The Influence of Biogenic and Synthetic Starting Materials on the Properties of Porous Hydroxyapatite Bioceramics

2014 ◽  
Vol 614 ◽  
pp. 11-16 ◽  
Author(s):  
Kristine Salma-Ancane ◽  
Liga Stipniece ◽  
Janis Locs ◽  
Vitalijs Lakevičs ◽  
Zilgma Irbe ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Precipitation Method ◽  
Porous Hydroxyapatite ◽  
Calcium Carbonates ◽  
Porous Bodies ◽  
Wide Range ◽  
Egg Shells ◽  
Viscous Mass

The aim of this study was to investigate the influence of biogenic and synthetic starting materials on properties of porous hydroxyapatite (HAp) bioceramics. HAp powders were synthesized by modified precipitation method using biogenic calcium carbonates (ostrich (Struthio camelus) egg shells, hen (Gallus gallus domesticus) egg shells, snail (Viviparus contectus) shells) and synthetic calcium oxides (Sigma-Aldrich and Fluka). Specific surface area, molecular structure and morphology of obtained powders were determined. As-synthesized HAp powders had a varied specific surface area with a wide range from 83 to 150 m2g-1 depending on CaO source. Porous bodies of HAp were prepared by in situ viscous mass foaming with NH4HCO3 as pore forming agent. Foamed and dried green bodies were sintered at 1100 °C. The obtained bioceramics were investigated using Archimedes method, field emission scanning electron microscopy and Brunauer-Emmett-Teller method. There are considerable differences between porous HAp bioceramics structures prepared from different sources of CaO. The choice of starting material substantially affects the macro-and microstructure of prepared porous bioceramics.

Synthesis of Novel Core-Shell Structured Hydroxyapatite/Meso-Silica for Removal of Methylene Blue from Aqueous Solutions

2012 ◽  
Vol 463-464 ◽  
pp. 543-547 ◽  
Author(s):  
Cheng Feng Li ◽  
Xiao Lu Ge ◽  
Shu Guang Liu ◽  
Fei Yu Liu
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Core Shell ◽  
Adsorption Desorption

Core-shell structured hydroxyapatite (HA)/meso-silica was prepared and used as absorbance of methylene blue (MB). HA/meso-silica was synthesized in three steps: preparation of nano-sized HA by wet precipitation method, coating of dense silica and deposition of meso-silica shell on HA. As-received samples were characterized by Fourier transformed infare spectra, small angle X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. A wormhole framework mesostructure was found for HA/meso-silica. The specific surface area and pore volume were 128 m2•g-1 and 0.36 cm3•g-1, respectively. From the adsorption isotherm, HA/meso-silica with the great specific surface area exhibited a prominent adsorption capacity of MB (134.0 mg/g) in comparison with bare HA (0 mg/g). This study might shed light on surface modification of conventional low-cost adsorbents for removal of organic pollutants from aqueous solutions.

Comparative Assessment of Effectiveness of Calcium Silicate Dispersions Produced Using Sucrose and Lactose as Components of Composite Cement Binder

2021 ◽  
Vol 1017 ◽  
pp. 11-20
Author(s):  
Evgeny A. Shoshin ◽  
Valeria V. Strokova ◽  
Zheng Mao Ye
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Calcium Silicate ◽  
Setting Time ◽  
Inhibitory Effect ◽  
Main Element ◽  
Residual Content ◽  
Nucleation Effect ◽  
Wide Range

