Effect of Experimental Conditions on the Chemical Composition of Hydroxyapatite Synthesized by Chemical Precipitation

MRS Advances ◽  
2017 ◽  
Vol 2 (61) ◽  
pp. 3851-3857 ◽  
Author(s):  
Jorge López-Cuevas ◽  
Juan C. Rendón-Angeles ◽  
José L. Rodríguez-Galicia ◽  
Carlos A. Gutiérrez-Chavarría
Keyword(s):  
Particle Size ◽  
Chemical Composition ◽  
Room Temperature ◽  
Ambient Air ◽  
Chemical Precipitation ◽  
Molar Ratio ◽  
Experimental Conditions ◽  
Molar Ratios ◽  
Pure Phase ◽  
Suspension Ph

ABSTRACTHydroxyapatite [HAp, Ca5(PO4)3(OH)] was synthesized by chemical precipitation, using H3PO4 and Ca(OH)2 as chemical precursors. The precursors were slowly mixed in suitable proportions aiming to obtain Ca/P molar ratios of 1.5, 1.67 or 2.0 in the reacting suspension. This was followed by 21.5 h of aging. Both reaction and aging stages were carried out under an atmosphere of still ambient air and under continuous stirring, either at room temperature, 60 or 90 °C. The precipitates were characterized by ICP-AES and XRD. The results suggested that the most suitable Ca/P molar ratio for the production of pure phase HAp is Ca/P = 1.67, as long as the initial Ca(OH)2 particle size and/or the suspension pH are carefully controlled, especially when the synthesis is carried out above room temperature.

Fe3O4 Magnetic Preparation by Bauxite Ore Washing Fine Mud

2014 ◽  
Vol 1010-1012 ◽  
pp. 961-965
Author(s):  
Jian Qiang Xiao ◽  
Guo Wei He ◽  
Yan Jin Hu
Keyword(s):  
Particle Size ◽  
Aging Time ◽  
Average Particle Size ◽  
Xrd Analysis ◽  
Test Methods ◽  
Raw Material ◽  
Molar Ratio ◽  
Average Particle ◽  
Experimental Conditions ◽  
Particle Size Analyzer

Bauxite waste sludge as a raw material, the use of reverse chemical coprecipitation synthesize Fe3O4. Researching temperature, precipitation concentration, aging time and Fe2+/Fe3+ molar ratio effect on the particle size, morphology. Optimal experimental conditions: temperature 70 °C, the precipitant NaOH mass ratio of 10%, aging time 3h, Fe2+/Fe3+ molar ratio of 2:3. Test methods using a laser particle size analyzer, XRD analysis of the products were characterized, the product is Fe3O4, the average particle size of 0.11mm.

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.

Modeling the influence of chemical composition on compressive strength behavior of alkali-activated phosphorus slag cement using statistical design

2018 ◽  
Vol 45 (12) ◽  
pp. 1073-1083 ◽  
Author(s):  
Hamideh Mehdizadeh ◽  
Ebrahim Najafi Kani
Keyword(s):  
Compressive Strength ◽  
Chemical Composition ◽  
Statistical Design ◽  
Molar Ratio ◽  
Statistical Experimental Design ◽  
Molar Ratios ◽  
Strength Behavior ◽  
Optimum Chemical Composition ◽  
Optimum Chemical ◽  
Alkali Activated

In this study, a statistical experimental design based on response surface methodology (RSM) has been applied to predict and optimize the compressive strength of alkali-activated phosphorus slag in different ages (3, 7, and 28 days). For this purpose, the binder samples were prepared with different molar ratios of SiO2/Na2O (S/N), Na2O/Al2O3(Na/Al), and H2O/Al2O3(H/Al) as alkali activator. Results showed that S/N molar ratio plays its role in early ages of curing and Na/Al molar ratio, and showed its significant effect on 7 and 28 days of compressive strength. H/Al molar ratio had the most significant effect on compressive strength compared to the other parameters. The derived RSM models were statistically adequate and could be used to predict the compressive strength. The optimum chemical composition of activator to obtain the highest compressive strength was achieved as 0.39, 1.34, and 30 for S/N, Na/Al, and H/Al molar ratios, respectively, with compressive strength of 30, 65, and 100 MPa at 3, 7, and 28 days of curing.

scholarly journals Synthesis of Calcium Orthophosphates by Chemical Precipitation in Aqueous Solutions: The Effect of the Acidity, Ca/P Molar Ratio, and Temperature on the Phase Composition and Solubility of Precipitates

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1009
Author(s):  
Mykola V. Nikolenko ◽  
Kateryna V. Vasylenko ◽  
Victoria D. Myrhorodska ◽  
Andrii Kostyniuk ◽  
Blaž Likozar
Keyword(s):  
Solid Phase ◽  
Chemical Precipitation ◽  
Molar Ratio ◽  
Key Factors ◽  
Correlation Dependence ◽  
Molar Ratios ◽  
Calcium Orthophosphates ◽  
Calcium Cations ◽  
Solubility Isotherms ◽  
Solubility Products

