5)°, and the space group P\bar 1 with Z = 4.

scholarly journals Obtaining hydroxyapatite with different precursors for application as a biomaterial

Cerâmica ◽  
2019 ◽  
Vol 65 (373) ◽  
pp. 99-106
Author(s):  
K. A. S. Farias ◽  
W. J. B. Sousa ◽  
M. J. B. Cardoso ◽  
R. J. S. Lima ◽  
M. A. Rodriguez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Thermal Decomposition ◽  
Fourier Transform ◽  
Calcium Oxide ◽  
Crystal Size ◽  
X Ray Diffraction ◽  
Thermal Decomposition Process ◽  
X Ray ◽  
Scanning Electron

Abstract The hydroxyapatite (HAp) is a ceramic biomaterial with wide application in the bone regeneration. It can be obtained by different routes and different precursors. In this study, the synthesis of HAp was carried out by precipitation and subsequent thermal treatment using different calcium precursors: calcium hydroxide from synthetic origin and calcium oxide obtained from the eggshell. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. By SEM, variations of the crystal size and the concentration of agglomerates were observed. FTIR and XRD analyses proved the formation of HAp and how the (mineral and biological) precursors affected the microstructure. The thermal decomposition process of the calcium oxide obtained from the eggshell showed to be more effective for the synthesis of the hydroxyapatite, resulting in more stable morphology and microstructure.

The Synthesis and Characterization of NiCo2O4 Nanoparticles

2012 ◽  
Vol 512-515 ◽  
pp. 2467-2470 ◽  
Author(s):  
Hong Xiao Zhao ◽  
Bao Ming He ◽  
Jing Li ◽  
Hui Min Jia ◽  
Li Wei Mi
Keyword(s):  
Thermal Decomposition ◽  
Hydrothermal Method ◽  
Physical Adsorption ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Preparation Methods ◽  
Oxalate Precursor ◽  
X Ray ◽  
Scanning Electron

In this paper, NiCo2O4 nanoparticles were synthesized by three different methods. The applied preparation methods in this research are thermal decomposition of a mixed oxalate precursor, combustion synthesis and hydrothermal method. The crystalline phase, morphology and specific surface area (BET) of the resultant samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and nitrogen physical adsorption, respectively. The research found that the hydrothermal method is a promising method to prepare NiCo2O4 nanoparticles.

scholarly journals Transition metal complexes with pyrazole based ligands, part 27: Structural and thermal characterization of cobalt(II) halide and pseudohalide complexes with 4-acetyl-3-amino-5-methylpyrazole

2007 ◽  
Vol 72 (12) ◽  
pp. 1281-1293 ◽  
Author(s):  
Vukadin Leovac ◽  
Zoran Tomic ◽  
Katalin Mészáros-Szécsényi ◽  
Ljiljana Jovanovic ◽  
Milan Joksovic
Keyword(s):  
Thermal Decomposition ◽  
Solid State ◽  
Transition Metal Complexes ◽  
Thermal Characterization ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Vis Spectroscopy

The crystal and molecular structures of four tetrahedral structurally similar [Co(aamp)2X2] complexes (aamp = 4-acetyl-3-amino-5-methylpyrazole, X = Cl, Br, I and NCS) were determined by X-ray diffraction analysis and are discussed in detail. It was found that the different capacity of the ligand X (NCS vs. Cl, Br, I) for the formation of non-bonding contacts influence the mode of molecular association in the solid state. The complexes were characterized by UV-Vis spectroscopy. The first step of the thermal decomposition of the compounds was checked and is discussed in the view of the IR spectrum of the intermediate isolated from [Co(aamp)2Br2] by the quasi-isothermal technique.

Synthesis and characterization of robust three-dimensional chiral metal sulfates

RSC Advances ◽  
2014 ◽  
Vol 4 (92) ◽  
pp. 50435-50442 ◽  
Author(s):  
J. N. Behera ◽  
Joydeep Bhattacharjee ◽  
Satoshi Horike ◽  
Subba R. Marri ◽  
Prem P. Dahiya
Keyword(s):  
Thermal Decomposition ◽  
High Temperature ◽  
First Principles ◽  
Three Dimensional ◽  
Ammonium Ion ◽  
Synthesis And Characterization ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray

Chiral three-dimensional Mg(ii) and Mn(ii) sulfates have been synthesized, well characterized and studied from first-principles calculations. High temperature X-ray diffraction, thermogravimetric analysis and DFT calculations reveal that the structures of both the compounds remain intact even after the thermal decomposition of the ammonium ion.

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