scholarly journals Influence of low-temperature reaction time on morphology and phase composition of short calcium phosphate whiskers

2019 ◽  
Vol 13 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Monika Biernat ◽  
Zbigniew Jaegermann ◽  
Paulina Tymowicz-Grzyb ◽  
Gustaw Konopka
Keyword(s):  
Hydrogen Peroxide ◽  
Phase Composition ◽  
Reaction Time ◽  
Calcium Phosphate ◽  
Biphasic Calcium Phosphate ◽  
Calcium Pyrophosphate ◽  
Temperature Reaction ◽  
Test Results ◽  
Lower Temperature ◽  
Hydrothermal Methods

The present work shows the results of the synthesis of multiphasic calcium phosphate whiskers from a mixture of biphasic calcium phosphate (?-tricalcium phosphate (?-TCP) and calcium pyrophosphate (CPP)) in the hydrogen peroxide solution-mediated process carried out in different time ranges. The process was performed at considerably lower temperature than typical hydrothermal methods used for obtaining of whiskers. Test results show that using the above-mentioned procedure triphasic calcium phosphate consisting of hydroxyapatite (HA),(?-TCP) and CPP can be obtained, where the whiskers are formed mainly from hydroxyapatite. It was found that morphology, phase composition and specific surface area of the reaction product can be controlled by changing the reaction time. The obtained triphasic HA/?-TCP/CPP short whiskers may be considered as a promising biocompatible and resorbable reinforcement in composites for bone tissue engineering with a faster resorption rate than that of HA.

Experimental Study on Cyclohexane by Catalytic Oxidation Using H2O2/Ferrous Sulfate

2011 ◽  
Vol 233-235 ◽  
pp. 1288-1291
Author(s):  
Jiao Jing Zhang ◽  
Bing Bai ◽  
Hua Song
Keyword(s):  
Hydrogen Peroxide ◽  
Experimental Study ◽  
Reaction Time ◽  
Catalytic Oxidation ◽  
Ferrous Sulfate ◽  
Atmospheric Condition ◽  
Temperature Reaction ◽  
Catalyst Amount ◽  
Volume Reaction ◽  
Solvent Volume

Catalytic oxidation of cyclohexane to cyclohexanone and cyclohexanol using hydrogen peroxide over ferrous sulfate catalyst at atmospheric condition was studied. Effect of the solvent volume, catalyst amount, hydrogen peroxide volume, reaction temperature, reaction time on reaction was investigated. Results showed that using 10 mL of acetone, 0.02 g of a ferrous sulfate and 0.5 mL of hydrogen peroxide at thereaction temperature of 80 °C for 8 h, the conversion of cyclohexane was 35.35%, the total selectivity of cyclohexanone and cyclohexanol was 94.06%.

Selectively Catalyzed Oxidation of Benzyl Alcohol by FeIII–TAML/Hydrogen Peroxide

2015 ◽  
Vol 723 ◽  
pp. 601-604 ◽  
Author(s):  
Ran Li ◽  
Ge Wang ◽  
Yan Chun Liu ◽  
Xiao Bin Chen ◽  
Zhi Min Sun ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Time ◽  
Benzyl Alcohol ◽  
Reaction Temperature ◽  
Oxidation Reaction ◽  
Macrocyclic Ligands ◽  
Temperature Reaction ◽  
Oxidation Of Benzyl Alcohol ◽  
Catalyzed Oxidation

Benzyl alcohol was selectively oxidized to benzaldehyde with iron (III) complexed to tetra amido macrocyclic ligands (FeIII–TAML) as catalyst and 30% H2O2 as oxidant. The effect of reaction temperature, reaction time, solvent, amount of catalyst and oxidant on the reaction of catalyzed oxidation of benzyl alcohol were explored. The conversion and selectivity of this oxidation reaction were calculated from calibrated GC yields of benzyl alcohol and benzaldehyde. When oxidation reaction was conducted under the conditions: solvent NMMO: ethanol = 1: 1, n (H2O2): n (benzyl alcohol) = 2, n (catalyst): n (benzyl alcohol) = 1%, temperature 80 ̊C and reaction time 60 minutes, the conversion was 91.23% and the selectivity was 90.12%.