Studies on chemical precipitation of the calcium orthophosphates have shown that their phase compositions do not vary depending on molar ratio Ca/P but are sensitive to solutions acidity and temperature. These are two key factors that determine the phase transformation progress of metastable phases into less soluble precipitates of the phosphates. It was proposed to compare calcium orthophosphates solubility products with calcium cations quantities in their formulas. It was found that there was a linear correlation between calcium orthophosphates specific solubility products and their molar ratios Ca/P if hydroxyapatite and its Ca-deficient forms were excluded from consideration. It was concluded that the relatively large deviations of their solubility products from the found correlation should be thought of as erroneous data. That is why solubility products were changed in accordance with correlation dependence: pKS for hydroxyapatite was 155, pKS for Ca-deficient hydroxyapatites was 114–155. The solubility isotherms, which were calculated on the basis of the corrected pKS values, coincided with the experimental data on solid-phase titration by Pan and Darvell.

Study on the Preparation and Properties of Piezoelectric Glass-Ceramic Sr0.5Ba0.5Nb2O6

2013 ◽  
Vol 669 ◽  
pp. 204-207
Author(s):  
Shan Jiang ◽  
Jing Wen Lv ◽  
Tao Zheng
Keyword(s):  
Particle Size ◽  
Glass Ceramic ◽  
Crystalline Phase ◽  
Room Temperature ◽  
Glass Ceramics ◽  
Molar Ratio ◽  
Spectral Transmittance ◽  
Melting Method ◽  
Ceramic Samples ◽  
Analytical Reagents

Series of ferroelectric glass-ceramic samples of Sr0.5Ba0.5Nb2O6 were synthesized by melting method. Firstly, analytical reagents were melted for 30 minutes at 1440°C after being grinded evenly according to a certain molar ratio, then annealed for 10 hours from 550°C to room temperature, finally it was sustained for 4 hours at constant temperature about 700°C. The hardness and transmittance parameters of SBN glass-ceramic were tested. Results indicated the sample had the best property when the amount of Nb2O5 was 10mol%, whose hardness reached 506 kg/mm2, and spectral transmittance was higher than 35% . XRD spectra of this sample indicated this SBN glass-ceramics contained a large number of Sr0.5Ba0.5Nb2O6 crystalline phase and a small amount of Sr0.3Ba0.7Nb2O6 phase. The particle size was about 50 nm.

Effects of Si/Al Molar Ratio on Morphology of Mullite Nanocomposite Synthesized from Kaolin

2011 ◽  
Vol 682 ◽  
pp. 55-59
Author(s):  
Nan Chun Chen ◽  
Wei Wang ◽  
Ai Ping Deng ◽  
Han Mei Ao ◽  
Quan Hong Li
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Aspect Ratio ◽  
Size Distribution ◽  
Calcination Temperature ◽  
Grain Size Distribution ◽  
Distribution Patterns ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Low Aspect Ratio

Mullite nanocomposite was synthesized using kaolin with different Si/Al molar ratios in the range of 1.1- 4.31. The synthesized samples were analyzed and characterized using XRD and SEM techniques and effects of Si/Al molar ratio on mullite nanocrystal morphology have been investigated. SEM results showed that the mullite nanocomposite synthesized from kaolin with different Si/Al molar ratios had different morphologies and distribution patterns of particle size. It was found that the mullite nanocrystals with relatively homogenous grain-size distribution, low aspect ratio, and little agglomeration were produced from the precursors made from kaolin with a Si/Al ratio of 1.1-2.33 at calcination temperature of 1100-1250 oC.

Effects of Synthesis Parameters on Hydrothermal Synthesis of NaA Zeolite

2010 ◽  
Vol 148-149 ◽  
pp. 1444-1448
Author(s):  
Lin Lin Yuwen ◽  
Meng Fu Zhu ◽  
Hong Bo Su ◽  
Xiu Dong You ◽  
Cheng Deng ◽  
...  
Keyword(s):  
Particle Size ◽  
Molar Ratio ◽  
Crystallization Time ◽  
X Ray Diffraction ◽  
Molar Ratios ◽  
Naa Zeolite ◽  
Optimum Synthesis ◽  
Synthesis Parameters ◽  
Particle Size Analyzer ◽  
Crystal Particle

In this research, NaA zeolite samples were synthesized from aluminosilicate solution through hydrothermal method. The effects of different parameters such as the SiO2/Al2O3, OH-/Si and H2O/Na2O molar ratios of the initial gel solution, crystallization time and temperature on the crystallinity and morphology of the synthesized zeolites were investigated. The final products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size analyzer. The experiment results indicated that the SiO2/Al2O3 molar ratio had influence on morphology and size of the synthesized zeolites, the optimum range of SiO2/Al2O3 molar ratio for synthesizing NaA zeolite was 1.5-2. Alkalinity (OH-/Si and H2O/Na2O molar ratio) had a significant effect on particle sizes of the synthesized zeolites, the higher the alkalinity, the smaller the crystal particle size. In addition, it was found that crystallization temperature during hydrothermal treatment played an important role in reducing the over all reaction time. The crystallization time had effect on the crystallinity of the synthesized zeolites. Finally, the optimum synthesis parameters can be proposed in order to synthesize NaA zeolite with desirable particle size, crystallinity and morphology.