Silicate micro- and nano-additives are multifunctional in relation to cement systems. Their application can solve a wide range of technological problems while maintaining the economic efficiency of technical solutions. The effect of silicate additives and fillers is determined by their level of dispersion, due to which the technologies for producing nano- and submicro-sized dispersed materials are being developed. The combination of mechanochemical synthesis of modified calcium hydrosilicates with subsequent thermolysis makes it possible to produce calcium silicate dispersions (SCD), which differ in polymodality of the fractional composition including submicro (10–7–10–6 m) and microdimensional (≥10–6 m) modes. The main element of the technology is the use of modifying carbohydrate, which acts as a stabilizer of hydrated phases of silicates. A comparative study of SCD produced using sucrose (sSCD) and lactose (lSCD) revealed the effect of these carbohydrates on the properties of sSCD and lSCD, as well as their effectiveness as a component of cementitious composite binder. It was found that the level of adsorption of modifying carbohydrate determines the physical properties of SCD (granulometry, specific surface area). The relatively high residual content of free sucrose (0.24%) in the composition of sSCD prevents the consolidation of silicates nanoparticles formed during the thermolysis, causes a high content of submicro sized fractions and a high specific surface area with sSCD (26.3 ± 0.7 m2/g). Lactose is absorbed by the silicate phase; the residual content of free lactose does not exceed 0.028% of lSCD. The low content of stabilizing carbohydrate contributes to the development of nanoparticle consolidation, a decrease in the specific surface area of lSCD to 13.0 ± 0.2 m2/g and content of submicrosized fractions. The residual content of free carbohydrates and particle size characteristics of sSCD and lSCD determine the nature of their influence on Cement-SCD-based concrete setting and hardening. The presence of residual sucrose in the composition of sSCD and fine fractions determines the competitive nature of the processes of retardation of hardening and acceleration of hardening of the cement system due to the nucleation effect, as a result of which the curve of the setting time is extreme. In addition, the inhibitory effect of sucrose reduces the strength of concrete on the 7th day. By the 28th day, the inhibitory effect of sucrose has been overcome, and concrete samples demonstrate an 18% increase in compressive strength with a sSCD content of 30%. The low content of residual free lactose in the composition of lSCD causes the nucleation effect. As a result, there is a monotonous reduction in the setting time of concrete mix with an increase in the content of lSCD in the composition of HF, as well as a significant increase in concrete strength (up to 127%) on the 7th day. At the same time, on the 28th day the strength of concrete increases slightly

scholarly journals 3-D image-based numerical computations of snow permeability: links to specific surface area, density, and microstructural anisotropy

2012 ◽  
Vol 6 (5) ◽  
pp. 939-951 ◽  
Author(s):  
N. Calonne ◽  
C. Geindreau ◽  
F. Flin ◽  
S. Morin ◽  
B. Lesaffre ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Three Dimensional ◽  
Analytical Models ◽  
Simple Relationship ◽  
Snow Density ◽  
Average Value ◽  
Wide Range ◽  
Snow Samples

Abstract. We used three-dimensional (3-D) images of snow microstructure to carry out numerical estimations of the full tensor of the intrinsic permeability of snow (K). This study was performed on 35 snow samples, spanning a wide range of seasonal snow types. For several snow samples, a significant anisotropy of permeability was detected and is consistent with that observed for the effective thermal conductivity obtained from the same samples. The anisotropy coefficient, defined as the ratio of the vertical over the horizontal components of K, ranges from 0.74 for a sample of decomposing precipitation particles collected in the field to 1.66 for a depth hoar specimen. Because the permeability is related to a characteristic length, we introduced a dimensionless tensor K*=K/res2, where the equivalent sphere radius of ice grains (res) is computed from the specific surface area of snow (SSA) and the ice density (ρi) as follows: res=3/(SSA×ρi. We define K and K* as the average of the diagonal components of K and K*, respectively. The 35 values of K* were fitted to snow density (ρs) and provide the following regression: K = (3.0 ± 0.3) res2 exp((−0.0130 ± 0.0003)ρs). We noted that the anisotropy of permeability does not affect significantly the proposed equation. This regression curve was applied to several independent datasets from the literature and compared to other existing regression curves or analytical models. The results show that it is probably the best currently available simple relationship linking the average value of permeability, K, to snow density and specific surface area.

Synthesis and Photocatalytic Property of BiVO4/FeVO4 Composite Novel Photocatalyst

2010 ◽  
Vol 129-131 ◽  
pp. 784-788 ◽  
Author(s):  
Min Wang ◽  
Qiong Liu ◽  
Dong Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photocatalytic Property ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Triclinic Phase ◽  
Xrd Patterns

BiVO4/FeVO4 composite photocatalyst samples were prepared by calcining the mixture of FeVO4 and BiVO4 precusor which were prepared through liquid phase precipitation method for further increasing the photocatalytic efficiency of FeVO4. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microsoope（SEM）and specific surface area (BET). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under visible light. The XRD patterns indicate that BiVO4/FeVO4 composite photocatalysts consist of triclinic phase and the lattice was not distorted beacause of doping Bi. But the morphology change greatly and the specific surface area has little change. In the experimental conditions used, the optimal photocatalytic activity for all the prepared samples was reached when BiVO4 doping was 22 at%. The degradation rate of MO was increased by 20％ or so than that of pure FeVO4.

scholarly journals Manufacture of Fine-Pored Ceramics by the Gelcasting Method

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Bronisław Psiuk ◽  
Anna Gerle ◽  
Małgorzata Osadnik ◽  
Andrzej Śliwa
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Design Theory ◽  
Nanoporous Materials ◽  
Silica Sol ◽  
High Porosity ◽  
Simple Method ◽  
Fine Grained ◽  
Wide Range

The fine-pored materials represent a wide range of applications and searches are being continued to develop methods of their manufacturing. In the article, based on measurements on fine-grained powders of Al2O3, TiO2, and SiO2, it has been demonstrated that gelcasting can be relatively simple method of obtaining of nanoporous materials with high values of both specific surface area and open porosity. The powders were dispersed in silica sol, and the gelling initiator was NH4Cl. The usefulness of experiment design theory for developing of fine-pored materials with high porosity and specific surface area was also shown.

