Effect of Synthesis Temperature and Ca/P Ratios on Specific Surface Area of Amorphous Calcium Phosphate

2016 ◽  
Vol 721 ◽  
pp. 172-176 ◽  
Author(s):  
Jana Vecstaudza ◽  
Janis Locs
Keyword(s):  
Calcium Phosphate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Amorphous Calcium Phosphate ◽  
Calcium Phosphates ◽  
Synthesis Temperature ◽  
Molar Ratios ◽  
Different Temperatures ◽  
Low Crystalline

Amorphous and low crystalline calcium phosphates are prospective candidates for bone implant manufacturing. Amorphous calcium phosphate (ACP) preparation technologies could be improved in terms of specific surface area (SSA) of obtained products. Current study is dedicated to the effect of synthesis temperature and Ca and P molar ratios (Ca/P) on SSA of ACP. Higher SSA can improve bioactivity of biomaterials. ACP was characterized by XRD, FT-IR, SEM and BET N2 adsorption techniques. Spherical nanoparticles (<45 nm in size) were obtained independently of initial Ca/P ratio and synthesis temperature. For the first time comparison of SSA was shown for ACP obtained at different temperatures (0 °C and 20 °C) and Ca/P molar ratios (1.5, 1.67 and 2.2).

Synthesis of Amorphous Calcium Phosphate: A Review

2020 ◽  
Vol 850 ◽  
pp. 199-206
Author(s):  
Marika Mosina ◽  
Janis Locs
Keyword(s):  
Calcium Phosphate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Amorphous Calcium Phosphate ◽  
Molar Ratio ◽  
Synthesis Conditions ◽  
Synthesis Routes

The aim of this study is to summarize various synthesis routes of amorphous calcium phosphate (ACP), focusing on properties, especially Ca/P molar ratio and specific surface area (SSA) of obtained ACP. The effects of synthesis conditions on properties of final products are analysed and discussed.

Amorphous Calcium Phosphate Biomaterials with High Specific Surface Area

2021 ◽  
Author(s):  
◽  
Jana Vecstaudža
Keyword(s):  
Calcium Phosphate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Amorphous Calcium Phosphate ◽  
Synthesis Method ◽  
High Specific Surface Area ◽  
Structure Stability ◽  
Tissue Replacement ◽  
New Synthesis

The Doctoral Thesis is devoted to synthesis and characterization of amorphous calcium phosphate materials with emphasis on their specific surface area. Ways of optimization of an existing synthesis method are investigated experimentally as well as the development of a new synthesis method for obtaining amorphous calcium phosphate with specific surface area value close to the biological calcium phosphate (>100 m2/g). Amorphous calcium phosphate obtained with the developed method is studied for its structure, stability, thermal properties, furthermore, dense amorphous calcium phosphate bioceramics has been developed using the principles of cold sintering process. The developed biomaterials are intended for bone tissue replacement and regeneration. The Thesis is prepared as a collection of articles. It contains a summary and four publications.

scholarly journals Improve in CO2 and CH4 Adsorption Capacity on Carbon Microfibers Synthesized by Electrospinning of PAN

Fibers ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 81 ◽  
Author(s):  
Reyna Ojeda-López ◽  
J. Marcos Esparza-Schulz ◽  
Isaac J. Pérez-Hermosillo ◽  
Armin Hernández-Gordillo ◽  
Armando Domínguez-Ortiz
Keyword(s):  
Specific Surface ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Gas Adsorption ◽  
Morphological Structure ◽  
Different Temperatures ◽  
Ch4 Adsorption ◽  
Stabilization Temperature ◽  
Carbon Microfibers

Carbon microfibers (CMF) has been used as an adsorbent material for CO2 and CH4 capture. The gas adsorption capacity depends on the chemical and morphological structure of CMF. The CMF physicochemical properties change according to the applied stabilization and carbonization temperatures. With the aim of studying the effect of stabilization temperature on the structural properties of the carbon microfibers and their CO2 and CH4 adsorption capacity, four different stabilization temperatures (250, 270, 280, and 300 °C) were explored, maintaining a constant carbonization temperature (900 °C). In materials stabilized at 250 and 270 °C, the cyclization was incomplete, in that, the nitrile groups (triple-bond structure, e.g., C≡N) were not converted to a double-bond structure (e.g., C=N), to form a six-membered cyclic pyridine ring, as a consequence the material stabilized at 300 °C resulting in fragile microfibers; therefore, the most appropriate stabilization temperature was 280 °C. Finally, to corroborate that the specific surface area (microporosity) is not the determining factor that influences the adsorption capacity of the materials, carbonization of polyacrylonitrile microfibers (PANMFs) at five different temperatures (600, 700, 800, 900, and 1000 °C) is carried, maintaining a constant temperature of 280 °C for the stabilization process. As a result, the CMF chemical composition directly affects the CO2 and CH4 adsorption capacity, even more directly than the specific surface area. Thus, the chemical variety can be useful to develop carbon microfibers with a high adsorption capacity and selectivity in materials with a low specific surface area. The amount adsorbed at 25 °C and 1.0 bar oscillate between 2.0 and 2.9 mmol/g adsorbent for CO2 and between 0.8 and 2.0 mmol/g adsorbent for CH4, depending on the calcination treatment applicated; these values are comparable with other material adsorbents of greenhouse gases.