Preparation of 2-Methyl-1,4-Naphthoquinone(vitamin K3) by Catalytic Oxidation of 2-Methylnaphthalene with Sulfuric Acid as Catalyst

2013 ◽  
Vol 634-638 ◽  
pp. 664-668
Author(s):  
Ming Hao Zhou ◽  
Ting Feng Yan ◽  
Hong Yan Zhu ◽  
Guo Min Xiao
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Sulfuric Acid ◽  
Reaction Time ◽  
Vitamin K ◽  
Target Product ◽  
Temperature Reaction ◽  
Product Selectivity ◽  
Vitamin K3 ◽  
Substrate Conversion

The oxidation of 2-methylnaphthalene(2-MN) to 2-methyl-1,4-naphthoquinone(2-MNQ, Vitamin K3) was accomplished in acetic acid with the application of hydrogen peroxide as oxidant. The yield of 2-MNQ was up to 81.3% when sulfuric acid used as catalyst. The catalyst exhibits excellent substrate conversion and target product selectivity. Different parameters affecting the oxidation of 2-methylnaphthalene with hydrogen peroxide catalyzed by sulfuric acid were described, such as reaction temperature, reaction time, dosage of hydrogen peroxide, and amount of sulfuric acid. Compared with the traditional methods for the preparation of Vitamin K3 with yield of only 30-50%, this method presented could be more effective, economical and ecofriendly.

Influence of Phase Composition on Degradation and Resorption of Biphasic Calcium Phosphate Ceramics

2007 ◽  
Vol 361-363 ◽  
pp. 1043-1046 ◽  
Author(s):  
Helmar Mayr ◽  
Susanne Schlüfter ◽  
Rainer Detsch ◽  
Günter Ziegler
Keyword(s):  
Phase Composition ◽  
Calcium Phosphate ◽  
Bone Substitute ◽  
Biphasic Calcium Phosphate ◽  
Microscopic Analysis ◽  
Raw 264.7 Cells ◽  
Degradation Behaviour ◽  
Calcium Phosphate Ceramics ◽  
Bone Substitute Materials ◽  
Substitute Materials

In this study the degradation behaviour of pure hydroxyapatite (HA), pure tricalcium phosphate (β-TCP) and four biphasic calcium phosphate ceramics was studied to gain information about the influence of the phase composition on this property with the aim to tailor individually adapted bone substitute materials. The chemical dissolution of each ceramic composition was measured by its release of calcium ions into a buffered solution. With decreasing HA content in the ceramics the degradation rate increased. Cell experiments were carried out with stimulated osteoclast-like RAW 264.7 cells. Using biochemical, genetic and microscopic analysis, the differentiation of the cells on the ceramic samples was studied. The monocytic precursor cells differentiated into osteoclast-like cells on all ceramics. The strongest cell differentiation into osteoclast-like cells was found on ceramics with HA/β-TCP ratios of 80/20, 60/40 and 40/60. Cells on these ceramics had many nuclei and the largest cell size. As a result of resorption, lacunas were found on all ceramics except β-TCP. All these experimental results proved the influence of the phase composition on degradation and resorption of calcium phosphate ceramics. Biphasic calcium phosphate ceramics with HA/β-TCP ratios of 80/20 and 60/40 exhibited the most promising properties to serve as synthetic bone substitute materials because for integration in the physiological bone remodeling process the implanted bone substitute materials should have optimized dissolution and resorption properties.