The Influence of Sinterng Temperature on the Phase, Microstructure and Textual Properties of Hollow Hydroxyapatite Microspheres

2011 ◽  
Vol 239-242 ◽  
pp. 2274-2279 ◽  
Author(s):  
Ying Chun Wang ◽  
Wen Hai Huang ◽  
Ai Hua Yao ◽  
De Ping Wang
Keyword(s):  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Sintering Temperature ◽  
Total Pore Volume ◽  
Precipitation Method ◽  
Simple Method ◽  
Air Atmosphere

A simple method to prepare hollow hydroxyapatite (HAP) microspheres with mespores on the surfaces is performed using a precipitation method assisted with Li2O-CaO-B2O3(LCB) glass fabrication process. This research is concerned with the effect of sintering temperature on the microstructure evolution, phase purity, surface morphology, specific surface area, and porosity after sintering process. The microspheres were sintered in air atmosphere at temperatures ranging from 500 to 900 °C. The starting hollow HAP microspheres and the sintered specimens were characterized by scanning electron microscope, X-ray diffractometer, specific surface area analyzer, and Hg porosimetry, respectively. The as-prepared microspheres consisted of calcium deficient hydroxyapatite. The results showed that the as-prepared hollow HAP microspheres had the highest specific surface areas, and the biggest total pore volume. The pore size distribution of the as-prepared hollow HAP microspheres were mainly the mesopores in the range of 2～40 nm. The specific surface area and total pore volume of hollow HAP microspheres decreased with increasing sintering temperature. Whereas the mean pore size increased with increasing sintering temperature. It showed that at 700°C, Ca-dHAP decomposes into a biphasic mixture of HAP and β-calcium phosphate(TCP).

Influence of Zinc Oxide Nanograins on Properties of Epoxidized Natural Rubber Vulcanizates

2017 ◽  
Vol 748 ◽  
pp. 79-83 ◽  
Author(s):  
Rudeerat Suntako
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Natural Rubber ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Epoxidized Natural Rubber ◽  
Precipitation Method ◽  
Cure Characteristics ◽  
Permanent Set

Zinc oxide (ZnO) nanograins are synthesized by precipitation method filled epoxidized natural rubber compared to conventional ZnO. The synthesized ZnO nanograins are characterized by X-ray diffraction and transmission electron microscopy and found that average primary size of ZnO synthesized around 40 nm and the specific surface area of 28.72 m2 g-1. Furthermore, the cure characteristics, rubber mechanical properties and permanent set were investigated. The obtained results are found that the ZnO nanograins significantly affected to cure characteristics, rubber mechanical properties and permanent set. This is due to small grain size and large specific surface area.

scholarly journals Removal efficiency and mechanism of bio-treated coking wastewater by catalytic ozonation using MnO2 modified with anionic precursors

2020 ◽  
Vol 26 (5) ◽  
pp. 200394-0
Author(s):  
Jie Zhang ◽  
Ben Dong ◽  
Ding Ding ◽  
Shilong He ◽  
Sijie Ge
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Catalytic Performance ◽  
Catalytic Ozonation ◽  
Relative Content ◽  
Precipitation Method ◽  
Coking Wastewater ◽  
Physiochemical Properties ◽  
Removal Efficiencies

In this paper, MnO<sub>2</sub> catalyst were firstly prepared and modified by four kinds of anionic precursors (i.e., NO<sub>3</sub><sup>-</sup>, AC<sup>-</sup>, SO<sub>4</sub><sup>2-</sup> and Cl<sup>-</sup>) through redox precipitation method. After that, bio-treated coking wastewater (BTCW) was prepared and employed as targeted pollutants to investigate the catalytic ozonation performance of prepared-MnO<sub>2</sub> catalyst was investigated and characterized by the removal efficiencies and mechanism of the prepared bio-treated coking wastewater (BTCW), which was employed as the targeted pollutants. Specifically, the effects of specific surface area, crystal structure, valence state of Mn element and lattice oxygen content on catalytic activity of MnO<sub>2</sub> materials were characterized by BET, XRD and XPS, respectively. Results showed that COD of BTCW could be removed 47.39% under MnO<sub>2</sub>-NO<sub>3</sub><sup>-</sup> catalyst with 2 h reaction time, which was much higher than that of MnO<sub>2</sub>-AC<sup>-</sup> (3.94%), MnO<sub>2</sub>-SO<sub>4</sub><sup>2-</sup> (12.42%), MnO<sub>2</sub>-Cl<sup>-</sup> (12.94%) and pure O<sub>3</sub> without catalyst (21.51%), respectively. So, MnO<sub>2</sub>-NO<sub>3</sub><sup>-</sup> presented the highest catalytic performance among these catalysts. The reason may be attributed to a series of better physiochemical properties including the smaller average grain, the larger specific surface area and active groups, more crystal defect and oxygen vacancy, higher relative content of Mn<sup>3+</sup> and adsorbed oxygen (O<sub>ads</sub>) than that of another three catalysts.

