Characterisation of Purified Gypsum and Insoluble Impurities Obtained from Phosphogypsum Waste

In this study, the chemical and phase composition of two samples of phosphogypsum from the waste dumps of the Industry of ChemicalProducts “Elixir – Prahovo” (Serbia) were examined, as well as the possibility of recrystallization of gypsum from an aqueoussuspension of phosphogypsum. The negative effect of higher temperatures on the solubility of calcium sulfate (13.08 mmol/dm3 at95°C vs. 15.43 mmol/dm3 at 40°C) was utilized. In several repeated cycles, calcium sulfate component was progressively dissolvedin water at room temperature and then precipitated at 100°C, using the same liquid phase throughout the experiment. Therefore,phosphogypsum was separated into recrystallized (purified) gypsum, insoluble residue and supernatant, and the mass balance forthe experiment was calculated. Elemental, XRD and SEM-EDS analyses were performed on raw phosphogypsum, purified gypsumand insoluble residue. The whiteness of raw phosphogypsum and purified gypsum were determined and compared. The main objectiveof the study was to investigate the nature of insoluble impurities, in order to define and optimize the methods for their removalduring a potential industrial processing of phosphogypsum.

Download Full-text

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19922302 ◽

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.

Download Full-text

High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

Functional Materials Letters ◽

10.1142/s1793604719500322 ◽

2019 ◽

Vol 12 (03) ◽

pp. 1950032 ◽

Cited By ~ 2

Author(s):

Yuchen Deng ◽

Yaming Zhang ◽

Nanlong Zhang ◽

Qiang Zhi ◽

Bo Wang ◽

...

Keyword(s):

Thermal Conductivity ◽

Silicon Carbide ◽

Grain Size ◽

Phase Composition ◽

Room Temperature ◽

Vapor Transport ◽

Physical Vapor Transport ◽

Growth Substrate ◽

Sic Ceramics ◽

Evolution Of Microstructure

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

Download Full-text

Representation of VLE and liquid phase composition with an electrolyte model: application to H3PO4–H2O and H2SO4–H2O

Fluid Phase Equilibria ◽

10.1016/s0378-3812(01)00688-4 ◽

2002 ◽

Vol 194-197 ◽

pp. 729-738 ◽

Cited By ~ 17

Author(s):

Mourad Cherif ◽

Arbi Mgaidi ◽

Mohamed Naceur Ammar ◽

Manef Abderrabba ◽

Walter Fürst

Keyword(s):

Phase Composition ◽

Liquid Phase ◽

Model Application ◽

Liquid Phase Composition

Download Full-text

Preparation of Li3PS4–Li3PO4 Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

Electronic Materials ◽

10.3390/electronicmat2010004 ◽

2021 ◽

Vol 2 (1) ◽

pp. 39-48

Author(s):

Nguyen H. H. Phuc ◽

Takaki Maeda ◽

Tokoharu Yamamoto ◽

Hiroyuki Muto ◽

Atsunori Matsuda

Keyword(s):

Solid Solution ◽

Solid State ◽

Liquid Phase ◽

Room Temperature ◽

Reaction Medium ◽

Magic Angle Spinning ◽

Resonance Spectroscopy ◽

Synthesis Methods ◽

Magic Angle ◽

Angle Spinning

A solid solution of a 100Li3PS4·xLi3PO4 solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li2S, P2S5 and Li3PO4 was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li3PO4 were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li3PO4 remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS33− unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0.

Download Full-text

On the Chemistry of Tetrabenzyl Thiuram Disulfide and Tetramethyl Thiuram Disulfide with Bis (Triethoxysilylpropyl) Tetrasulfide in Silica Compounds

Rubber Chemistry and Technology ◽

10.5254/1.3547778 ◽

2003 ◽

Vol 76 (4) ◽

pp. 876-891 ◽

Cited By ~ 1

Author(s):

R. N. Datta ◽

A. G. Talma ◽

S. Datta ◽

P. G. J. Nieuwenhuis ◽

W. J. Nijenhuis ◽

...

Keyword(s):

High Performance ◽

Room Temperature ◽

Succinic Anhydride ◽

Dynamic Properties ◽

The Other ◽

Resonance Spectroscopy ◽

Reaction Products ◽

Negative Effect ◽

Higher Temperature ◽

Analytical Tools

Abstract The use of thiurams such as Tetramethyl thiuram disulfide (TMTD) or Tetrabenzyl thiuram disulfide (TBzTD) has been explored to achieve higher cure efficiency. The studies suggest that a clear difference exists between the effect of TMTD versus TBzTD. TMTD reacts with Bis (triethoxysilylpropyl) tetrasulfide (TESPT) and this reaction can take place even at room temperature. On the other hand, the reaction of TBzTD with TESPT is slow and takes place only at higher temperature. High Performance Liquid Chromatography (HPLC) with mass (MS) detection, Nuclear Magnetic Resonance Spectroscopy (NMR) and other analytical tools have been used to understand the differences between the reaction of TMTD and TESPT versus TBzTD and TESPT. The reaction products originating from these reactions are also identified. These studies indicate that unlike TMTD, TBzTD improves the cure efficiency allowing faster cure without significant effect on processing characteristics as well as dynamic properties. The loading of TESPT is reduced in a typical Green tire compound and the negative effect on viscosity is repaired by addition of anhydrides, such as succinic anhydride, maleic anhydride, etc.

