scholarly journals Synthesis of Hydroxyapatite by Interfacial Reaction in a Multiple Emulsion

2007 ◽  
Vol 2007 ◽  
pp. 1-4 ◽  
Author(s):  
Isao Kimura
Keyword(s):  
Interfacial Reaction ◽  
Aqueous Phase ◽  
Single Phase ◽  
Nitrate Solution ◽  
Calcium Nitrate ◽  
Phosphate Solution ◽  
Multiple Emulsion ◽  
Hydrogen Phosphate ◽  
Dipotassium Hydrogen Phosphate ◽  
Initial Ph

Interfacial reaction in a multiple emulsion, which is one of methods for producing inorganic microspheres, was applied to synthesize hydroxyapatite. The multiple emulsion was a W/O/W emulsion, made of dipotassium hydrogen phosphate solution as an inner aqueous phase, benzene as an oil phase, and calcium nitrate solution as an outer aqueous phase. The reaction was carried out in the multiple emulsion for 24 hours at 323 K. The crystalline phase was varied with an initial pH of the inner aqueous phase, and single phase hydroxyapatite was synthesized at an initial pH of 12. The products were composed of porous microspheres of less than 3 μm in size. The microspheres were composed of nanospheres of less than 120 nm in size. By considering the mass balance, it was suggested that each nanosphere was formed in an inner aqueous phase droplet.

Effect of Dipotassium Hydrogen Phosphate and Calcium Nitrate on Strength and Microstructural Properties of Geopolymer Mortar

2019 ◽  
Vol 821 ◽  
pp. 486-492
Author(s):  
Norbaizurah Rahman ◽  
Amalina Hanani Ismail ◽  
Andri Kusbiantoro
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
Setting Time ◽  
Relevant Literature ◽  
Calcium Nitrate ◽  
Microstructural Properties ◽  
Hydrogen Phosphate ◽  
Strength Performance ◽  
Dipotassium Hydrogen Phosphate

Adoption of coal fly ash (Class C) as the main source material for geopolymers would cause rapid setting to the fresh geopolymer mortar or concrete. This behaviour explained the limited application of this material in the construction industry. On the other hand, calcium nitrate (Ca (NO3)2) and dipotassium hydrogen phosphate (K2HPO4) are alternative admixtures that known to extend the setting time of fresh geopolymers. However, their effect on the strength and microstructural properties remain unclear due to the limitation of relevant literature from previous studies. Therefore, this study aims to investigate the effect of these admixtures in fly ash based geopolymer system, particularly to its strength performance. The effects of adding Ca (NO3)2 and K2HPO4 were evaluated at dosages of 0.5%, 1.5%, and 2.5% (by fly ash weight) in the geopolymer mixture, and samples were cured at room temperature. Hardened geopolymer specimens were measured for their compressive strength, porosity, and microstructural characteristic. The inclusion of 0.5% of alternative chemical reagents was found as the optimum proportion and able to enhance the compressive strength of the geopolymer mixtures. However, efflorescence was detected on the surface of the hardened specimen when K2HPO4 was included in its mixture. This phenomenon is influenced by the presence of monovalent and trivalent anions in the system namely nitrates and phosphates. In this study, each anion had a particular role in each stage of geopolymerisation, and determined the quality via crystal growth control and influenced the development of aluminosilicate structures.

