scholarly journals Influence of the Mixing Ways of Reactants on ZnO Morphology

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Lining Yang ◽  
Lan Xiang
Keyword(s):  
Thermodynamic Analysis ◽  
Room Temperature ◽  
Molar Ratio ◽  
Solution Composition ◽  
Initial Molar Ratio ◽  
Zno Particles

ZnO particles with various morphologies were synthesized by mixing ZnSO4and NaOH solutions at 25°C followed by aging of the suspensions at 40–80°C for 2.0 h, keeping the initial molar ratio of Zn2+to OH−at 1 : 4. ZnO irregular plates were prepared by adding NaOH to ZnSO4whileε-Zn(OH)2rhombic particles were produced using the opposite mixing way. After aging of the slurries at 80°C for 2.0 h, the ZnO plates were kept stable while theε-Zn(OH)2rhombic particles were converted to ZnO whiskers with a length of 1.0–4.0 μm and a diameter of 0.03–0.3 μm. Thermodynamic analysis indicated that the formation of the Zn-bearing precipitates (ZnO orε-Zn(OH)2) at room temperature was connected closely with the solution composition.

scholarly journals Pure hydroxyapatite synthesis originating from amorphous calcium carbonate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michika Sawada ◽  
Kandi Sridhar ◽  
Yasuharu Kanda ◽  
Shinya Yamanaka
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Room Temperature ◽  
Molar Ratio ◽  
Final Phase ◽  
Amorphous Calcium Carbonate ◽  
Phosphate Compound ◽  
Synthesis Strategy ◽  
Phosphorylation Reaction ◽  
Subsequent Calcination

AbstractWe report a synthesis strategy for pure hydroxyapatite (HAp) using an amorphous calcium carbonate (ACC) colloid as the starting source. Room-temperature phosphorylation and subsequent calcination produce pure HAp via intermediate amorphous calcium phosphate (ACP). The pre-calcined sample undergoes a competitive transformation from ACC to ACP and crystalline calcium carbonate. The water content, ACC concentration, Ca/P molar ratio, and pH during the phosphorylation reaction play crucial roles in the final phase of the crystalline phosphate compound. Pure HAp is formed after ACP is transformed from ACC at a low concentration (1 wt%) of ACC colloid (1.71 < Ca/P < 1.88), whereas Ca/P = 1.51 leads to pure β-tricalcium phosphate. The ACP phases are precursors for calcium phosphate compounds and may determine the final crystalline phase.

scholarly journals Crystal structure of the new hybrid material bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate

2015 ◽  
Vol 71 (11) ◽  
pp. 1384-1387
Author(s):  
Marwen Chouri ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Molar Ratio ◽  
Water Molecules ◽  
Site Symmetry ◽  
Two Dimensional ◽  
Slow Evaporation ◽  
Solution Ph

The title compound bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH = 1) containing bismuth(III) nitrate and 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10]4−bioctahedra (site symmetry -1) separated by layers of organic 1,4-diazoniabicyclo[2.2.2]octane dications [(DABCOH2)2+] and water molecules. O—H...Cl, N—H...O and N—H...Cl hydrogen bonds lead to additional cohesion of the structure.

Efficient synthesis of pyrido[2,3-d]pyrimidine-7-carboxylic acids catalyzed by a TiO2/SiO2 nanocomposite in aqueous media at room temperature

2018 ◽  
Vol 73 (9) ◽  
pp. 641-645 ◽  
Author(s):  
Sepehr Sadegh-Samiei ◽  
Shahrzad Abdolmohammadi
Keyword(s):  
Heterogeneous Catalyst ◽  
Carboxylic Acids ◽  
Room Temperature ◽  
Aqueous Media ◽  
Reaction Times ◽  
Molar Ratio ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Moderate Reaction ◽  
Recyclable Heterogeneous Catalyst

AbstractA novel and efficient synthesis of eight 5-aryl-1,3-dimethyl-2,4-dioxo-1,2,3,4,5,8-hexahydropyrido[2,3-d]pyrimidine-7-carboxylic acids using a TiO2/SiO2 nanocomposite with a molar ratio of 1:1 as a recyclable heterogeneous catalyst is described. The desired products, five of which are new, are formed in short reaction times (2–3 h) with high to excellent yields (94%–98%) under very moderate reaction conditions (room temperature, aqueous media).

scholarly journals Initial Investigation into the Leaching of Manganese from Nodules at Room Temperature with the Use of Sulfuric Acid and the Addition of Foundry Slag—Part I

