多孔羟基磷灰石的制备与表征

羟基磷灰石(HA)以其良好的生物相容性和生物活性成为重要的骨修复材料。实验以α-Ca3(PO4)2为原料采用水热合成法制备了多孔羟基磷灰石板材。借助XRD、SEM和FTIR研究了产物的物相组成、微观结构和化学组成。结果表明:随着水热时间的延长,HA析晶更完整且呈针状分布。经1200℃处理后进行的水热反应,形成的孔较均匀且细小。反应过程吸收了部分CO2,但未进入结构。该材料从结构和尺寸方面考虑能够用于生物医用材料。     

纳米羟基磷灰石的制备及表征

采用化学沉淀法制备了羟基磷灰石纳米粒子,并且通过扫描电子显微镜(SEM)、X射线衍射(XRD)、红外光谱(IR)等测试手段,对其进行了表征。实验结果表明:以Ca(OH)2和H3PO4为原料所制备出的纳米羟基磷灰石纳米粒子多呈针状或短棒状,平均粒径20~25 nm,长75~80 nm,且大小均匀,分散性好。尺寸和形状更接近人体骨磷灰石结构,并能与骨形成牢固的化学结合,是一种很有应用前景的人工骨和人工口腔材料。     

费托合成"蛋壳"型钴基催化剂的制备及表征

采用无定形SO2为载体,制备出蛋壳型F-T合成催化剂,考察了钴基催化剂的结构和还原性能.结果表明催化剂的反应活性在很大程度上取决于氧化钴的量.在温度250℃,压力2MPa,空速500 h-1条件下,"蛋壳"型催化剂上CO转化率为33.8%～65.6%,C5 选择性为75.3%～82.7%.     

Replacement of hydroxyapatite from chicken eggshell waste for ceramic properties improvement

The chicken eggshell waste from food processing was synthesized as the hydroxyapatite for fluxing agent replacement in ceramic manufacturing. The main fluxing agents in Thailand ceramic manufacturing are natural potash feldspar (k-feldspar) and animal bone ash. To overcome the problems of inconstant properties and the lack of k-feldspar, the hydroxyapatite from chicken eggshell waste was selected as fluxing agent for the enhancement of the ceramic product. In this work, the hydroxyapatite with 0, 5, 10, and 15 wt% was replaced with the k-feldspar in the ceramic samples. The results revealed the physical and mechanical properties of the ceramic samples with various hydroxyapatite contents were investigated after heat treatment in the temperature range of 1000–1200 °C. The ceramic samples added with hydroxyapatite have higher linear shrinkage and bulk density as compared with the ceramic sample without hydroxyapatite. The apparent porosity and water absorption decreased to near zero after the heat treatment at a temperature of 1200 °C. Moreover, the results showed that the physical properties affected the mechanical properties improvement after the hydroxyapatite addition and heat treatment process.     

羟基磷灰石纳米粉体的制备及表征

采用化学沉淀法合成纳米羟基磷灰石粉体,考察了反应物浓度及配比、体系pH、分散剂用量、反应温度及时间等因素对产品平均粒度的影响.通过单因素实验摸索工艺参数范围,选择主要参数进行正交实验,得到较适宜的工艺条件.用粒度检测仪、透射电镜、红外光谱仪和X射线衍射仪等对粉体的粒度和结晶度进行了表征.结果表明:在最佳工艺条件下制得的羟基磷灰石粉体能达到纳米级,粒度分布均匀,且纯度较高,结晶度较好.     

Processing of natural resourced hydroxyapatite from eggshell waste by wet precipitation method

Abstract

Abstract

In the present paper, synthesis of hydroxyapatite (HAp) powder from eggshell waste is produced through wet precipitation process at 50–55°C. The thoroughly washed and dried eggshell powder is treated with dilute nitric acid followed by diammonium hydrogen phosphate under controlled reaction conditions such as pH, temperature, stirring time, etc. to obtain white HAp precipitate. The formation of the HAp phase and its thermal stability were identified through thermogravimetric/differential thermal analysis, Fourier transform infrared spectroscopy and X‐ray diffraction studies at different calcined temperatures. The dried powder at 90–100°C was wet ball milled for several hours and compacted to cylindrical shapes at a lower pressure of 850?kg?cm^?2. The green compacts were sintered at different temperatures for 2?h in dry atmosphere. Average grain sizes of sintered samples are mostly in submicrometre range. The morphologies of the green as well as sintered compacts were observed by field emission scanning electron microscopy.     