Download Full-text

Synthesis of CaWO4:(Eu3+,Tb3+) Thin Films by a Two-Step Method at Room Temperature

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.710.170 ◽

2013 ◽

Vol 710 ◽

pp. 170-173

Author(s):

Lian Ping Chen ◽

Yuan Hong Gao

Keyword(s):

Thin Film ◽

Thin Films ◽

Phase Composition ◽

Room Temperature ◽

Electrochemical Techniques ◽

Luminescent Properties ◽

X Ray Diffraction ◽

Step Method ◽

X Ray ◽

Rare Earth Doped

It is hardly possible to obtain rare earth doped CaWO4thin films directly through electrochemical techniques. A two-step method has been proposed to synthesize CaWO4:(Eu3+,Tb3+) thin films at room temperature. X-ray diffraction, energy dispersive X-ray analysis, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that (Eu3+,Tb3+)-doped CaWO4films have a tetragonal phase. When the ratio of n (Eu)/n (Tb) in the solution is up to 3:1, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Tb element; on the contrary, when the ratio in the solution is lower than 1:4, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Eu element. Under the excitation of 242 nm, sharp emission peaks at 612, 543, 489 and 589 nm have been observed for CaWO4:(Eu3+,Tb3+) thin films.

Download Full-text

Quantitative Phase-Composition Analysis of Liquid-Phase-Sintered Silicon Carbide Using the Rietveld Method

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.2000.tb01548.x ◽

2004 ◽

Vol 83 (9) ◽

pp. 2282-2286 ◽

Cited By ~ 36

Author(s):

Angel L. Ortiz ◽

Francisco L. Cumbrera ◽

Florentino Sánchez-Bajo ◽

Fernando Guiberteau ◽

Huiwen Xu ◽

...

Keyword(s):

Silicon Carbide ◽

Phase Composition ◽

Liquid Phase ◽

Rietveld Method ◽

Composition Analysis ◽

Quantitative Phase ◽

Phase Composition Analysis ◽

Sintered Silicon

Download Full-text

Solvent-free hydrogenation of cyclohexene over Rh-TUD-1 at ambient conditions

RSC Advances ◽

10.1039/c8ra07639a ◽

2018 ◽

Vol 8 (60) ◽

pp. 34370-34373 ◽

Cited By ~ 3

Author(s):

Mhamed Benaissa ◽

Abdullah M. Alhanash ◽

Ahmed T. Mubarak ◽

Morad Eissa ◽

Taher Sahlabji ◽

...

Keyword(s):

Liquid Phase ◽

Room Temperature ◽

Hydrogenation Reaction ◽

Solvent Free ◽

Ambient Conditions ◽

Total Conversion ◽

Free System ◽

Liquid Phase Hydrogenation ◽

System P ◽

Solvent Free System

Total conversion of cyclohexene to cyclohexane was achieved in a liquid phase hydrogenation reaction at room temperature, 1 atm H2 pressure and solvent-free system.

Download Full-text

Low-temperature degradation resistance and plastic deformation of ATZ ceramics stabilized by CaO

Journal of Physics Conference Series ◽

10.1088/1742-6596/2103/1/012075 ◽

2021 ◽

Vol 2103 (1) ◽

pp. 012075

Author(s):

AA Dmitrievskiy ◽

DG Zhigacheva ◽

VM Vasyukov ◽

PN Ovchinnikov

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Plastic Deformation ◽

Compressive Strength ◽

Phase Composition ◽

Low Temperature ◽

Uniaxial Compression ◽

Calcium Oxide ◽

Tetragonal Phase ◽

Room Temperature

Abstract In this work, the phase composition (relative fractions of monoclinic m-ZrO2, tetragonal t-ZrO2, and cubic c-ZrO2 phases) and mechanical properties (hardness, fracture toughness, compressive strength) of alumina toughened zirconia (ATZ) ceramics, with an addition of silica were investigated. Calcium oxide was used as a stabilizer for the zirconia tetragonal phase. It was shown that CaO-ATZ+SiO2 ceramics demonstrate increased resistance to low-temperature degradation. The plasticity signs at room temperature were found due to the SiO2 addition to CaO-ATZ ceramics. A yield plateau appears in the uniaxial compression diagram at 5 mol. % SiO2 concentration. It is hypothesized that discovered plasticity is due to the increased t→m transformability.

Download Full-text