Biomimetic Preparation of ha Precursors at 37°C in Urea- and Enzyme Urease-Containing Synthetic Body Fluids

1999 ◽  
Vol 599 ◽  
Author(s):  
D Bayraktar ◽  
A C. Tas
Keyword(s):  
Single Phase ◽  
Calcium Nitrate ◽  
Calcium Hydroxyapatite ◽  
Chemical Precipitation ◽  
Calcium Nitrate Tetrahydrate ◽  
Hydrogen Phosphate ◽  
Synthetic Bone ◽  
Nitrate Tetrahydrate ◽  
Phosphate Salts ◽  
Diammonium Hydrogen

AbstractAn important inorganic phase of synthetic bone applications, calcium hydroxyapatite (HA, Ca10(PO4)6(OH)2), was prepared as a single-phase and sub-micron bioceramic powder. Carbonated HA precursors were synthesized from calcium nitrate tetrahydrate and diammonium hydrogen phosphate salts dissolved in “synthetic body fluid” (SBF) solutions, containing urea (H2NCONH2) and enzyme urease, under the biomimetic conditions of 37°C and pH 7.4, by using a novel chemical precipitation technique.

Calcium phosphate with high specific surface area synthesized by a reverse micro-emulsion method

MRS Advances ◽  
2016 ◽  
Vol 1 (11) ◽  
pp. 723-728 ◽  
Author(s):  
Tomoaki Sugiyama ◽  
Shusuke Akiyama ◽  
Toshiyuki Ikoma
Keyword(s):  
Calcium Phosphate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nitrate Solution ◽  
Calcium Nitrate ◽  
Phosphate Solution ◽  
Crystalline Phases ◽  
Emulsion Method ◽  
Micro Emulsion

ABSTRACTA reverse micro-emulsion method has been investigated to control crystal morphology in a nanometer region and to increase specific surface area for calcium phosphate. The nanocrystals with the control of its morphology is a candidate of drug delivery carriers. This study investigated the effects of mixing volume ratios of two surfactants, tween80 (T) and aliquate 336 (A) in kerosene as an oil phase, and pH values in the nano-region on crystalline phases and specific surface area of calcium phosphate synthesized by the reverse micro-emulsion method. A di-ammonium hydrogen phosphate solution including phosphoric acid at pH of 6.3 and a calcium nitrate solution at pH of 5.7 were adjusted, and both the solutions were separately added into the kerosene with the surfactants. Both the emulsions were then mixed at the same volume and the Ca/P ratio of 1.0, and stirred at room temperature for 24 hours. The crystalline phases were dependent on the T amounts; pure DCPD with the specific surface area of 6.7 to 12 m2/g was obtained at the T/A ratio of 4, the mixture of DCPD and DCPA with that of 48 to 162 m2/g was at the ratios of 5 to 8, and a low crystalline HAp with 163 m2/g was at the ratio of 9. These specific surface areas of DCPD (T/A=4) and HAp (T/A=9) were apparently higher than those prepared with a wet method, 7.8 times and 1.8 times respectively. DCPA with 43 m2/g was successfully produced to decrease the pH of phosphate solution at T/A of 9. The change of crystalline phases would be explained as follows; the increase of T amount decreased the micro-emulsion sizes to reduce bulk water to be DCPA, and increased the pH to precipitate HAp nanocrystals.

Preparation of U(VI) and Th(IV) α-sources from calcium nitrate solutions by combining solvent extraction and electrodeposition procedures

2002 ◽  
Vol 90 (5) ◽  
Author(s):  
A. Elyahyaoui ◽  
R. Zarki ◽  
A. Chiadli
Keyword(s):  
Solvent Extraction ◽  
Aqueous Phase ◽  
Nitrate Solution ◽  
Calcium Nitrate ◽  
Spectrometric Analysis ◽  
Simple Method ◽  
Aqueous Phase Acidity ◽  
Source Preparation ◽  
Ph Range ◽  
Nitrate Solutions

SummaryA simple method of preparing α-sources for alpha spectrometric analysis of uranium and thorium is investigated by combining solvent extraction and electrodeposition procedures. Extraction of these actinides is performed by diethyl ether from calcium nitrate solution with various nitric acid concentrations. Recoveries of 90–100% are obtained for uranium and 83.5% for thorium. Good resolutions are also achieved under optimum conditions.The dependence of the overall yield of U(VI) and Th(IV) is examined in relation to the aqueous phase acidity. A procedure combining solvent extraction and electrodeposition is proposed for a selective α-source preparation of U(VI) and Th(IV). Uranium is first extracted at pH range about 1 to 2. At this acidity, thorium remains in the aqueous phase and may be subsequently extracted from this after acidification with 2 M HNO