Property of Nanoporous Metal-Organic Frameworks at Different Synthesis Temperature

2012 ◽  
Vol 427 ◽  
pp. 123-127
Author(s):  
Yuan Hui Ma ◽  
Lei Zhang ◽  
Cheng Chun Tang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Reaction Temperature ◽  
Metal Organic Frameworks ◽  
Synthesis Temperature ◽  
Structure Stability ◽  
Nanoporous Metal ◽  
Metal Organic ◽  
Ft Ir

The nanoporous metal-organic frameworks were synthesized under solvothermal conditions using organic solvent dimethylformamide. The samples were characterized by XRD, SEM, TGA, FT-IR and specific surface area for their properties difference. When the reaction temperature rises, the particle size becomes larger. All TGA curves are the basically same, the framework structure begins to be destroyed from 500°C up to around 600°C. The metal-organic frameworks accepted at reaction temperature 190°C have larger specific surface area and better structure stability.

Effect of pH, Molar Ratio of Fuel to Nitrates and Calcination Temperature on the Glycine-Nitrate Synthesis of Nano CoAl2O4

2010 ◽  
Vol 68 ◽  
pp. 176-181 ◽  
Author(s):  
Seyyed Hamid Jazayeri ◽  
Federica Bondioli ◽  
Shiva Salem ◽  
Ali Allahverdi ◽  
Mansoor Shirvani ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Precursor Solution ◽  
Molar Ratio ◽  
Effect Of Ph ◽  
Molar Ratios ◽  
Metal Nitrates ◽  
Powder Characteristics

In this research, solution-based combustion synthesis is applied to prepare the spinel CoAl2O4 pigment from precursor solution of Al(NO3)3 .9H2O, Co(NO3)2 .6H2O and glycine. Effect of pH values (2.5, 7, 10.5), molar ratio of fuel to metal nitrates in the precursor solutions (1.5, 2) and subsequent calcination temperature (800, 1000, 1200 °C) on the powder characteristics are described. Gel formation, morphologies, specific surface area and colour of the powder are characterized using DTA/TG, XRD, TEM, BET and UV-Vis. The results indicate that the crystalline spinel CoAl2O4 is formed at all different Gl/(metal nitrates) molar ratios, pH and temperatures and higher temperature promote the increase of the crystallite size. According to TEM figures most of the particles calcined at 800 and 1000 °C has sizes less than 50 and 100 nm, respectively. Corresponding to results of BET experiment, specific surface area has its maximum values at pH 7 and decreases with increasing of temperature. Finally, colorability test indicates the complete stability of the synthesized powder in the glass matrix.

Novel Al2O3–SiO2composite aerogels with high specific surface area at elevated temperatures with different alumina/silica molar ratios prepared by a non-alkoxide sol–gel method

RSC Advances ◽  
2016 ◽  
Vol 6 (7) ◽  
pp. 5611-5620 ◽  
Author(s):  
Xiaodong Wu ◽  
Gaofeng Shao ◽  
Xiaodong Shen ◽  
Sheng Cui ◽  
Ling Wang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Elevated Temperatures ◽  
Inorganic Salt ◽  
Sol Gel ◽  
High Specific Surface Area ◽  
Gel Method ◽  
Molar Ratios ◽  
Composite Aerogels

We have developed a new sol–gel route to synthesise Al2O3–SiO2composite aerogels with different alumina/silica (Al/Si) molar ratios using an inexpensive inorganic salt.

scholarly journals Influence of Structure-Directing Additives on the Properties of Poly(methylsilsesquioxane) Aerogel-Like Materials