scholarly journals A Case Study of Waste Scrap Tyre-Derived Carbon Black Tested for Nitrogen, Carbon Dioxide, and Cyclohexane Adsorption

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4445 ◽  
Author(s):  
Zuzana Jankovská ◽  
Marek Večeř ◽  
Ivan Koutník ◽  
Lenka Matějová
Keyword(s):  
Activated Carbon ◽  
Carbon Black ◽  
Specific Surface ◽  
Surface Area ◽  
Sorption Capacity ◽  
Specific Surface Area ◽  
Textural Properties ◽  
Pyrolytic Carbon ◽  
Surface Areas ◽  
Wide Range

Waste scrap tyres were thermally decomposed at the temperature of 600 °C and heating rate of 10 °C·min−1. Decomposition was followed by the TG analysis. The resulting pyrolytic carbon black was chemically activated by a KOH solution at 800 °C. Activated and non-activated carbon black were investigated using high pressure thermogravimetry, where adsorption isotherms of N2, CO2, and cyclohexane were determined. Isotherms were determined over a wide range of pressure, 0.03–4.5 MPa for N2 and 0.03–2 MPa for CO2. In non-activated carbon black, for the same pressure and temperature, a five times greater gas uptake of CO2 than N2 was determined. Contrary to non-activated carbon black, activated carbon black showed improved textural properties with a well-developed irregular mesoporous-macroporous structure with a significant amount of micropores. The sorption capacity of pyrolytic carbon black was also increased by activation. The uptake of CO2 was three times and for cyclohexane ten times higher in activated carbon black than in the non-activated one. Specific surface areas evaluated from linearized forms of Langmuir isotherm and the BET isotherm revealed that for both methods, the values are comparable for non-activated carbon black measured by CO2 and for activated carbon black measured by cyclohexane. It was found out that the N2 sorption capacity of carbon black depends only on its specific surface area size, contrary to CO2 sorption capacity, which is affected by both the size of specific surface area and the nature of carbon black.

Gold Cementation by Dendritic Zinc Powders in Percolation Mode

2020 ◽  
Vol 989 ◽  
pp. 543-547
Author(s):  
K.D. Naumov ◽  
Vladimir G. Lobanov
Keyword(s):  
Particle Size ◽  
Physical Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Alkaline Solutions ◽  
Wide Range ◽  
Zinc Powders ◽  
Cyanide Solutions

In present article gold cementation features from cyanide solutions using dendritic zinc powders are studied. The powders were obtained by electroextraction from alkaline solutions. Powders with different physical properties were obtained by means of change in current density (from 0.5 to 2 A/m2) and NaOH concentration in solution (from 100 to 400 g/dm3) at the constant zinc concentration (10 g/dm3). The physical properties of mentioned powders were studied using SEM (Jeol JSM-6390LA), BET (Gemini VII 2390) and laser diffraction (Sympatec HELOS & RODOS). It is shown that electrolytic powders have high specific surface area, which is 1.8–2.6 times larger than the surface area of ​​the zinc powder currently used for cementation. At that electrolytic powders particle size is 8-22 times larger than the particle size of powder currently used for cementation. The reason of high specific surface area is the electrolytic zinc powders dendritic structure. It was found that the obtained powders precipitate gold from cyanide solutions with a greater efficiency in a wide range of productivity. Laboratory unit simulating Merrill-Crow technology was used for cementation. Immediately ahead conducting the experiments, Na2SO3 was added to the solution in excess to remove dissolved oxygen. Zinc powders were plated by dendritic lead before loading into the laboratory setup by cementation. Lead was added as acetate (Pb (CH3COO)2). The consumption of lead acetate was 10% by weight of zinc. Correlation between the powders physical properties and the gold extraction is shown.

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