Minerals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 565 ◽  
Author(s):  
Norman Toro ◽  
Nelson Herrera ◽  
Jonathan Castillo ◽  
Cynthia Torres ◽  
Rossana Sepúlveda
Keyword(s):  
Particle Size ◽  
Sulfuric Acid ◽  
Acid Concentration ◽  
Room Temperature ◽  
Sulfuric Acid Concentration ◽  
Extraction Rate ◽  
Molar Ratio ◽  
Independent Variables ◽  
Initial Investigation ◽  
Optimization Methodology

In this study, the surface optimization methodology was used to assess the effect of three independent variables—time, particle size and sulfuric acid concentration—on Mn extraction from marine nodules during leaching with H2SO4 in the presence of foundry slag. The effect of the MnO2/Fe ratio and particle size (MnO2) was also investigated. The maximum Mn extraction rate was obtained when a MnO2 to Fe molar ratio of 0.5, 1 M of H2SO4, −320 + 400 Tyler mesh (−47 + 38 μm) nodule particle size and a leaching time of 30 min were used.

scholarly journals Synthesis, Characterization and Antifungal Studies of Adducts of p- Ethylphenyldithiocarbonates of Copper(II)

2019 ◽  
Vol 31 (8) ◽  
pp. 1819-1824
Author(s):  
Shivangi Sharma ◽  
Renu Sachar ◽  
G.D. Bajju ◽  
Vikas Sharma
Keyword(s):  
Magnetic Susceptibility ◽  
Electron Spin Resonance ◽  
Room Temperature ◽  
Molar Conductance ◽  
Octahedral Geometry ◽  
Molar Ratio ◽  
Spectral Studies ◽  
Distorted Octahedral Geometry ◽  
Distorted Octahedral ◽  
Spin Resonance

A series of adducts of p-ethylphenyldithiocarbonates of copper(II) [(p-C2H5C6H4OCS2)2Cu] with ethyl pyridines and chloro pyridines have been synthesized in 1:2 molar ratio. They were characterized by elemental analysis, magnetic susceptibility and molar conductance measurements, infrared, electronic, electron spin resonance and mass spectroscopy, NMR and thermogravimetric analysis. In addition, antifungal studies of these adducts were also performed. The results revealed that the adducts have 1:2 stoichiometry, non-electrolytic and paramagnetic at room temperature. On the basis of spectral studies, a distorted octahedral geometry is proposed around copper(II) ion. ESR studies depicted elongated axial symmetry of Cu(II)adducts with nitrogen donors. Moreover, the adducts also showed potential antifungal activity against Fusarium oxysporium.

Desulfurization from Gasoline by Polymer Resin at Room Temperature and Atmospheric Pressure

2011 ◽  
Vol 396-398 ◽  
pp. 1283-1286
Author(s):  
Jian Peng Zhu ◽  
Chun Hu Li ◽  
Jia Ling Chen ◽  
Ying Wei Luo
Keyword(s):  
Reaction Time ◽  
Sulfur Content ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Oxidative Desulfurization ◽  
Sulfur Compounds ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Polymer Resin ◽  
Mild Conditions

Abstract. Investigation of polymer resin as catalyst in the oxidative desulfurization (ODS) process has revealed that the method can be applied to make a relative high removal of sulfur compounds. The reaction conditions, including temperature, amount of oxidant and reaction time were studied. The best result occurs under mild conditions with respect to room temperature and atmospheric pressure, to remove 75.54% of the totle sulfur content in the presence of H2O2 with an O/S molar ratio of 17. Possible mechanism is also disscussed.

scholarly journals Room-temperature dissolution and chemical modification of cellulose in aqueous tetraethylammonium hydroxide–carbamide solutions

Cellulose ◽  
2019 ◽  
Vol 27 (4) ◽  
pp. 1933-1950 ◽  
Author(s):  
Juho Antti Sirviö ◽  
Juha P. Heiskanen
Keyword(s):  
Chemical Modification ◽  
Charge Density ◽  
Microcrystalline Cellulose ◽  
Room Temperature ◽  
Molar Ratio ◽  
Cellulose Modification ◽  
Tetraethylammonium Hydroxide ◽  
Cellulose Concentration

AbstractThe room-temperature dissolution of cellulose in aqueous tetraethylammonium hydroxide (TEAOH) in the presence of carbamides (ureas) was investigated. Without carbamide, 35 wt% TEAOH was able to dissolve cellulose (microcrystalline cellulose) up to 3 wt%, whereas carbamides—such as urea, N-methylurea, N-ethylurea, 1,3-dimethylurea, and imidazolidone—were able to improve the dissolution of cellulose. At 5 wt% cellulose concentration, the highest carbamide contents in the solvent still able to dissolve cellulose within 1 h were 56 and 55 wt% of 1,3-dimethylurea and N-methylurea, respectively. When using urea, up to 15% of cellulose could be dissolved in a solution containing 22 wt% of urea. To demonstrate the possibility of the use of a carbamide-based solvent in cellulose modification, cationic cellulose was produced using glycidyltrimethylammonium chloride (GTAC). At a molar ratio of 1:3 of cellulose and GTAC, all the studied TEAOH–carbamide solvents produce cationic cellulose with higher charge density compared to the reference NaOH–urea solvent.