Surface Characteristics and Osteoinductivity of Biphasic Calcium Phosphate Ceramics with Different Sintering Temperature

2006 ◽  
Vol 309-311 ◽  
pp. 1299-1302 ◽  
Author(s):  
Hong Song Fan ◽  
Toshiyuki Ikoma ◽  
C.Y. Bao ◽  
H.L. Wang ◽  
Ling Li Zhang ◽  
...  
Keyword(s):  
Phase Composition ◽  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Biphasic Calcium Phosphate ◽  
Sintering Temperature ◽  
Surface Characteristics ◽  
Affecting Factors ◽  
Micro Structure ◽  
Factors Affecting ◽  
Distinct Temperature

Calcium phosphate (Ca-P) biomaterials have been proved to show osteoinductivity, however the affecting factors and mechanism are still unclear now. In this study, the surface characteristics of biphasic Ca-P ceramics (hydroxyapatite/tricalcium phosphate; HA/TCP) sintered at the distinct temperature were investigated and the mechanism of the osteoinductivity was discussed. The osteoinductivity of HA/TCP ceramics increased with decreasing the sintering temperature. The different surface micro-structure resulted from different sintering temperature includes phase composition, surface micro-structure, and surface potential. These characteristics should be the important factors affecting osteoinductivity.

Preparation of Dense Biphasic Calcium Phosphate Ceramics Using Eggshell Derived Nanopowders

2011 ◽  
Vol 110-116 ◽  
pp. 3645-3649
Author(s):  
Iis Sopyan ◽  
S. F. Adlina ◽  
S.A. Mohamad
Keyword(s):  
Calcium Phosphate ◽  
Mechanical Strength ◽  
Biphasic Calcium Phosphate ◽  
Hardness Test ◽  
Calcium Pyrophosphate ◽  
X Ray Diffraction ◽  
Calcium Source ◽  
Second Phases ◽  
Increasing Temperature ◽  
Compacting Pressure

This paper discusses the dependence of microstructure and mechanical properties of sintered biphasic calcium phosphate (BCP) on sintering temperature and compacting pressure of BCP dense bodies. BCP nanopowders were prepared via hydrothermal method using eggshell as the calcium source, followed by compaction into circular disc shape at various pressure and sintered pressureless in air at various sintering temperatures. X-ray diffraction analysis of nanopowders revealed the existences of hydroxyapatite (HA) as the main phase, with β-tricalcium phosphate (β-TCP) and calcium pyrophosphate (CPP) as the second phases. Morphological evaluation by scanning electron microscopy showed BCP exhibited uniform microstructure at low temperature and coalescence of pores and exaggerated grain growth at increasing temperature. Mechanical strength tests shown by compression strength and Vickers’ hardness test revealed an increase of strength with increasing temperature of up to 1100°C, after which it dropped. Mechanical strength also proved to be better with higher compacting pressure.

Comparison of Biphasic Calcium Phosphate Bioceramics Fabricated Using Different Techniques

2011 ◽  
Vol 222 ◽  
pp. 255-258
Author(s):  
Kristine Salma ◽  
Zilgma Irbe ◽  
Dmitrijs Jakovlevs ◽  
Natalija Borodajenko ◽  
Liga Berzina-Cimdina
Keyword(s):  
Phase Composition ◽  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Biphasic Calcium Phosphate ◽  
Mechanical Mixture ◽  
Preparation Technique ◽  
Homogeneous Microstructure ◽  
Intimate Mixture ◽  
Sintering Properties ◽  
Preparation Techniques

In this work three different preparation techniques of biphasic calcium phosphate (BCP) bioceramics (consisting of both hydroxyapatite (HAp) and β-tricalcium phosphate (TCP)) are compared: sintering of synthetic calcium-deficient apatites (CDAs) (intimate mixture of HAp and TCP - SBCP), sintering of mechanical mixture of synthetic HAp and apatitic tricalcium phosphate (Ap-TCP) - MBCP and sintering of mechanical mixture of synthetic HAp and calcium metaphosphate glass (CMG) - GBCP. Two different HAp/TCP phase ratios were investigated: 20/80 and 60/40. Phase composition, microstructure, sintering properties and microporosity of obtained BCP bioceramics were investigated. The open porosity of prepared BCP bioceramics is strongly influenced by phase composition and preparation technique. BCP bioceramics SBCP and MBCP have homogeneous microstructure, whereas GBCP has inhomogeneous inclusions of dense TCP. High content of hydroxyapatite (HAp) phase in MBCP and SBCP correlates with high microporosity.

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