Study on Optimization of Fermentation Condition for Nitrilase-Producer Escherichia Coli BL21 (DE3)/pET-Nit

2011 ◽  
Vol 175-176 ◽  
pp. 192-196 ◽  
Author(s):  
Li Li Feng ◽  
Jian Fei Zhang ◽  
Hui Luo ◽  
Zheng Li ◽  
Hong Jie Zhang
Keyword(s):  
Escherichia Coli ◽  
Recombinant Strain ◽  
Culture Medium ◽  
Culture Conditions ◽  
Fermentation Condition ◽  
Hydrogen Phosphate ◽  
Strain Bl21 ◽  
Initial Ph ◽  
Potassium Hydrogen ◽  
Optimization Of Fermentation

The paper concentrated on the optimization of the recombinant strain BL21 (DE3)-PE7-Nit. The component of culture medium and the culture conditions were optimized. The optimized medium was: yeast extract 10 g/l, L-glutamate sodium 8 g/l, MgSO4.7H2O 0.7 g/l, Isopropyl-β-D-thiogalactopyranoside 0.3 mmol/L, potassium hydrogen phosphate 0.5 g / L, phosphate Potassium 0.5 g / L and the culture condition was: initial pH 7.0, inoculum 2%. The result showed that the activity of nitrilase prepared with these conditions increased by 130.37 % through optimization.

Luminescence Intensity Enhancement of Copper Doped Hydronium Alunite Synthesized under Hydrothermal Conditions Using Sulfates Solution

2014 ◽  
Vol 90 ◽  
pp. 127-132
Author(s):  
Yuichiro Kuroki ◽  
Takashi Hatsuse ◽  
Tomoichiro Okamoto ◽  
Masasuke Takata
Keyword(s):  
Crystal Structure ◽  
Luminescence Intensity ◽  
Single Phase ◽  
Elemental Sulfur ◽  
Nitrate Solution ◽  
Hydrothermal Condition ◽  
Copper Nitrate ◽  
Hydrothermal Conditions ◽  
Photoluminescence Peak ◽  
Blue Photoluminescence

A novel phosphor, copper doped hydronium alunite ((H3O)Al3(SO4)2(OH)6:Cu), exhibiting a blue photoluminescence peak at a wavelength of 420 nm was successfully synthesized from aluminum and copper sulfates solution under hydrothermal condition (240 °C, 60 min). The measurement of XRD revealed that the obtained products were single phase with a crystal structure of (H3O)Al3(SO4)2(OH)6. Luminescence intensity of (H3O)Al3(SO4)2(OH)6:Cu synthesized from sulfates solution was 6.2 times higher than that from an aluminum nitrate solution mixed with an elemental sulfur and a copper nitrate solution. The increase of luminescence intensity was resulted from an improvement of the crystallinity of (H3O)Al3(SO4)2(OH)6.

TBP extraction of lanthanides from molten calcium nitrate hydrate

2002 ◽  
Vol 90 (2) ◽  
Author(s):  
Hajimu Yamana ◽  
Hideki Asano ◽  
Toshiyuki Fujii ◽  
Ryuta Goto ◽  
Hirotake Moriyama
Keyword(s):  
Water Content ◽  
Calcium Nitrate ◽  
Phosphate Solution ◽  
Extraction Equilibrium ◽  
Nitrate Hydrate

SummaryExtraction equilibrium of lanthanides between tri-butyl phosphate solution and molten calcium nitrate hydrate, which is generally called a hydrate melt, was studied radiochemically. The dependence of the extractions on the water content of the melt was studied at 70 °C in the range of

Sign in / Sign up

Export Citation Format

Share Document