Preparation and characterization of aliphatic polyurethane and hydroxyapatite composite scaffold

Novel porous composite scaffolds for tissue engineering were prepared from aliphatic biodegradable polyurethane (PU) elastomer and hydroxyapatite (HA). It was found that the aliphatic PU was possible to load up to 50 wt % HA. The morphology and properties of the scaffolds were characterized by scanning electron microscope, X‐ray diffraction, infrared absorption spectra, mechanical testing, dynamic mechanical analysis, and in vitro degradation measurement. The results indicated that the HA/PU scaffolds had an interconnected porous structure with a pore size mainly ranging from 300 to 900 μm, and 50–200 μm micropores existed on the pores' walls. The average pore size of macropores and micropores are 510 and 100 μm, respectively. The compressive strength of the composite scaffolds showed higher enhancement with increasing HA content. In addition, the polymer matrix was completely composed of aliphatic component and exhibited progressive mass loss in vitro degradation, and the degradation rate depended on the HA content in PU matrix. The porous HA/PU composite may have a good prospect to be used as scaffold for tissue engineering. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of porous hydroxyapatite through polymeric sponge method

Porous hydroxyapatite samples were prepared via polymeric sponge method using commercial hydroxyapatite (HA) powder. The effects of sintering rate, stirring time and HA concentration on porosity, compressive strength and crystallinity of the porous bodies were evaluated. The study found that a faster sintering rate resulted in higher apparent density, higher compressive strength and better crystallinity. A longer stirring time also yielded the same results. 42 wt.% HA concentration was found to be the optimal concentration to achieve higher compressive strength and crystallinity, and lower porosity. The compressive strength of the porous bodies varied from 1.8 to 10.5 MPa for a porosity gradient of 34.3–59.8%. The results showed that the compressive strength is strongly dependent on porosity. Mechanically, the HA porous bodies developed in the study can be accepted as bone implants as the average compressive strengths are well within that of cancellous bone.     

Preparation and physicochemical characterization of hydroxyapatite coatings on zinc surfaces

This work presents a study on an alternative coating method based on electrochemical techniques which are designed to form a crystalline hydroxyapatite layer very similar to the process corresponding to the formation of natural bone. In this study, a sample electrochemical method of coating the solid surfaces of zinc, with a film of apatite, was developed. The hydroxyapatite deposit was investigated by means of scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and chemical analysis. The data suggest that the method utilized in this work can be successfully applied to obtain deposition of uniform coatings of crystalline hydroxyapatite on zinc substrates. As a result, both the lattice parameters a and c of the apatite layer decreased with increasing Zn fraction.     

Preparation and characterization of hydroxyapatite macrobeads based on pneumatic extrusion dripping

Extrusion dripping is a facile method for the preparation of millimetre-size macrobeads. In this work, a pneumatic extrusion dripping system has been established to fabricate hydroxyapatite macrobeads with a controlled size. The size of the hydroxyapatite spherical beads could be tailored by adjusting the dripping parameters. This work is believed to provide an alternative method for the fabrication of hydroxyapatite macrobeads that can be used in bone regeneration.     

Preparation and characterization of gelatin/hydroxyapatite nanocomposite for bone tissue engineering

Homogeneous gelatin/hydroxyapatite (GEL/HA) nano‐composites were synthesized by a novel in situ precipitation method, and its corresponding characterizations, including composition, morphology, pore structure, thermal stability, mechanical strength, and biocompatibility, were carried out. High‐magnified scanning electron microscope (SEM) images indicated that nano‐HA with particle size ranging from 20 to 50 nm were uniformly distributed in GEL matrix and tightly integrated with organic phase. Wide angle X‐ray diffraction (XRD) analysis and transmission electron microscope (TEM) images showed that, during the process of mineralization, there existed preferred oriented growth of HA crystals along (002) and (211) crystal planes. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) indicated that, the thermal stability of GEL molecules enhanced by hybridizing with HA nanocrystals. Interconnected porous GEL/HA nanocomposites with pore size ranging between 50 and 350 μm were prepared by a freeze‐drying method. This pore size was adequate for bone tissue engineering (BTE) applications. In addition, in vitro MG63 osteoblast‐like cell culture illuminated that GEL/HA nanocomposites had excellent cytocompatibility and could promote proliferation of cells. These results suggested that GEL/HA nanocomposite might be an ideal bone substitute. POLYM. COMPOS., 38:1579–1590, 2017. © 2015 Society of Plastics Engineers     

Preparation and characterization of hydroxyapatite/chitosan–gelatin network composite