Gels ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 6 ◽  
Author(s):  
Marta Ochoa ◽  
Alyne Lamy-Mendes ◽  
Ana Maia ◽  
António Portugal ◽  
Luísa Durães
Keyword(s):  
Specific Surface ◽  
Bulk Density ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Porosity ◽  
Poly Ethylene Glycol ◽  
Optimum Amount ◽  
Molar Ratios ◽  
Fine Control ◽  
Poly Ethylene

The effect of glycerol (GLY) and poly(ethylene glycol) (PEG) additives on the properties of silica aerogel-like monoliths obtained from methyltrimethoxysilane (MTMS) precursor was assessed. The tested molar ratios of additive/precursor were from 0 to 0.1 and the lowest bulk densities were obtained with a ratio of 0.025. When a washing step was performed in the sample containing the optimum PEG ratio, the bulk density could be reduced even further. The analysis of the material’s microstructure allowed us to conclude that GLY, if added in an optimum amount, originates a narrower pore size distribution with a higher volume of mesopores and specific surface area. The PEG additive played a binder effect, leading to the filling of micropores and the appearance of large pores (macropores), which caused a reduction in the specific surface area. The reduction of the bulk density and the microstructural changes in the aerogels induced by adding a small amount of these additives confirm the possibility of fine control of properties of these lightweight materials. The achieved high porosity (97%) and low thermal conductivity (~35 mW·m−1·K−1) makes them suitable to be used as thermal insulators.

Pore structure of pyrolyzed scrap tires

2008 ◽  
Vol 62 (1) ◽  
Author(s):  
Zuzana Koreňová ◽  
Juma Haydary ◽  
Július Annus ◽  
Jozef Markoš ◽  
L’udovít Jelemenský
Keyword(s):  
Thermal Decomposition ◽  
Carbon Black ◽  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nitrogen Flow ◽  
Solid Matter ◽  
Scrap Tires ◽  
Different Temperatures

AbstractInternal structure of carbon black produced by pyrolysis (CBp) of rubber samples from the top and bottom parts of sidewall and tread of a passenger car tire was investigated in nitrogen flow at different temperatures. The pore structure (specific surface area, pore size distribution, and porosity) of CBp and commercial CB, was compared. The development of pore structure and the increase of the specific surface area were most intensive during the thermal decomposition at temperatures ranging from 300°C to 500°C. This is caused by the intensive release of volatiles during the pyrolysis. After the pyrolysis was finished, at temperatures above 500°C, further decomposition of solid matter was associated with a slight increase of the specific surface area.

scholarly journals INFLUENCE OF SYNTHESIS TECHNO-CHEMICAL PARAMETERS ON PHYSICOCHEMICAL CHARACTERISTICS OF BIOMIMETIC CALCIUM-PHOSPHATE NANOCOMPOSITE DOPED BY SILICATE AND CARBONATE ANIONS

2020 ◽  
Vol 5 (10) ◽  
pp. 47-56
Author(s):  
M. Troubitsin ◽  
Viet Hung Hoang ◽  
L. Furda
Keyword(s):  
Calcium Phosphate ◽  
Specific Surface ◽  
Crystallite Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Average Pore Size ◽  
Average Crystallite Size ◽  
Average Pore ◽  
The Impact

The object of our investigation is a biomimetic calcium-phosphate nanocomposite doped by silicate and carbonate anions (BMHAP) synthesized by chemical deposition from aqueous solutions. The obtained samples are investigated using X-ray phase analysis (XRD), FTIR spectroscopy, and low-temperature nitrogen adsorption (BET method). The influence of the techno chemical synthesis parameters on the products characteristics (including phase composition, crystal lattice parameters, average crystallite size, specific surface area) is evaluated. The study on the effect of the synthesis temperature shows that with increasing in temperature from 22°C to 80°C, reveals a slight increase in the parameters of unit cells a and c, which leads to an increase in its volume. There is also a tendency towards a decrease in the average size of coherent scattering regions of crystallites (from 7,52 to 4,65 nm) and specific surface area (from 192,51 to 74,72 m2/g), but the pore volume and average pore diameter of the synthesized powders increases. The effect of the aging time of the sediment in the mother liquor is studied from 0,5 to 24 hours. It is found that with an increase in the maturation time of the sediment, the percent crystallinity of the powders improves by 1,7 times, an increase in the specific surface area from 163,43 to 192,51 m2/g and a slight decrease in the pore volume and average pore size of the samples are observed. The impact of the stirring rate of the reagents is investigated. An increase in speed from 300 to 1300 rpm has been shown to decrease the average crystallite size from 8,80 to 6,41 nm, and as a result, to increase the specific surface area of the synthesized samples from 178,58 to 192,51 m2/g, respectively.

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