Synthesis of ZnO at Different Atomic Proportion Produced by Chemical Precipitation

2012 ◽  
Vol 1481 ◽  
pp. 127-133
Author(s):  
A. Medina ◽  
L. Béjar ◽  
G. Herrera-Pérez
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Composition ◽  
Chemical Precipitation ◽  
Growth Direction ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wurtzite Crystal Structure ◽  
Transmission Electron

ABSTRACTZinc oxide (ZnO) nanoparticles were produced using chemical precipitation synthesis with a molar ratio of 1:1, 1:2 and 1:3. The structure, chemical composition and morphology were investigated by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). XRD and EDS demonstrated that the all particles formed at different atomic proportion were of wurtzite crystal structure with the same chemical composition. SEM and TEM showed the formation of hexagonal particles with a molar ratio of 1:1 while the samples synthesized with a molar ratio 1:2 and 1:3 showed a circular shape. HRTEM and Fast Fourier Transform (FFT) demonstrated that the all particles were formed with a preferable [0001] growth direction.

Nature of mixed iron and aluminium gels as affected by Fe/Al molar ratio, pH and citrate

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 511-519 ◽  
Author(s):  
A. Violante ◽  
C. Colombo ◽  
G. Cinquegrani ◽  
P. Adamo ◽  
P. Violante
Keyword(s):  
Citric Acid ◽  
Short Range ◽  
Room Temperature ◽  
Ammonium Oxalate ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Long Period ◽  
Ph Values ◽  
Presence And Absence

AbstractThe nature and mineralogy of mixed Al and Fe(III) gels (initial Fe/Al molar ratios (Ri) of 1.0 and 2.5) formed at pH values ranging from 4.0 to 10.0, both in the presence and absence of citric acid (citrate/Fe + AI molar ratio (Rcit) of 0.01 and 0.1) and aged for a long period at room temperature and at 50°C have been studied. The complexes showed considerable differences in the mineralogy of the precipitation products. The samples formed at Ri = 1.0 contained ferrihydrite at pH 4.0, ferrihydrite + gibbsite at pH 5.0-7.0, and hematite + Al(OH)3polymorphs + ferrihydrite at pH 9.0-10.0. The samples formed at Ri = 2.5 had greater quantities of poorly crystallized ferrihydrite. Large amounts of Fe+Al (25-82%) were solubilized from the samples aged for 60 days at 50°C by ammonium oxalate. The addition of increasing concentrations of citrate to the gel suspensions containing equimolar amounts of Fe and AI strongly inhibited the formation of Al(OH)3polymorphs both at pH 5.0 or 8.5 by promoting the formation of short-range ordered materials. Citrate added initially to Fe-Al solutions (R*cit = 0.1) completely inhibited formation of crystals even after 135 days at 50°C.

scholarly journals Synthesis of Water-Repellent Coating for Polyester Fabric

2021 ◽  
Vol 5 (5) ◽  
pp. 747-754
Author(s):  
Nur Nabilah Mohd Za’im ◽  
Hartina Mohd Yusop ◽  
Wan Norfazilah Wan Ismail
Keyword(s):  
Particle Size ◽  
Sol Gel ◽  
Polyester Fabric ◽  
Molar Ratio ◽  
Water Repellent ◽  
Hydrophobic Property ◽  
Sem Images ◽  
Water Contact ◽  
Molar Ratios ◽  
Good Surface

A new hydrophobic hexyltrimethoxysilane (HTMS) coating for polyester fabric was successfully synthesized via a one-step water-based sol-gel method under acidic condition. Five different molar ratios of HTMS: water (1;40, 1:30, 1:20, 1:12 and 1:3) were prepared and the solution was deposited onto the polyester fabric by a simple dip-pad-cure process. The effect of water content on hydrophobicity was evaluated by manual testing on the treated polyester fabric samples. The effectiveness of hydrophobicity properties was further characterized using water contact angle (WCA) measurement. The optimized molar ratio of 1:3 was found to obtain the best hydrophobic property of 136.2° with particle size 115.3 µm measured using Particle Size Analyzer (PSA). Fourier transform infrared spectroscopy (FTIR) analysis confirmed the success of sol gel process with the presence of Si-O-Si band, which was also determined using energy dispersive X-ray spectroscopy (EDX). The Scanning Electron Microscopy (SEM) images revealed a good surface morphology of the homogenous thin xerogel coating with no visible cracks. Using HTMS without combinations of other precursors resulted in rough surface structure due to the low surface energy caused by long-chain alkyl silane in the HTMS coating and this provided the treated polyester fabric with good hydrophobicity. Doi: 10.28991/esj-2021-01309 Full Text: PDF

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