A novel composite composed of hydroxyapatite (HA) and a network formed via cocrosslinking of chitosan and gelatin with glutaraldehyde was developed. Two preparation methods are described in detail. A porous material, with similar organic–inorganic constituents to that of natural bone, was made by a unique sol–gel method. The formation of the network in the presence of HA was characterized using IR analysis. The morphology of the composites was also examined using SEM. In addition, XRD was applied to estimate the change in the component crystal. The results indicate that the presence of HA does not retard the formation of the chitosan/gelatin network. On the other hand, the polymer matrix has hardly any influence on the high crystallinity of HA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2929–2938, 2000     

孔形羟基磷灰石负载锶化合物催化剂的制备与表征

通过在873 K焙烧Sr(NO₃)₂/孔形羟基磷灰石，成功地制备了一种新型的固体碱催化剂，并对其进行TG-DTA、XRD、IR、SEM、BET和碱强度表征。结果表明，在873 K，发生固相离子交换反应——Ca₅［PO₄］_3-y(CO₃·OH)_y］(OH)+SrOCa_5-xSr_x［PO₄］_3-y(CO₃·OH)_y］(OH)+ Ca_xSr_1-xO，孔形羟基磷灰石表面上的新相Ca_xSr_1-xO能抑制羟基磷灰石的分解，并能阻止羟基磷灰石的重结晶，使羟基磷灰石在高温下保持孔形结构。用此固体碱催化剂催化大豆油与甲醇的酯交换反应，可使豆油的转化率达到85%。     

Preparation and characterization of nanocomposite polyelectrolyte membranes based on Nafion ionomer and nanocrystalline hydroxyapatite

In this study nanocrystalline hydroxyapatite (nHA) was synthesized and characterized by means of FT-IR, XRD and TEM techniques and a series of proton exchange membranes based on Nafion^® and nHA were fabricated via solvent casting method. Thermogravimetric analysis confirmed thermal stability enhancement of the Nafion^® nanocomposite due to the presence of nHA nanopowder. SAXS and TEM analyses confirmed the incorporation of nHA into ionic phase of Nafion^®. Furthermore, the incorporation of elliptical nHA into the Nafion^® matrix improved proton conductivity of the resultant polyelectrolyte membrane up to 0.173 S cm⁻¹ at 2.0 wt% of nHA loading compared to that of 0.086 S cm⁻¹ for Nafion^® 117. Also, the inclusion of nHA nanoparticles into nanocomposite membranes resulted in a significant reduction of methanol permeability and crossover in comparison with pristine Nafion^® membranes. Membrane selectivity parameter of the nanocomposites at 2.0 wt% nHA was calculated and found to be 106,800 S s cm⁻³, which is more than two times than that of Nafion^® 117. Direct methanol fuel cell tests revealed that Nafion^®/nHA nanocomposite membranes were able to provide higher fuel cell efficiency and also better electrochemical performance in both low and high concentrations of methanol feed. Thus, the current study shows that nHA enhances the functionality of Nafion^® as fuel cell membranes.     

Eco-friendly preparation and structural characterization of calcium silicates derived from eggshell and silica gel

In this work, the preparation of calcium–silicate-based composites consisting of natural waste from calcium source as eggshell and silica gel from a desiccator as a silicon source both presenting alternative materials for cheap preparation of eco-friendly calcium–silicate bioceramics has been investigated. The effect of the CaO/SiO₂ ratio on microstructural properties has also been studied. The pseudowollastonite formation has been observed in the case of 40 wt.% CaO and 60 wt.% SiO₂ with lowest porosity and highest density 2.6 g/cm³. In the case of 50 wt.% CaO and 50 wt.% SiO₂, the phase transformation from pseudowollastonite to wollastonite was observed. Increasing the calcium content caused higher apparent porosity with 19%. It was shown that the development of novel ceramics from reused waste, eggshell, or silica can be an optimal solution for the low-cost preparation of calcium silicates with potential applications in medicine or cement, food industry.     

Sequential optimization strategy for hyaluronic acid extraction from eggshell and its partial characterization

The optimization of hyaluronic acid (HA) extraction from eggshell was studied by using a sequential experimentation approach. Using the results of factorial experiments, optimization experiments were carried out by response surface methodology. The experimental data as well as the validation tests showed the optimum performance when the extraction pH and time were bounded in the ranges of 3.4–3.5 and 3–3.4 days, respectively, at 9 °C. The purified HA was characterized by FTIR spectrum, harmonic mean size and average molecular weight. The study depicted the potential of eggshell as an alternative source for HA extraction to use in industry and medicine.     