LARGE ROOM TEMPERATURE MAGNETORESISTANCE IN (La0.7Sm0.3)0.7Sr0.3MnO3/Agx COMPOSITES

2005 ◽  
Vol 19 (30) ◽  
pp. 4467-4473 ◽  
Author(s):  
XIAO-BO YUAN ◽  
YI-HUA LIU ◽  
CHENG-JIAN WANG ◽  
LIANG-MO MEI
Keyword(s):  
Experimental Data ◽  
Grain Boundaries ◽  
Room Temperature ◽  
Composite System ◽  
Molar Ratio ◽  
Ag Addition ◽  
Brillouin Function ◽  
Spin Clusters ◽  
Good Agreement

The effects of Ag addition in the composite ( La 0.7 Sm 0.3)0.7 Sr 0.3 MnO 3/ Ag x (abbreviated as LSSMO/Ag x) has been studied. The results showed that Ag addition induces the decrease in resistivity (ρ) due to the improvement of grain boundaries resulted from the segregation of Ag on the grain surfaces. In addition, 27% molar ratio of Ag addition induces a large room temperature magnetoresistance (MR) ratio of 35%. The good agreement of experimental data with Brillouin function indicates that the MR behavior in this composite system accounts for the spin-dependent hopping of the electrons between the spin clusters.

scholarly journals Electrical Conductivity Studies on Co(II), Cu(II),Ni(II) and Cd(II) Complexes of Azines

2008 ◽  
Vol 5 (4) ◽  
pp. 797-801 ◽  
Author(s):  
M. Revanasiddappa ◽  
Syed Khasim ◽  
S. C. Raghavendra ◽  
C. Basavaraja ◽  
T. Suresh ◽  
...  
Keyword(s):  
Room Temperature ◽  
Molar Conductance ◽  
Molar Ratio ◽  
Temperature Conductivity ◽  
Physical Methods ◽  
Alcoholic Medium ◽  
Electrical Conductivities ◽  
Powder Samples ◽  
Higher Temperature ◽  
Uv Visible

1-Phenyl-4-(2'-hydroxyphenyl-1-yl)di-imino azine, {1P-4-(2' HPDA)} 1, 4(2'-hydroxyphenyl-1-yl)di-imino azine, {1, 4-(2' HPDA)} are derived from benzophenone hydrozone with different aldehydes in presence of few drops of concentrated hydrochloric acid in alcoholic medium. Metal(II) complexes have been prepared by salts of CoCl2, CuCl2, NiCl2and CdCl2reacting with azine ligands dissolved in alcohol in the molar ratio of (1:2). The prepared complexes were characterized by using various physical methodsviz. elemental, molar conductance, magnetic susceptibility, IR, NMR, XRD and UV-Visible. Conductivity of the powder samples were measured by two probe method. Measured electrical conductivities of Co(II), Cu(II), Ni(II) and Cd(II) complexes of azines are reported in this paper. It is found that at room temperature these complexes show insulator behavior. At higher temperature conductivity increases linearly, showing semi conducting behavior.

Thermodynamic Analysis of Chemical Vapor Deposition Progress for SiC Coatings

2014 ◽  
Vol 633 ◽  
pp. 183-188 ◽  
Author(s):  
Ming Wei Chen ◽  
Hai Peng Qiu ◽  
Jian Jiao ◽  
Xiu Qian Li ◽  
Yu Wang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Thermodynamic Analysis ◽  
Reaction Temperature ◽  
Vapor Deposition ◽  
Raw Materials ◽  
Chemical Vapor ◽  
Molar Ratio ◽  
System Pressure ◽  
Optimal Reaction Temperature ◽  
Sic Coatings

Equilibrium compositions of chemical vapor deposition progress for silicon carbide (CVD-SiC) coatings with MTS/H2 mixture system were calculated by means of HSC Chemistry5.0 code, and influences of the reaction temperature (T), the system pressure (P) and the composition of raw materials (molar ratio of H2 to SiCH3Cl3, β) were investigated. Thermodynamic analysis showed that the value of nC /nSiC in reaction product decreased to a minimum and then increased with the increase of the reaction temperature between 700-1600°C, which meant an optimal reaction temperature existed theoretically for CVD-SiC coatings with highest purity. Furthermore, CVD-SiC coatings with high purity were obtained by experiments under the reaction pressure of 10kPa, H2/SiCH3Cl3 value of 10 and reacton temperature of 1100°C, which was in accordance with the theoretical prediction.

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