羟基磷灰石涂层的制备研究

以五氧化二磷、无水乙醇、硝酸钙为原料,通过溶胶-凝胶法制备羟基磷灰石涂层.选用2mm/s的速度浸渍提拉载玻片,在载玻片上进行涂膜,经60℃干燥后在650℃保温3h,可在载玻片上得到羟基磷灰石涂层.研究结果表明:制备溶胶合适的配比为nCa(NO3)2·4H2O:nP2O5=10:3,即Ca/P原子比=5:3(约等于1.67).     

Alternative green preparation of mesoporous calcium hydroxyapatite by chemical reaction of eggshell and phosphoric acid

Eggshell is a rich source of CaCO₃ with a high purity content of more than 96.35% w/w and a potential raw material for calcium hydroxyapatite preparation. Mesoporous and nano-particulate calcium hydroxyapatite was prepared from duck eggshell from the chemical reaction with phosphoric acid followed by the calcinations at 800, 900, and 1000°C for 2 hours. The optimum condition to obtain the high purity calcium hydroxyapatite was by sintering calcium phosphate Ca₃(PO₄)₂ at 1000°C for 2 hours. The average particle size, pore diameter, specific surface, and true density of the sample sintered at 1000°C for 2 hours were 101.93 ± 12.15 nm, 98.96 Å, 2.12 m²/g, and 3.02 g/cm³, respectively, appearing as a soft fine powder with a white color. The raw duck eggshell is a potential candidate as a bio-ceramic material to prepare calcium hydroxyapatite suitable for use in various bio-applications such as bone tissue engineering, drug and gene delivery, remineralizing agent in toothpaste, and bone void fillers for orthopedic and restoration.     

Preparation and characterization of magnetite/hydroxyapatite/chitosan nanocomposite by in situ compositing method

Chitosan is an important kind of biomaterial that is widely used in medical applications. One of the key concerns about its use is the preparation of composites used for bone engineering. Aim of this study concerns the preparation of three‐dimensional nanocomposites having potential use in bone repair and regeneration. The magnetite/hydroxyapatite/chitosan nanocomposites were prepared via in situ compositing method by preparing precursor solutions and molds with chitosan membrane. These nanocomposites were characterized by chemical, spectroscopic, magnetic, and morphological methods. X‐ray diffraction analysis results demonstrate the formation of magnetite and hydroxyapatite in the chitosan matrix. FTIR analysis indicates that inorganic nanoparticles were chemically bound to the amino and hydroxyl groups in CS molecules. From TG/DTA data, it can be concluded that during preparation raw materials were almost perfectly incorporated into the nanocomposites, and the decrease in decomposition temperatures indicates the formation of chemical bonds between inorganic nanoparticles and chitosan molecules. TEM results show that the maximum size of inorganic particles in the magnetite/hydroxyapatite/chitosan nanocomposites was under 50 nm, and these particles were dispersed homogeneously in the chitosan matrix. From the magnetic measurement, it could be concluded that the nanocomposites were superparamagnetic, which is also the peculiarity of nanomagnetites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation,characterization, and physicomechanical properties of glass-ceramic foams based on alkali-activation and sintering of zeolite-poor rock and eggshell

This study reports the fabrication of novel glass-ceramic foams for thermal insulation to minimize the energy consumption in the buildings. Different combinations of zeolite-poor rock/eggshell powders (with eggshell content varying from 0 to 20 wt%) have been used to produce the foams through alkali-activation and reactive sintering techniques. The produced glass-ceramic foams were characterized based on their structural, thermal, and mechanical characteristics. The heat treatment process and the foaming patterns are examined by a heating microscope, and the findings reveal an excellent foamability of the utilized alkali-activated mixture in the range of 800–950 °C. The microstructure and the pore size of the acquired foams are investigated using a scanning electron microscope (SEM) and computed tomography (CT) analysis. The crystallinity and phase composition of the prepared samples were investigated via X-ray diffraction (XRD). The experiment findings reveal that raising the eggshell content is favorable to gas production, but it affects the liquid phase creation resulting in inconsistent pore size distribution. The appropriate eggshell content is 4%, and the optimal heat treatment temperature is 900 °C. The produced ceramic foams possess a density ranging from 0.54 to 1 g/cm³, thermal conductivity around 0.07–0.4 W/mK, and compressive strength values between 1.2 and 6.7 MPa. The results indicate that the ceramic foams created could be a feasible choice for applications in constriction as thermal insulation materials.